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## Über dieses Buch

This book gathers papers presented at the 2019 Movement, Health & Exercise (MoHE) Conference and International Sports Science Conference (ISSC). The theme of this year’s conference was "Enhancing Health and Sports Performance by Design". The content covers (but is not limited to) the following topics: exercise science; human performance; physical activity & health; sports medicine; sports nutrition; management & sports studies; and sports engineering & technology.

## Inhaltsverzeichnis

### Determination of Cardiac Function Using Impedance Cardiography During Jogging With and Without Breast Support

The goal of this study was to use a non-invasive method of impedance cardiography to investigate the consistency of cardiac variables, in parallel with metabolic function. Thirteen healthy females underwent two randomized jogging conditions: without breast support (NB) and with breast support (jogging bra, JB). Cardiorespiratory and metabolic functions were continuously recorded at rest, during exercise on the treadmill at a constant speed of 4 mph at 60, 70 and 80% of age-predicted maximum heart rate followed by a 5-min recovery. The results showed that there were no significant differences in resting cardiac variables, including cardiac output (CO), heart rate (HR), stroke volume (SV), end diastolic volume (EDV), end systolic volume (ESV) and cardiac index (CI). The parallel intensity-dependent characteristics of both cardiorespiratory and metabolic variables during jogging were also determined. The results showed normal cardiac functions during and after jogging with no significant differences of CO, HR, SV, EDV, ESV and CI between two conditions (P > 0.05). Metabolic variables showed no significant differences between the two conditions (P > 0.05) for oxygen consumption ($${\dot{\rm{V}}\rm{O}}_{\text{2}}$$), carbon dioxide production ($${\dot{\rm{V}}\rm{CO}}_{2}$$) and respiratory exchange ratio (RER). With narrow ranges of the standard errors of the mean and parallel alterations of metabolism at rest, during exercise and recovery from two conditions, this study concluded that a non-invasive impedance cardiography method can possibly reflect changes of both cardiorespiratory and metabolic functions. In addition, it is suggested that breast supports in females during treadmill running induce no limitations on both cardiorespiratory and metabolic functions.

Kunanya Masodsai, Rungchai Chaunchaiyakul

### Changes in Immune Response to Moderate Exercise in Active Trainees

Many questions are still reaming about the mechanism by which regular moderate training to the magnitude of the specific immune response. The purpose of this study was to investigate the influence of regular moderate training on specific immune response in human body.A less air polluted zone of Burdwan, West Bengal, India was selected for this study. Total 32 male subjects chosen out of which 18 subjects (mean age 25 ± 2.06 years) treated as regular habit of Moderately Trained (MT) group and 14 subjects (mean age 22.5 ± 1.79 years) were act as Sedentary Control (SC) group from the same area. Specific immune variables such as Immunoglobulin G (IgG), CD4 (Helper T cells) percentage, CD4/CD8 ratio, Albumin and Albumin Globulin ratio were examined. Mean, SD and independent ‘t’ test were used for statistical analysis by using IBM SPSS 20.0 version software.The higher mean were observed in MT group compared to SC group in all specific immune variables although there was no significant difference found between both groups.Regular moderate training habit may be increased in modulating the specific Immune response which is a possible biologic efficiency to foster the defense against disease on human health.

Aparup Konar, Sridip Chatterjee, Samiran Mondal

### Effects of Attentional Focus Among Novices and Elite Athletes in Sprinting Performance

The main objective of this study was to investigate the effects of focus of attention among novice and elite athletes influenced the performance of short distance sprint (20 m) and maximum velocity speed (40 m). Sixty participants novice (n = 30) and elite (30) completed two trials for 20 m and 40 m sprint pre and post-test. Both novice and elite participants were randomly assigned to an internal focus group (IF), external focus group (EF) and control group (CONT). The IF group were focusing on component of body movement whilst EF group focusing on the movement outcomes. Then CONT group with no specific instruction. The participants involved three times per week for a month. Results shows in 20 m sprint test, there was a significant difference in IF and control group (novice) and EF, IF and CONT group (elite). While for 40 m sprint test, there was a significant different for IF and control group for novice. However, for elite athletes results shows a significant different in EF group. Overall finding indicates, adopting and external focus attention for novice and elites athletes enhance in reduction of times (second) in sprinting performance. Moreover, adopting external focus instruction resulted in shorter time (sec) among novice and elite athletes in sprinting performance.

Saidatul Nur Syuhadah Mohamed Sabadri, Jeffrey Low Fook Lee, Shaza Mohd Shah, Nursyaidatul Hafiza Madzlan, Maisarah Mohd Saleh

### The Effects of Myofascial Release Using Foam Rolling and Resistance Band Assisted Stretching on Malaysian Rugby Players’ Lower Body Power and Flexibility

Integrating warm-up and stretching prior to performing physical activities has been shown to enhance sporting performance prevent injuries. Foam rolling, also known as myofascial release is widely applied in sport settings as a warm-up. However, there is limited evidence on its effectiveness on lower body power and flexibility among ruggers. This study aimed to compare the effects of myofascial release using foam rolling (MFR) and resistance band assisted stretching (RB) on lower body power and flexibility among Malaysian rugby players. Fifteen elite Malaysian male rugby players were exposed to three warm-up routines consisted of a total body dynamic warm-up (DYN), a total-body dynamic warm-up with foam rolling session (MFR), and total-body dynamic warm-up with resistance band assisted stretching (RB). Following general warm-up in each condition, participants performed flexibility and power tests. Differences in test results between conditions (DYN vs. MFR vs. RB) were investigated using one-way ANOVA. Findings revealed no significant differences in test results for both variables, however MFR recorded a superior performance of power relative to others.

Nurul Afiqah Bakar, Nurul Hidayah Amir, Ammar Md Zaini, Luke Nikol, Mohd Hazwan Zikri Abdul Halim

### The Effects of High Intensity Functional Interval Training on Selected Fitness Components Among Young Badminton Players

The main objective of this study was to measure the effect of high intensity functional interval training on aerobic fitness, agility and sprint among young badminton players. A total of 16 male badminton players aged between 13 and 15 years old volunteered for this study. Participants were randomly divided into two groups, Experiment (n = 8) and Control (n = 8) based on aerobic fitness assessment result. The Experimental group (EG) performed a high intensity functional interval training exercise while the Control group (CG) performed traditional training whereby a routine exercise that was usually carried out in their training program over a period of 10 weeks. The high intensity functional interval training consisted of change of direction (COD) elements where the athlete moved to respond to a sound stimuli that was activated by a wireless sensors. The training intensity was 80–95% HRmax; work-to-rest ratios of each repetition is 1:1 (3 min work: 3 min rest) 2 sets training (with had 5 repetitions per set) and rest between each set of training is 4 min. Data was collected at three-time points; T1-pre, T2-post five weeks and T3-post ten weeks training. Repeated measures mixed ANOVA yielded significant interactions over time in the performance of the 20 m Multistage Fitness; Four Corner Agility and Sprint 20 m. The results show that there were a significant difference between EG and CG for 20 m Multistage Fitness and Four Corner Agility; F(1,14) = 4.663, (p < .05) and F(1,14) = 5.443, (p < .05). Whereas no significant different for sprint performance; F(1,14) = .351, (p > .05) between the EG and CG. In conclusion, the EG showed $${\dot{V}}\text{O}_{{2\text{max}}}$$ and agility performance increased significantly after 10 weeks of high intensity functional interval training without negatively influencing the sprinting ability.

Pathmanathan K. Suppiah, Angelica Joanne Joummy, Md. Safwan Samsir, Muralindran Mariappan, Hasnol Noordin, Abdul Mu’iz Bin Nor Azmi

### The Effect of Amplitude (Response Complexity) in Choice Reaction Time

Research has shown that reaction time (RT) increases as a function of elements and amplitude. Hence, this study aimed to investigate how invalid information regarding the numbers of elements and magnitude of movement influenced programming prior to movement initiation and during movement execution in choice RT. Twelve self-declared undergraduate students with right-handed performed a total of 150 trials of aiming movements with pen along the track way on Calcomp III digitizing tablet sample rate 200 Hz. The visual of the cursor displays on the computer monitor positioned straight in front of the participants. The participants were directed to move the cursor as quickly as possible in a continuous manner to the targets indicated by the four possible stimuli (i.e., 1S, 1L, 2S and 2L). Repeated measures ANOVA revealed that RT was quicker in valid than in invalid conditions F = (3,33) = 13.390, p < 0.05. When early invalid information concerning the precue and stimulus was specified, RT and movement time increased as a function of elements and amplitude. These findings indicated that reprogramming occurred prior to movement initiation during RT. However, the time required to reprogrammed movements did not vary as a function of features of the response.

Mohd Syrinaz Azli, Mohar Kassim, Jorrye Jakiwa, Siti Azilah Atan, Emmy Hainida Khairul Ikram

### Effect of Medial Longitudinal Arch Height on Static and Dynamic Balance Among UiTM Female Athletes

The purpose of this study were to identify the effect of medial longitudinal arch (MLA) height on static and dynamic balance among female athletes. The participants of this study were the active female athletes from Universiti Teknologi MARA (UiTM), Samarahan Branch. The participants were divided into three groups according to their foot arch which include low (n = 30), normal (n = 30) and high (n = 30) arch height. The foot arch or structure was measured by using the wet test (WT). The stork stand test (SST) was used to assess participant static balance (SB), while the balance beam speed test (BBST) was used to assess participant dynamic balance (DB). Significant level was set at p < .05. The result showed that there was a significant difference between groups on SB (p = .041) and DB (p = .0001) test. There was also a significant difference (p = .014) between SB and DB for high arch group. There was no significant difference between SB and DB on low arch (p = .153) and normal arch (p = 1.00). Thus, the MLA height have effect on static and dynamic balance.

Salvastore Sam, Nur Khairunisa Abu Talip

### The Relative Age Effect in Malaysia Youth Athletes

The over-representation and selection of players born in the early part of a year compared to those born later is called the relative age effect (RAE). Previous studies have shown this phenomenon exist among popular sport such as ice hockey and football. The over representation of relatively older and biologically matured players were assumed due to bigger physique, thus provide more advantage. The aim for this study was initially to determine if a relative age effect present in the sample of athletes competing in MSSM across Malaysia in 2015. The athletes birth date (n = 9,756) athletes participating the 2015 MSSM national level age group (U12, U15, U18) competitions) were obtained from the Director of Sports Department, Ministry of Education Malaysia. The Chi-square goodness of fit test was used to analyze on each age group between female and male and overall data of each age group. The result showed there were an existence of RAE in female and male athletes in each age group and also the present of RAE. There were more players born in the first three months of the year (Jan–Mar) compared to the last three (Oct–Dec). The over representation of early born players is suggested that they may have been selected based on their physical advantage and the selectors may have missed out skillful but physically less advantaged players.

Shaza Mohd Shah, Jeffrey Low Fook Lee, Nursyaidatul Hafiza Madzlan, Saidatul Nur Syuhadah Mohamed Sabadri, Maisarah Mohd Saleh

### The Acute Effects of Exercises Order During Upper-Lower Body Alternated Supersets Among Trained Men

The aim of this study was to determine and compare the acute effects of exercise order during upper-lower body alternated supersets. This study was conducted by using quantitative time series experimental design. Twenty resistance-trained men performed different exercises order of upper body (bench press) and lower body (squat) exercises; (i) upper body to lower body (order A) and (ii) lower body to upper body (order B) in random arrangement for three sets with 120 s rest inter-set. All participants performed both exercises at 75% of their one repetition-maximum (1RM) value. Muscles activation and repetitions completed were recorded during both exercises order. Repeated measure analysis of variance (ANOVA) was used to analyse the different of all variables. Results showed order A produced higher upper body muscles activation (pectoralis major: ρ < .05, triceps brachii: ρ < .05) and number of repetitions completed (ρ < .05) in bench press for all three sets compared to order B. In contrast, order B showed higher lower body muscles activation (rectus femoris: ρ < .05, biceps femoris: ρ < .05) in squat compared to order A. Number of repetitions completed during squat were higher during order B compared to order A in the first set, ρ < .05. In conclusion, the results of this study suggested that the order of exercises performed in a resistance training session will determine the benefits gained. The findings of this study could be used as guideline for individuals involved in strength and conditioning to plan a better resistance training program for achieving their own specific goals.

### Body Composition and Muscular Performance of Malaysian Young Male State Level Weightlifting, Cycling and Squash Athletes

The present study investigated the differences in body composition and muscular performance of Malaysian young male state level weightlifting, cycling and squash athletes. Forty-four participants (mean age: 17.1 ± 1.6 years old) were divided into sedentary control, weightlifting, cycling and squash groups with 11 participants for each group. Participants’ body composition, hand grip strength, back and leg strength as well as resting heart rate and blood pressure were determined. One way ANOVA was performed for statistical analysis. The present study found that weightlifting group exhibited statistically significant higher body weight (p < 0.001) compared to cycling and sedentary control group. Weightlifting group also showed higher percentage of body fat and fat-free mass (p < 0.05) when compared to the cycling group, and higher fat-free mass (p < 0.01) than the sedentary control group. In addition, weightlifting athletes showed significantly greater hand grip strength (p < 0.01), as well as back and leg strength (p < 0.01) compared to sedentary controls, cycling and squash athletes. Cyclists had lower resting heart rate compared to weightlifting and squash athletes. The present study findings implying that body composition and muscular performance of the athletes are dependent on sports events they were involved in.

Norsuriani Samsudin, Foong Kiew Ooi, Chee Keong Chen

### Development of a Soccer-Specific Running Protocol for Young Soccer Players

The aim of this study was to assess the reliability of a novel soccer simulation protocol (SSP), which was designed to replicate the activity pattern typically recorded in U15 soccer player’s match-play. Twenty male outfield soccer players (n = 20, 1.67 ± 0.4 m, 55.3 ± 8.4 kg) from the Sekolah Sukan Bukit Jalil (SSBJ) volunteered to participate in this study. The SSP was performed on two occasions to determine test-retest reliability. Sprint speed (km·h−1) was measured in one direction (15 m) using 5 Hz (with interpolated 10 Hz output) global positioning system unit. Physiological, physical capacity and perceptual scales were also monitored. The SSP running intensities were devised in a cyclical pattern required the participants to complete 4 × 20 min blocks of exercise separated by 3 min recovery. No significant difference was observed between trials in peak sprint speed (p = 0.930), perceptual scales (RPE; p = 0.835, FS; p = 0.751, FAS; p = 0.222), countermovement jump (p = 0.280) and heart rate (p = 0.330) between trials. The physiological and physical performance was observed repeatable and reliable (ICC = 0.85 to 0.98, SEM 0.01 to 0.6). In conclusion, the SSP’s appears to be reliable protocol that replicated the physical demands of youth soccer match play.

Siti Azilah Atan, Mohar Kassim

### The Potentiating Effects of an Eccentric Load on Horizontal Jumps Among Handball Players

The objective of this research is to examine the effects of eccentric loading protocol across different time courses using two different conditions (105% repetition maximum and 125% repetition maximum) on a horizontal jump to potentiate activation. Fourteen (n = 14) participants (age 21 ± 1.5; height 171.4 ± 4.8 cm; body mass 65.9 ± 5.4 kg) performed standing broad jump (SBJ) trials on two separate test sessions at least 96 h apart. Each participant needed to undergo baseline (pre) of the jumping and was measured. Next, 105% (105RM) and 125% (125RM) leg presses were performed. After performing the leg press, subjects needed to perform SBJ at 3, 6, 9, and 12 min. The difference in SBJ performance between 105% (105RM) and 125% (125RM) has been analyzed for statistical significance. The statistical significance has been set at p > 0.05. There were significant differences across the time, p = 0.00 (p < 00.5) but no significant differences for both conditions, p = .85 (p > 0.05). However, the highest mean for 105% 1RM improvement was recorded at 6 min (T6 = 2.549) whereby for 125% 1RM, it was found at 3 min (T3 = 2.545) respectively. In conclusion, pre-conditioning loading at 105% 1RM and 125% 1RM is effective in improving SBJ performance at 3 and 6 min after loading.

M. N. Muhammad Zulqarnain, A. Jasmi, T. Wahidah, S. M. P. Sharifah Maimunah, Adam Linoby

### The Confirmatory Factor Analysis of the Malay Language Revised Competitive State Anxiety Inventory-2 (CSAI-2R) Among Adolescent Malaysian State Level Athletes

The study aims to validate the Malay-language version of the Revised Competitive State Anxiety Inventory-2 (CSAI-2R) using confirmatory factor analysis (CFA). The data were collected from the state level adolescent Malaysian athletes across 21 different sports. A total of 685 athletes participated in the study (males 62%, females 38%), with the mean age of 17.0 (SD = 3.6). A standard forward-backwards translation was performed to translate the 17-items CSAI-2R from the original English version. All the participants filled the CSAI-2R Malay version questionnaire. The results of the initial hypothesised model did not show a good fit to the data (RMSEA = .060, CFI = .848, TLI = .822, SRMR = .048). Subsequent model modifications were made by adding correlation among the items’ residuals within the same factor which resulted in good fit indices (RMSEA = .038, CFI = .940, TLI = .926, SRMR = .035). The final measurement model comprised all 17 items of the Malay language CSAI-2R. The internal consistency coefficients measured by Cronbach’s alpha were .741, .619, and .775 for somatic state anxiety, cognitive state anxiety, and self-confidence. Overall, the results indicated that the Malay language CSAI-2R could be used to assess the multidimensional component of the competitive anxiety among adolescent Malaysian state-level athletes.

Liew Guo Chen, Hairul Anuar Hashim, Ngien Siong Chin, Yee Cheng Kueh, Garry Kuan

### Conventional Jump Warm-Up with and Without Jumping Rope on Jumping Ability Among Volleyball Players

Volleyball is a sport that required the athlete to have a powerful lower limb especially during jumping. The purpose of this study was to investigate the acute effect of warm up with jumping rope versus without jumping rope on leg power among university volleyball players. Sixteen (n = 16) university volleyball athletes range age between 18 to 25 years old. The randomized cross-over design was employed as each of the subject was undergone the no warm-up (NWU), conventional jump warm up with jumping rope (WJR) and warm up without jumping rope (WoJR) that was assessed by Vertical Jump (VJ) test and Standing Broad Jump (SBJ) test with one week of recovery period between the tests to avoid the carry over effect. The data has been analyzed by Statistical Package of Social Science SPSS 22.0. One-way Repeated Measure Analysis of Variance (ANOVA) was employed to observe the effect of NWU, WoJR and WJR on VJ and SBJ among volleyball athletes. The results shown that there is no significant difference between WoJR and WJR on VJ (p = .497), and there was also no significant difference between WoJR and WJR on SBJ (p = .231). However, there was a significant difference measured between of NWU and WoJR on VJ (p = .020).

Lawrence Balang Bungkong, Nur Khairunisa Abu Talip, Wan Firdaus Wan Chik

### Identification of Running, Jogging and Walking Activities for Female Athletes Indoor Hockey in 2016 PON Matches

This study is aimed to identify running, jogging and walking activities of female athletes in every indoor hockey. It is done by calculating the overall average running, jogging and walking activities for female athletes who compete in three matches. This study is also purposed to determine the distance from each activity of running, jogging and walking so that coaches can get the parameters in preparing the training program. In this study, the researcher considered quantitative research as the design. To collect the data, the researcher utilized a descriptive approach to analyze the video match of the East Java women’s hockey team in the 2016 National multi-event championship. Based on the result, it is explained that the athlete’s average running, jogging and walking activities are 3365.92 m with an average run of 1306.92 m, the average jogging is 535.06 m and the average walking is 523.94 m. The conclusion of this study is the most dominant running activity is 55.24%, while running and walking are almost as big as 22.62% and 22.14%.

### Carbohydrate Mouth Rinsing in Thermoneutral Enhances Prolonged Running Performance Compared to Hot-Humid Environment

Rinsing with carbohydrate (CHO) has been shown to provided ergogenic benefits on exercise performance of duration up to 1 h. However, the effect of CHO mouth rinsing within varying environmental conditions remains indistinct. The objective of the study was to investigate the effect of CHO mouth rinsing the effects of CHO mouth rinse on time to exhaustion (TTE) running performance in thermoneutral (TN) and hot-humid (HH) environment. Twelve well- trained male endurance runners (mean ± SD; age: 25 ± 3 years; body fat: 7.8 ± 1.8%; VO2peak: 59.8 ± 4.0 mL kg−1 min−1) performed steady-state running exercise at speed eliciting 70% of VO2peak until exhaustion. In a double-blind, randomised cross over design, two of the trials were conducted in a TN (20 ℃, 40% RH) with another two in a HH (30 ℃, 70% RH) environment. Each of the runners rinsed their mouth with either a 6% CHO solution, or a taste matched placebo (PLA) solution intermittently during exercise. A significant main effect of environment (TN vs. HH; p < 0.001) on running performance and a significant effect on treatment was detected (CHO vs. PLA; p < 0.001) however, no interaction effect between the 2 variables (p = 0.197). CHO mouth rinse improves TTE in TN compared to HH environment (80.2 vs 53.2 min; p < 0.001). A significantly higher heart rate, oxygen consumption, rectal temperature, skin temperature, and body temperature were recorded in the HH compared to the TN trials (p < 0.05). The psychological scale of arousal level and perceived rating exertion showed a significant difference in TN compared to HH trials (p < 0.05) but not for gastrointestinal comfort and mood state (p > 0.05). There was no difference between plasma glucose or lactate between trials (p > 0.05). These data demonstrated that distinct influence of the environmental condition on the efficacy of CHO mouth rinsing and endurance running exercise performance. The increased in cardiovascular and physiological strain during the exhaustive running exercise observed in a heat environment were the key reasons for decreased exercise performance when compared to a cooler environment.

Harris Kamal Kamaruddin, Cheong Hwa Ooi, Ahmad Munir Che Muhamed

### Which Joint Angle Changes Have Most Influence on Dart Release Speed?

A three-segment angle-driven model of dart throwing was developed to observe which joint angle of the upper limbs has most influence on the dart release speed. A subject performing 10 dart throwing trials were recorded using a motion analysis system. Subsequently, the joint angle time histories of individual trial were put in into the simulation model. The model calculated resultant dart release speed for each recorded trial and each trial was matched accurately. Systematically substituting a constant value to each joint angle, and observing the changes on dart release speed indicated that dart release speed was most susceptible to forearm extension/flexion. During coaching or performance, attention should be focused on this joint angle because any changes could have a substantial effect on the dart release speed.

Nurhidayah Omar, Farah Syahida Abdul Nasir, Ahmad Faizal Salleh

### The Influence of Anthropometrics, Physical Fitness, and Technical Skill on Performance of U-12 Youth Soccer Players in Malaysia

The present study is aimed at developing a capability index for performance in soccer and explore its differences with regards to specific skills and fitness-related attributes in the sport. A total of 87 adolescent soccer athletes aged 12 years old were recruited as participants. Relative performance namely anthropometrics, physical fitness, and soccer technical skill are assessed as dependent variables. The Principal Component Analysis (PCA), Cluster Analysis (CA) and Discriminant Analysis (DA) were used to achieve the purpose of this study. The CA analysis grouped the performance of the players into three different clusters namely; high (18 players), moderate (45 players) and low (24 players). The PCA reveals a moderate to very strong dominant range of 0.63 to 0.96 of factor loading on soccer performance. The DA analysis was applied with the defined clusters as independent variables (IV) whilst the physical, fitness, as well as the skill attributes are treated as dependent variables. It was demonstrated that a number of performance related variables could differentiate the relative performances of the players. The findings from the study highlighted the dominant attributes of U-12 Malaysian youth soccer players which could be beneficial to the coaches and players in identifying the suitable biological and physiological variables inherent to the soccer relative performance.

Ahmad Bisyri Husin Musawi Maliki, Mohamad Razali Abdullah, Mohamad Shafaat Fadzil, Muhd Faris Nazer, Muhammad Hafiz Zufaimey Ismail, Khairie Koh Abd Hadi Koh, Noraini Nazarudin, Siti Musliha Mat-Rasid, Mohd Syaiful Nizam Abu Hassan, Amr Alnaimat, Muhammad Rabani Hashim, Hafizan Juahir, Rabiu Muazu Musa

### Identifying Element of Academic Enhancement Support for Student-Athlete Using Fuzzy Delphi Method

Mohd Zulfadli Rozali, Saifullizam Puteh, Faizal Amin Nur Yunus, Affero Ismail, Thariq Khan Azizuddin Khan

### A Review of Pathways Towards Expert Performance on Elite Youth Athletes

The objective of this paper was to review research publications related to the developmental pathways of elite youth athletes in sport activities. The method that had been used was PRISMA statement. Articles from Scopus database were obtained from 1956 until 2019. The key words that had been used were “deliberate play”, “deliberate practice”, “Developmental Model of Sport Participation”, “early diversification”, “early specialization” and “expertise”. The finding showed that there was total number of 10330 articles from all countries and had been stratified by following the scopes of terms of sport and athlete, duplicating journals and non-related journals. The additional criteria were the journals focusing on developmental and the language was written in English only. A number of 15 related journals had selected in this study. This review demonstrated that both pathways either by specialization or diversification can lead to the elite performance level. However, future studies need to investigate the training activities of this elite performers during their involvement at elite level.

### The Relationship Between Organizational Commitment and Internal Service Quality Among the Staff in Majlis Sukan Negeri-negeri in Malaysia

The objective of this study is to investigate the relationship between organizational commitment and internal service quality among the staff in Majlis Sukan Negeri-negeri in Malaysia. The respondents of this study were selected using multi-stage sampling method. 155 staff in Majlis Sukan Negeri-negeri in Malaysia were selected for this research purpose. This study is a non-experimental research using questionnaire as the instrument. The data were analyzed using Statistical Package for Social Sciences (SPSS) version 20. The data obtained were analyzed descriptively (mean, standard deviation, and percentage). While for inferential analysis, parametric statistic tests were used (t-test, One-way ANOVA, Pearson correlation and multiple regression). The study found that the mean score for organizational commitment and internal service quality were at a high level. The result also showed that organizational commitment was not found to have significant positive relationship with internal service quality. The findings of this study can assist the human resources to understand the elements that will affect the internal service quality in an organization. This study could make an important contribution to extant research in sports management and organizational behavior to improve how staff committed to their organizations.

Phylicia Phoa Siew Ching, Mohamad Nizam Nazarudin, Pathmanathan K. Suppiah

### Accessibility Dimensions (Factors) of Parks and Playgrounds

The design for each park and playgrounds was purported in contributing a healthy lifestyle among the public. The most crucial element in the designing the parks and playgrounds was the accessibility. Studies upon accessibility had been done in the previous years in determining the importance of accessibility towards the publics. Therefore, the current study aims to identify factors dimension that influence the attendance of parks and playground. Through a model developed by Wang et al. (2015), the park accessibility can be divided into five dimensions. The dimension focused in the present study are physical and social dimension. Physical dimension included number and area of parks, proximity and walkability. As for the social dimension, the items included were safety and shared activities. 120 visitors Male (n = 60) and female (n = 60) completed questionnaire pack assessing the study variables. Finding from this study indicate that both dimensions share a similar preference by the visitors.

Ellail Ain Mohd Aznan, Ahmad Fikri Mohd Kassim, Nurul Hidayah Amir, Mohd Khairulanwar Md Yusof, Mohd Syafiq Miswan, Nur Anis Fatima Amir

### Influence of Individual Physical Activity on EMG Muscle Activation Pattern

Regular physical activity (PA) is associated with significant physiological health benefits for all individuals where various objective and subjective tools were used for evaluating PA. The aimed of this study is to access individual muscle activation and its relationship with their daily physical activity characteristics. A total of seven male subjects voluntarily participated in this study. Physical activity of each individual was derived from long, self-administered International Physical Activity Questionnaire (IPAQ) while the muscle activation was recorded from vastus lateralis muscle using wireless electromyography (EMG) system. Each subjects are required to perform maximum voluntary contraction of knee extension exercise. Both time domain features; root mean square and frequency domain features; mean frequency, median frequency were extracted from the raw EMG signals and its relationship was compared with MET-min/week scores obtained from IPAQ using Pearson correlation analysis. Regression line was also been plotted in order to observe the EMG muscle activation pattern. Overall, root mean square value showed the best correlation between IPAQ data and EMG muscle activation data. Different muscle activation pattern can also been observed between time and frequency domain features, where time domain feature which is RMS showed decreasing trend of muscle activation with the increasing of PA. This findings suggest that overall physical activity scores were moderately correlated with some EMG features, thus further attention should be given when only relying on IPAQ to classify active or inactive individual.

Maisarah Sulaiman, Aizreena Azaman, Azli Yahya

### Immediate Effect of Single Bout of Karate Exercise on Heart Rate

Background: Physical activity of moderate intensity when incorporated in the daily routine provides a holistic development of the body and improves the overall health status. Heart rate acts as a marker of cardiac modulation by the sympathetic and vagal components of the autonomic nervous system. The immediate changes in terms of rise and recovery of heart rate levels after performing a bout of karate exercise may indicate the status of cardiovascular fitness levels of a physically active individual. The purpose of this study was to observe the immediate effect of a schedule karate regimen as a moderate exercise intervention on heart rate. Method: To fulfill the purpose of the study fifteen physically active male adults pursuing the Bachelor of Physical Education course were considered as subjects of the study. Purposive sampling method was used for collection of data. They were provided a continuous karate training protocol of ten minutes bout and their heart rate was recorded in three time intervals: pre intervention for ten minutes, during exercise and post recovery up to ten minutes. Holter test was used for measuring continuous heart rate. Results and Findings: The mean resting heart rate was recorded as 55.73 ± 5.17 beats/min, which with single karate bout went up to 144.20 ± 9.16 beats/min and again recovered in the 10th minute to 69.33 ± 5.96 beats/min. Repeated measure of ANOVA indicated that there was a significant difference in resting, exercise and recovery heart rates. Conclusion: It can thus be interpreted that the karate training protocol shows significant change of heart rate among pre, during and post exercise period.

Puneet Bhattacharya, Sridip Chatterjee

### Incorporating Traditional Games in Physical Education Lesson to Increase Physical Activity Among Secondary School Students: A Preliminary Study

Physical education (PE) lesson is an important avenue for delivering physical activity (PA) opportunities during school hours. Non-sport activities like traditional games can be a practical way to promote PA during PE lesson, especially among those who are less inclined in sports. This study aims to determine whether playing traditional games during PE lesson can lead to greater PA compared to a ‘free-play’ PE lesson among secondary school students. A total of 56 subjects (Form 1: n = 27; Form 2: n = 29; mean age: 13.4 ± 0.5 years; mean BMI: 21.8 ± 4.9 kg/m2) from a school in Keramat, Kuala Lumpur were consented by their parents to participate in this study. PA was measured by using accelerometry (Actigraph GT3X+), on two separate PE lesson periods: PE lesson incorporated with traditional games and ‘free-play’ PE lesson. Subjects wore accelerometers for a total of 40 min during each PE lesson to determine total activity counts and moderate-to-vigorous physical activity (MVPA). The chosen traditional games were Galah Panjang and Baling Selipar. Mean total activity counts (p = 0.007) and time spent in MVPA (p = 0.006) were 20% and 19% greater respectively, during traditional games-based PE lesson compared to ‘free-play’ PE lesson. Time spent in sedentary activity was 45% lower during traditional games-based PE lesson (5.3 ± 4.3 min) compared ‘free-play’ PE lesson (10.7 ± 11.7 min; p = 0.006). Boys appeared to be 25% more active than girls in this study. In conclusion, incorporating fun and meaningful activities like traditional games during PE lessons can serve as an alternative strategy to promote PA during school hours. Further studies are warranted to determine other types of traditional games that may promote PA in girls.

### Muscle Strength in Male Youth that Play Archery During Leisure Time Activity

Archery involves repetitive isometric contraction of muscles, however, there is a paucity in scientific evidence that describes the muscle strength in those receiving archery training. This study aimed to determine the differences in maximum force in selected groups of muscles between healthy youth with regular archery training and those without any background of resistance training. A case-control study design was adopted to compare between youth with archery training as subjects (n = 40) and youth without any background of resistance training as control (n = 78). Both groups were matched based on age, race, education level, income, time spent for weekly physical activities, and body composition. Muscle strength was assessed via JTech Commander PowerTrack MMT and the forces were recorded in Pound-force (lbf). Subjects with archery training showed significantly (p < 0.05) higher mean of muscle strength’s maximal force as compared to the control group in shoulder motions such as higher abduction strength (11%), adduction strength (15%), flexion and extension strength (19%). Elbow motion showed significantly higher extension strength by 17%. Similarly, higher lower body muscle strength was also found in subjects with archery training as compared to subjects in the control group in their hip motions for abduction (16%) and adduction (21%) and knee motion for extension (25%). Training in archery has a significant impact on muscle strength of both upper and lower body as shown in these youths. Therefore, serious attention should be given archery and be further promoted as a physical activity in the enhancement of health.

Norsham Juliana, Izuddin Fahmy Abu, Nadia Ahmad Roslan, Nur Islami Mohd Fahmi Teng, Abd Rahman Hayati, Sahar Azmani

### The Effect of Zone, Gender, RAE and Fitness Variables Towards Fitness Status and Anthropometric Attributes of Children in Malaysia

This research aims to identify the influence of zone, gender, RAE, and fitness performance variables and their relationship with physical fitness and anthropometric attributes of Malaysian children. Data were obtained from 43607 participants aged 7 years old in Malaysia. The participants completed the multiple of test (anthropometrics, standing broad jump, twenty-meter speed, sit and reach and hand wall toss). Data interpretation was carried out using analysis of variance as well as principal component analysis (PCA). The PCA was computed to determine the appropriate components with an eigenvalue greater than 1 (eigenvalue > 1.0). Further analysis performed with varimax rotation demonstrated that some domain variables are able to distinguish children performances. The finding indicates that high performance children are attributed to considerable higher anthropometry and are lacking in flexibility as well as leg and hand strength amongst other variables (p < 0.05). The overall findings revealed that zone, gender, RAE, fitness, and anthropometry do have an influenced toward children physical fitness performance in Malaysia.

Ahmad Bisyri Husin Musawi Maliki, Mohamad Razali Abdullah, Siti Musliha Mat-Rasid, Hafizan Juahir, Mohd Syaiful Nizam Abu Hassan, Nik Naleesa Nasuha Rusmadi, Muhammad Ziyad Yazid, Fatin Zulaikha Azmin, Tengku Nur Arnie Tengku Ghazali, Amr Salem Falah, Muhammad Rabani Hashim, Rabiu Muazu Musa

### Offline LabVIEW-Based EEG Signals Analysis to Detect Vehicle Driver Microsleep

Microsleep is often known as unintended loss of attention and alertness within short period of time briefly between a second up to 30 s. Microsleep might be dangerous to vehicle driver especially for long-distance driver due to unawareness and loss of focus towards surrounding environment. Thus, microsleep detection system based on Electroencephalogram (EEG) signals is proposed in this research to prevent the drivers to involve in the accidents. For investigation purpose, six samples are chosen to obtain their brain signals using NeuroSky Mindwave Mobile Headset and eegID mobile application in two different states which are relax state for 5 min and driving state for 1 h. Besides, a Graphical User Interface (GUI) is constructed using LabVIEW to analyze the EEG signals. The captured EEG signals then, are undergone pre-processing to remove noises and undesired artifacts. Bandpass filter is then applied to brainwaves to split the signals into Alpha and Theta waves. The patterns of these waves are examined and analyzed using power spectrum technique to search for unique features that might relate to microsleep event. The kNN classifier is employed to classify the selected features in term of Standard Deviation (SD) and Spectral Centroid (SC). The best classification accuracy for SD and SC features are obtained at 82.83% and 77.65% respectively for 80:20 training-testing ratios. Besides, the analysis of EEG Alpha and Theta band using Short-Time Fourier Transform (STFT) technique able to localize the EEG signals to indicate the exact time of the microsleep occurrence. The alarm system and steering vibration motor are assembled and will be activated for any detection of microsleep event.

N. Sulaiman, K. S. Goh, M. Rashid, S. Jadin, M. Mustafa, M. Z. Ibrahim, F. Samsuri

### Vision Based Automated Badminton Action Recognition Using the New Local Convolutional Neural Network Extractor

Performance analysis is essential in sports practice where the athlete is evaluated to improve their performance. Due to the rapid growth of science and technology, research on automated recognition of sports actions has become ubiquitous. The implementation of automated action recognition is an effort to overcome the manual action recognition in sport performance analysis. In this study, we developed a model for automated badminton action recognition from the computer vision data inputs using the deep learning pre-trained AlexNet Convolutional Neural Network (CNN) for features extraction and classify the features using supervised machine learning method which is linear Support-Vector Machine (SVM). The data inputs consist of badminton match images of two classes: hit and non-hit action. Before pre-trained AlexNet CNN was directly extracting the features, we introduced the new local CNN extractor in recognition pipeline. The results show that the classification accuracy with this new local CNN method achieved 98.7%. In conclusion, this new local CNN extractor can contribute to the improvement of the performance accuracy of the classification task.

### Investigation of Different Time-Series Segmented Windows from Inertial Sensor for Field Hockey Activity Recognition

Sport activity recognition has become one of the primary sport performance analysis contributions as it offers a notational data for tactical analysis and planning. In developing of activity recognition algorithm, searching for the best window segmentation size within time-series data is one of the parameters that contribute to the performance of algorithm in term of the accuracy rate. Yet, previous studies on activity recognition have implemented a different fixed size of window in segmenting the specific activities and the performance of activity recognition algorithm along with the changes of window size is still uncertain. Thus, this study is investigating the performance of field hockey activity recognition algorithm based on inertial sensor time-series data with different window segmentation size. The study was conducted on 11 subjects who worn the inertial sensors on their chest and waist while performing the six common field hockey activities which are passing, drive, drag flick, dribbling, receiving and tackles. The performance of each size of windows were observed and evaluated by using Cubic support vector machine (SVM). Among the different window sizes studied, this study found 1.5 s and 2.0 s are among the top in producing high accuracy rate for recognizing the field hockey activity that represent the movement from chest and waist with 89.6% and 91.4% accuracy respectively.

Norazman Shahar, Nurul Fathiah Ghazali, Muhammad Amir As’ari, Tian Swee Tan, Mohamad Fauzi Ibrahim

### Effect of Stroke Rate Increment on Power Output and Foot Asymmetries Force Among Malaysian University Rower

Generating effective power output during the drive phase in rowing sport is very important, whereby producing more speed to manoeuvre the boat. Asymmetrical force production on foot stretcher may affect the performance of rowers. Therefore, the aim of this study is to determine the correlation between asymmetrical foot force and power output during increment of stroke rate. Eight male Malaysian university rowers (Age 21.4 ± 1.8 years; Height 175.9 ± 4.9 cm; Mass 76.4 ± 6.5 kg; Training experience 3.1 ± 0.8 years) performed a 60s increment trial at six different stroke rates on a Concept2 rowing ergometer. The ergometer was installed with load sensors at the handle and both foot stretchers to measure the pulling force and resultant foot force respectively. Asymmetries of foot force were calculated using symmetry index formula. Results showed that the peak power output increased up to 23.9% from lower to higher stroke rates. At low stroke rates (18 spm), the symmetrical index for peak force was 5.2 ± 8.8% and the average resultant force was 7.1 ± 1.3%. Meanwhile at higher stroke rates (pace race), the symmetrical index for peak force was 1.7 ± 44.5% and the average resultant force was 1.2 ± 2.9%. The power output increased with increment of stroke rate, however, less significant showing to the symmetry index on Malaysian university rower.

Fakhrizal Azmy Nasruddin, Ab Aziz Mohd Yusuf, Mohd Azizi Abdul Rahman, Muhammad Ridwan Jaafar, Hadafi Fitri Mohd Latip, Muhamad Noor Harun

### Object Detection Approach Using Single Shot Multibox Detector for Sprinting Movement Recognition

The current movement detection tool is using the motion analysis system by attaching the reflective balls to specific places on the body and special cameras will measure the three-dimensional location of the reflective balls. Object detection in sports for athletes movement recognition is still new in this era. Thus, the object detection is one of the Convolution Neural Network (CNN) approaches that use image processing and computer vision to detect the type of object within a certain class in digital images and videos. Sprinting is the movement selected specifically for this study because of the biomechanics of its movement. The dataset was created based on the digital images per frame from athletes sprinting. Single Shot Multibox Detector is the most accurate algorithm for the object detection model and it has been proven by PASCAL VOC 2012. Hence, this algorithm helped to train the images and create the dataset for the system to run the object detection. An evaluation process to measure the accuracy of sprinting detection was tested and the value was greater than 80% by using intersection over union (IOU) method. Several videos of sprinting from the subjects had been tested with the machine learning and thus the sprinting detection was detected in that video with the scoring label above 70%. A comparison result was discussed in term of speed taken from two different athletes to finish the sprint regarding the score value and number detection produce in a video. The detection of sprinting would a stepping stone to make a real-time movement recognition in sports and also could be advanced to the prediction of talent in junior athletes.

### Physical Fatigue Prediction Based on Heart Rate Variability (HRV) Features in Time and Frequency Domains Using Artificial Neural Networks Model During Exercise

Awareness on fatigue level is important for people in order to understand their physiology in daily activities. This situation become more critical when involving physical exercise and reach the maximum threshold fatigue which can lead to injury. Additionally, sedentary people become the most group who is difficult to understand and know their fatigue condition based on feeling compared to the recreational exercise people and sports athlete. Therefore, this study is aims to help sedentary to predict the level of fatigue based on HRV features using artificial neural network (ANN). Eighteen sedentary peoples who are volunteer to participated in this study required to perform fatigue-induced protocol to achieve the heart rate maximum (HRmax). Those participants were run on the treadmill with speed intensities from 4 km/h to 12 km/h depends on their ability. During running, single-lead ECG was attached on the chest by using Ag/AgCl wet electrodes. The raw signals which accumulate together with noise and motion artefacts were then filtered in 4th order Butterworth filter. A new signal of HRV was used to analyze by extracting the features in each level of fatigue based on Edward’s Method zones. Eight features of time and frequency domains were selected in the neural network as input and predicts the fatigue zones as an output. HRV and HRmax were found as significant parameters to detect fatigue by differentiate its pattern in pre and post exercise. The results reveal that the prediction model with accuracy as high as 80.6% in the output of five fatigue classes. The results presented here may facilitate improvements in identifying the level of fatigue based on prediction algorithm compared to the RPE method during physical exercise.

Zulkifli Ahmad, Mohd Najeb Jamaludin, Ummu Kulthum Jamaludin

### The Effect of Compression Socks on Running Kinematics in Experience and Novice Runners

The purpose of this study was to examine whether wearing compression socks (CS) and smooth socks (SS) during running could change the kinematics parameters among experienced and novice runners. Kinematic parameters which include the ground contact time, stride length, swing time and heel strike were measured to compare the effects between compression and smooth socks. Eight experience and eight novice runners (Age 23.6 ± 1.4 years) were selected for this study. All participants were required to complete a laboratory-based Bruce protocol treadmill test with two different sock conditions (CS and SS) which being separated by seven days of washout periods. The kinematics parameters were determined during four constant submaximal speeds of stage 1, 2, 3 and 4 and were measured during last 30 s of each stage. Data on kinematic parameters were analysed using mixed-model ANOVA. Results revealed that there were significant differences (p < .05) only for the novice runners while wearing the CS as compared to SS (significantly higher values of swing time, stride length and heel strike). The findings of this study suggest that wearing compression socks seems to significantly alter running kinematics in novice runners.

Muhammad Hanis Jefry, Hosni Hasan, Mohd Azim Nural Azhan, Mohd Iqbal Misnon, Raja Mohamed Firhad Raja Azidin, Hashbullah Ismail

### The Classification of Skateboarding Trick Manoeuvres: A K-Nearest Neighbour Approach

The evaluation of skateboarding tricks is commonly carried out subjectively through the prior experience of the panel of judges during skateboarding competitions. Hence, this technique evaluation is often impartial to a certain degree. This study aims at classifying flat ground tricks namely Ollie, Kickflip, Shove-it, Nollie and Frontside 180 through the use of Inertial Measurement Unit (IMU) and a class of machine learning model namely k-Nearest Neighbour (k-NN). An amateur skateboarder (23 years of age ± 5.0 years’ experience) executed five tricks for each type of trick repeatedly on a customized ORY skateboard (IMU sensor fused) on a cemented ground. A number of features were extracted and engineered from the IMU data, i.e., mean, skewness, kurtosis, peak to peak, root mean square as well as standard deviation of the acceleration and angular velocities along the primary axes. A variation of k-NN algorithms were tested based on the number of neighbours, as well as the weight and the type of distance metric used. It was shown from the present preliminary investigation, that the k-NN model which employs k = 1 with an equal weight applied to the Euclidean distance metric yielded a classification accuracy of 85%. Therefore, it could be concluded that the proposed method is able to classify the skateboard tricks reasonably well and will in turn, assist the judges in providing more accurate evaluation of the tricks as opposed to the conventional-subjective based assessment that is applied at present.

Muhammad Ar Rahim Ibrahim, Muhammad Amirul Abdullah, Muhammad Nur Aiman Shapiee, Mohd Azraai Mohd Razman, Rabiu Muazu Musa, Muhammad Aizzat Zakaria, Noor Azuan Abu Osman, Anwar P. P. Abdul Majeed

### The Application of Artificial Neural Networks in Predicting Blood Pressure Levels of Youth Archers by Means of Anthropometric Indexes

The present investigation aims at measuring as well as predicting blood pressure (BP) levels using anthropometric indexes. A standardised systolic blood pressure, (STBP) and diastolic blood pressure (DSBP) coupled with anthropometric evaluations of Body Mass Index waist to hip ratio, waist to height ratio, body fat percentage, and calf circumference was carried out on 50 youth archers. A Backward Regression Analysis (BRA) was used to determine the anthropometrics indexes that could predict both the STBP and DSBP whilst two models, namely Multiple Linear Regression (MLR) and Artificial Neural Networks (ANN) were developed based on the most correlated anthropometry. The BRA identified calf circumference (CC) as the highest correlated predictor for both STBP and DSBP. The ANN model developed demonstrated a better prediction efficacy against the MLR with an R2 as well as the mean absolute percentage error values of 0.95, 0.95, 0.050 and 0.06 as compared to MLR 0.26, 0.25, 8.46, 6.56 in the prediction of both the STBP and DSBP, respectively. It is evident from the present study that the BP levels of youth archers could be reliably measured using only their CC index.

Rabiu Muazu Musa, Muhammad Zuhaili Suhaimi, Anwar P. P. Abdul Majeed, Mohamad Razali Abdullah, Siti Musliha Mat-Rasid, Mohd Hasnun Arif Hassan

### Prevalence of Cardiovascular Risk Factors Among Professional Football Athletes in Sabah, Malaysia

Cardiovascular death is the leading cause of mortality worldwide including Malaysia. This is a pilot study to identify the prevalence of cardiovascular risk among professional footballers in Sabah, Malaysia as well as to differentiate the risk factors among adolescent and adult footballer group. Data was collected using the standard Pre-Participation Evaluation (PPE) registry including demographic data, medical history, family history, anthropometric data, vital signs, physical examination and blood sampling during pre-participation health screening for Sabah Football club in Sports Medicine Clinic, Queen Elizabeth Hospital, from 1st December 2017 – 30th January 2018. A total of 55 participants were involved in this cross-sectional study. Descriptive and association analysis was performed using SPSS V22. Obesity and dyslipidemia are the major CVD risks seen among Sabah footballer with 74% of the footballers having CV risk factors. Three out of four footballers were having at least one cardiovascular (CV) risk factor. Overweight showed the highest prevalence (n = 27; 47%), followed by high LDL cholesterol (n = 20; 36%), and smoking (n = 18; 30.9%). However, all athletes showed low Framingham scoring. There were significant differences in diastolic blood pressure (p = 0.017), BMI (p = 0.015), total cholesterol (p = 0.038) and LDL cholesterol (p = 0.034) between adolescent and adult athletes. The alarming rise of cardiovascular risk factors among football athletes in Sabah calls for primary and secondary prevention strategies to improve cardiovascular health in this population.

### External Snapping Hip Syndrome: A Case Report of a Professional Hockey Player

The External Snapping Hip Syndrome is characterized by a snapping on the lateral region of the hip. It can be painful or painless associated with audible or palpable snapping which occurs during certain provocative movements. Iliotibial Band, Tendon Fascia Latae, and Gluteas Maximus has been implicated as the involved structure in this form of snapping hip. The goal of treatment is to achieve pain-free functional activities especially in an athlete. This is a case of External Snapping Hip Syndrome presented occurring in a Field Hockey Athlete which was diagnosed clinically and confirmed by Dynamic Ultrasound investigation. The focus of rehabilitation program in this case was a combination of active and passive exercise stretching as the provision of hip guard. This lead to an improve function and safe return to his sports.

Muhammad Yusri Yunus, M. G. Matthew, Redzal Abu Hanifah

### Ouch! My Hip Hurts: A Rare Case Report of Rectus Femoris Muscle Tear Causing Failure in Hip Extension

A unique case is presented of a patient who is unable to fully hip extend in a rectus femoris muscle tear. Rectus femoris muscle is a type of quadriceps muscle, which is the most involved muscle in strain pathologies. Rectus femoris involves primarily in hip flexion and knee extension. We report a 23 year old young man who sustained injury to his right hip after a game of ‘sepak takraw’ whereby he fell on his right gluteus after a bicycle kick in the air. He sought medical attention immediately as he was unable to extend his hip and presented with a palpable painful mass over his right gluteal and proximal thigh region. This is the first reported case of rectus femoris tear presenting with failure of hip extension.

Lavinen Kumar Sugumar, G. M. Mariam, M. Y. Yau

### A Randomized Controlled Trial of the Effects of Dietary Nitrate Supplementation on Blood Pressure, Exhaled Nitric Oxide Level and Maximal Isometric Handgrip Strength in Pre-hypertensive Women

It is still not known whether dietary nitrate can improve blood pressure (BP) and muscular strength in prehypertensives women. The current study investigated the effects of chronic (14-day) nitrate-rich beetroot extract supplementation on the blood pressure responses, maximal isometric handgrip strength and breath nitric oxide level in pre-hypertensive women. In a double-blind, randomized, crossover design, 9 prehypertensives females completed all assessments at pre-supplementation (as control; PRE) and 2-h after orally consumed beetroot extract (BRE; 250 mg·kg−1·day−1) and placebo (PLA; red coloring powder with negligible NO3− and NO2− content), with a washout period of 10 days separating each trial. BRE reduced systolic blood pressure (BRE: 126 ± 2.2 vs. PLA: 132 ± 4.0 vs. PRE: 131 ± 3.2 mmHg; P < 0.05). Similarly, diastolic blood pressure (BRE: 80 ± 4.6 vs. PLA: 84 ± 4.5 vs. PRE: 82 ± 4.4 mmHg; P < 0.05) and mean arterial pressure (BRE: 95 ± 3.5 vs. PLA: 100 ± 3.7 vs. PRE: 98 ± 3.4 mmHg; P < 0.05) were all lowered following BRE supplementation. However, no statistically significant changes were observed in maximal isometric handgrip strength across the trial condition. Additionally, resting fractional exhaled nitric oxide was elevated by ~124% and ~138% compared to the PRE and PLA condition, respectively (both P < 0.05). These findings suggest chronic (14-day) beetroot extract supplementation can significantly improve BP indices in the high-normal BP (prehypertension) population, but not handgrip strength.

Adam Linoby, Ameerul Adzim Azrin, Mohd Aizzat Adnan, Nur Hidayah Asilah Za’don, Mohd Hanifa Sariman, Muhammad Zulqarnain Mohd Nasir, Raja Nurul Jannat Raja Hussain

### The Effect of Various Carbohydrate Concentrations Mouth Rinsing on Intermittent Running Performance

Endurance exercise performance has been shown to improved with carbohydrate (CHO) mouth rinsing. While multiple studies to elucidate the effectiveness of CHO mouth rinsing continue, most of the studies have utilized 6.4% CHO solutions. The impact of higher CHO concentration on exercise performance remains inconclusive. The aim of this study was to determine the effectiveness of various concentrations of CHO mouth rinse solutions on intermittent running performance. In a double-blind, placebo (PLA) controlled crossover design, 8 recreational endurance runners [age (mean ± SD): 22 ± 1 years; body mass: 62.9 ± 5.9 kg] completed 3 experimental trials. Each trial consisted of standardized breakfast (2 h prior) followed by Yo-Yo Intermittent Recovery Test-Level 1 (Yo-Yo IRT-1) run to exhaustion. Prior the start of the exercise, subjects mouth rinsed with 25 mL of either 6%, 21% CHO and a taste-matched PLA solution for 10 s. Distance covered, level of exhaustion, heart rate (HR), blood glucose, perceived exertion (RPE), perceived arousal scale (FAS) and gastrointestinal scale (GI) were recorded during each trial. There were no significant differences in distance covered (p = 0.07) or level of exhaustion (p = 0.17) between 6%, 21% and PLA trials. There was a significant effect of time on HR (p < 0.001); nevertheless, no significant difference between trials (p = 0.24). There was no difference on blood glucose (p = 0.69) or any of the psychological markers (RPE, p = 0.10; FAS, p = 0.85; GI, p = 0.37). In conclusion, CHO mouth rising with higher solutions concentration of 6% or 21% provide no ergogenic advantage over a PLA solution, and that there was no does-response relationship between solution concentration and Yo-Yo IRT-1 running performance. Further research is warranted to examine the possibility of any dose-response effect of CHO mouth rinse during exercise for more than 30 min.

Nur Athirah Idrus, Al Hafiz Abu Bakar, Mohd Faiz Putra Abd Razak, Norfaezah Mohd Rosli, Ahmad Fikri Mohd Kassim, Harris Kamal Kamaruddin

### Nitrate-Rich Red Spinach Extract Supplementation Increases Exhaled Nitric Oxide Levels and Enhances High-Intensity Exercise Tolerance in Humans

Acute and chronic administration of dietary inorganic nitrate source, such as beetroot, can promote Nitric Oxide (NO) production via the nitrate-nitrite-NO pathway and improves exercise performance. However, whether NO3− rich red spinach extract (RSE) could prominently elicits similar effects remains unclear. The current study therefore evaluated the effects of chronic (15-day) NO3− rich RSE supplementation on resting blood pressure (BP) breath NO production and high-intensity exercise tolerance. Eleven healthy males were randomly allocated in a double-blind, crossover trial design to receive 15-day of red spinach extract (RSE; 4 g·day−1 containing ~6 mmol of NO3−) and placebo (maltodextrin), with a washout period of not less than 7 days separating each trial. On day 15 of supplementation, participants completed a resting fractional exhaled NO (FeNO) measurement prior to an exhaustive high intensity exercise. The systolic BP were significantly lowered, and FeNO levels were higher (p < 0.05; p < 0.001), following RSE trial (124 ± 3 mmHg; 41 ± 14 ppb), compared to the PRE (129 ± 4; 21 ± 5 ppb) and PLA treatment (128 ± 4 mmHg; 21 ± 6 ppb), respectively. The time-to-exhaustion (TTE) in the high-intensity exercise increased during the RSE (764 ± 221 s) compared the placebo (642 ± 198 s) (p = 0.024). These findings suggest chronic dietary NO3− supplementation from red spinach source reduces BP and demonstrated to be a practical ergogenic intervention, partly through improving nitric oxide bioavailability.

### The Role of Fitness Status in the Performance-Enhancing Effects of Dietary Inorganic Nitrate Supplementation: Meta-analysis and Meta-regression Analysis

A systematic evaluation of current evidence was conducted to clarify the potential of training status to influence the exercise performance enhancing (ergogenic) effect of dietary inorganic nitrate supplementation. Studies were located via PubMed, ProQuest and SPORTDiscus electronic databases reported according to the guidelines outlined in the statement of Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Thirty-four studies met the inclusion criteria (70 trials). Random-effects meta-analyses was conducted, and meta-regressions were performed in a model with a priori potential moderator variables. Subgroup analysis revealed that NO3– supplementation was ergogenic in the lowest fitness category (i.e. $$\dot{V}\text{o}_{{2{ \hbox{max} }}}$$ < 55.0 ml·kg−1·min−1) [standardized mean difference (SMD) = 0.17 (95% CI: 0.07 to 0.27, p = 0.001], but elicited no significant effect in the upper realms of fitness category ($$\dot{V}\text{o}_{{2{ \hbox{max} }}}$$ > 55.0 ml·kg−1·min−1) p > 0.05). Meta-regression revealed that baseline $$\dot{V}\text{o}_{{2{ \hbox{max} }}}$$ and supplementation duration was negatively (R2 = −0.11, 95% CI: −0.02 to −0.00, p = 0.035) and positively (R2 = 0.40, 95% CI: 0.00 to 0.05, p = 0.047) associated with the mean performance change between NO3– and control condition, respectively. The current analysis indicates that NO3– supplementation can enhance exercise performance with an ergogenic effect more likely in untrained subjects and as the duration of supplementation increases.

### An Overview of a Dietary Pattern Among Malaysian Endurance Athletes in Relation to Glycemic Index

Nowadays, there is a significant increase in endurance sports participation globally. The types, amount and timing of meals consumed by the endurance athletes will influence the endurance performance. This study aims to identify the commonly consumed foods among endurance athletes and their relation to the glycemic index (GI). A preliminary cross-sectional study was conducted among 20 endurance athletes. A set of the questionnaire assessed on respondents’ background, anthropometry and 24-h diet recall was administered through face-to-face interview with the respondents. The food items that contributed to the highest percentage of energy and macronutrients intake represented the commonly consumed foods. The GI value of the foods was determined based on the reference to the published value. The findings showed that white rice (GI = 83), fried rice (GI = 59), fried chicken, cordial drink (GI = 66) and malt-based drink (GI = 55) were among the top contributors to the total energy intake. The findings from this study provided the idea of the commonly consumed foods among endurance athletes in relation to GI. It can provide a foundation to develop the mixed-meal menus that meet the dietary requirement and preferences of the endurance athletes.

Zaini Bahari, Nik Shanita Safii, Ahmad Munir Che Muhamed

### Coach-Athlete Relationship and Coaching Effectiveness in Team Sports Athletes

The coach-athlete relationship plays an integral role in the team and individual sports setting. Previous research suggests that the relationship between coach and athlete can be viewed as central to effective coaching. Coaching effectiveness view as the extent to which coaches can implement their knowledge and skills to positively affect the learning and performance of their athletes. Therefore, this research aimed to investigate the athlete’s perception of the coach-athlete relationship and coaching effectiveness in team sports. 120 athletes, Male (n = 60) and Female (n = 60) from (Netball n = 36, Football n = 40, Hockey n = 44) types of sports completed questionnaire pack assessing the study variables. An adapted question of The Coach-Athlete Relationship Questionnaire (CART-Q), were used to measure the athletic relationship, and Coaching Effectiveness Scale (CES) was used to measure coaching effectiveness. Results revealed that there were no significant differences for the dimension of coach-athlete relationship with all the three types of sports excluded for “commitment”, and there were no significant differences for dimensions of coaching effectiveness with all the three types of sports. Further, results showed that there were no significant differences for all the three dimensions of the coach-athlete relationship between genders and, there were no significant differences for all the four dimensions of coaching effectiveness between genders. In conclusion, coaching effectiveness and coach-athlete relationship affects to the optimal development and learning of the athletes in team sport.

Ahmad Fikri Mohd Kassim, Wan Faizal Iskandar Wan Abdullah, Siti Jameelah Md Japilus, Asmahan Shahirah Azanuar Yusri

### Motivation in Physical Activity: Smartphone Sport Tracker Applications

Physical activity is one of the ways that can reduce the risk to get obesity and chronic disease. The smartphone sport tracker application is one of innovative device that people can use to motivate them involve in physical activity. In this study researcher investigate satisfaction and motivation level of people who involved in physical activity with using smartphone sport tracker application. The intervention cross-sectional research design was used in this study. The Post-Study System Usability Questionnaire (PSSUQ) and Motivational for Physical Activity and Exercise/Working Questionnaire are used as instruments in this study. Research participants were 50 peoples who involved in physical activity at Taman Bandar Kuantan recreational park. Result shows intrinsic motivation slightly higher than extrinsic motivation in performing physical activity. This study found that the smartphone sport tracker application alone can’t lead people to motivate them in performing physical activity.

### The Relationship Between Motivation and Leadership Style Among PKNS Football Academy Players

In the past study, there was limited information on the relationship between leadership style and motivational factor among athletes. The purpose of this study is to determine this relationship towards sports performance. The subjects of this study are the athletes from the PKNS Football Academy. A total of 81 athletes from the football club had participated in the study and 81 questionnaires were distributed to each of them. Each participant must complete two types of questionnaires that represent the coaching behaviour and motivational factor. In addition, the questionnaire for leadership style is the Revised Leadership Scale for Sport (RLSS) to determine the coaching behaviour that represents five variables, which are autocratic, democratic, social support, positive feedback, and training and instruction. On the other hand, the second questionnaire that is intended for motivational factor is the Revised Sport Motivation Scale (SMS-II) to examine the types of motivation, which are intrinsic and extrinsic motivation. For data analysis, the descriptive statistics (frequency and percentage statistics) and inferential statistics both utilise Pearson’s correlation test. The result of this study indicates that for leadership style, most of the players preferred to have a democratic leadership compared to other types of leadership. For motivational factor, players are likely to have an intrinsic motivation in order to play sport because of eagerness and willingness to play, compared to having an extrinsic motivation that refers to a behaviour driven by external rewards. The overall correlation was low and negative relationship between both variables (r = − .284; p = 0.01). As a conclusion, the coaching leadership style and types of motivation are some of the factors that can influence the sport performance.

Syed Husin Syed Ahmad, Vincent Parnabas

### The Effects of Brain Breaks Physical Activity Solutions on Processes of Change in Physical Activity Among the Malaysian Primary School Children

Brain Breaks Physical Activity Solutions (BBPAS) is a web-based structured physical activity video supplied by Global Community Health and HOPSports and is supported by United Nations’ 17 Sustainable Development Goals. Research shows that BBPAS can stimulate student’s health and learning as well as being specifically designed for school settings. The purpose of the study is to investigate the effects of BBPAS on process of change in physical activity among Malaysian primary school children. A total of 148 male and 139 female students aged 10 to 11 years old (mean age = 10.51 ± 0.50) volunteered to participate in this study. Purposive sampling was used to divide the students into intervention (n = 128) and control (n = 159) groups. Students in the intervention group underwent BBPAS five times per week for twelve weeks. Mixed repeated measure of variance (ANOVA) was used to analyse the questionnaires administered at three time points (pre-, mid- and post-test). Mixed repeated ANOVA showed significant interaction effects for cognitive process, F(2, 284) = 3.678, p-value $$\left( {\upeta_{\text{p}}^{2} } \right) = 0.26\left( {0.25} \right)$$. Post-hoc analysis revealed significant decrease in control group (pre- to post-) with no change in the intervention group. In addition, there were significant interaction effects for behavioural process, F(2, 283) = 5.905, p-value $$\left( {\upeta_{\text{p}}^{2} } \right) = 0.003\left( {0.040} \right)$$. Post-hoc analysis revealed significant increase in the intervention group (at all time points) while in the control group, significant increment was only found at mid to post-test. BBPAS was successful in improving the process of change towards physical activity. Thus, BBPAS could be recommended to be use throughout Malaysian primary schools.

Hussein Rizal, Mawar Siti Hajar, Ayu Suzailiana Muhamad, Garry Kuan

### The Effects of Brain-Breaks on Short-Term Memory Among Primary School Children in Malaysia

Introduction: Brain-breaks is a physical activity video that is designed for school settings to stimulate student’s physical health, learning and cognitive function. However, its effects on short-term memory have not been determined to date. Purpose: This study aimed to investigate the effects of brain-breaks on short-term memory among primary school children in Malaysia. Methods: A total of 159 male and 176 female students aged 10 to 11 years old (mean age = 10.51 ± .50) from two schools in Kelantan were recruited. Purposive sampling was used to divide the students into intervention (n = 183) and control (n = 152) groups. The brain-breaks session lasted only for five minutes where the students in the intervention group perform the exercises during the school day (i.e. five times per week) for twelve weeks. Short term memory was assessed using the Digit Span Test. This test was carried out at pre-, mid- and post-test. Mixed repeated measure analysis of variance was used to analyse the data. Results: There was a significant effect on time, F (2, 298) = 25.659, p-value $$\left( {\upeta_{\text{p}}^{2} } \right) = .001\left( {.147} \right)$$ and interaction, F (2, 298) = 16.822, p-value $$\left( {\upeta_{\text{p}}^{2} } \right) = .001\left( {.101} \right)$$ on the short-term memory. Short term memory was significantly different between both groups, F (1, 299) = 15.44, p-value (ηp2) < .001 (.049). Conclusion: Brain-breaks was successful in improving the primary students’ short-term memory. Future research should consider adding other tests to measure the cognitive domains of students to understand the benefits of Brain-breaks further.

Mawar Siti Hajar, Hussein Rizal, Ayu Suzailiana Muhamad, Garry Kuan

### Effects of Using EEG Neurofeedback Device to Enhance Elite Bowlers’ Performance

Participation in a sports activity is highly competitive, and self-regulation via neuro-feedback training is one way of increasing performance by helping athletes to control focus and reducing anxiety. A cross-over design randomized, controlled trial was conducted at the tenpin bowling National Training Center, to determine whether the use of a EEG-MUSE neuro-feedback training enhances the performance and reduces the anxiety of tenpin bowlers. Eleven physically healthy tenpin bowlers, aged 15–21 years old were randomly allocated into the two conditions, the control and EEG-MUSE neuro-feedback training. Participants, when received the EEG-MUSE neuro-feedback intervention, obtained higher game score (358 ± 28) as compared to the control (344 ± 23). However, the difference was not significant (p > 0.05). The Revised competitive sport anxiety inventory (CSAI-2R) scores were also not significantly different between both conditions. Short-term neuro-feedback training did not improve bowling performance. A more extended period of neuro-feedback training may be warranted.

Qasim Raza, Marilyn Li Yin Ong, Garry Kuan

### Transcranial Direct Current Stimulation Enhances Skill-Related Fitness Among the Under-15 Football Players

The body’s central nervous system plays an essential role in preventing fatigue and enhance exercise tolerance. The non-invasive technique of transcranial direct current stimulation (tDCS) can provide insight into the relationship between brain function and exercise performance. The objective of this study was to examine the difference in skill-related fitness between tDCS stimulation and non-stimulation among the Malaysian under-15 elite football players. This is a cross-over, randomised controlled trial study under the Malaysian National Football Development Programme (NFDP). Twenty participants aged between 14 to 15 years old, with at least two years of competitive experience representing the state, participated in this study. The participants’ anthropometric assessment of weight, height, body mass index (BMI), and body composition fat were measured. The participants were randomly assigned to receive 20 min of tDCS or sham stimulation. Skill-related fitness assessments consisted of sit and reach, hand grip strength, back and leg strength, standing long jump, vertical jump, 1-min sit-up and 1-min push up test were measured after the stimulation. The results showed that the participants who received tDCS stimulation showed a trend in improvement although showing no significant effect of tDCS stimulation on back and leg strength, standing long jump, and 1 min sit-up. The results showed that tDCS could enhance the skill-related fitness of football players.

Mohammad Saifatullizam Mustafa, Marilyn Li Yin Ong, Siti-Azrin Ab Hamid, Garry Kuan

### Perceived Risk and Perceived Competence in White Water Rafting Activity at Kampar River, Gopeng, Perak

This study aimed to identify the level of perceived risk and perceived competence in white water rafting activity. Dimension of an Adventure Experience (DAE) was used to measure the level of perceived risk and perceived competence. 404 sample of white water rafting participant in Kampar River, Perak, Malaysia have participated in this study. The result indicated a significant increase in perceived competence and a significant decrease in perceived risk, after the participant engaged in the activity. The comparison between groups revealed a significant difference on measure of perceived risk and perceived competence.

Hajar Asmidar Samat, Nelfianty Mohd Rasyid, Thariq Khan Azizuddin Khan, Mohd Noorazlan Ab Aziz, Mustakim Hashim, Helme Basal

### The Effects of Integrating Biofeedback Training into a 12-Week Periodized Training Program on Galvanic Skin Response and Anxiety Level Among Junior Archers

This study investigated the effects of integrating biofeedback training into a 3-month periodized training program on psychophysiological outcomes among junior archery athletes. Twenty-one junior archers (age = 15.0 ± 1.7 years) participated in the study. Participants were matched according to their shooting scores and they were assigned into either three groups; biofeedback training (BFT), physical training (PT) and control groups (CON). Both experimental groups underwent three months of periodized training program, while the control group continued the normal routine training until end of the study period. All parameters were measured at baseline, pre-intervention, mid, and post-intervention. The results of mixed factorial analysis of variance (ANOVA) revealed a significant interaction between experimental groups across the measurement sessions (p < 0.05) for galvanic skin response (GSR). The finding showed that the experimental groups had significantly better reduction in GSR value compared to the control group. No significant interactions between the experimental groups across the measurement sessions for somatic anxiety, cognitive anxiety as well as self-confidence. However, the results indicated a pattern of decrement in somatic and cognitive anxiety among participant in the experimental groups. Furthermore, similar pattern was observed for the self-confidence after the intervention for the experimental groups. It can be implied that biofeedback training program and physical training program are equally effective in improving the psychophysiological among junior archers compare to the normal routine training.

Mon Redee Sut Txi, Hairul Anuar Hashim, Oleksandr Krasilshchikov

### Changes in Galvanic Skin Responses Following a Single Session Training of Progressive Muscle Relaxation Technique Among Adolescent Football Players

The present study compared the immediate effects of a single session of seven and sixteen muscle groups progressive muscle relaxation training on galvanic skin response (GSR) variables: time to stabilization (Ts), stabilization score (Ss), tonic skin conductance adaptation level (ScAL), tonic skin conductance no.of skin fluctuation (SFs), mean of tonic skin conductance (Sc), and coping response. Twenty-six adolescent football players (Mean age = 13.4 yr., SD = 0.5) who were inexperience in PMR training were randomly assigned to either a seven or sixteen muscle groups PMR or a control group. GSR variables were recorded in the first five minutes prior to the start of PMR exercise (pretest) and immediately after PMR exercise (posttest). The results revealed a significant (p < 0.05) improvement in ScAL for both PMR groups immediately after relaxation session. However, only sixteen muscle groups PMR reported a significant improvement in SFs compare to the control group. Control group produced significantly longer Ts from pre to post test. The results suggest that that a longer version PMR (16 muscle groups) lead to better immediate effects especially for inexperienced trainees.

Sharifah Maimunah Syed Mud Puad, Hairul Anuar Hashim

### Backmatter

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# Homework Help: Subbing t=∞ into Integral

1. Apr 27, 2010

### frenzal_dude

1. The problem statement, all variables and given/known data
Hi, I need to find the Fourier Transform of:

g(t) = (e^-t)Sin(Wct)u(t)

where Wc=2πFc
and u(t) is the step function which is equal to 1 if time is +ve and 0 otherwise.

2. Relevant equations
I know that g(t) = (e^-t)[e^jWct - e^-jWct]/2j = [e^-t(1+jWc) - e^t(-1-jWc)]/(2j)
(0<=t<=∞, because of step function u(t))

3. The attempt at a solution
Therefore the Fourier Transform would be:
[1/(2j)]*∫([e^-t(1+jWc) - e^t(-1-jWc)])(e^-jWt)dt

= [1/(2j)]*∫([e^-t(1-jWc+jW) - e^t(-1-jWc-jW)])dt (limits: t=∞ to t=0)

= [1/(2j)][(e^-t(1-jWc+jW))/(-(1-jWc+jW)) - (e^t(-1-jWc-jW))/(-1-jWc-jW)] (sub in: t=∞ to t=0)

If you sub t=+/-∞, the exponential could be 0 or it could be infinite depending on whether 1-jWc+jW and -1-jWc-jW are -ve or +ve.
How can we know if they are positive or negative?

Hope you guys can help!
David.

Last edited: Apr 28, 2010
2. Apr 28, 2010

### gabbagabbahey

I'd assume that Wc ($\omega_c$?) is real-valued.

$$\lim_{t\to\infty}e^{-zt}=0[/itex] So long as the real part of $z$ is positive. Also, if $g(t)$ is zero for negative $t$, why is one of your integration limits $-\infty$? 3. Apr 28, 2010 ### frenzal_dude so is it also true to say: [tex]\lim_{t\to\infty}e^{zt}=0[/itex] so long as the real part of $z$ is negative? If that's true that helps me out A LOT! This is something not even my Signal Processing lecturer could explain to me, he told me 'he'd get back to me' and he never did. Thankyou so much for your help! Btw I fixed up the limits, you're right it's from t=infinity to t=0 4. Apr 28, 2010 ### frenzal_dude btw this is the answer I got: [tex]\frac{\omega + j}{(\omega_c-w)^2+1}$$

5. Apr 29, 2010

### gabbagabbahey

Yes, it's fairly easy to show simply by splitting $z$ into real and imaginary parts. Say $z=x+jy$, where $x$ and $y$ are real-valued. Euler's formula then tells you

$$e^{zt}=e^{(x+jy)t}=e^{jyt}e^{xt}=\cos(yt)e^{xt}+j\sin(yt)e^{xt}$$

As $t\to\infty$, both $\sin(yt)$ and $\cos(yt)$ oscillate between $0$ and $1$ more and more rapidly, and hence are bounded. Meanwhile, $e^{xt}$ goes rapidly to zero if $x<0$ and so its product with any bounded function will also approach zero.

That doesn't look quite right, you'd better show your calculations.

Last edited: Apr 29, 2010
6. Apr 29, 2010

### frenzal_dude

Here's my working out:

$$g(t)=e^{-t}sin(\omega _ct)u(t)= e^{-t}(\frac{1}{2j}e^{j\omega _ct}-\frac{1}{2j}e^{-j\omega _ct})u(t)$$

Last edited: Apr 29, 2010
7. Apr 29, 2010

### frenzal_dude

$$\therefore G(f) =\frac{1}{2j}\int_{0}^{\infty }(e^{j\omega _ct-t}-e^{-j\omega _ct-t})e^{-j\omega t}dt=\frac{1}{2j}\int_{0}^{\infty }e^{j\omega_ct-t-j\omega t}-e^{-j\omega_ct-t-j\omega t}dt$$

8. Apr 29, 2010

### frenzal_dude

$$\frac{1}{2j}\int_{0}^{\infty }e^{j\omega_ct-t-j\omega t}-e^{-j\omega_ct-t-j\omega t}dt=\frac{1}{2j}[\frac{e^{t(j(\omega_c-w)-1)}}{j\omega_c-1-j\omega}-\frac{e^{-t(j(\omega_c+w)+1)}}{-j\omega_c-1-j\omega}]t=\infty ,t=0$$

9. Apr 29, 2010

### frenzal_dude

$$=-\frac{1}{2j}[\frac{1}{j(\omega_c-\omega)-1}+\frac{1}{j(\omega_c+\omega)+1}]=\frac{\omega_c+\omega+j}{2(\omega_c+\omega)^2+2}+\frac{\omega_c-\omega-j}{2(\omega_c-\omega)^2+2}$$

10. Apr 29, 2010

### gabbagabbahey

Ermm... you mean $g(t)=e^{-t}\left(\frac{1}{2j}e^{j\omega _ct}-\frac{1}{2j}e^{-j\omega _ct}\right)u(t)$, right? You can't get rid of the $u(t)$ until you put it into the integral and use the fact that $\int_{-\infty}^{\infty}f(t)u(t)dt=\int_{0}^{\infty}f(t)dt$

This looks fine, but it doesn't simplify to what you wrote originally.

11. Apr 29, 2010

### frenzal_dude

do you mean what I wrote originally by this: $$\frac{\omega + j}{(\omega_c-w)^2+1}$$

I realised where I went wrong and tried it again.

With my final answer, which I hope is now correct, I tried getting a common denominator to make it into one fraction but the fraction ended up being even more complicated, so I thought I'd just leave the answer as how I gave it before

(btw here was the fraction I got when I simplified it: $$\frac{\omega_c(\omega_c^2+\omega^2+1)-2\omega^2-2\omega j}{(\omega_c^2+\omega^2+1)-4\omega^2}$$)

12. Apr 30, 2010

### gabbagabbahey

Personally, I wouldn't worry so much about making the denominator real and instead concentrate on putting it over a common denominator:

\begin{aligned}-\frac{1}{2j}\left[\frac{1}{j(\omega_c-\omega)-1}+\frac{1}{j(\omega_c+\omega)+1}\right] &= -\frac{1}{2j}\left[\frac{j(\omega_c+\omega)+1+j(\omega_c-\omega)-1}{\left(j(\omega_c-\omega)-1\right)\left(j(\omega_c+\omega)+1\right)}\right] \\ &= -\frac{1}{2j}\left[\frac{2j\omega_c}{j^2(\omega_c^2-\omega^2)-2j\omega-1}\right] \\ &= \frac{\omega_c}{\omega_c^2-\omega^2+2j\omega+1} \end{aligned}

13. May 2, 2010

### frenzal_dude

Thanks for the help.

Quick question in regards to $$\lim_{t\to\infty}e^{-zt}=0$$

What if z is only imaginary? ie. the real part is 0.

How would you sub t=∞ into this: $$e^{j(\omega_1 t+\Theta_1)-jwt}$$

14. May 3, 2010

### gabbagabbahey

If the real part is zero, then the limit won't exist. You can use Euler's formula to show this.

format: plain


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# How do you rationalize the denominator and simplify sqrt(3)/(sqrt(7)-2)?

Mar 2, 2018

$\frac{\sqrt{21} + 2 \sqrt{3}}{3}$

#### Explanation:

To rationalize the denominator, the best move is to multiply the numerator and denominator by the reciprocal of the denominator (which is the denominator but with the middle sign reversed).

$\frac{\sqrt{3}}{\sqrt{7} - 2} \cdot \textcolor{b l u e}{\frac{\sqrt{7} + 2}{\sqrt{7} + 2}}$

(sqrt(3)(sqrt(7)+2))/((sqrt(7)-2)(sqrt(7)+2)

From here, we can simplify the numerator and denominator.

$\sqrt{\alpha} \sqrt{\beta} = \sqrt{\alpha \beta} \to \sqrt{3} \sqrt{7} = \sqrt{21}$

$\sqrt{3} \left(\sqrt{7} + 2\right) = \textcolor{red}{\sqrt{21} + 2 \sqrt{3}}$

$\left(\sqrt{7} - 2\right) \left(\sqrt{7} + 2\right) = 7 + \cancel{2 \sqrt{7} - 2 \sqrt{7}} - 4 = \textcolor{red}{3}$

$\frac{\sqrt{3}}{\sqrt{7} - 2} = \textcolor{red}{\frac{\sqrt{21} + 2 \sqrt{3}}{3}}$


text:
iheartfood one year ago #1: When you heat an air-filled balloon, what happens inside with regard to the movement of air molecules? A. The collisions of air molecules against the wall of the balloon are weaker. B. The collisions of air molecules against the wall of the balloon are stronger. C. The collisions of air molecules against the wall of the balloon do not change. **my answer: B is that right?? @aaronq :)

1. iheartfood

#2: You have 0.5 L of air at 203 K in an expandable container at constant pressure. You heat the container to 273 K. What is the volume of air? A. 0.37 L B. 0.67 L C. 1.5 L D. 0.25 L **myanswer: B. 0.67 L is that right?

2. iheartfood

#3: You place a balloon in a closed vacuum chamber at standard temperature and pressure (STP). You decrease the chamber temperature by half but keep the pressure constant. What happens to the balloon? A. It reduces in size by half. B, It stays the same volume. C. It doubles in volume. D. It expands to four times the original volume. *my answer: A is that irhgt?

3. aaronq

they both are correct

4. aaronq

3 is good too

5. iheartfood

#4: A balloon contains 0.5 L of air at 273 K. Its volume increases to volume of 0.75 L at constant pressure. What is the temperature of air inside the balloon? A. 137 K B. 182 K C. 205 K D. 410 K **my answer: D. 410 K is that right?? and yayy :)

6. aaronq

for #4, if you increase the volume the temp will go down

7. iheartfood

#5: This question appears on a quiz. "A 1.0 L balloon has a temperature of 273 K. When the temperature changes to 30°C, what is the volume?" A student answers 0.11 L. Which of the following explanations is true? (C = K 273; K = C + 273.) A. The student did not solve for the correct parameter, and the answer should be 1.11 L. B. The student did not solve for the correct parameter, and the answer should be 0.90 L. C. The student did not put the temperatures in the same units, and the answer should be 0.90 L. D. The student did not put the temperatures in the same units, and the answer should be 1.11 L. **My answer: D not too sure tho... is that right? :/

8. iheartfood

so #4 is wrong then>?? idk what it is :(

9. aaronq

for #4, you use P1V1=P2V2 plug the numbers in and you can't ever get a wrong answer.. unless you put them in the wrong place

10. iheartfood

i don't even know haha :/ like how do u plug them in? cuz i definitely didn't do it right :/

11. aaronq

for #5, the "student" divided 30/273.. so i would say wrong parameters.. idk how someone would do that though

12. iheartfood

like what goes where?

13. iheartfood

wait so the answer to #5 is this? A. The student did not solve for the correct parameter, and the answer should be 1.11 L.

14. aaronq

P=pressure V= volume on one side is the set for the system at one point, then across the equal sign for the change

15. aaronq

for #5, 1.11L is not the correct answer...

16. iheartfood

so #5 is B. The student did not solve for the correct parameter, and the answer should be 0.90 L. ???? and I'm confused about #4 now haha :/ could u pls show me how u do it? :/

17. iheartfood

heres how i think it is based off what u said.. :/ .5/273=.75/x and solve for x? is that right?

18. iheartfood

and i got x=409.5 which is about 410K.. which is D.. but you said that #4 isn't D right?? :/ so i don't know what to do now :( @aaronq what do i do for it then?

19. aaronq

no they're not being divided

20. aaronq

PV=nRT it's basically based off the ideal gas law, PV/nRT of one system equals PV/nRT of the other $\frac{ P _{1}V _{1} }{ n _{1}RT _{1} }=\frac{ P _{2}V _{2} }{ n _{2}RT _{2} }$ when all the variables like T or n are constant, it simplifies to P1V1=P2V2

21. iheartfood

okay so how do i apply that with the values that they give me?

22. aaronq

so for number 4, (0.5 L)(273 K)= (0.75 L)(T) (0.5 L)(273 K)/(0.75 L) = T

23. iheartfood

oh so i get 182.. which is answer choice B right?

24. iheartfood

and was #5's answer B. The student did not solve for the correct parameter, and the answer should be 0.90 L. ??

25. aaronq

yes

26. iheartfood

yes to both 4 and 5? haha

27. aaronq

4 yes, 5 idk the student did both, not change his temperature units, and divided the wrong way...

28. iheartfood

okay... so which would u go with for 5?? cuz idk haha

29. aaronq

i would go with C, because the student still got an answer in litres... somehow lol

30. iheartfood

okay haha :) thanks!!!:)

31. aaronq

no prob! :)

32. Not the answer you are looking for?
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# Why OLS perform better than LASSO?

I am comparing OLS and LASSO regression for survey data. I have n>p, but I think my data is high-dimensional data as the p is 3000 and n is 48000. I am using k cross-validation. The results are quite surprising as from R-squared and MSE, the OLS performs much better than LASSO. I have read several discussions and papers previously, but still, I can't figure out why...

• are you looking at in-sample or out-of-sample performance? Apr 29, 2022 at 14:32
• both. results for both samples are showing that OLS perform better Apr 29, 2022 at 14:48
• Why is it surprising? Have you considered how your OLS is estimated in the n<<p regime? Also, the No Free-lunch Theorem applies. Apr 29, 2022 at 14:55
• sorry, I corrected my question. p=3000 and n=48000. so it is n>p. But I think I still can categorize it as high-dimensional data, correct me if I'm wrong. One that I'm aware is LASSO will perform better than linear regression in high-dimensional data through regularization/shrinkage. But I don't find it in my case. Apr 29, 2022 at 15:08

This is one example of a "curse of dimensionality" described for LASSO in An Introduction to Statistical Learning, second edition, at the end of Chapter 6.

With a large number of potential predictors and LASSO forced to choose a comparatively small number among them, there's an increasing risk as p increases that some truly insignificant predictors might by chance have an association with outcome in a particular data sample and be included erroneously. That might also lead to omission of truly significant predictors and poor generalizability.

With OLS in this scenario, all of your potentially important predictors are available to the final model. With a 16:1 n:p ratio, that probably isn't at much risk of overfitting. For prediction, throwing away predictors (even "insignificant" ones) doesn't typically do much good unless you are overfitting. So OLS wins here.

• Would you expect Ridge regression to perform better since it would not completely remove predictors from the model?
– Eli
Apr 29, 2022 at 17:02
• @Eli better than LASSO but maybe not better than OLS in this particular case, as you might not need any penalization at all with your fairly high n:p ratio. Penalization (ridge or LASSO) trades off an increase of bias for a decrease in variance when applied to new cases. If your model isn't overfitting and thus has low variance on new cases, there is no need for that tradeoff. In general, however, ridge can do better than LASSO for predictions if you don't need to cut down on the number of predictors and many are outcome-related, or than OLS when you are close to overfitting. Try it and see.
– EdM
Apr 29, 2022 at 17:09