The impact of COVID-19 on sedentary behavior among Chinese university students：a retrospectively matched cohort study

Purpose: This study was to estimate the impact of COVID-19 on sedentary behavior for Chinese university students during the pandemic period, as well as explore how sedentary behavior changed as a function of gender. 
Methods: We conducted an online questionnaire (the Sedentary Behavior Questionnaire) on 1487 (947 males & 513 females; Age 19.72± 1.32yr., BMI = 21.12 ± 4.50) students from one university in China during the pandemic period and students retrospectively recalled pre-pandemic physical activity levels (March 29- April 15, 2020). Sedentary behavior was measured using the short version of the Sedentary Behavior Questionnaire (SBQ). Sedentary behavior of social isolation in a typical week during the COVID-19 pandemic period and before the COVID-19 pandemic were measured based on SBQ. The data were analyzed using a paired-samples t-test. Chi-square tests were to compare categorical variables. 
Results: Before the COVID-19, on weekdays, survey participants averaged engaged in 11.41 (SD =3.93) hours of SB, 10.97 (SD = 3.85) hours of SB in males, 12.25 (SD =3.94) hours of SB in females; on weekends, survey participants averaged engaged in 13.18 (SD =4.06) hours of SB, 12.74 (SD = 3.96) hours of SB in males, 14.04 (SD =4.11) hours of SB in females. During the COVID-19, on weekdays, survey participants averaged engaged in 13.34 (SD =3.78) hours of SB, 12.90 (SD = 3.67) hours of SB in males, 14.19 (SD =3.83) hours of SB in females; on weekends, survey participants averaged engaged in 14.48 (SD =3.93) hours of SB, 14.10 (SD = 3.81) hours of SB in males, 15.22 (SD =4.04) hours of SB in females. Overall, on weekdays, COVID-19 on average appeared to increase SB by 1.93 (16.91%↑, 95% CI = 1.74, 2.12) hours, an increase in daily total SB by 1.92 (17.50%↑, 95% CI = 1.92, 2.15) hours for males, and an increase 1.94 (15.84%↑, 95% CI = 1.62, 2.27) hours in females. On weekends, COVID-19 on average appeared to increase SB by 1.30 (9.86%↑, 95% CI = 1.12, 1.48) hours, an increase in daily total SB by 1.36 (10.68%↑, 95% CI = 1.13, 1.58) hours for males, and an increase 1.18 (8.40%↑, 95% CI = 0.87, 1.50) hours in females. 
Conclusions: The COVID-19 led to an increase in sedentary behavior of Chinese university students. The total sedentary time of female students per week was higher than that of male students. Public policy action might be urgently needed to decrease the sedentary behavior of Chinese university students.