Which of the following is NOT true regarding red muscle fibre
(Increased muscle fibre length): (79-Guyton 12n edition; 173-AK-jain 5th; 107- Ganong 24th)White (fast) muscle fibre (Type II)Red (slow) muscle fibres (Type I)1. Here muscle fibres are large in diameter with high glycogen capacity and AT pase activity because they are pale due to less amount of myoglobin content, therefore called white' muscle fibresThese muscle fibres are of moderate diameter and moderate glycogen capacity with low ATPase activity, because they are darker than other muscle fibers, therefore called red muscle fibers)2. They are innervated by large fast conducting motor neurons (size principle neurons) ie having 50 times the contractile force of the smallest units, there fore also called fast ' muscle fibersThey are innervated by small, slow conducting motor neurons therefore also called 'slow' muscle fibres3. Their muscles have short twitch durations (7.5 msec) and are specialized for fine rapid and skilled movement eg extraocular muscles and muscles of the handThese muscles respond slowly (twitch duration 100 msec and long latency and are adapted for long sustained, slow posture maintain contractions eg long muscles of limb and muscle of the back)4. These muscles get fatigued easily (less vascular, fewer mitochondria)These muscles are resistance to fatigue and most usedmuscle {Highly vascular abundant mitochondria)5. They are particularly suited for high intensity workbout that can be sustained for only short period timeThey are required to perform work when endurance type activities are performed ie to perform low intensity work over long periods of time such as athletes running bicyclist and swimmers6. Prone to O2 debt (because their resting blood flow is low being 3ml / 100 g/min)Unlikely to be exposed to 02 debt
Decrease glycolytic enzyme
Increase blood flow
Increased muscle length fibre
Used for aerobic activity
General