Question

You are talking with a friend who has recently started an exercise regimen, and they comment that they are planning to quit because they experience muscle soreness following their workouts. In your communication assignment for this week explain why this occurs. You should focus on the molecular mechanism of muscle contraction and how muscles become fatigued. You should also discuss the ways muscles adapt to changing activity levels at the molecular level as you encourage them to increase their fitness level.

Answer 1

Muscle contraction mechanism can be explained by cycle of molecular events which involve mysoin filaments and actin. During muscle contraction there is formation of actin myosin complex , the actin myosin complex undergoes a power stroke and both of them are separated bringing about muscle contraction. There is another molecule involved called troponin which has three sites namely I, T , C . The troponin C site helps in releasing Calcium which is required for muscle contraction. In smooth muscle there is absence of this troponin C and there is calmodulin to provide calcium .

Now to understand how muscles get fatigue one need to understand that stenosis exercise cause depletion in ATP and calcium reserves along with depletion in oxygen supply to the muscle. Due to decreased oxygen supply and increase in work done there occurs anaerobic respiration leading to accumulation of Lactic acid and thus fatigue.