Question

Explain what is happening in muscle cells at a biochemical level as the intensity and length of workouts increases over time.

Answer 1

Each myosin molecule contains a globular head and tail portion. The binding of ATP (adenosine triphosphate) to the head region of myosin hydrolyzes the ATP to ADP (adenosine diphosphate), releasing the phosphate bond; this hydrolysis provides the energy for muscle contraction. Then the thick myosin filaments slide over the thin stationary actin filaments.

High energy components such as “creatine phosphate” contain phosphorus, which regenerates the ATP from ADP. The enzyme creatine phosphokinase increases the synthesis of creatine phosphate whenever the ATP levels are high.

With prolonged exercise, the creatinine phosphate levels decrease, and the muscles become fatigued. The muscles shift to anaerobic metabolism and produce lactic acid as a by-product, which later causes muscle soreness.