Final answer:
The body relies on anaerobic energy production from ATP and creatine phosphate during the initial stages of activity, followed by anaerobic glycolysis once ATP from creatine phosphate is depleted. Glycolysis breaks down glucose to produce ATP and lactic acid, providing energy for about 90 seconds of muscle activity.
Step-by-step explanation:
During the first few minutes of activity, the body initially relies on anaerobic energy production from ATP and creatine phosphate. Creatine phosphate can supply energy at a very high rate for approximately 8-10 seconds. As ATP produced by creatine phosphate is depleted, the body then turns to anaerobic glycolysis to produce more ATP. This process breaks down glucose to produce ATP and pyruvate, with pyruvate being converted to lactic acid when oxygen is not available, which can lead to muscle fatigue and soreness.
The transition to glycolysis results in a slower rate of ATP availability compared to the rapid generation from creatine phosphate, but it can still support muscle activity for about 90 seconds. Eventually, as oxygen supply catches up due to increased heart and lung activity, aerobic respiration can commence, using oxygen to create ATP for longer periods of muscle exertion.