The partial catabolism of glucose to generate ATP occurs in anaerobic cellular respiration. This system can provide enough energy for about 30-40 seconds of maximal muscle activity (e.g., 300-meter race).
Muscular activity lasting more than 30 seconds depends increasingly on aerobic cellular respiration (reactions requiring oxygen). This system of ATP production involves the complete oxidation of glucose via cellular respiration (biological oxidation).
Only 40% of the energy released in muscle activity is useful as work
The remaining 60% is given off as heat
Dangerous heat levels are prevented by radiation of heat from the skin and sweating