Final answer:
Active muscle cells can burn 50 times more energy during vigorous activity compared to resting because of the high energy demands, prompting a shift from aerobic to anaerobic metabolism for ATP production.
Step-by-step explanation:
When you participate in vigorous activity, your very active muscle cells can burn 50 times more energy compared to muscle cells at rest. This higher energy demand is because aerobic respiration, a process that breaks down glucose in the presence of oxygen to produce ATP, is more efficient when more energy is required.
During rest, the energy required for muscle function is comparatively lower, and thus, the rate of ATP consumption is less. However, during intense activities, such as sprinting or heavy lifting, the demand for energy is so great that the body cannot deliver oxygen quickly enough to the muscles to meet the demand solely through aerobic metabolism. As a result, the muscles rely more on anaerobic metabolism, which includes the breakdown of creatine phosphate as well as the conversion of pyruvic acid to lactic acid. Aerobic respiration is responsible for approximately 95% of the ATP production in resting or moderately active muscles, but during high-intensity exercises, energy production shifts to life up to these high energy demands.