What is a significant indicator that Liz is performing anaerobic exercise?

When assessing indicators of anaerobic exercise, one significant marker is the instant fatigue and need to stop. Anaerobic exercise typically involves high-intensity effort performed over a short period, where the body relies on energy sources stored in the muscles rather than oxygen. During this type of exercise, such as sprinting or heavy weightlifting, the body can quickly deplete its energy reserves, leading to rapid fatigue.

The demand for oxygen exceeds the available supply, causing a buildup of lactic acid and resulting in a sense of immediate exhaustion. This fatigue can be so intense that it requires the individual to stop the exercise quickly. This characteristic contrasts sharply with aerobic activities, where the body can sustain exercise for longer durations at a manageable intensity. Consequently, the rapid onset of fatigue is a clear indicator of anaerobic exercise, demonstrating the physical limitations imposed by such high-intensity efforts.