Which of the following best describes anaerobic exercise?

Anaerobic exercise is characterized by high-intensity activities performed over short durations, in which the body relies on energy sources stored in the muscles rather than oxygen. This type of exercise engages fast-twitch muscle fibers and involves activities such as sprinting, heavy weightlifting, and high-intensity interval training (HIIT). During anaerobic conditions, the body breaks down glucose for energy in the absence of oxygen, leading to the production of lactate. This energy pathway allows for quick bursts of power and strength but can only be sustained for brief periods due to the rapid accumulation of fatigue-inducing byproducts.

In contrast, the other descriptions reflect aerobic conditions—where sustained, lower-intensity activities rely on oxygen for energy and involve endurance-building exercises. Activities that require oxygen and are performed over longer durations primarily utilize slow-twitch muscle fibers and focus on increasing cardiovascular efficiency. Recognizing the distinction between aerobic and anaerobic exercise is crucial for designing effective training programs tailored to specific fitness goals.