Which of the following exercises is primarily anaerobic?

The exercise that is primarily anaerobic is weightlifting. Anaerobic exercises are those that involve short bursts of high-intensity effort where the body primarily relies on energy sources stored in the muscles, rather than oxygen from breathing. Weightlifting fits this description as it consists of lifting heavy weights for a few repetitions, often requiring maximal effort in a short duration, which cannot be sustained for long periods. This is because the energy demand exceeds the oxygen supply available, leading to reliance on anaerobic metabolism.

In contrast, jogging, swimming, and cycling at a moderate pace are mostly aerobic activities. These exercises are performed at a level where oxygen supply meets the energy demands of the body, allowing for prolonged participation. They rely on aerobic metabolism, which utilizes oxygen to convert carbohydrates and fats into energy over longer durations. This fundamental difference in how energy is produced during these types of activities helps to clarify why weightlifting is classified as primarily anaerobic.