Which statement best defines anaerobic exercise?

• A. Long-duration activity where the heart can supply all oxygen needed.
• B. Short bursts of physical activity where the heart can't supply the oxygen that muscles use fast enough.
• C. A steady state activity where oxygen supply exceeds demand.
• D. Any exercise performed at low intensity.

Answer: (B)

Anaerobic exercise involves short, high-intensity efforts where the muscles work so hard that the heart and lungs can’t supply oxygen quickly enough to meet the demand. In these moments, energy comes from pathways that don’t require oxygen, like the phosphagen system and anaerobic glycolysis, which can produce quick bursts of energy but also lead to fatigue sooner. This is why such efforts can be sustained only briefly, unlike activities where oxygen supply can meet or exceed the demand.

Long-duration activities that the body can supply all the oxygen needed are aerobic. A steady state where oxygen supply exceeds demand is also aerobic. Exercising at low intensity is typically aerobic as well, since it doesn’t push the body into a high-oxygen-demand state.