What best describes anaerobic exercise?

• A. Intense short bursts with no oxygen
• B. Long, slow endurance with oxygen
• C. Requires only flexibility
• D. Involves extended cardio sessions

Answer: (A)

Anaerobic exercise involves very high-intensity activity performed in a short time, where the muscles rely on energy sources that don’t require oxygen. When demand for quick energy outpaces the oxygen supply, the body taps into the phosphagen system for instant bursts and anaerobic glycolysis for slightly longer efforts. These pathways produce energy without using oxygen, but fatigue sets in quickly, usually within a couple of minutes, which is why such efforts are brief and explosive.

This is different from aerobic exercise, which uses oxygen to sustain lower-intensity activity over longer periods. The option describing long, slow endurance with oxygen fits that aerobic pattern, while flexiblity-only or extended cardio sessions don’t capture the high-intensity, short-duration nature of anaerobic work.