What percentage marks the anaerobic threshold?

• A. 60%
• B. 80%
• C. 70%
• D. 90%

Answer: (B)

The key idea is the point at which the body shifts from mainly aerobic energy production to relying more on anaerobic metabolism, causing lactate to start accumulating in the blood. This anaerobic threshold is reached at a high exercise intensity, typically around 80% of maximum oxygen uptake (VO2 max) for many people. That’s why 80% is the best choice—it's the commonly cited benchmark in GCSE PE for when the body crosses into anaerobic-dominated energy production. The other percentages represent intensities where aerobic metabolism still predominates (60% and 70%), or an even higher, near-max effort rather than the threshold itself (90%).