Which activities are considered anaerobic in nature based on duration and intensity?

• A. Activities lasting more than five minutes at low power
• B. Activities under two minutes with moderate to high power
• C. Endurance running for 30 minutes
• D. Light resistance training with long rest periods

Answer: (B)

Anaerobic efforts are defined by short duration and high intensity, when the body relies on energy systems that don’t require oxygen to produce ATP quickly. When you perform work that lasts under about two minutes at moderate to high power, the body's immediate energy sources—ATP-PC (phosphagen) and anaerobic glycolysis—drive most of the effort. Oxygen delivery isn’t the limiting factor for these bursts, so the dominant energy pathway is anaerobic.

That’s why the option describing under-two-minutes duration with moderate to high power fits best. In contrast, activities lasting more than five minutes at low power draw on aerobic metabolism, where the body uses oxygen to sustain energy production over longer periods. Endurance running for 30 minutes is a classic aerobic activity. Light resistance training with long rest periods involves low work intensity and ample recovery, so it doesn’t rely primarily on anaerobic energy to the same extent.