What units are used to measure aerobic exercise intensity?

• A. kcal
• B. METs
• C. Watts
• D. Steps

Answer: (B)

Measuring how hard the body is working during aerobic activity is about intensity relative to resting energy use, and METs (metabolic equivalents) do exactly that. One MET represents the energy cost of sitting quietly and serves as a baseline. Activities are assigned MET values that reflect how many times higher their energy demand is compared with rest, so you can compare effort across different activities and different people. This makes METs a standard way to express aerobic intensity, allowing clear categorization like light, moderate, and vigorous effort.

Other options don’t capture intensity in the same way. kcal measures total energy expended, not how hard the activity feels or costs per unit time. Watts reflects instantaneous power output for equipment like bikes or step machines, which is modality-specific and doesn’t translate across activities. Steps quantify volume of movement, not how strenuous that movement is. While some methods use %VO2max or %HRR to indicate intensity, METs provide a widely used, cross-activity standard to describe how demanding an activity is relative to resting metabolic rate.