Rhythmic movement — walking, cycling, swimming — that raises heart rate and trains the heart, lungs and muscles to use oxygen.
How it works, step by step
Muscles demand more ATP.
Heart rate and breathing rise to deliver oxygen.
Over weeks, the heart pumps more per beat and muscles grow more mitochondria.
Resting heart rate often falls.
How much
At least 150–300 minutes of moderate or 75–150 of vigorous activity a week for adults.
Something beats nothing
Benefits start with small amounts — even short walks count.
Evidence & sources
Adults should do 150–300 minutes a week of moderate-intensity aerobic activity, or 75–150 minutes of vigorous activity. Evidence: strong. Known: Based on a systematic review by the Physical Activity Guidelines Advisory Committee. Unknown: Optimal amounts for specific outcomes. Source: US Department of Health and Human Services, Physical Activity Guidelines for Americans, 2nd edition (2018).