Cardio: easy days, hard days, and why both matter
Most cardio should be easy enough to talk through. One or two harder sessions a week build fitness fast. Both are needed.
The full lesson
Cardio is any activity that raises your breathing for a while: walking, cycling, swimming, dancing, jogging, sports. Two rules: (1) Most of it — about 80% — should be easy, talking pace. That builds the engine without wearing you down. (2) Once you have a base of four weeks or more, one session a week can be harder: intervals (1 minute faster, 2 minutes easy, repeated 6 times) or a steady "comfortably hard" 20 minutes. That builds fitness faster than the same time at one pace.
Athletes and performance goals add a second quality session and one long easy session. Everyone else gets nearly all the health benefit from the easy days plus one harder day.
Remember
- 80% easy, 20% harder.
- Intervals after a four-week base.