Ask ten people how much cardio they should be doing and you will get ten answers, most of them wrong in one direction or the other. The internet has convinced a subset of lifters that cardio kills gains. It has convinced a subset of runners that anything less than an hour a day is inadequate. Neither position matches what large public-health bodies actually recommend, or what the evidence supports.
The recommendation, in its plainest form, has been remarkably stable for two decades. It is also more achievable than most people assume.
The number to know
The U.S. Physical Activity Guidelines for Americans, the World Health Organization, and the American College of Sports Medicine all converge on roughly the same target for adults:
- 150 to 300 minutes of moderate-intensity aerobic activity per week, or
- 75 to 150 minutes of vigorous-intensity aerobic activity per week, or
- An equivalent combination of both
Moderate intensity means you can talk but not sing. Vigorous means you can only get a few words out at a time. Notice the range: 150 minutes is the floor at which meaningful health benefits appear. 300 is where the dose-response curve starts to flatten for most outcomes, though additional benefits continue past that point at diminishing returns.
What that actually looks like
Two hundred minutes a week — a reasonable middle of the range — works out to about 30 minutes, six days a week, or 45 minutes, four to five days a week. It can be a brisk walk, a bike commute, an easy jog, a rowing session, or a stretch of vigorous yard work.
It does not need to happen in one block. The old guideline of "at least ten minutes at a time" was removed in the 2018 update precisely because the evidence no longer supports it. Short bouts count. A ten-minute walk after lunch is not a compromise; it is a legitimate contribution to your weekly total.
If you are meeting the 150-to-300 minute range each week and training strength twice, you are, on paper, doing more than roughly 75% of American adults.
Why cardio matters even if you're strong
Muscle strength and cardiorespiratory fitness are somewhat independent physiological systems, and both independently predict mortality risk. A powerful lifter with poor VO2 max has a worse long-term prognosis than that same lifter would with a moderate aerobic base.
Aerobic exercise develops mitochondrial density, capillary networks, stroke volume, and metabolic flexibility — all of which support daily function and recovery from heavier training. Even competitive powerlifters benefit from a modest cardio floor.
Vigorous is more time-efficient
The two-to-one ratio in the guidelines (150 moderate equals 75 vigorous) reflects real physiology. Vigorous aerobic work produces more cardiorespiratory adaptation per minute — although with higher perceived effort and, in some populations, higher joint or cardiovascular risk.
For a healthy adult short on time, 25 minutes of hard cycling three days a week technically meets the vigorous guideline. Whether it also meets your other goals — enjoyment, sustainability, low soreness — is a separate question.
The muscle-strengthening companion
The cardio guideline is always paired with a resistance-training guideline: muscle-strengthening activities involving all major muscle groups on two or more days per week. This is not optional if you care about aging well. Cardio alone will not preserve muscle mass, bone density, or fall resistance.
A weekly template that satisfies both: three 40-minute aerobic sessions plus two 30-minute strength sessions. Total time commitment: roughly three hours.
The bottom line
- 150 minutes moderate or 75 minutes vigorous per week is the evidence-based floor
- More helps, up to about 300 moderate minutes, then benefits taper
- Short bouts count toward your weekly total
- Cardio does not replace strength training, and strength training does not replace cardio
- Consistency at the floor beats sporadic heroics at the ceiling
Most adults who feel they "never do enough cardio" would be surprised to find that a brisk 30-minute walk five days a week already meets the recommendation. The bar is lower than the fitness industry lets on. What matters is clearing it, week after week.