The CDC's physical activity guidelines call for adults to get at least 150 minutes of moderate-intensity aerobic activity weekly (30 minutes across five days, for instance), or 75 minutes of vigorous activity. On top of that, they call for muscle-strengthening work covering all major muscle groups at least twice a week. The two are listed as separate and equally necessary — not alternatives to choose between.
What cardio does that lifting doesn't
The American Heart Association arrives at the same 150-minutes-a-week figure, but from a cardiovascular-health angle. It points to lower blood pressure, improved cholesterol, and reduced long-term heart disease risk — outcomes that resistance training, however good for building strength and muscle, doesn't reliably produce on its own.
Will cardio hurt your gains?
At sensible doses, generally not. Lifters often worry about the "interference effect" — the idea that endurance work blunts strength and hypertrophy gains. That effect does show up at high volumes of intense endurance training, but a moderate amount of cardio, in line with the CDC's 150-minute figure, is unlikely to meaningfully compete with a structured lifting program for most people. The more realistic risk is under-recovering from too much combined volume, not cardio itself canceling out lifting progress.
How to fit both into a week
Most lifters can hit the CDC's aerobic target with 2–3 moderate cardio sessions of 20–30 minutes. Schedule them on non-lifting days, or after rather than before a lifting session, so leg strength isn't compromised heading into a heavy squat or deadlift day. Anyone following a Full Body or Upper/Lower training split will find it leaves more open days for cardio than a 5–6 day Push/Pull/Legs split does. Factor that into the weekly schedule instead of defaulting to the same days every time.
The takeaway
National guidelines treat strength training and cardio as two separate requirements to satisfy each week, not competing priorities. At moderate volumes, cardio supports recovery and cardiovascular health without meaningfully cutting into lifting progress.