Cardio kills your strength gains
Short answerSort of
On this page
Sort of, and much less than gym lore says. A 2022 analysis of 43 studies found that adding cardio to the same lifting program made no difference to maximum strength or muscle size. Only explosive power, like jumping, dipped a little, and mostly when both were done in the same session. For health, doing both beat either one alone by a wide margin.
What we’d do
Lift twice a week and walk most days, and don’t worry about it. If you do hard running or cycling too, put it on a different day from lifting, or at least a few hours apart. If you have to do both in one session and strength is your priority, lift first. Only athletes who need to jump or sprint should think harder than that.
If you remember three things
- Max strength and muscle size held up when cardio was added, across 43 studies.
- Explosive power dipped a little, mostly when both were in the same session.
- Both together went with the fewest deaths. About 45% fewer, in 147,374 US adults.
Where the idea came from
In 1980 the physiologist Robert Hickson ran a 10-week experiment with three groups. One lifted five days a week, one did hard endurance training six days a week, and one did both programs in full. For seven weeks, the combined group got stronger at the same rate as the lifters. Then their strength leveled off, and in weeks 9 and 10 it fell, while the lifters kept climbing.
The finding got a name, the interference effect, and it’s been repeated in gyms ever since as “cardio kills gains”. But look at what the combined group was doing. That was 11 sessions a week of hard training, 70 to 80 minutes on most days. Very few people train like that.
A picture from daily life
If you work two full-time jobs, you’ll be worse at both by the end of the month. That doesn’t mean a walk after work makes you worse at your job.
Hickson’s combined group had two full-time jobs. Two lifting sessions and some walking is one job and a hobby.
What 43 studies found
In 2022 a team led by Moritz Schumann pooled 43 studies that compared lifting alone with the same lifting plus aerobic training. These were the results for the combined groups.
| Effect of adding cardio | |
|---|---|
| Maximum strength | No difference |
| Muscle size | No difference |
| Explosive strength, like jumping | A small drop |
| Explosive strength, both in one session | A bigger drop than with 3 or more hours between |
Things that might have mattered didn’t. The type of cardio, how often people did it, how trained they were and how old they were made no clear difference. The one thing that did was timing, and only for explosive power.
Why both is better
The studies of long life point hard the other way. In the Harvard study of 147,374 US health professionals, people who walked 150 to 300 minutes a week and didn’t lift had 26% fewer deaths than people who did neither, and people who did plenty of both had about 45% fewer. In a 2022 review of 16 studies, people who did both had 40% lower risk of death than people who did neither. Do I need cardio if I lift weights?
When to think about it
The fair point
The interference effect is real. Hickson saw it, and explosive power did drop a little in the 2022 analysis.
Who should care
Mostly athletes. If your sport depends on jumping or sprinting, or you’re training for huge volumes of both, separate your hard cardio and lifting by a few hours or a day, and lift first if they share a session. For everyone lifting twice a week to be strong and healthy, walking, cycling or running on the other days costs no measurable strength and adds a lot.
How much cardio to do, and what kind, is on exercise.guide.
4 sources
- Hickson RC, Interference of strength development by simultaneously training for strength and endurance, European Journal of Applied Physiology, 1980europepmc.org
- Schumann M and others, Compatibility of concurrent aerobic and strength training for skeletal muscle size and function: an updated systematic review and meta-analysis, Sports Medicine, 2022pmc.ncbi.nlm.nih.gov
- Zhang Y and others, Long-term resistance training with all-cause and cause-specific mortality, British Journal of Sports Medicine, 2026pmc.ncbi.nlm.nih.gov
- Momma H and others, Muscle-strengthening activities are associated with lower risk and mortality in major non-communicable diseases, British Journal of Sports Medicine, 2022pmc.ncbi.nlm.nih.gov
