Doing a short cardio session after weight training probably won’t boost your gains – here’s why

Spend long enough on fitness social media and you’ll see the same tip. Finish every weight training session with about 15 minutes of cardio to boost your “gains”. But does it actually work? Probably not as much as you’d think.

Doing cardio and weight training in the same exercise programme is known as “concurrent training”. This includes doing cardio in the same session as your weights, or on separate days.

For years, people thought concurrent training held back strength and muscle gains. This worry goes back to 1980 when a ten-week study found that people who did both on the same days, within two hours of each other, built less strength than those who only lifted.

This became known as the “interference effect”: the idea that cardio gets in the way of building muscle and strength. And there’s some logic to keeping cardio short. A 2012 review found that the longer and more often people did cardio alongside their lifting, the more it ate into their strength, muscle and power gains. That puts a 15-minute bout at the low-risk end.

But research has come a long way since 1980, and now shows the interference effect may not be as significant as once thought.

A major 2022 review pooled 43 studies involving 1,090 people. It compared people who did cardio alongside a weights programme against people who only did the weights programme.

Adding cardio made no real difference to how much muscle people built or how much stronger they got. That held whether the cardio was cycling or running.

A 2026 review of 17 earlier analyses covering 144 studies reached the same conclusion. It also found that adding cardio improved aerobic fitness without costing strength, power or muscle.

This research clearly shows that a cardio finisher isn’t going to wreck progress. But it’s also worth noting that this research didn’t suggest adding cardio made muscle or strength gains any bigger. On average, people who did cardio and weights gained similar muscle and strength to those who only lifted, though there are two exceptions to this finding.

The first is explosive strength, the kind you use to jump or sprint. This improved slightly less when people added cardio. But that dip only showed up when cardio and weights were done within 20 minutes of each other. When the two were at least three hours apart, it wasn’t there. A finisher done straight after lifting falls inside that window.

The second is experience. Across 27 studies, adding cardio held back leg strength gains in experienced gym-goers – but only when both were done in the same session. Beginners saw no clear difference. The 2026 review points out that there’s very little research on elite athletes, though, and they’re the people most likely to notice even a small dip in performance.

There’s also an early hint that adding cardio could affect the muscle fibres themselves. These are the individual cells that make up a muscle.