Combining cardio and strength training: what research says

General information, not medical advice. If you have symptoms, discuss them with your GP or physiotherapist.

Combining cardio and strength training in the same week is everyday practice for many athletes. Cardio here means endurance training, such as cycling, running or swimming. Yet you often hear that endurance training slows down muscle growth. Below you can read what systematic reviews find about this, what the order within one session changes and how much time you best leave between two sessions.

What the WHO recommends

The World Health Organization (WHO) recommends that adults do 150 to 300 minutes of moderate-intensity or 75 to 150 minutes of vigorous-intensity endurance activity per week, or a combination of both. In addition, the WHO asks for muscle-strengthening activities on at least two days a week for all major muscle groups (Bull and colleagues, 2020). The guideline stresses that you need both types of activity regularly. How to fill those strength days is covered in the article on how much strength training per week is useful. For the endurance minutes you could, for example, choose an easy session in zone 2, a pace at which you can still talk comfortably.

Combining cardio and strength training: what does research say?

The idea that endurance training slows down strength and muscle growth is called the interference effect in sports science. Schumann and colleagues (2022) pooled 43 studies in healthy adults who trained under supervision for at least four weeks. Each time they compared the same strength programme with and without extra endurance training.

For maximal strength and muscle growth they found no disadvantage from the extra endurance training. Explosive strength did improve less, meaning how high you jump or how quickly you produce force. Whether people cycled or ran, how often per week they combined, whether they were untrained or active beforehand and whether the average age was below or above 40 did not change those results. The authors rate the risk of a slowing effect as rather low and write that most people, including recreational athletes, benefit from both types of training.

There are limitations too. Most studies were of moderate quality, and the intensity of the endurance training could not be analysed because the studies did not describe it consistently.

What an older meta-analysis found

Wilson and colleagues (2012) arrived at a somewhat stricter picture with 21 studies. In their view, the disadvantage depended on the type of endurance training, how often you do it and how long it lasts. Strength training combined with running led to less muscle growth and smaller strength gains, combined with cycling it did not. More frequent and longer endurance training went together with smaller gains in muscle growth, strength and explosive strength. So the two reviews differ on running and cycling. Schumann and colleagues point out that Wilson also counted other tests as explosive strength.

Which order within one session?

If you combine both in one session, strength first seems more favourable for leg strength. Eddens and colleagues (2018) pooled 10 studies with mostly untrained and recreationally active participants. Those who did strength first and endurance afterwards gained on average 6.9 percentage points more in dynamic leg strength, measured as the heaviest weight you can lift once in, for example, a knee bend or leg press. For muscle growth, static strength, fitness (maximal oxygen uptake) and body fat percentage, the order made no difference. Murlasits and colleagues (2018) found something similar: strength first gave on average 3.96 kilograms more leg strength, while fitness improved equally in both orders.

If your main priority is fitness, the order matters little according to both reviews. Then simply choose what is practical.

Same day or separate days?

For muscle growth and maximal strength, it made no difference in the analysis by Schumann and colleagues whether both types of training were done in one session, on the same day or on separate days. For explosive strength it did: the disadvantage showed up mainly when both were done in one session with at most 20 minutes in between, and not when at least three hours separated them. If jumping or sprinting matters in your sport, it can help to keep strength training and endurance training at least three hours apart.

How to spread your training across the week, with rest days and now and then a lighter week, is covered in the article on rest day or deload. If you feel tired for weeks or your performance drops, look at the signs of too little recuperation.