Concurrent Training: Doing Strength and Endurance Work in One Program

Quick Intro

Concurrent training means training for strength and for endurance within the same program, such as lifting weights three days a week and running or cycling on two others. Most people who exercise for general fitness do some version of this. The question it raises is whether one type of training interferes with the other.

The Idea in Plain Terms

Strength training and endurance training push the body in different directions. Strength work calls for large, forceful muscle contractions and builds muscle size and the ability to produce force. Endurance work calls for repeated, lower-force contractions over a long time and builds the heart, the blood supply to muscle and the muscle’s ability to use oxygen.

The worry about combining them is called the interference effect. It was first described in the early 1980s, and it comes from two lines of reasoning. The first is at the cellular level. Endurance exercise activates a signaling molecule called AMPK, while muscle building relies on a pathway called mTOR, and in laboratory settings the two signals can work against each other. The second is practical: fatigue from one type of session can reduce the quality of the other, and total training time and recovery are limited.

The size of the effect in real people has been argued over for decades. The details that could matter include how often endurance sessions are done, how long they last, what kind of exercise they use and how close together the two types of session are.

A Worked Example

A week that combines both, offered as an illustration:

Hard sessions of each type are kept apart, and the easy endurance work sits on days that do not clash with heavy leg work.

What the Research Shows

A 2012 meta-analysis by Wilson and colleagues, covering 21 studies, found that higher frequency and longer duration of endurance training were associated with smaller gains in muscle size, strength and power. It suggested running had a larger interfering effect than cycling, though that detail is reported mainly through secondary summaries.

A larger 2022 meta-analysis by Schumann and colleagues pooled 43 controlled trials of at least four weeks. It concluded that combining aerobic and strength training did not interfere with gains in maximal strength or muscle size compared with strength training alone. This held regardless of whether the aerobic training was cycling or running, how often the sessions were done, training status and age. Some analyses suggest explosive power, the ability to produce force quickly, may be affected more than strength or size, though this is the least settled part of the picture.

Together the two reviews suggest that for most people the interference is small, and that it can matter more for people chasing maximal power or training with very high endurance volume.

Who It Suits

• Almost anyone training for general health and fitness, since public health guidance recommends both aerobic and muscle-strengthening activity.
• Athletes in sports that need both strength and endurance.
• People who enjoy both kinds of training.

It needs more planning for those competing in a strength or power sport, where the priority is clear, and for those with a high volume of endurance work.

How to Use It

1. Decide which quality is the priority and give it the best-recovered slots in the week.
2. Separate hard strength and hard endurance sessions by at least six hours, or place them on different days.
3. If both happen on the same day, many people lift first when strength is the priority.
4. Keep most endurance work easy or moderate.
5. Eat enough to support both, because the total energy cost is high.
6. Monitor recovery and cut back one type if progress or sleep suffers.

Common Misunderstandings

It is not a case where cardio ruins muscle growth. The largest review found no meaningful interference for size or maximal strength.

It is not free of trade-offs. Time, energy and recovery are limited, and heavy volume of one type leaves less for the other.

It is not only for athletes. General health guidance includes both aerobic and strength work.

FAQ

Should I lift or do cardio first? If strength is the priority, lift first. If endurance is the priority, do the endurance session first.

Is running worse than cycling for muscle gains? One older analysis suggested so, and the larger recent analysis found no difference.

How much cardio is too much? There is no fixed limit. Interference is more likely when endurance volume is high relative to recovery.

Does it affect power? Possibly, to a small degree, so power athletes plan the mix with care.

Where This Comes From

Wilson JM and colleagues, 2012, concurrent training: a meta-analysis examining interference of aerobic and resistance exercises (Journal of Strength and Conditioning Research; 21 studies). Schumann M and colleagues, 2022, compatibility of concurrent aerobic and strength training for skeletal muscle size and function: an updated systematic review and meta-analysis (Sports Medicine, 52, 601 to 612; 43 trials). The AMPK and mTOR explanation is a laboratory finding, not a measured effect in training studies.

Related to: body recomposition, the interference effect, HIIT and MICT. Exercises that fit a mixed week include Barbell Back Squat and Brisk Walking.