December 7, 2024, 2:18 pm | Read time: 5 minutes
If you want to build muscle, you have to do strength training – nothing else? A study from 2021 says otherwise. When it comes to hypertrophy, the researchers seem to be able to give a clear training recommendation.
If you want to build muscle, it is often assumed that you should only focus on strength training. Is endurance training even counterproductive in this case? Many athletes ask themselves this question. In a small Swedish study of eight men, researchers found that a combination of both types of training is ideal: muscle building is apparently promoted by a brief focus on endurance training immediately before strength training – on one condition.1
Overview
Combining Endurance and Strength Training to Build Muscle?
Earlier studies have already looked at endurance and strength training in men. One study from 2013, for example, suggests that combining both types of training is beneficial for muscle growth or at least does not stand in the way of it.2 Another, on the other hand, concluded that sweaty endurance workouts could reduce the effects of strength training.3 What these studies have in common: The subjects focused on the same muscle groups for both endurance and strength.
But what would the effect be if the legs were stressed during endurance training and then the arms during strength training? This is exactly what a Swedish research team from Stockholm investigated. For their study, the scientists decided to test the combination of cycling and upper-body training.
This is How the Swedish Study went
Different Workouts
The researchers recruited eight athletically active men and measured their fitness and strength in the first step. In the second step, on another day, the test subjects completed a workout consisting of two parts. The men started with a high-intensity interval training session on the bike. They pedaled as fast as possible for four minutes, followed by a three-minute break. They repeated this cycling sequence five times so that they cycled for a total of 20 minutes. After a short break of a few minutes, the endurance part was followed by strength training. During this, the participants performed exercises for the arms and shoulders on training equipment designed for this purpose. Step three of the study again took place on a separate day. Now, the eight men had completed the strength training again, but without first getting on the bike for 20 minutes.
Collection of Blood and Tissue Samples
In order to recognize the effect of endurance units on muscle growth, the researchers took blood and small tissue samples from the triceps muscles of the test subjects. They did this several times: once before training, a second time immediately afterward, a third time 90 minutes later, and finally again three hours after the end of the workout. According to study author Marcus Moberg, this was also the reason why the study was only carried out with men. Such biopsies are not so easy to perform on the less pronounced triceps muscles of women and could even cause injuries.
Examination of the Samples
In the final step of the study, the researchers examined the blood and muscle tissue samples taken under a microscope. Their aim was to identify substances that indicate how the muscles react to the workouts. The focus was on proteins and markers of gene activity, which are thought to influence endurance and muscle mass.
Endurance Training Supports Strength Training and Muscle Building
The blood and tissue analysis showed that after strength training alone, the men’s muscles were teeming with proteins and genetic markers known to promote muscle growth. The same substances were also abundant after cycling training, but other proteins and gene activities associated with improved endurance were also present.
The men’s muscles appeared primed to increase in both size and endurance after the dual training, with no evidence that cycling had interfered with the equipment exercises at a molecular level. Instead, endurance training appeared to extend and amplify the expected benefits of strength training.
“The most intriguing finding is that some biochemical factors induced by endurance training in the legs entered the bloodstream and were then able to influence processes in a completely different muscle group in a way that appears to be beneficial for the training adaptations in the arms,” Moberg explained. “It’s almost as if the endurance training in the legs was transferred to the arms to some degree.”
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Classification of the Study
The results of this study reflect what is already postulated in sports science. Endurance training prior to strength training leads to increased muscle growth.
Indeed, all forms of physical activity trigger the release of various signaling molecules that have systemic effects throughout the body. However, it must be said that due to the invasiveness of the sampling, the study was, of course, only carried out on a very small scale. Only eight athletes were examined. Therefore, the significance of the results should be treated with caution. Further research is needed to confirm the findings.
In principle, it is always advisable to combine endurance training with strength training. This is because it stabilizes the cardiovascular system in particular, which is also heavily stressed during strength training.