Cardio Training and Muscle Building: Friend or Foe?

Man stretching

Many people in the fitness and bodybuilding world still believe that endurance training interferes with muscle building. But is their fear of losing muscle mass due to cardio workouts really justified? Let’s take a closer look.

Endurance and strength training can impact each other negatively

Yes, it’s true. Endurance and strength training can have a negative influence on each other, but only if they are combined in a disproportional way that conflicts with the actual training goal itself. A bodybuilder wanting to pack on muscle will not achieve optimal training results when half of his or her workouts consist of excessive cardio training. Just as a marathon runner will not improve his or her running performance by pumping heavy weights in the gym every day.

The big challenge for sports, requiring both a high degree of strength as well as plenty of endurance, is finding the right balance. The only way to develop in both areas is by ensuring an adequate recovery period after applying the training stimulus. But this is often precisely the problem when you try to improve in both areas at the same time. As a rule of thumb, you should never attempt a strength (muscle) building session when your muscles are already fatigued. You will not be able to work out at the necessary intensity to create an effective training stimulus. And, the risk of injury increases when you lift heavy weights with tired muscles because your stabilizing muscles are weakened and your coordination is impaired.

Man and woman running

Does cardio training lead to muscle loss?

As long as you provide your body with enough high-quality protein, complex carbohydrates and essential fats and you give your muscles time to recover, endurance training definitely does not lead to muscle loss. In fact, it’s quite the contrary. Regular cardio workouts can actually have a positive effect on your muscle building.

  • The cardiovascular system works better and more efficiently, including an increase in capillary growth in the muscles. This improves muscle circulation.
  • Oxygen and nutrients are transported more quickly and metabolic wastes are removed faster.
  • It improves your stamina and speeds up your recovery. That way you can work out more often and at higher intensities.
  • It can help reduce your body fat percentage.

Fitness couple training together in the gym.

Can a combined program of strength and cardio training lead to even bigger muscle gains than a pure muscle building program?

According to Tommy R. Lundberg and his Swedish research team, endurance training not only indirectly benefits muscle building, it can even directly contribute to muscle growth. In a study published in 2013 in the Journal of Applied Physiology, he comes to the conclusion that a combination of endurance and resistance exercise leads to greater muscle growth than strength training alone. These findings are further supported by a new study published in 2016, once again by a Swedish research team headed by Zuzanna Kazior. The results of this study, however, contradict the findings of several other research papers showing that a combined training program does indeed interfere with muscle growth.

Bottom line:

Cardio training should be a regular part of strength training. The fear that endurance workouts, when incorporated properly, will lead to muscle mass loss is unfounded. The positive effects of regular cardio training are scientifically proven and they also help build muscle indirectly.


Herwig Natmessnig As a former professional athlete (whitewater slalom), Herwig lives for fitness. Whether in competition or just for fun, he can never turn down a challenge. View all posts by Herwig Natmessnig