Does Long Distance Running Make You Lose Muscle?

When you take a look at serious long-distance runners, one quick assumption that people can make about long-distance running is that it can make you lose muscle mass. Think about world-class long-distance runners like Paula Radcliffe, Mo Farah, Haile Gebrselassie, and Kenenisa Bekele. One thing they have in common is their lean body shape.

In short, there is some truth to the impact that long-distance running could have on muscle mass. Let’s first take a step back and cover how muscle gets built. Also referred to as muscle hypertrophy, the general process of building muscle happens when the fibers of the muscle sustain some damage. The body then repairs the muscles, which helps it grow in size and mass. When this happens, it’s important for the rate of muscle protein synthesis (MPS) to exceed the rate of muscle protein breakdown (MPB).

With short-distance running, we know runners are likely to go through workouts that act as a strong stimulus for MPS. Weight-training, for example, is a strong stimulus for MPS and it is required for those who take short-distance running seriously in order to build explosive strength.

Long-distance running, on the other hand, may inhibit muscle growth. Long-distance running has a tendency to put a lot of stress and strain on the body for an extended period of time. Experts on this matter share that having stress hormone (cortisol) in the body might inhibit the growth of muscles.

There is also the mental aspect of long-distance running. The training regimen that one has to go through for long-distance running can be quite grueling. The last thing a long-distance runner may want to add to their training schedule is a leg workout day. Naturally, this will also contribute to a loss in muscle mass if a runner doesn’t stay consistent with doing some strength-based exercises.

Last but not least, there is also the difference in diet between a short-distance and long-distance runner. For obvious reasons, a long-distance runner cannot afford to bulk up as having too much body mass will make it harder for them to sustain a long-distance run. The type of diet they follow may not make it easy for them to build consistent muscle mass.