There’s at least one type of completion where muscle mass holds back your performance. Even with greater strength and more muscle, sprinters can’t win a distance race against marathon-trained athletes. According to research published in the Proceedings of the National Academy of Sciences, these athletes are separated by a protein called PGC-1alpha.

Aerobic endurance-trained effort is fueled by oxygen. Anaerobic exercises like weight lifting and sprinting let muscle produce energy without oxygen. This leads to the buildup of lactate which results in fatigue. Endurance training stimulates the production of the PGC-1alpha protein which alters enzyme composition to reduce lactate production.

True Strength Moment: Both competitive and recreational athletes tend to plan their training around performance in a single sport. This research illustrates the metabolic changes training can produce. Of course, there’s nothing that says a sprinter can do some distance work. Marathoners might have something to gain in the weight room. Rounding our deficits in physical ability won’t hurt your performance.