Assuming that bodyfat% remains low (6-15%), how does having a lot of muscle mass affect performance in sprinting-type events (50m-400m), middle distance runs (800m-5K) and endurance runs (10K-100K)?

I have read quite some articles stating that strength training helps improve running performance, since more strength means that taking a step requires less %force output of your 1RM it is now possible to run longer and/or faster. It's also not true that strength training only works your type II muscle fibers (which aren't used that much in endurance runs). It actually strengthens your type I fibers aswell.

I've also read that neuromuscular efficiency tends to reach near-maximal state fairly soon in a resistance program (beginner stage, around 140kg 1rm proper depth squat according to stronglifts.) In order to see further reasonable strength gains, it is said that you have to increase your muscle mass. Therefore, assuming that one is fairly proficient with the big compound lifts, the most important factor in strength differences should be muscle mass.

So since muscle mass is very heavily related to strength, and strength gains improve running performance, does muscle mass really slow me down in running?


1 Answer 1


The current theory states that there's two types of muscle mass, sarcoplasmic, and myofibrallar. Sarcoplasmic is mostly fluid, nigh useless. You can elicit sarcoplasmic adaptation through high reps, low intensity. Think body building. Myofibrillar is actual functional mass, i.e. a farmer who bales hay all day every day.

So, in the end, make sure the mass you build is actually useful-lift big, lift correctly, lift often. The "burn" so often associated with training is your enemy in this case. Make sure you approach your training with sound logic.

If the mass is myofibrillar in nature, you'll see good benefit.

Trying to answer quickly apologies for lack of sources.

  • This is informative, but does nothing to answer the question.
    – JohnP
    Jul 16, 2015 at 14:53
  • @JohnP the question was "does muscle mass really slow me down in running". The answer is only if gains are Sarcoplasmic in nature. I said "Sarcoplasmic gains are nigh useless". As I said, "if the mass is myofibrillar in nature, you'll see good benefit." Jul 16, 2015 at 18:03
  • In a very limited sense. As you get more towards endurance, it's a tradeoff against mass and energy consumption versus what you get out of it. Sprinters need very muscular upper bodies, endurance, not so much. I should have said "little" rather than nothing, it needs clarification/expansion.
    – JohnP
    Jul 16, 2015 at 18:13
  • Are you suggesting that more upper body mass is undesirable in an endurance runner? Jul 16, 2015 at 18:48
  • Absolutely. It consumes oxygen and fuel, and doesn't serve much in the way of propulsion, unlike sprinters.
    – JohnP
    Jul 16, 2015 at 19:30

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