Bigger Muscles May Be Harming Your Performance


For many athletes and competitive sportspeople, there’s a general assumption that more muscle means better performance. We’re talking here about athletes that require a wide ranging fitness that demands a wide range of physical competencies. People who need to be strong, fast and powerful, while also having good relative strength and stamina, and a good cardiorespiratory capacity.

More muscle does not increase performance in sport UNLESS that increase in muscle is accompanied by and increase in strength (which is usually but not always the case).

And when there IS an increase in muscle (and therefore probably total bodyweight), there needs to be a risk/reward analysis of whether this will actually increase overall performance.

The increase in muscle mass needs to be relative to the overall increase in strength. For example, 5kg more muscle in a 100kg athlete needs to be accompanied by AT LEAST a 5% increase in strength (both absolute and relative) in that athlete.

And this doesn’t take into account the increased metabolic demands placed on the body by increased muscle. Aerobic activities become more difficult with more muscle, because not only is there a greater body mass to move, but there is more muscle to service (delivering fuel/O2 and removing waste).

All of the above is not to say that more muscle (hypertrophy) is not needed, because in many cases it is. 

The above only tells us that it isn’t hypertrophy that’s important, it’s strength.

That being said, hypertrophy (or more accurately, ‘cross sectional area of a muscle’) IS an important factor in strength, but it’s not the only factor. Other contributing factors are:

  • Improved capacity for motor unit recruitment.
  • Changes in neuron firing pattern efficiency.
  • Alternations within the muscle fibres’ contractile elements. (McArdle, Katch and Katch, 2001)

It is possible to experience large gains in muscle mass (increased cross-sectional area) without as significant gains in strength. These can come about by single joint isolation exercise (which makes up a lot of traditional bodybuilding). These ‘non-compound’ movements are not as potent as ‘compound’ exercises in eliciting the three ‘non-cross-sectional-area’ factors I list in the previous paragraph.

To summarise the above. Hypertrophy is important, but only if it results in a proportionate (at least) increase in strength, and doesn’t result in a proportionate reduction in aerobic capacity (across different energy systems).

Now of course, this is all relative to the athlete.

A skinny marathon runner who wants to be a well rounded athlete definitely needs hypertrophy. Not only that, but they can afford to have a drop in aerobic capacity (because THAT’S NOT THEIR LIMITING FACTOR IN COMPETITION).

And there’s the key phrase.

Training an athlete who needs level ability across a wide range of elements of fitness is about juggling the wide range of competencies they’re required to demonstrate. And they’re only as proficient an athlete as they are proficient in their weakest link.

The standard periodisation model for athletes is a bit broken. It doesn’t make sense that a 100kg athlete with a 200kg squat would complete a preparatory mesocycle that biased towards absolute strength, when that’s clearly not their limiting factor. Sure, our ex marathoner needs that, but not our ex powerlifter.

Everyone’s starting point is different, therefore everyone’s periodisation should be different.

Instead of something like the following:

  • Mesocycle 1: Hypertrophy
  • Mesocycle 2: Strength
  • Mesocycle 3: Endurance
    (oversimplified to make a point)

Maybe it should look something like:

  • Mesocycle 1: That athlete’s major weakness
  • Mesocycle 2: That athlete’s major weakness + that athletes minor weakness.
  • Mesocycle 3: That athlete’s major weakness + that athletes minor weakness + that athlete’s strength.

Short answer, if a lack of hypertrophy is the factor which limits performance, it should be trained.

So that’s all good, but brings us to the question of HOW this hypertrophy/strength balance should be achieved.

Kubo et. al. (2021) compared strength gains to hypertrophy gains (remember, we want the former, not the latter – actually, in a perfect world, we want as much strength as possible with as little hypertrophy as possible).

They compared sets of 4, 8 and 12 reps, and the effects they had on both strength and hypertrophy.

Regardless of set size, hypertrophy changes were similar. However, 4 and 8 rep sets resulted in significantly more strength than the 12 rep set.

The 12 rep set is therefore the OPPOSITE of what we want for a well rounded athlete. The subjects became a lot heavier but only a little but stronger. Therefore, their relative strength DECREASED.

If you just want to get bigger, the rep range doesn’t really matter. ‘Olden days’ physiology had us believe that 10-12 reps was the ‘hypertrophy range’. But science simply doesn’t support this.

If you want bigger muscles, do sets of all sizes (with intensity).

If you want more strength (AS WELL as hypertrophy), do smaller sets.

If you want to be a more well rounded athlete, do all of the above, and more (making sure you’re also taking into account the ‘non-cross-sectional-area’ strength factors. 


Dan Williams

Dan Williams


Dan Williams is the Director of Range of Motion and leads a team of Exercise Physiologists, Sports Scientists, Physiotherapists and Coaches. He has a Bachelor of Science (Exercise and Health Science) and a Postgraduate Bachelor of Exercise Rehabilitation Science from The University of Western Australia, with minors in Biomechanics and Sport Psychology.

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