Hypertrophy: What is it?

Arnold was quite successful at stimulating hypertrophy of the biceps.

What we’re really talking about is muscular hypertrophy. “Hypertrophy” – used both as a verb and a noun – is Latin for “grow larger”. So, when we talk about hypertrophy, we’re talking about anything that makes your muscle mass increase.

Muscles can get bigger – or hypertrophy – in several ways:

  • Hyperplasia – an increase in the number of muscle cells that make up a muscle.
  • Sarcoplasmic Hypertrophy – an increase in the volume of muscle cells caused by fluid retention within the cell. In effect, the cell swells up.
  • Myofibrillar Hypertrophy – an increase in the amount of contractile protein contained in the muscle cells.
  • Swelling – not really hypertrophy; this is the “pumped up” look you get after exercise. It disappears in a few hours.

Hypertrophy: How do I get it?


Muscular hyperplasia is different from muscle hypertrophy, but because it increases muscle mass, plenty of people want it. Unfortunately, it’s difficult to get. The only sure-fire way to stimulate hyperplasia is with Human Growth Hormone (HGH) supplementation, which usually requires a physician’s prescription and a reason other than the purely cosmetic. There is no definitive conclusion about whether it’s possible to stimulate hyperplasia; research is scant, inconclusive, and often contradictory.  Suffice it to say that hyperplasia is best left to professional bodybuilders and movie stars.

Sarcoplasmic Hypertrophy

Fluid retention in the muscle cells is fairly easy to achieve.

Supplementation with creatine – which seems almost de rigueur among even the most casual of bodybuilders – is a transitory way to achieve modest sarcoplasmic hypertrophy.

Bodybuilding magazine (and the web writers who learned their trade from these magazines) will have you convinced that bodybuilders generate massive amounts of sarcoplasmic hypertrophy by lifting weights with relatively high repetitions – 10 reps or more. Whether this is true is debatable. Most bodybuilders bulk up just like everyone else: they use low reps and heavy weight. It is only during contest prep phases that bodybuilders increase the reps.

Sarcoplasmic hypertrophy is the mechanism responsible for maximum hypertrophy. That is, if you want to be really big, you want maximum sacroplasmic hypertrophy.

Myofibrillar Hypertrophy

Stuffing a muscle cell full of contractile protein – the myosin/actin pairs known as myofibrils – causes myofibrillar hypertrophy. Unfortunately, it’s not possible to achieve the same sort of muscular size with this mechanism as it is with sarcoplasmic hypertrophy.

Lifting heavy weights with low reps stimulates myofibrillar hypertrophy. It also builds strength levels past the point possible with sarcoplasmic hypertrophy, even though the muscles may be smaller overall.


Various activities cause muscles to swell. None of these is considered hypertrophy, but since they result in a (temporary) increase in the size of muscles, I’ll include them here for the sake of completeness.

Lifting, especially in the high-rep ranges, “pumps up” your muscles. The capillaries that supply blood to the muscle cells dilate, filling the muscle with blood and fluid. This pump disappears within hours.

Micro-trauma caused by heavy exercise results in an immune response. This swelling may be barely-noticeable, and it generally takes at least a day to develop. The increase in muscle size is negligible.

Creatine supplementation forces water into the muscle cells. This semi-permanent swelling mimics sarcoplasmic hypertrophy. It quickly fades after supplementation ceases.

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{ 10 comments… read them below or add one }

A Dreamer January 27, 2010 at 8:57 pm

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needed that information thanks June 17, 2010 at 9:57 pm

you couldnt have put it any other way. thats great reading.


Jon September 23, 2010 at 4:21 am

thanks very much, helped me with my PE A-level homework!


dan May 16, 2011 at 10:18 am

i know both types of hypertrophy occur together but at different ratios based on load and reps used but does sarcoplasmic hypertrophy cause strength gains? also when people talk about causing microtrauma (the main cause of hypertrophy?) and why does the sarcoplasm become bigger, what is its use?
cheers dan


faiz bapikee October 26, 2011 at 4:28 pm

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Todd January 4, 2012 at 1:44 pm

Great site, thanks for the great work.

Two questions:
1. Is Sarcoplasmic hypertrophy fairly temporary, while myofibrillar hypertrophy is more permanent (with maintenance of course)? After working out I usually look bigger for a few days and then it starts to go away and I always thought that this was “swelling”, but you say that it only lasts a few hours, so it must be sarcoplasmic hypertrophy. I also only use creatine right before and/or after workouts – could that have something to do with it?

2. How long does it take for hypertrophy to kick in vs. the initial neuro-muscular (I may be using the wrong term here) gains? Is it a matter of time, a matter of number of workouts or a combination? Are there ways to bring it on faster?



Thomas January 6, 2012 at 6:25 am

You’re just seeing the “pumped up” temp-swole look that happens after a high-volume workout. I think most of it goes away in “a few hours”, but I suppose if you’re really defined, you will see it for longer than that. I’m surprised you see it for a “few” days (which, in my book means 3 or 4 days), but anything’s possible. In any event, you’re not seeing hypertrophy immediately after a workout. It takes a long time to build up real, permanent muscle size.

Creatine levels build up in the body over a period of a week or so. So I don’t think you’re seeing any immediate results from your creatine supplementation.

If I knew how to bring on hypertrophy faster, I’d be wealthy! Good luck!


Abhishek February 17, 2012 at 11:50 am

Great work…hats off to you..


Classicist June 10, 2014 at 4:06 pm

As an etymological side note, hypertrophy is not Latin but Greek (ὑπερ τροφη), and means ‘over growth’.


kley December 3, 2014 at 4:09 am

Simple and easy learning for new comers


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