How to Build Muscle Mass (hypertrophy)

How to Build Muscle Mass (hypertrophy)


“the enlargement of an organ or tissue from the increase in size of its cells”


As it applies to exercise we are mostly concerned with muscle hypertrophy; the enlargement of muscle fibres. Not to be confused with hyperplasia which is an increase in the number of muscle fibres; it has never been seen in the lab to happen in human muscles tissue but there is some evidence to suggest it does exist. From Supertraining, page 65;


“Some scientists have suggested that the reason many bodybuilders or other athletes have muscle fibers which are the same size (or smaller) versus untrained controls is due to a greater genetic endowment of muscle fibers. That is, they were born with more fibers. If that was true, then the intense training over years and decades performed by elite bodybuilders has produced at best average size fibers. That means, some bodybuilders were born with a bunch of below average size fibers and training enlarged them to average size.”


We’ll look at hypertrophy. If you have spent any time reading message boards on the subject you’ll have seen talk of two types of hypertrophy; sarcoplasmic and sarcomere.

Sarcoplasmic hypertrophy is an increase in the sarcoplasm of a muscle (the area that holds liquid proteins, glycogen and other substances that support contraction).

Sarcomere hypertrophy is an increase in the size of the actual muscle fibre elements that connect and contract with each other (Actin and Myosin). Gym rat logic and message board gurus tell you that you can have one or the other depending on how you train.



This idea came about after the observation that a bodybuilder is not as strong as a powerlifter of equal size. Legend has it that powerlifters have sarcomere hypertrophy as they lift heavier weights and bodybuilders have sarcoplasmic as they lift lighter weights for higher reps which causes them to store more fuel and require less actual fibre growth (they clearly hadn’t read this post on strength and skill).

This idea caught on with no evidence from the lab to suggest it’s validity and has now become almost law among message boards. So far as I can find (and I have searched high and low) there has not been any evidence to suggest that you can train to increase one over the other to any meaningful or noticeable degree.

Yes both types of hypertrophy exist, no you can’t train for one specifically.

If one increases then so does the other; one doesn’t exists without the other. The strength difference between equal sized bodybuilders and powerlifters is a matter covered in the strength post linked to above.

If you only lift heavy then you will still hypertrophy your sarcoplasm. If you only lift lighter weights to failure then you will still hypertrophy your sarcomere’s. Hand in hand hypertrophy.

How to Hypertrophy Muscle

A hard task indeed. Have you ever seen those people that just seem to grow no matter how they train? Then there’s the rest of us.

Mike Mentzer

Easy Gainer?

If you are anything like me you have to bust a gut to see even the slightest increase in size. Your training has to be spot on, your diet needs to be in order and your lifestyle too (boozing every weekend won’t help matters).

Aside from having your diet in order (a discussion for another time) which we’ll assume you do, lets talk about the training for hypertrophy;

You’ll hear that training for size is the same as training for strength but that usually leads down a road that ends in frustration chasing after ever increasing weights. Most of the time this results in poor technique, injuries, cheating and worse yet, quitting. Yes, it can work over the long haul and strength should be a goal but not the way most media will tell you to.

Some will tell you that is about workload and how much of it you can perform, which leads to tired and weakened muscles. Intensity of effort is the cry of many.

It is said that you must train to absolute failure to stimulate hypertrophy and anything less just wont cut it but this also leads to poor form, exhausted bodies and battered motivation.


Get to the choppa!

As usual in life, the answer is somewhere in the middle of all the above.

Yes, weight is important, yes volume is important and yes effort is important but an extreme in any direction is usually the wrong direction.

We need adequate weight on the bar, not because weight/tension/strain or force alone causes hypertrophy but simply to recruit the muscle fibres we want to hypertrophy. Nowhere near as much weight as historically mandated by ego or the naturally gifted for muscle growth. Over the last decade some really interesting research has revealed that hypertrophy occurs at very low intensities (in terms of percentage of one repetition maximums), as low as 30%. The caveat here is that the work must be carried out to muscular *failure ( a point where no further reps can be performed despite your maximum all out effort).



The Father of Effort Based Training A Jones


We need adequate volume/workload to stimulate the muscle (after all we can’t work the muscle with no volume at all). Again research has shown that workload alone is not enough to cause hypertrophy. Two groups of people both perform the same volume of work or workload but group one does it with 90%1RM and group two does it with 30% which means group two doesn’t even come close to working to fatigue. Whilst the workload is matched…the results certainly are not. The 90% 1RM group stimulates greater protein synthesis.


Effort is the key here as 90%1RM recruits far more muscle fibres than the 30% work matched (and thus not to failure). When a third group was tested with 30%1RM to muscular failure (but not work matched) the protein synthesis was similar between 90%1RM and 30%1rm to failure…..failure training causes more fibres to be recruited too. Workload alone is not the answer.

We need intensity of effort to ensure nervous system activity and thus recruitment of the big fibres. As mentioned previously; when training to failure is pitted against training without failure the higher effort of failure training can make up for a lack of weight BUT is training to all out failure needed and what happens at failure that doesn’t happen without it?


Fatigue, Failure, Effort and Hypertrophy


Muscles have lots of fibres in them and they are called into action (recruited) depending on a) how much weight they need to lift/force is needed b) how much fatigue is building up. A really heavy weight/high force requires most or all of the fibres to be recruited as does a lighter weight lifted more times; when fatigue builds up more and more fibres are called into action to help the first batch of fibres that are now tiring.


A motor unit connected to muscle

Now this is where things get interesting and why it is likely that most people see better results for hypertrophy when lifting moderate weights rather than really heavy ones. Those of you that grow muscle quickly and easily are likely already hard wired with a greater number of fast twitch motor units and needn’t worry too much about the following as you can generate high local muscular effort with far less fatigue accumulation and less working time.

The bigger fast twitch muscles fibres are controlled by a bigger and more powerful motor unit (part of the nervous system the carries a signal to contract) and the smaller and weaker slow twitch muscle fibres are controlled by a smaller and weaker motor unit BUT when surgery is performed and a large fast twitch motor unit is swapped to control the smaller and weaker slow twitch muscle fibres something pretty cool happens;

the once small and weak slow twitch fibres start changing to become bigger fast twitch fibres.

Now I am not suggesting we have surgery but it does hint at the controlling factor for hypertrophy. If a muscle fibre can be enlarged by swapping to a bigger more powerful motor unit which sends a much bigger electrical current then intensity of effort looks to be a major factor in play.


Intensity of Effort

An intelligent reader may look back at what has been written and ask “why not just lift as heavy as possible if effort and recruitment are all that are needed?” and a good question it would be. More testing is needed but for some people simply lifting heavier weights doesn’t equal maximum nervous system input for some reason unknown to me (perhaps it is an offloading to other supporting muscles and bracing). If you have ever tried a one repetition maximum attempt you will note how technique tends change and we try to use as many other muscles to help out, for example;


When we perform a chin up with a moderate weight we are able to do so while keeping our knees still and without swinging about. Now we try the same with a  much heavier weight and we see our knees hitching up and swing comes into the action. This may allow us to move more weight but with the help of other muscles which only serves to take the effort off the targeted muscles.


woman chin up


If you were to compare the heavy versus moderate attempts as a single repetition then the heavier cheating rep may well show that the nervous activity is actually greater BUT if you were to continue the moderate weight repetition to failure or very near failure* you would find that the nervous system activity soon increases beyond that of the heaver cheating rep.

*there is some evidence to suggest that nervous system activity peaks a few reps before failure and then drops back down again on the last failure rep.

This is the stage in the play where volume takes centre stage. One set to failure or near failure is not enough for most people outside of the beginner stages to stimulate hypertrophy but as we know from earlier, simply performing more volume on it’s own is not enough (volume or time under tension has a point of diminishing returns at around 5 sets which roughly works out about 60 – 100 seconds recruitment time).

The extra volume must be performed whilst fatigued enough to keep the nervous system activity/fibre recruitment as high as possible (this is where some individuals with a high percentage of fast twitch fibres get lucky as they can produce really high levels of effort and thus recruitment without the need for as much fatigue).

This can be accomplished in two ways. The simplest is to perform multiple sets to failure or near failure. How many sets? Somewhere between 3 on the low end and 8 on the high end is where the research is pointing us right now. More sets may well yield more hypertrophy but in smaller and smaller quantities.


EPsom Personal trainer


How much rest to take between sets?

It doesn’t really appear to matter for hypertrophy purposes. It pans out like this;

If you rest for longer periods (60 seconds and upwards) it simply means that you’ll end up being able to perform more reps per set with each set consisting of a few more reps that have slightly lower nervous system activity (fibre recruitment) during the early stages until the fatigue builds up again.

If you chose to rest for shorter periods (10-60 seconds) you’ll end up with less reps per set but each rep, right from the start of the set, is likely to be high effort (and thus high recruitment) right from the word go.

What’s important for us is the number of high effort reps is somewhere between 20 and 50…ish (60-100 seconds..ish). As always it depends on the individual: factors such as bone structure, muscle belly length etc. Some need more volume, others not so much.

It boils down to how much time you have spare to train. Longer rest periods obviously mean a longer workout.




  • Fast twitch fibres grow more readily and they can produce higher effort, faster
  • A lack of fast twitch fibres needs to be made up for with fatigue to induce the same high effort
  • Work volume alone is not enough (but slower twitch fibres may need longer time at recruitment to be stimulated)
  • Weight alone is not enough
  • Singular high effort attempts are not enough
  • Combining a heavy enough weight with a high enough effort for enough total volume gets the job done


That’s a fairly comprehensive look at hypertrophy, the different types and how to go about achieving it.


Brought to you by your Epsom and Surrey based Personal Trainer, Richard Ham Williams.


If you decide you want to build some muscle and need Personal Training to help you then give me a call or drop me an email

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