Sep 12, 2020 / by Jon Bellis / No Comments

How should I train to build muscle? As a private personal trainer Northampton, we get this question a lot.. And it’s a great question. Everyone should aim to maintain or build muscle as they get older. That’s because muscle is essential for so many reasons. It’s good for your health; it’ll strengthen your bones, improve your physiology, help you burn calories and enable you to do more, with lower risk, in everyday life. But it will also help you look good. Everyone looks better with a bit of tone. You’ll have a better shape, a better look after losing weight, rather than being all skin and bone with skin hanging off you.

Of course, the best way to build and maintain muscle is to perform resistance training. But so many people work out with weights without making progress or achieving the look they want. Why is that? Often it comes down to the way you eat between training sessions. You don’t build muscle in the gym, you manufacture it between training sessions, so proper nutrition is crucial. But, more usually, the issue is with the way you train. If you are not maximising the stimulus that leads to muscle growth, you’re going to see unsatisfactory results.

What do we mean by ‘the way you train’? That’s a good question! If you’re new to lifting weights, you may be surprised by how many different ways you can change your training. We call these training variables. Get these variables right, and you can optimise your response to training.

Here we look at what stimulates muscle growth and discuss how to trigger those stimuli by manipulating your training variables.


Factors affecting muscle growth

Before we list the factors relevant to your training variables, let’s discuss mTOR.



We’ve discussed mTOR previously. It’s a protein molecule that is the primary activator of muscle protein synthesis – that’s muscle growth. The research on this is still evolving, and the mechanisms are complex, but for this article, we’ll mention three primary stimulators of mTOR:


Amino acids

The presence of amino acids, especially leucine, via the digestion of protein, will stimulate mTOR and activate muscle protein synthesis.


Mechanical tension

Via an as-yet-unidentified mechanoreceptor, mTOR is thought to be stimulated by mechanical stress. We assume that this is dose-dependent: the more force you apply and the greater the number of times or duration over which you employ that force, the more you will stimulate mTOR.



Hormones such as testosterone and Insulin-like Growth Factor 1 (IGF-1), are both influenced by multiple factors; one of those is weight training. The right kind of training will trigger increased levels of both hormones, at least transiently.


For this discussion on training variables, we’ll ignore the first of these, amino acids, as that’s more of a nutrition factor.

So, with mTOR introduced, let’s look at the key factors to consider when manipulating your training variables.


Maximise mechanical tension

It’s essential to put as much mechanical stress through the muscles as possible. Let’s just clarify what that means. It isn’t necessarily all about the amount of weight you use.

We’ll use the biceps curl as an example. When you curl the weight, the force acts downwards, and the opposing muscle force acts in the opposite direction and along the length of the muscle. At a microscopic level, you have actin and myosin protein filaments. Actin contains binding sites for the myosin heads to attach, rather like a ratchet mechanism. When you contract the muscle to raise the weight, the actin and myosin protein filaments move over each other, shortening the muscle. It is at this level that the aforementioned mechanosensitive proteins exist.

The mechanical stress we are talking about is the muscle contractile force and nervous input required to cause the actin and myosin filaments to slide over each other and shorten the muscle. As you’ll see, this is an important distinction from merely the amount of weight you lift.

There are lots of training variables that affect the stress put through the muscle. But, in short, the mechanical growth stimulus is the force applied to the muscle times the overall time under tension. So, any training variable that manipulates the force or the time under stress will have a bearing on muscle growth.


Train to failure

Training to failure means you must train to the point where you can’t perform another repetition of an exercise. This is important if you want to stimulate the maximum number of muscle fibres.

The Henneman size principle explains this. This principle says that the largest motor neurons – and fastest twitch fibres – are recruited only when maximum effort is required. Before that, you recruit the smaller motor neurons first. As they fatigue, you need more effort to move the weight, and the larger motor neurons are then called into play.

The fastest twitch fibres have the greatest potential for hypertrophy, so you must bring them into play and fatigue them. This will only happen once the smaller and slower fibres have been fatigued. In practice what this means is that you must put in the effort. You have to train with as much intensity and effort as you can, or you’re not going to fatigue all your muscle fibres fully.

Note that you can fatigue the very fast-twitch fibres by going super heavy. But then you will fail to recruit the intermediate fibres. That means you will exhaust fewer of your overall quota of muscle fibres and so limit the growth potential. Science, and experience, suggest that the optimal number of repetitions to fatigue the maximum number of muscle fibres is between 8–12.


Use a lot of energy

When you train with weights, you get a temporary increase in testosterone and growth hormone, which will in turn stimulate IGF-1 and mTOR.

Testosterone levels increase most when you use the maximum number of muscles and nerves. That generally means big full body or compound exercises like squats, deadlifts, bench press, pull-ups and so on.

The best way to stimulate growth hormone is to use a lot of energy and puff hard. You can achieve this by choosing big moves and resting for only a short period, getting a lot done in a short space of time.

You can increase both hormones simply by using a lot of energy on challenging exercises, moving quickly between sets. Don’t toil for hours, though, as you may start to impact your hormone response negatively. Choose big moves, get the job done and get out in no more than an hour.


Get a pump

A pump is when your muscles feel swollen and tight after training. It’s caused by the muscle cells swelling as they take in more fluid during training.

We’ll cover the pump in a second instalment of this article. But, for now, I’m going to state that getting a pump requires training in a different way. The techniques for getting a pump oppose the advice we’re giving in this article to some extent. That doesn’t mean that you can’t have both. You can – but it means you need to structure your workout in a certain way so that both contribute.

You don’t have to ‘chase the pump’ to make good progress. Following the guidance in this article, you’ll be able to get toned and, if you want to, beefy! But if you’re going to hone your physique or enter a competition, for example, then the pump is essential. Even if you don’t have those aspirations, you might fancy getting a pump just because it feels great.


So, with the key factors identified, let’s talk about training variables.


How should I train to build muscle? Optimise your training variables



Choose the right weight. That doesn’t mean the heaviest you can lift for one rep; it means the heaviest you can lift for 8-12 quality reps.

But be careful. Don’t get all silly and start lifting weights that are too heavy. You’ll injure yourself. Use proper, safe technique. Or as we say, use good form. Choose a weight that is very challenging when you lift with good form. Make sure you get to the point where you can’t complete another rep and try to ensure this is somewhere between 8 and 12 reps


The negative

It’s easy to think lifting weights is all about lifting. That’s only half of it. It’s also about lowering. We call the lifting part the positive or concentric contraction and the lowering part the negative or eccentric contraction.

It’s crucial you lower the weight under control. When you do that, you are using a lot of force to slow down the lowering. The myofibrillar ratchet is going in reverse even though your applying the force in the opposite direction. This difference in muscle activation leads to different adaptations in the muscle.

Ideally you want all types of adaptations, so if you fail to control the negative, you’re missing out.

Another reason to control the negative is to avoid injury. If you’re out of control, you’re going to overstretch something and damage yourself.



First, if you lift and lower the weights too quickly, you’ll end up ‘bouncing’ at the end ranges of your movements. You’re using the elastic properties of your connective tissues to help with the lifting. Not only does that take mechanical stress away from the muscles, but it’s potentially damaging.

Second, you’ll also be using poor form if you start throwing the weight around. More than likely, you’ll be jerking your body to achieve more speed. And, of course, that takes the stress off the target muscles.

Third, and probably the most compelling reason to slow it down is that muscles generate more force at slow contraction speeds. That’s because a slower contraction allows more time for the actin and myosin filaments to form connections (crossbridges).

The more crossbridges you form, the more mechanoreceptors you will stimulate and the more you’ll stimulate mTOR.

So, if you want to maximise the mechanical stimulus on a muscle, deliberately slow it down — two seconds up, three seconds down. You may get fewer reps, but you’ll get better results.



Let’s look at the biceps curl again.

Simple biomechanics of the biceps curl. How should I train to build muscle

Maximum applied force

First, In the picture above, the greatest force on the muscle occurs when the forearm is horizontal. Here, the force of the weight is acting perpendicularly to the forearm. We say the ‘moment arm’ is at its longest when it is perpendicular to the applied force. It is at this point that the muscle has to generate the most force.

Hold that thought for now.


Maximum generated force

Second, now consider the force-length relationship of a muscle. Note that a muscle can generate the most force around the middle of its range, when it is neither stretched nor shortened.


Length tension relationship of musculotendinous units. How should I train to build muscle

Match maximum applied force to maximum generated force

Now let’s put those two observations together. You should choose exercises that allow you to apply the most force to a muscle when the muscle is able to generate the most force. In other words, you want the point at which your moment arm is longest to coincide with the middle of the muscle’s range where it is strongest.

In the biceps curl example, the moment arm is longest when the forearm is horizontal, and this also coincides with the middle of the range for the biceps muscle where it is strongest. It is neither stretched nor shortened. So this exercise, the way it is shown, is perfect.

Now imagine you lie face down but keep your upper arm parallel to your torso. The applied force will be greatest when the muscle is fully contracted because that’s when the forearm is horizontal. But your muscles cannot generate as much force in that position, so your maximum applied force – that is, weight used – will necessarily have to be less. As you lower the weight, the angle of the applied force changes and the overall applied force reduces. At the point where the muscle is in its mid-range, and strongest, the applied force is much less than the force the muscle can generate. The result is a much-reduced overall mechanical stress on the muscle.

So, in practice?

What does this mean in practice? If you want to maximise mTOR through mechanical stress, choose exercises and ranges of motion that maximise the applied force when the target muscle is strongest. Here are some examples:

  • Biceps: Standing barbell curls
  • Triceps: Cable pushdowns
  • Thighs: Squats to at least parallel
  • Shoulders: Lateral raises and shoulder presses
  • Chest: Bench press
  • Back: Pull-ups

Hamstrings are an interesting one. Romanian deadlifts hit the hamstrings hardest in their fully stretched position. Lying hamstring curls provide a better match between force applied and force capability. A good hamstring routine for growth should include both knee flexion and hip extension – i.e., both exercises.

Woman being spotted on dumbbell bench press

Notice how these are all old school basics? There’s no fancy stuff. The fancy stuff might serve you well if you’re after a pump, but if you want to elicit muscle growth through mTOR’s mechanoreceptors, traditional basics are the way to go.



Use as full a low-risk range as you can. You have to form a lot of crossbridges to go from a fully stretched muscle to a fully contracted muscle. More crossbridges means more opportunity to stimulate the mechanoreceptors and more metabolic by-products to provide signals for recovery and adaptation. Partial reps might be appropriate if you’re trying to get a pump but, if you want to stimulate mTOR through the accumulated application of muscle force, a full range is essential.

Myosin and actin filaments in a sarcomere showing different lengths



We almost covered this earlier. By intensity I mean give it everything you’ve got and make sure you can’t get another rep. If you stop one or two reps short of failure, you haven’t trained all your muscle fibres.

However, you can do better than failure. If you can’t lift the weight one more time, you’ll usually be able to lower it at least one more time. Once you hit concentric failure, there are ways to keep the set going until you hit eccentric failure. We call that absolute failure. It’s not appropriate for every exercise, and it comes with some risk, so I’d regard it as an advanced technique. But I mention it because it shows that, even when you think you’re spent, there’s probably a little left in the tank. Empty the tank for best results.



Form covers several training factors, including lifting posture, tempo, range and so on. Here we’re talking about lifting posture.

Adopting the right posture when lifting will not only minimise risk, it will maximise the force applied to a target muscle. Let’s say you’re targeting your thighs with squats. If you bend too much at the waist and round your back, you’re risking injury for a start. But you’re also taking the stress off the thighs and putting some of it in your back, glutes and hamstrings.

Man being spotted on squats

Lift with impeccable form if you want to put the maximum force through the target muscles.


Set duration

This is more or less pre-determined. If you’re keeping your reps nice and smooth and controlled and you’re getting 8-12 reps, then your set is going to last 40-60 seconds. That sounds like a long set, doesn’t it? Try it and see what results you get.


Exercise choice

We’ve already talked about choosing the exercise that puts maximum stress through the muscle when the muscle is strongest. That’s one consideration.

Another consideration is the number of muscles activated. The more muscles you activate, the more motor neurons that get involved, the better the hormonal response. To meet that requirement, choose big basic movements like squats, bench press, deadlifts, pull-ups and so on. That’s handy, because those tend to be the same exercises that put maximum stress through the target muscles at the right part of their range of motion.

Legs of a man doing leg press


Rest between sets

You may have heard conflicting advice on this one. This is one area where getting a pump conflicts with generating maximum force.

If you’re looking for a pump, short rests work best. But if you want to generate maximum force on consecutive sets, you’ll do better waiting 2 minutes or more. That will give your muscles enough time to recover, refuel and be ready to go again with maximum output.

We do a lot of supersets, working opposing muscle groups on alternate sets. That way, we create about 3 minutes rest between sets for the same exercise and keep up the pace of the workout. Keeping up the pace, if you’re fit enough, helps you get more work done in a shorter space of time and improve growth hormone release. You can do a whole-body workout in this fashion by pairing the right exercises together: chest and back; shoulders and legs; biceps and triceps.



My view is that if you work intensely enough and maybe throw in the odd rest-pause set, then three sets twice a week will be enough. Ultimately, if your weights or reps are going up every workout, you’re making progress and gradually, over time, putting more mechanical force through the muscles.

If you’re not working intensely enough or you’re taking performance-enhancing drugs, then you’ll probably need, or be able to recover from, more sets.

So, should you stop short of failure and do more sets, or hit failure and keep the set count down? It’s an easy choice for me. Work as hard as you possibly can, fail on each of three sets, get the job done and create time for the rest of your life.

You can still incorporate variety by choosing different exercises in each workout, stimulating your muscles differently each time.


Rest between workouts

Your muscles need time to recover before you hit them again. They should recover, adapt and get a little stronger after a particular time. After that peak of recovery, if you don’t train them again, they’ll return to where they were and ultimately even below that. You should aim to hit a muscle when it is at that recovery peak, so that you are continually getting a little bit stronger. How long is the length of recovery to that peak? That depends on genetics, nutrition, training experience and so on. In my experience, 3 to 4 days is about right. That means hitting a muscle twice a week with a short sharp workout should do very nicely. The Glute Guy provides an excellent explanation of training recovery, including some great diagrams like the one below.

Sequenced training recovery curves showing optimal frequency.

Elite level bodybuilders may hit a muscle once a week, but they will annihilate the muscle in that workout, achieving failure many times, doing lots of sets and using intensity techniques. They have great genetics and additional ‘help’, so their muscles can recover from that sort of bashing. But for mere mortals like you and me, that may be too much from which to recover adequately.

Your nervous system needs time to recover too. That means you need to take a break from training during the week so you can give all your workouts your full nervous input. You might train five days a week taking two days rest, or you may find you perform better by training 2-3 times a week. Either way, aim to hit each muscle group twice a week with a short, brutal workout.



You certainly need variety in terms of exercise selection. If you just do the same exercises all the time, then you’re only stressing the target muscles in one orientation. There may be some muscles that never get adequately trained because they are not taken anywhere near fatigue during the sets. Choose a different exercise to hit the muscles differently so that everything gets a chance to experience fatigue, to adapt to the training stimulus and grow.

Take your back, for example. If you just do pull downs, then your lats will get a good hiding, but your rhomboids and upper traps won’t receive much of a stimulus. But if you also do rows, then these other muscles get much more involved.

Even within the same muscle, you might find the distal portion of the muscle is emphasised more by one exercise and the proximal portion by another. So, you can even alter the ‘look’ of your muscles by making appropriate exercise choices. You can typically ‘feel’ where an exercise is creating the most fatigue.



Who knew weight training could be so varied and exciting!

If you’re a devotee like me, then you’ll know there is no end to the fun and the interest that a programme of lifting can create. But, mainly, there’s no end to the challenges. You can be dedicated to your gym habit and toil away for hours without making progress. The challenge is to optimise your training variables to maximise muscle growth.

To me, though, the biggest challenge is always intensity. This is the variable is see missing most often in trainees. It’s not that trainees lack self-discipline and motivation. It’s just that working to proper agonising failure takes grit and determination. It feels horrible, and it requires you to get way outside your comfort zone. And it takes practice to master it. But, as long as you are persistent and courageous in your lifting, you will master it.

Are you feeling informed and inspired? Then get out there and lift!


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