Muscle gain is a matter of adaptation. During a personal training session focused on this, you stress and cause intentional damage to your muscles. When they repair from this, they do so bigger and more capable so that they can deal with the next time they’re put under such stress.

It’s a survival system. It makes sure that if on Occasion No 1 you managed to escape or fight off a predator using your current physical capabilities, you returned stronger upon Occasion No 2.

Imagine you simplify your body and it consists of six key muscles. When you first start doing any kind of general exercise, all six will receive stress to adapt to, because they’re involved in most movements.

Think running, jumping, squatting, climbing, pushing and pulling. Over time you will adapt and be able to deal with these full-body movements.

Once you’ve built the muscular ability to last a workout, then it’s a matter of your cardiovascular system staying capable. You last as long as it can feed oxygen to the necessary parts of your body.

One or the other will eventually hold you back and that’s when you can’t work out any more.

The science behind muscle-building

Muscle-building training focuses on targeting very specific muscles each time you train. It focuses the damage done during that window.

In this theoretical simplified system, an hour means you’re only spending 10 minutes of each workout training each key muscle. This is no longer enough to cause damage and adaptation. You’ve stagnated and are getting faster at completing the previous set of exercises.

You start spending more time on each muscle to fatigue and damage it more. This involves switching to three key muscles per workout so that each one is getting an average of 20 minutes of attention and training per session.

You keep training this way, using various movements and techniques. You increase the load, changing up the order of your movements and number of repetitions used, until you once again hit a plateau.

Your personal trainer then moves you onto only two muscles per session, so now each one is getting a massive 30 minutes of destruction. Once again it must repair to tolerate this.

This is where most people stop at their max capacity and the only route to progress is increasing the volume of weight they’re lifting. See, at this rate, you’d need three workouts to stimulate all six key muscles.

If you decreased the number of muscles per session again you’d only hit each one once a week. This is not enough volume, contrary to most people thinking they need a “chest day” and a “back day”.

Professional bodybuilders can do this because they take drugs that allow them to recover faster. They are able to manage such sessions twice a week.

For those not taking performance enhancing drugs, there’s a fine balance with this. Most personal trainers who focus on hypertrophy understand it, but many do not. Plus, it’s quite difficult to find movements that only target one group at a time exclusively.

It has to be very isolated, and this restricts the variety of movements you can use to stimulate growth, plus the total weight used. You must bear in mind that individual muscles need enough rest time between sessions to undergo the repair process. You can hit them too often.

Complete muscle growth cannot be achieved through pure isolation. Yes, the muscle is put at a mechanical disadvantage in these situations so it is experiencing maximum stimulation and “activation”, but it is not experiencing maximum load.

Involving it in a movement with other muscles that shifts a huge load is crucial to completely stimulate the fibres in a muscle.

Which brings you to what was mentioned previously about repetition ranges. Part of a personal trainer’s job is to play with these variables to create a complete adaptation of the muscle.

Understanding your muscles

Muscles have two different types of fibres in them which are used for different requirements.

In each muscle you have fast-twitch fibres that you use for very heavy or very fast movements, but fatigue quickly. You then have slow-twitch fibres that focus on lighter movements at a slower pace and for a longer period. Think sprinting versus jogging.

There are also two different ways you can increase the size of muscles: myofibrillic and sarcoplasmic.

• Myofibrillic hypertrophy is increasing the number of fibres within your current volume of muscle.

• Sarcoplasmic hypertrophy is increasing the amount of fuel your muscles can store around your fibres.

Both aspects are crucial for mass development.

Therefore your weights used, repetition ranges, time under tension, and movement tempo affect this.

Your personal trainer manipulates these factors to achieve total stimulus and growth. It is a dark art that is as often over-simplified as it is over-complicated.

Joompa is a digital platform that facilitates the sourcing and booking of freelance, mobile personal fitness coaches. Available on iOS or via www.joompa.com.my