Building lean muscle can be a complex and confusing process. Some want to develop a lean, toned body and some want to dramatically increase muscle size for aesthetics or sports performance.

There are a number of factors to consider – how much weight to lift, how many sets and reps to complete, how long to rest between sets – the list goes on. The good news is that is that it doesn’t have to be so tricky to understand, and in the short article below I have identified 5 things we must consider when setting out to build muscle, and how each element intricately affects the others.

Let’s talk Hormones

When we overload the musculo-skeletal system with resistance training, arguably one of the most important changes with regards to muscle building is our hormone profile. When we perform certain exercises at the correct intensity (more on that later), we can influence the amount of hormone activity in our body. Specifically, there are three hormones which hold the key to our muscle building capabilities; Insulin-Like Growth Factor (IGF-1), Testosterone and Human Growth Hormone. The good news is that all three are known to ‘spike’ (and therefore aid muscle building) when the body is placed under certain stressors.

Muscle Damage and Metabolic Stress

Building lean muscle is essentially a process of damage and re-building. In layman’s terms – when we lift weights and work our muscles hard enough to elicit damage to the muscle cells, we create micro-traumas. Once our bodies sense that this has occurred in the various tissues – it begins to work on rebuilding them, which, with enough rest before damaging them again, will become slightly thicker. Working our muscles at the correct level to prompt muscle growth requires metabolic stress – most commonly recognised by the rush of lactic acid towards the end of a set.


So if the goal of training is to increase the levels of IGF-1, Testosterone, Growth Hormone, Muscle Damage and Metabolic Stress in any given workout – how many sets and reps should you complete? The answer is 4 sets of 6-12 repetitions, and this is related to the specific energy systems employed by the body to perform at this level. To take this point further, research also suggests that some exercises should be performed to failure (the point at which you cannot physically complete any more repetitions because your muscles are fatigued) towards the latter stages of your workout. Workouts specifically targeted to build lean muscle should include more than one exercise for each muscle group – to initiate the muscle damage process.

An important factor relating to intensity is the speed of movement. If strength and power is the goal, then explosive exercises such as power cleans and jump squats are appropriate. For muscular growth, however, muscles should be placed under tension for slightly longer. When performing the squat, an appropriate tempo for muscle building is 3-1-2-1. This means taking 3 seconds to reach the bottom of the squat, pause for a second at the bottom, pushing back up over 2 seconds and pausing at the top. Working with a set tempo will ensure that the muscles are under tension (and therefore increasing muscle damage and metabolic stress) for longer.

Exercise Selection

One frequent question on this topic relates to the sorts of exercises we should complete to bring about the above responses – multi-joint movements such as squats and deadlifts, or isolated exercises which target specific muscles such as chest flyes on the cable machine? The answer is both.

Sports scientists have used EMG testing to assess the various muscle activation cycles when different exercises are performed, and, it is universally agreed that the greatest rate of muscle building is achieved when we select exercises which test muscle groups from various joint angles.

The argument for working muscles in isolation therefore, is mainly to enhance the activation or strength of an underdeveloped muscle – contributing to muscle symmetry and greater posture. On the other hand, multi-joint exercises such as squats and deadlifts increase overall muscle activation because the core muscles, the upper back, and legs are all placed under tension for the duration of the set.

At OPUS, we believe that the combination of isolation exercises combined with multi-joint exercises is the most efficient way to develop lean muscular growth due to the stressors placed upon the muscles from varying angles.

Rest Interval

The final training consideration is the rest intervals between sets. Short rest intervals of less that 30 seconds can certainly increase the amount of metabolic stress (and therefore the the ‘burn’ from lactic acid and hydrogen), but this can extremely limit capacity to replicate the same output in the subsequent set. Long rest periods of 3 minutes or more will certainly allow the muscles to recover and strength output to be greater, but the metabolic stress will not be so high. Therefore, to build lean muscle, rest periods of around 60-90s between sets seems to be optimal to stimulate the hormonal and metabolic responses within the cells.

So, taking all of the above into account, follow these guidelines if your goal is to increase lean muscle mass;

1. Complete a mixture of isolation and multi-joint exercises which stimulate muscles from various angles

2. Select challenging weights to ensure that metabolic stress and hormone secretion is increased

3. Complete 4 sets of 6-12 repetitions, with more than one exercise on each muscle group

4. Rest for 60-90 second between sets

5. Ensure that each repetition is performed with control in each phase of the movement to ensure the muscles are contracting for longer periods of time during each set.