For those of you that regularly resistance train and have muscle building or toning goals, gym closures through the COVID-19 pandemic are particularly challenging. Most of us don’t have heavy enough weights or machines at home to carry on working out as normal. This inevitably means that we are destined to lose our well-earned muscle, right? At the very least, we will have to drop our muscle building goals for now, won’t we? 

It is common knowledge that we need heavy weights to continue to grow, but this is only partially true – “heavy” is relative to the rep range we are using. Whilst heavy resistance training is undoubtedly effective at growing muscle, it isn’t absolutely necessary, and is not the mechanism that drives muscle growth. The primary mechanism in muscle growth is actually an overload in mechanical tension. For our purposes, ‘overload’ refers to a stressor (exercise, in this case) needing to be challenging enough to create the need for the body to adapt to it. Mechanical tension, on the other hand, is the type of force that tries to stretch something. When mechanical tension overload is picked up by mechanoreceptors in the cell, it is transformed into a chemical signal for DNA and ribosomes located in the muscle to build new proteins, and therefore muscle. 

Contrary to popular belief, muscle growth does not result from muscles tearing and growing again – though admittedly, this is a byproduct in the process. How, then, do we generate enough mechanical tension in a set to create overload and muscular growth? 

Firstly, we can generate mechanical tension by lifting heavy weights. As long as the weights we are lifting are heavy enough, each repetition will cause enough mechanical tension on all muscle fibres simultaneously and overload them. Alternatively, we can lift lighter weights to the point of failure, or fatigue. This method works because when we start a set of lighter weight exercise, we only use smaller, low threshold motor units (collections of muscle fibres and the nerves that activate them) because that is all we need to complete the movement. When these motor units become fatigued and can no longer keep up, the body switches to larger units until they become fatigued, and so on until all motor units and the fibres they are attached to have been fatigued.

This last effect is known as ‘Hennemen’s size principle’. Put simply, the principle states that as more force is needed, motor units are recruited in order, from small to large, to deal with the magnitude of the force. This means we will only ever use the motor units that are needed in a given moment – which surely means that there will be cases where some units are never recruited. If they are not recruited, why would they grow? This is where heavy weight training comes in. Heavy weight training recruits all units simultaneously, by sheer virtue of how heavy the weights we are looking to handle are.

Continuing to the point of fatigue is crucial thanks to the force-velocity relationship. Line graphs of this effect are easy to find on Google, but the simple takeaway is that as repetition speed or tempo decreases, we can generate greater forces. Conversely, as repetition speed or tempo increases, we cannot generate as much tension. This is because our muscles contract as a result of two muscle cells (myosin and actin) ‘latching’ onto each other, so that they can slide muscle filaments over each other and effectively shorten our muscles, before sliding back out and giving the appearance of lengthening.

The amount of force a muscle can generate is partially dictated by how many myosin and actin bridges have been created. As repetitions slow down, there is more time for bridges to be created and produce maximal force. This makes sense intuitively if we think of what it is like to lift weights. As we lift heavier weights, we naturally cannot lift them as fast – because the amount of force and tension we need to generate to lift them is so much greater. We have to slow down contraction speeds to effectively lift the weight. The problem is that we cannot intentionally slow down repetitions, because then we would be a long way away from fatigue, and thus would not yet be recruiting high threshold motor units – making our goal of muscular growth unattainable.

For an effective weight training set, therefore, we need to fulfil two main criteria:

  1. Producing high levels of effort
  2. Performing reps at slow speeds

We need to train close to fatigue or failure, whichever comes first. As long as any given set is coming close to either of these states, rather than because of technical failure (e.g. losing balance or introducing additional muscle groups) then we have an effective set that will stimulate growth. Do enough of these sets on a consistent basis, along with a diet that supports it, and we will continue to grow. As long as we are willing to put in the work, we should have no trouble continuing to grow muscle at home, therefore.

Whilst we can train to failure with light weights easily at home, a time effective way to avoid needing to do high repetition sets is to use intensity techniques – getting more results out of less time. One of our favourite and most effective intensity techniques is the rest pause method. The rest pause method uses an activation or initial fatigue set, then short rest periods to keep us close to failure and allow us to continue doing mini-sets that still fulfill our criteria for an effective set (high levels of effort and slow repetition speeds), with fewer repetitions. This practice allows us to accumulate the most effective reps in the shortest time. An example of how this would look with press ups is shown below:

  1. Initial failure (or close to failure) set – 25 repetitions
  2. 3-5 deep breaths
  3. Second set to failure (or close to failure) – 8 repetitions
  4. 3-5 deep breaths
  5. Third set to failure (or close to failure) – 6 repetitions
  6. 3-5 deep breaths
  7. Four set to failure (or close to failure) – 4 repetitions
  8. Done!

Count all main and mini sets as full sets rather than straight sets – as long as they are close to fatigue or contain 5 or more reps. This method is excellent for any at-home exercise you can perform that would require you to do high repetition sets to reach failure, and research has shown that it is as effective as using straight sets. 

A study by Prestes et al. (2019) compare six weeks of volume-equated resistance training in either the form of straight sets or with the rest pause method, and found that muscular gains were roughly equivalent between the two groups – but actually significantly greater in the thighs of people using the rest-pause method compared to straight sets. Long story short, you lose nothing by employing this method in at-home training. You can stay on track with your muscle building or toning goals, and in some cases, achieve greater growth than you could have hoped for in the gym. Try for yourself and see how you get on.