The importance of overload when training for hypertrophy
Types of overload
There are 2 kinds of overload:
Acute overload- the idea that your training must reach a certain threshold to cause improvements.
Progressive overload- the idea that your training must get harder as you progress, to stay at the threshold where you can still stimulate improvements. This can be done by increasing volume, load, frequency or duration.
Training variables
To achieve overload and progress, you must train in a way that stimulates progress. There are many variables to take into account when training for hypertrophy, the most important one is tension, followed by volume, relative effort, range of motion (ROM), metabolite accumulation, cell swelling, mind-muscle connection, movement velocity and muscle damage. Bear in mind all these variables affect one another to some degree.
Tension
It has been proven that the more tension sensed in the muscle, the more muscle growth is stimulated. You can get tension in the muscle by lifting a low weight (for instance a water bottle), but this will only activate a small amount of motor units and nearly all only slow-twitch muscle fibres (as opposed to fast-twitch muscle fibres), these are small and less prone to growth, so this will therefore cause no noticeable muscle growth. Basically, you must use a heavy enough weight to activate mechanoreceptors, located throughout the muscles, and create a signalling cascade which results in an increase in protein synthesis and therefore muscle growth. The weight shouldn’t be too heavy however as this causes fatigue or prevents sufficient volume, inhibiting how long mechanoreceptors are activated for.
Volume
Spending a large time under tension will ensure optimal muscle growth, as this will ensure that mechanoreceptors are activated for as long as possible, you can do this by increasing volume. To increase volume you must increase reps, sets or both. You therefore may believe that performing high-rep sets is best for muscle growth, but this is not the case, you should aim to train over multiple rep ranges throughout a training block, including 20-30 reps, 10-20 reps and 5-10 reps, to hit all muscle fibres in a muscle evenly. The problem with high reps sets is that they really challenge your cardiovascular abilities, meaning you are likely to finish your set before you have had the chance to really challenge your muscles. For sets, it is best to incrementally add 0-4 sets every week, depending on how your recovery is going in between sessions, otherwise, if you accumulate too much fatigue you may need to perform a recovery session (a session with low intensity), half-week (3-4 consecutive days of low intensity training) or take a deload week too early. When looking at volume to train with there are many things to take into account, maintenance volume (MV) is the volume to train with that will cause no muscle loss or muscle gain. Minimum effective volume (MEV) is the minimum amount of volume needed that will cause muscle growth. Maximum adaptive volume (MAV) is the maximum amount of volume needed that will cause the maximum muscle growth, without being too much volume that it causes diminishing returns. Maximum recoverable volume (MRV) is the amount of volume you can train to whilst still seeing results, beyond this will cause muscle loss. MV, MEV, MAV and MRV change considerably depending on the individual and the muscle that you are focusing on. When choosing how much volume to train with during an exercise here is one thing to take into account, say you perform 3 sets of bent-over rows and in each set you felt the exercise was more stimulative to muscle growth than the last, then it makes sense to add a set to this exercise for extra back growth, as the fourth set is likely to be even more stimulative to growth than any of the other 3 sets. You can accidentally add too many sets if your programme isn’t designed carefully enough, for instance adding volume to a bro split will likely be catabolic, as you will be training with too much volume in a single session.
Relative effort
The relative effort variable is how close to failure you push during a lift. Training close to failure during an exercise stimulates the larger, more growth-prone fast-twitch muscle fibres. The motor units that innervate these fast-twitch muscle fibres are mostly activated from five reps from failure (5 RIR) to complete failure (0 RIR). The growth stimulus between 5 RIR and 4 RIR is fairly large, the growth stimulus between 4 RIR and 3 RIR is a bit less than that, 3 RIR and 2 RIR is a bit less than that and 2 RIR and 1 RIR is a bit less than that and 1 RIR and 0 RIR is a bit less than that. The growth stimulus between 1 RIR and 0 RIR is therefore minimal, due to no extra motor unit recruitment. Judging RIR can be very difficult for beginners, so if you are just starting lifting, and you have good technique, take a set that you believe to be your 8 RM or so to complete failure in order to test your true abilities. However, beginners can still experience great benefits with a higher RIR than a more advanced lifter, so knowing their RIR exactly isn’t necessary, especially being that their RIR will increase very fast, but it is good to demonstrate to beginners their true abilities.
Range of motion
It is constantly proven that a larger ROM is superior to a smaller ROM, for stimulating muscle growth due to prolonging tension in the muscle. Increasing ROM activates different portions of muscle fibres throughout the exercise, creating a bigger, better-looking muscle. Stretching the muscle by using a full ROM is also more likely to add length to the muscle as opposed to just width, creating a more aesthetic muscle. A lack of ROM is the reason why isometric training will not cause any significant muscle growth, isometric training is also highly fatiguing, however, isometric training can be good to hit certain muscles or parts of certain muscles, for instance pausing for a second at the top of the concentric part of a row will hit the rhomboids and mid-traps, it will hit these muscles even more if you only half extend on the eccentric phase of a row, before performing another rep. Interestingly ROM is a reason why lat pulldowns and pull-ups are better for lat growth than rows, as the lats get more ROM. Performing a full ROM each exercise may not always be favourable as technique can begin to break down and it can cause pain and discomfort. “Partials”, meaning partial range of motion exercises, activate certain motor units innervating certain muscle fibres, but you likely get the same effects from performing a range of exercises for the same muscle providing they were all performed with the same relative effort, rendering partial movements useless for overall muscle growth, they also make progress hard to track, as rather than getting stronger you may just be decreasing ROM. Another problem with only partially performing a movement (like when people only squat halfway to parallel on a squat) is that the muscles and connective tissue get used to this ROM, so if you were to go just 2 or 3 inches deeper then you usually would you will likely fail the rep and have a high chance of tearing connective tissue, as you don’t have the connective tissue build up to cope with this ROM. All this ROM stuff may seem complicated, but basically perform a ROM where you feel a good stretch and contraction, if you struggle to perform a good ROM you should work on your technique and mobility to fix this. A good method to increase ROM is pausing at the point of a lift where you can’t stretch the muscle anymore, stay here for 1-2 seconds then complete the rep.
Metabolite accumulation
Anaerobic energy systems (The ATP-PCr system and glycolytic system) produce by-products which send signals for muscle growth, especially the by-product lactate. This is to say that the more metabolite accumulation present or the longer there present the more they will signal for muscle growth. The tension variable is intensified when metabolites are present in the muscle, this suggests that metabolite accumulation can have an indirect stimulus to muscle growth. Most metabolites accumulate close to failure, but I wouldn’t recommend training to complete failure, for reasons discussed earlier.
Cell swelling
lactate has a strong osmotic gradient, so when it builds up in muscle it pulls water into the muscle fibre causing it to swell. The swelling puts pressure on the cell membrane which stimulates amino acid transport, anabolism (protein synthesis), growth hormone and testosterone. Cell swelling stimulates more growth in fast-twitch muscle fibres than in slow-twitch muscle fibres. To get the cell swelling you must train with fairly low weights, as going too heavy means you will be using almost exclusively use the ATP-PCr system for energy, which doesn’t produce lactate. However, the primary cause of cell swelling is from muscle contractions which cause an increase in blood flow to the muscle and occlusion of venous outflow from the muscle contractions not allowing blood to leave the muscle. The rep range where cell swelling occurs differs in different people, people with a large quantity of fast-twitch muscle fibres may experience a good “pump” within the rep range of only 5-10, but most people will only experience a good “pump” from a higher rep range.
Mind-muscle connection
Mind-muscle connection is simply the awareness of the target muscle working during an exercise. This variable isn’t extremely important, but it is useful to tell if each of the other variables is present, for example, to try and sense the burn from metabolite accumulation in the biceps, during a set of bicep curls. The best rep range for mind-muscle connection is typically between 10-20 reps. A mind-muscle connection for a particular muscle can take a while to build during a certain exercise so try to adjust your technique and take time to practice with an exercise over a whole mesocycle before you just abandon it.
Movement velocity
Movement velocity is the speed at which you perform a rep. For safety reasons and to keep the muscles working you should rarely (if ever) rest at the top or bottom of the lift or just let the weight drop during the eccentric phase of a lift. The speed of each rep will also determine if slow or fast-twitch muscle fibres are activated, fast, explosive reps will stimulate a lot of fast-twitch muscle fibres, whilst slow reps will stimulate a lot of slow-twitch muscle fibres. The optimal speed to perform a rep usually is with a 2-3 second eccentric phase, a short touch-and-go style amortization phase, and a quick and controlled concentric phase, lasting roughly 1-2 seconds, this will obviously be difficult to maintain as reps get more challenging. The speed at which you perform different reps can change however, pausing at the bottom of a rep can be safer, can be useful to work around injuries or can be useful to work on technique. Quick explosive concentric movements may be useful to activate more motor units and therefore cause more growth, however, it is likely to be more fatiguing and throw-off technique, which increases the risk of injury and decreases mind-muscle connection. To put it simply don’t spend any longer than 3 seconds on the eccentric, pause and concentric phase of a lift, if you can.
Muscle damage
It is often suggested online that muscle damage isn’t just the most important variable for muscle growth but the only one, however, this is not the case at all, in fact, it is not clear if muscle damage causes hypertrophy or if they both occur due to the same or similar things. If muscle damage is too extreme muscles can consume nearly all resources and cause a decrease in muscle. After training feeling sore in the worked muscles or experiencing delayed onset muscle soreness (DOMS) up to a few days after training is a good sign that you are training optimally for growth, but getting very sore after training will likely lead to suboptimal growth as this means your muscles are probably too damaged and getting extremally sore after training can even lead to muscle loss.
What load to train with
You can gain large amounts of muscle from training with weights as low as 30% of your 1RM, however, training mostly with a weight between 75% and 85% of your 1RM seems to be optimal for muscle growth. It is believed that you can get similar hypertrophy results with any load as long as you push close to failure, but loads below 30% of your 1 RM where you have to perform a significant amount of reps before you reach anywhere near failure it is just fatiguing, and limits muscle activation, it also will take up resources reducing overall muscle growth, this means you will need to significantly reduce the load in the next set to reach this high rep range and you will miss out on a lot of muscle growth, therefore exercises in this rep range are known as junk volume, so if you really want to train with this extreme rep range I would recommend breaking up the session throughout the day so you have chance to recover. Loads above 85% of your 1RM are not favourable for muscle growth either, as there highly fatiguing, increase the risk of injury and reduce metabolite accumulation, cell swelling and mind-muscle connection. Loads below 75% of your 1RM are not optimal, as they stimulate more of the slower lease growth-prone muscle fibres than the larger more growth-prone muscle fibres. Even though load is important the best way to increase the rate of muscle growth is by increasing sets, instead of load or intensity, providing that you were already applying all of the previously discussed variables.
Are you training hard enough?
After a good simulative phew sets, it is normal to feel a decreased ability to generate high-force contractions in the target muscle and some soreness in the muscle, this is a good sign that you are exercising in a way that will stimulate muscular adaptions. DOMS is another good sign that you have had a simulative workout for growth in particular muscles, but you do not need to create soreness in the target muscles to have a good workout, in fact even if you do feel soreness in the target muscle, it doesn’t always mean you have had a good workout.
One thing that can significantly impact how hard you train is CNS fatigue from a stressful lifestyle, this will inhibit how hard you can push your muscles reducing muscle growth.
Thankfully there is a numerical way to find if a particular exercise is simulative enough for muscle growth, by taking the following quiz and adding up the score from each answer. You can use your total score from this quiz to measure the raw stimulus magnitude (RSM), of each exercise, which is basically how stimulating of muscle growth an exercise is for you, you can also find the RSM of different supersets to see if they're worth performing.
Question 1: How much did the training challenge the target muscles?
0- you barely felt aware of your target muscle during the exercise
1- you felt like your target muscles worked a bit
2- you felt a good amount of tension and a burn in the target muscle
3- you felt the tension and a burn close to your limit in the target muscle
Question 2: How much of a pump did you get in the target muscles?
0- there was no pump in the target muscle
1- there was a very mild pump in the target muscle
2- you got a decent pump in the target muscle
3- you got close to the maximal pump in the target muscle
Question 3: How much disruption was there in the target muscle?
0- you had no fatigue or soreness in the target muscle
1- you had some weakness and stiffness after the session in the target muscle, but you recovered by the next day
2- you had some weakness and stiffness after the session in the target muscle, as well as some the next day
3- you had a lot of weakness and stiffness in the target muscle after the session, as well as some for a few days or more after
If the exercise scored between 0-2 you may want to swap out the exercise at the end of a mesocycle. If the exercise scored between 3-6 you can keep this exercise in your mesocycle, but don’t rely on this exercise as your primary source of muscle growth in a particular muscle. If the exercise scored between 7-9 it is likely very simulative of muscle growth, but you may not want to use it too often as it may be overly fatiguing. This quiz is also useful to find out if you are performing at your MEV, which is important to know if you want to keep a muscle at the same size whilst another muscle or muscle group catches up, find this by first performing an exercise for the number of sets which you believe to be at your maintenance volume, then answer this quiz, if you scored between 0-1 you are likely training below you MEV and you, therefore, may want to increase the sets you perform this exercise for and then retake the quiz, if you scored between 2-3 you are likely training below or at your MEV and you, therefore, may want to increase the sets you perform this exercise for and then retake the quiz, if you scored between 4-6 you are likely training above or at you MEV and there is no need to change your training, finally, if you scored between 7-9 you are likely training well above your MEV and you, therefore, should significantly drop the number of sets you perform this exercise for. As you progress through the mesocycle you should add sets to the exercise which hits the muscle you are trying to maintain (the same as any other exercise). If you have stopped feeling sore or have had to increase your volume by 1 rep or more to hit the desired RIR, you may want to add some load to stop your reps from leaving the target rep range.
How to plan a mesocycle using the variables discussed earlier?
A mesocycle is a planned block of training, usually sandwiched in between 2 deload week. When training our sensitivity to volume usually adapts faster than our rep strength, so load, therefore, may not be enough to supply the tension needed, you therefore can increase volume, even if you can’t increase the load, this will yield the most benefits towards hypertrophy. I recommend increasing volume throughout a mesocycle so you can keep getting a good degree of metabolite accumulation and cell swelling, this can mean starting a mesocycle with about 3 sets for a particular exercise and ending it with about 6 sets, the sets you perform at the beginning of a mesocycle may seem low, but it reduces the risk of getting too fatigued too early and having to cut the mesocycle short so you can recover. I also recommend gradually increasing relative effort from about 3 RIR in the first week of a mesocycle, all the way down to about 0 RIR in the last week of the mesocycle, when combined with the increase in volume, this means that we can accumulate more and more metabolites and cell swelling as you progress through the mesocycle, leading to more overall muscle growth. This way of training will not cause too much fatigue too early in the fast-twitch muscle fibres, this means you will get more overall muscle growth and you can train for longer before a deload week. You could just consistently train at 2 RIR but this means you will miss out on any of the advantages of pushing closer to failure.
When deciding what rep range to perform in, remember it is good to change rep range regularly, so there will not be too much volume in a particular rep range, for example, if you have decided to up your sets significantly in the last week of a mesocycle, where you perform only 5-10 reps, you will adapt more to this rep range, as opposed to the higher rep range. It is therefore best to regularly change rep range, for example performing in the 10-20 rep range for biceps on a Monday and then on Thursday performing in the 20-30 rep range for biceps. I would also recommend performing more sets in the target rep range and with the exercise that you fill best stimulates muscle growth without causing too much fatigue. There is a chance that the exercise that you fill best stimulates muscle growth may change throughout a mesocycle due to exercise-specific fatigue, so feel free to shift some sets from a certain exercise onto another exercise, which hits the target muscles in a better way.
When deciding what exercises to perform and in what order, you must consider fatigue. A build-up of local fatigue across a session can be useful, as this means later in the session more metabolites will accumulate and you will get more cell swelling leading to more muscle growth. A build-up of central fatigue however is not as beneficial as this inhibits how hard you are able to push your muscles, particularly after 8 sets or so, this makes sessions which hit multiple muscles problematic. This means you should hit the muscles you really want to grow the most first, if you are not prioritising any muscles then just rotate the exercises that you perform at the start of each session.
I would like to thank Dr Mike Isratel, Dr James Hoffman, Dr Melisa Davies and Jarred Feather for much of the information provided in this article. Make sure to check them out and their book:
Disclaimer: use the information provided in this article at your own risk, as I will not be liable for any harm that may be caused by it.
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