Hypertrophy refers to the increase the in size of the individual muscle fibres which in turn leads to an increase in the cross-sectional area and volume of a muscle.
Over the last few years, we have made some advancements in the area of hypertrophy research. More specifically, the research now seems to suggest that tension is the primary driver of hypertrophy, while muscle damage and metabolic stress, which were previously believed to play a direct role in hypertrophy, appear to be indirect side effects of tension.
In fact, some research even suggests that too much muscle damage or metabolic stress may actually impede hypertrophy. As a result, the best way to train for hypertrophy may actually be to maximize muscle tension, while minimizing muscle damage and metabolic stress.
Here are 5 tips for structuring your workout to maximize hypertrophy.
Although studies have shown that similar hypertrophy can occur on a set per set basis using anywhere from 5 to 30 reps per set, neither too low nor too high reps is very efficient. When doing very low reps, you need more sets to accumulate sufficient volume, which increases the risk of overtraining [1].
When doing too many reps, the earlier reps don’t contribute in any meaningful way to the training stimulus. They simply act to bring you to a point of fatigue for those last 5 or so stimulating reps. In the process, you accumulate a lot of unnecessary fatigue, which limits the number of quality sets you can perform in a workout.
Therefore, using moderate loads between 6-12 reps per sets, is likely the sweet spot for hypertrophy. Anecdotally, this is the range in which most bodybuilders train.
The verdict for optimal volume dose per session for hypertrophy is not out yet, with some studies showing a clear dose-response relationship, and others showing no clear plateau at higher volumes. However, it is worth pointing out that those studies which showed no clear plateau with increasing volumes of up to 15 sets per body part per session, used incomplete rest periods [2,3].
Incomplete rest periods have been shown to lead to a blunted anabolic response [4,5]. As such, you might need to do more volume when using incomplete rest periods in order to get the same training effect, which is inefficient, and it increases the risk of overtraining.
Therefore, we generally recommend a moderate volume of 5-10 sets per body part per workout. Generally, the closer to failure that you work at, the lower the number of sets per body part should be.
When a muscle fiber produces maximal tension in the middle or at the top of the strength curve, it bulges outwards, which stimulates the fiber to increase in diameter. On the other hand, when a muscle fiber produces maximal tension at the bottom of the strength curve, it deforms longitudinally, which stimulates the fiber to increase in length [6].
As result, to stimulate maximal growth, you want to use at least two exercises for each body part targeting opposite ends of the strength curve. For example, for the hamstrings you could perform lying leg curl to overload the top of the strength curve, and Romanian deadlifts to overload the bottom of the strength curve.
Historically, shorter rest periods have been recommended for hypertrophy because it was believed that the acute increase in anabolic hormones and metabolic stress would promote hypertrophy.
However, as we mentioned earlier, shorter rest periods have actually been shown to blunt the anabolic response from a workout [4,5]. This is likely due to central fatigue inhibiting full motor unit recruitment on subsequent sets.
As a result, allowing ore complete rest, around 2-3 minutes between sets, may be optimal for hypertrophy.
A recent meta-analysis by Schoenfeld and colleagues found no difference in hypertrophy between weekly training frequencies of 1 to 3 times per muscle group, when weekly volume was equated [7]. However, there was a trend to favour higher frequencies when volume was not equated.
This makes sense, given that there is a limit to the amount of muscle building stimuli we can induce in a single workout, and it is possible to accumulate more weekly volume per muscle group when it is distributed over multiple sessions.
However, several studies have shown that recovery of strength after a strenuous workout can take up to 4 days [8]. Therefore, training any sooner than that would unlikely yield any further hypertrophic benefit, since full motor unit recruitment may be impaired if full strength recover has not taken place after a workout.
Therefore, it is likely that the optimal frequency per muscle group is twice a week. This allows you to accumulate more weekly volume per muscle group while still achieving full recovery between workouts.
