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Progressive overload: is it better to increase the load or the number of repetitions?

by P. Debraux | 4 October 2022

fitness, sport, science, training, workout, progressive overload, repetitions, loads, muscle, hypertrophy

To increase muscle mass, there is no better solution than resistance training. The concept is simple: performing movements against an external resistance. The loads used will create a mechanical tension in the muscle, this mechanical stimulus will then be transformed into a biochemical signal to stimulate muscle protein synthesis, and ultimately, allow muscle hypertrophy, provided that this stimulus is repeated regularly. But as the body adapts gradually to this stimulus, if it remains the same in intensity, the adaptations will also diminish...

The principle of progressive overload implies systematically subjecting the body, and more precisely the muscles, to increasingly intense stimuli in order to cope with the growing capacities of the muscle tissue. And although this overload can involve the variation of a large number of variables (intensity, volume, rest between sets, frequency), the most studied parameter is the evolution of the load lifted during the exercises while maintaining a certain range of repetitions. But since muscle hypertrophy is possible over a wide range of relative loads (30% to 80% of 1RM), what would be the results if progressive overload was achieved by increasing the number of repetitions?

The Study

To try to answer this question, a team of American researchers recruited 43 young resistance-trained volunteers (16 women and 27 men) who participated in an 8-week training program, and 38 of them completed the protocol. The participants were divided into two groups: a LOAD group that increased the load while keeping the number of repetitions constant and a REPS group that increased the number of repetitions while keeping the load constant. The training program consisted of 2 weekly sessions during which 4 sets of 8-12RM on 4 lower limb exercises were performed. The exercises selected were the back squat, leg extension, straight-leg calf raise and seated calf raise.

Each set had to be performed to failure. In the first workout, both groups had to perform the exercises with 8-12 repetitions. Then, in subsequent sessions, the LOAD group had to attempt to increase the load while maintaining the same number of repetitions while the REPS group had to attempt to increase the number of repetitions while maintaining the same load.

How participants fed was recorded by each participant using the MyFitnessPal.com app one week prior to the start of the protocol and during the final week.

To compare the impact of the two progression methods, the researchers assessed muscle thickness via ultrasound in the quadriceps and surae triceps, lower extremity power with a countermovement jump, maximal strength via assessment of 1RM squat in a Smith machine, and muscle endurance in the leg extension by performing as many reps as possible at 60% of 1RM.

Results & Analyzes

The main results of this study show that the two types of progression allow equivalent results to improve muscular adaptations over a training cycle of 8 weeks.

In terms of muscle hypertrophy, the two methods allowed a similar increase ranging from 6.7 to 12.9%. The only difference observed was in the rectus femoris, which had a slightly greater hypertrophy in the REPS group.

In terms of maximal strength, both groups gained an average of 20kg but the LOAD group had a slightly higher average improvement of about 10% (~2kg). However, the confidence interval ranged from -2.4 to +7.8kg, so this difference is questionable.

In terms of muscle endurance, both groups increased by an average of 7 reps, with no significant difference between the two groups.

In terms of muscular power, no progress was noted for either group.

Practical Applications

Over an 8-week training cycle, both progression strategies (by increasing repetitions or loads) seem to allow similar gains in hypertrophy for the lower limb muscles responsible for knee extension and plantar flexion. These initial results remain limited in their application in real-life situations. First of all, because of the duration of the study, only 8 weeks, it is difficult to know with certainty if one or the other mode of progression at long intervals would allow different or similar muscular adaptations. Secondly, because the level of the participants in this study was very heterogeneous. Although they had been practicing for at least 1 year, the strength levels were very different from each other. These results are therefore not transposable to a public of high-level athletes or highly resistance-trained individuals.

That being said, these two systems of progression are used regularly in the gym and are not mutually exclusive. In fact, we often recommend a combination of these two variables for progression. Depending on the exercise or muscle group being targeted, it is sometimes more difficult to add load than to add reps. Adding reps beyond a certain range of reps will decrease the relative percentage of load. So you don't have to stay within a range of 8-12 reps. You may very well continue to 15+ reps, and only then increase the load back to 8 reps and repeat this cycle. Keep in mind, however, that as you increase the number of reps, it will be necessary to push each set to muscle failure in order to stimulate hypertrophy in a similar manner to heavier loads. Also, while hypertrophy may be similar between an 80% load and a 30% load, the strength gains will not be the same in the long run. So don't try to stray too far from your initial reps range in your progression system.


  1. Plotkin D, Coleman M, Van Every D, Maldonado J, Oberlin D, Israetel M, Feather J, Alto A, Vigotsky AD and Schoenfeld BJ. Progressive overload without progressing load ? The effects of load or repetition progression on muscular adaptations. PeerJ, 2022.

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