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Impact of training frequency on muscle strength and hypertrophy

by P. Debraux | 21 January 2020

sport, fitness, resistance training, workout, frequency, mass, muscle, hypertrophy, strength, science

Gaining strength and muscle mass is the number one goal of most people engaged in resistance training. It's true that this activity is certainly the most effective way to achieve these objectives. However, for the training to bear fruit and optimize the expected results, it is essential to manipulate different variables: the frequency of the sessions, the volume, the intensity, the load, the rest between sets, the choice and the order of exercises, speed of execution, type of contraction and range of motion.

The training frequency refers to the number of workouts performed per week, and more specifically to the number of times a muscle group is worked in a weekly manner. Most bodybuilders work with a low-frequency, that is, they work each muscle group 1 to 2 times a week. Each session is devoted to 1 or 2 muscle groups, at most. This working method comes from bodybuilding and is called Split. Conversely, some use so-called Full-Body sessions where all the muscle groups are worked on each session. The frequency of this type of training is therefore higher with 3 to 6 weekly sessions. However, the question of which method is best suited to gain strength and muscle mass often arises. Many claim that Split is an advanced method since it is the method mainly used by bodybuilders (whose objective is to maximize muscle mass) and that it would allow greater volume and better recovery. However, and even if more and more studies have focused on Full-Body and high-frequency training, few studies have compared the effects of these two types of training at equal work volume. So, what would be the impact of high-frequency training on muscle strength and mass?

The Study

To answer this question, a team of international researchers (including Brad Schoenfeld) compared two different training frequencies but with equal volume. For this, the authors recruited 18 well-trained men (6.4 ± 2.4 years of experience) whose 1RM in squat was equivalent to at least 1.25 times their body mass and whose 1RM in bench press was equal to at least 1 time their body mass. The participants were divided into two groups: Split (n = 9), where each muscle group was worked 1 time per week and Full-Body (n = 9), where each muscle group was worked 5 times per week. Finally, each muscle group received the same training volume (15 sets of 10-12 RM). The experimental protocol lasted 8 weeks.

The training program was spread over 5 days for the two groups. It consisted of 25 exercises targeting the main muscle groups, 5 exercises per group. Thus, each day, each group performed 5 exercises. For each exercise, 3 sets of 10-12 RM were performed. The load was adjusted so that each sets was at muscular failure between 10 and 12 repetitions. The only difference between the two groups was in the distribution of the exercises. Each day, the Split group performed 5 exercises targeting a muscle group. And each day, the Full-body group performed 5 exercises targeting 5 muscle groups. Thus, if the Split group devoted 5 exercises to the pectoralis major in a single session, the Full-Body group distributed these 5 exercises over 5 days.

Before and after the 8 weeks of experimental protocol, the researchers evaluated for all the participants the maximum muscular force and the muscular thickness via ultrasound. For muscle strength, the 1RM in back squat, bench press, machine close-grip seated row were evaluated. For muscle hypertrophy, the researchers used ultrasound to measure the muscle thickness of the elbow flexors (biceps brachialis, brachialis and brachoradialis), the triceps brachialis and the vastus lateralis. In addition to this, the researchers also evaluated more precisely the nutritional intake of the participants over 2 non-consecutive weekdays and 1 weekend day, and this, 3 times throughout the duration of the protocol. Finally, the researchers quantified for each group the total load lifted each week and over the 8 weeks, and the internal training load via an RPE scale (Rate of Perceived Exertion).

Results & Analyzes

The main results of this study show that the increase in muscle strength was similar between the two groups and that a Full-Body training seems to allow an greater muscle hypertrophy in comparison with the Split at the level of the elbow flexors and the vastus lateralis. The difference for the triceps brachialis was not statistically significant, but the large effect size tended to favor the Full-Body group. In terms of calories ingested, the evaluations carried out did not show any differences either in terms of total calories, or in terms of the macronutrients distribution (protein, carbohydrate, lipid).

Regarding muscle hypertrophy, some authors have hypothesized that during a Split, advanced practitioners tend to do more sets than necessary to maximize the synthesis of muscle proteins, and that there are some "wasted" sets (not to mention neuromuscular fatigue). And so, in this case, it would be more interesting to keep the same number of series but to distribute them over several weekly sessions and thus increase the frequency of protein synthesis peaks. The results of this study seem to point in this direction.

It should also be noted that the Full-Body group accumulated a training load 22.3% significantly greater than that of the Split group. While the internal workload assessed by the RPE was no different between the two groups. Thus, the two groups worked as intensely as each other (each series was well done until failure). But although the number of sets and repetitions were the same for both groups. It seems that the distribution of the series over 5 days allowed the Full-Body group to load more easily than the Split group. Finally, it may be the higher total training load that can explain a greater gain in muscle mass. However, this greater hypertrophy did not translate into greater strength.

Practical Applications

This study tends to show that high-frequency training, here 5 times per week, allows similar gains in strength and greater gains in muscle hypertrophy compared to training at low-frequency, at equal volume. It is therefore wrong to believe that Split is a more advanced type of training than Full-Body. Rather, everything will depend on the pleasure felt and your ability to recover. Nevertheless, for those wishing to increase their muscle mass, it seems interesting to periodize a Full-Body training over the course of a long-term training cycle. This would introduce a new stimulus into training. This is also one of the limitations of this study. Most subjects used Split before the protocol. For those who fell into the Full-Body group, this created a new stimulus that could have played on the results of this study.


  1. Zaroni RS, Brigatto FA, Schoenfeld BJ, Braz TV, Benvenutti JC, Germano MD Marchetti PH, Aoki MS and Lopes CR. High resistance-training frequencey enhances muscle thickness in resistance-trained men. J Strength Cond Res 33 (7S) : S140-S151, 2019.

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