What Training Frequency is Best for a Single Body Part?

Training frequency is one of the many variables that we can manipulate in order to optimize our results and tailor regimens to the individual. This happens to be a more flexible variable in a sense that frequency can be chosen in part by what your schedule looks like and what training split you prefer. Also, considering the overall goal of the athlete can determine what body parts you may want to prioritize. All in all, we have an idea of how to use training frequency, but much more remains to be researched regarding the levels at which we employ it. 

Studies show that training once per week is inferior to training twice or three times per week. Training 2-3 times a week seem to show no difference in their respective effectiveness either, so this leaves some room to speculate about higher frequencies and if the trainee has a “upper limit” at which they can train a single body part, as opposed to the frequency at which one simply participates in resistance exercise (i.e. 3 lower body sessions versus 3 full body sessions). The study to be discussed will answer this question in the context of training a single muscle group (rather than a total training week in general) in order to narrow down what training frequency is best to enhance strength and hypertrophy of a targeted muscle.

Quick background

One of the most common questions any gym goer will ask concerns the amount of times per week they should train a particular body part for growth or strength. Training frequency can be defined as the number of resistance training sessions in which the same muscle group is trained within a period of time. In this case, we can consider training frequency to fall within a week’s time. 

The Study

Barcelos and colleagues sought to conduct the first ever study in which a training frequency of 5 times per week was compared to frequencies of 2 and 3 times per week in a single muscle group being trained. 20 untrained (considered recreationally active) men were split into three training conditions: resistance training 5 times a week (RT5), RT 3 times a week (RT3) and RT 2 times a week (RT2). Now, in order to mitigate any inter-subject variability (or vast differences that may be observed between each subject) this study used a unilateral design. This means that each subject’s leg was considered an “experimental unit,” and was randomly given one of the three experimental conditions.

The researchers adopted the RT5 protocol as a positive control due to the assumption that training 5 times per week compared to 2 or 3 times per week would maximize the muscle protein synthesis response in the individual. With this said, each subject was allocated RT5 as one of their training conditions, while the opposite leg was randomized into either RT2 or RT3.

Training protocol

All training protocols were done using the leg extension machine. Each training session consisted of three sets of 9-12 repetitions to muscular failure at 80% of the subjects’ respective 1RM. Muscular failure is defined as not being able to perform another repetition completely with proper form. The load was adjusted accordingly when the participants reached more than 12 repetitions in order to ensure each working set was challenging enough and kept trainees within the study’s specified repetition range while reaching failure.

Key Findings

The first finding which is not an unexpected one is that the total training volume (TTV) accumulated by the RT5 condition was significantly higher than that of the RT2 and RT3 conditions. In addition to this there we also no differences seen in between RT2 and RT3. Testing midway through the study period at week 4, and then again post-study at week 8, TTV values were shown to be significantly higher by week 8 compared to week 4 as well. 

As for the progression of this training volume over time, RT2 and RT3 showed to have a constant progression throughout the 8-week training period. However, RT5 portrayed a downward trend in TTV progression by the second half of the training period (week 4-week 8). This decline in progression for RT5 could very well be due to the shorter amount of recovery time in between training bouts compared to the lower frequency conditions. The higher frequency could impair muscle recovery and thus training volume progression as a result. 

As for strength and muscle mass, all three training frequencies were able to increase muscular strength by week 4 and week 8 of the training period, with no differences between the frequencies. All training frequencies showed similar gains in muscle mass as well despite the large difference in total training volume between the training frequencies. This can again be tied back to the rather large difference in recovery periods between the training frequencies – perhaps the RT5 condition didn’t reap any better results simply due to the little amount of time available for rest and repair.

Application

While a higher frequency training protocol produced a significantly higher total training volume, training 5 times per week does not prove to be superior for gaining strength and muscle mass compared to lower frequencies of 2 or 3 times per week. If we summed up the sets completed each week, RT2 and RT3 completed 6-9 weekly sets, whereas RT5 completed 15 sets per week. Researchers speculate that there could be a “ceiling effect” of some sort for training volume in a given time, although training recovery is one of the more important factors of the muscle and strength building process that the RT5 condition seemed to lack in here. Less would be more in this case, although more research can always be done concerning more trained populations.

The great thing about resistance training is that a lot of what we know can be modified and adapted based on the individual and their respective goals. The same can be said about training frequency for the most part. If you only have 3 days where you can hit the gym, you can make the most out of those sessions and still get some effective work in, all without compromising your progress. More than anything, total effort placed in those few training sessions will allow you to produce the muscular adaptations you want. Molding these training principles around your schedule (training splits, etc.) can simply be a secondary factor to consider in order to make it work for your lifestyle while allowing you to be adherent longer term.

References

Barcelos, C., Damas, F., Nobrega, S.R., et al. High frequency resistance training does not promote greater muscular adaptations compared to low frequencies in young untrained men. European Journal of Sport Science. 2018; 18:8, 1077-1082.