Why Training Muscle Groups More Often Than Once a Week May Increase Muscle Mass

In the world of bodybuilding and fitness, muscle groups are typically trained once a week. The rationale behind this approach is that muscles need rest to grow, and you must train so hard that you don't need to train for a week. However, recent studies suggest that training muscle groups more often than once a week may increase muscle mass.

A study conducted by Hackett et al. in 2013 found that the majority of bodybuilders in the study trained through a muscle group only once a week. However, the challenge with this approach is that the training volume has to be very high, and you have to do many sets to achieve optimal muscle growth.

When the per-session volume is cranked up high enough, it is possible to cause more muscle damage than growth. This is because a large amount of damage takes longer to heal than a small amount of growth takes to manifest. As a result, growth may be completed within a few days, while fatigue lingers for several more. This lingering fatigue can inhibit the potential stimulation of growth, leading to missed gains.

To address this issue, training muscle groups more frequently, rather than once a week, may be more beneficial. For example, instead of doing something like 18 sets in a single workout once per week and growing for three days per week, you could do three workouts of six sets each (the same total volume) spread out across the week. This way, you could grow for 4.5 days of the week (1.5 days after each session) and potentially achieve more total growth across the week.

Many bodybuilders swear by lower-frequency training, but this is likely because they cram an entire week'sweek's volume into minimal sessions and need the other days to recover from such dense training. However, science strongly suggests that training muscle groups more frequently than once per week would better serve these bodybuilders.

No study has ever found muscle growth elevated past about three days of training, but plenty have reported evidence of lingering fatigue for up to a week or more post-training. Therefore, training muscle groups more frequently may help avoid lingering fatigue's adverse effects and improve overall muscle growth.

In conclusion, training muscle groups more often than once a week may be a more effective way to increase muscle mass. By spreading the training volume across the week, you can achieve more total growth and avoid the adverse effects of lingering fatigue. While the once-a-week approach may work for some, the science strongly suggests that more frequent training of muscle groups may yield better results.

References:

Hackett, D., Johnson, N. & Chow, C. 2013. Training Practices and Ergogenic Aids Used by Male Bodybuilders. Journal of Strength and Conditioning Research 27(6), 1609–1617.

Schoenfeld, B. 2010. The mechanisms of muscle hypertrophy and their application to resistance training. The Journal of Strength & Conditioning Research, 24(10), 2857-2872.

Helms, E., Fitschen, P., Aragon, A., Cronin, J. & Schoenfeld, B. 2015. Recommendations for natural bodybuilding contest preparation: resistance and cardiovascular training. The Journal of Sport Medicine and Physical Fitness 55 (3), 164–178.

Phillips, S., Tipton, K., Ferrando, A. & Wolfe, R. 1999. Resistance training reduces the acute exercise-induced increase in muscle protein turnover. American Journal of Physiology-Endocrinology And Metabolism, 276(1), E118-E124.