Finding the Optimal Repetition Range for Muscle Growth

Strength training has become a popular fitness regimen as people become more aware of its benefits, which include increased strength, improved bone density, and better overall health. Regarding strength training, load, and intensity are two important concepts. 

Training load is one of the key concepts of manipulating hypertrophic resistance training. Load refers to the amount of external resistance used in an exercise, while intensity can be absolute or relative. Absolute intensity refers to the magnitude of the load used in a given movement. In contrast, relative intensity refers to the percentage of the load about a person's one-repetition maximum (1 RM).

In determining the repetition range, it is essential to consider the load used. Heavy loads (1-5 RM) develop maximum strength best, while light loads (15+ RM) develop the best metabolic properties of the muscles. Medium loads (6-12 RM) are often considered the best compromise to optimize muscle growth, as they are more time-efficient than light loads and less stressful on the joints and neuromuscular system than heavy loads.

Although muscle growth can be achieved over a wide repetition range, different repetition ranges have specific effects on adaptations to strength training. For example, heavy loads cause a high mechanical load and a stimulus for muscle growth. Still, achieving sufficient total volume to optimize muscle growth by using heavy loads alone is difficult. Light loads, on the other hand, allow for the best metabolic properties of the muscles, which eventually allows for more repetitions even with medium-weight loads.

Research suggests that using more repetitive loads can optimize muscle growth. Therefore, it may be justifiable to do most of the sets in the 6-12 RM repetition range and split the remaining volume into heavy and lighter repetition ranges. In addition, programming the repetition ranges for practical training can be done in various ways, such as using several different repetition ranges in a single exercise or sequencing the weights of varying repetition ranges over different exercise periods in a block periodization fashion.

In summary, finding the optimal repetition range for muscle growth involves considering the load used, the specific effects of different repetition ranges, and individual differences and preferences. While using medium-heavy loads (6-12 RM) provides the best practical benefit for muscle growth, incorporating more repetitive loads may optimize muscle growth. Finding the optimal repetition range for muscle growth involves balancing load, intensity, and practicality.

References:
Schoenfeld, B. J., Grgic, J., Van Every, D. W., & Plotkin, D. L. (2021). Loading recommendations for muscle strength, hypertrophy, and local endurance: a re-examination of the repetition continuum. Sports, 9(2), 32.

Schoenfeld, B., Fisher, J., Grgic, J., Haun, C., Helms, E., Phillips, S., ... & Vigotsky, A. (2021). Resistance training recommendations to maximize muscle hypertrophy in an athletic population: Position stand of the IUSCA. International Journal of Strength and Conditioning, 1(1).

Lasevicius, T., Ugrinowitsch, C., Schoenfeld, B. J., Roschel, H., Tavares, L. D., De Souza, E. O., ... & Tricoli, V. (2018). Effects of different intensities of resistance training with equated volume load on muscle strength and hypertrophy. European journal of sport science, 18(6), 772-780.

Lopez, P., Radaelli, R., Taaffe, D. R., Newton, R. U., Galvão, D. A., Trajano, G. S., ... & Pinto, R. S. (2021). Resistance training load effects on muscle hypertrophy and strength gain: Systematic review and network meta-analysis. Medicine and science in sports and exercise, 53(6), 1206.

Schoenfeld, B. J., Grgic, J., Ogborn, D., & Krieger, J. W. (2017). Strength and hypertrophy adaptations between low-vs. high-load resistance training: a systematic review and meta-analysis. The Journal of Strength & Conditioning Research, 31(12), 3508-3523.