What’s better for muscle growth?
Both single joint and multi joint exercises is considered to be essential for muscle growth in the gym and also for preventing boredom in your training routine. Resistance exercises can be classified considering the number of joints involved, such as multi joint (MJ) or single joint (SJ) exercises. Multi joint exercises engage multiple muscle groups, such as the squat which activates the core, glutes, quadriceps, and hamstrings. Single joint exercises, like leg extension, enable only the quadriceps.
Most popular recommendations for muscle growth recommend that weight training sessions should involve 8-10 exercises performed in multiple sets with both single and multi joint exercises. The question is: do you need to use isolation exercises, or can you can you get the maximum benefit from multi joint exercises? Previous studies have compared the effects of adding single joint exercises to a multi joint exercise program, and found no benefit regarding bicep strength and size, between a group performing only multi joint (lat pulldown) or a group performing just single joint exercises (biceps curl). The only issue with this study was that the total volume was different for the two groups. This lead many to question if the volume was the same, would the groups have had similar responses? Meaning that one group did only lat pulldowns, and the other group did lat pulldowns and bicep curls, so the number of sets performed was different.
The newest study in the Frontiers in Physiology found that when total workout volume was the same, multi joint exercises resulted in superior gains in performance compared to single joint exercises. However, both groups made equal increases in muscle size. 36 soccer players were trained with either single joint (SJ) or only multi joint (MJ) exercises. The programs lasted for eight weeks. The program is listed below for the study, in which all major muscle groups were trained; but one group trained the muscles using isolation exercises, whereas the other group used multi-joint exercises.
At the end of eight weeks, both protocols were equally efficient in improving muscle growth; however, training with MJ exercises provided higher gains in physical performance. To quote the researchers: “Both groups decreased body fat and increased fat-free mass with no difference between them. While both groups significantly increased cardiorespiratory fitness and maximal strength, the improvements in MJ group were higher than for SJ in VO2max, bench press 1 RM, knee extension 1 RM, and squat 1 RM. In conclusion, when total work volume was equated, RT programs involving MJ exercises appear to be more effective for improving muscle strength and maximal oxygen consumption than programs involving SJ exercises, but no differences were found for body composition.” According to the results, training with MJ exercises promoted superior strength gains in all exercises tested, which may be due to the higher neural challenge supported by MJ exercises. In conclusion, the study suggests that, if one wants to improve muscle growth, an exercise program composed of either SJ or MJ exercises may be of similar benefit. However, if the purpose is to promote general fitness, performing a resistance training program comprised of MJ exercises seems to bring better adaptations than SJ exercises alone.
Based on the this study, you can still make gains in muscle size using single joint exercises, but you get more BANG for your buck with multi joint exercises. It’s probably wise to use a combination of single and multi joint exercises for a great workout.
Paoli et al. (2017). Resistance Training with Single vs. Multi-joint Exercises at Equal Total Load Volume: Effects on Body Composition, Cardiorespiratory Fitness, and Muscle Strength. Front. Physiol., 22 December 2017 | https://doi.org/10.3389/fphys.2017.01105.
Gentil, P., Soares, S., and Bottaro, M. (2015). Single vs. Multi-Joint resistance exercises: effects on muscle strength and hypertrophy. Asian J. Sport. Med. 6:e24057. doi: 10.5812/asjsm.24057.
Gentil, P., Soares, S. R., Pereira, M. C., da Cunha, R. R., Martorelli, S. S., Martorelli, A. S., et al. (2013). Effect of adding single-joint exercises to a multi-joint exercise resistance-training program on strength and hypertrophy in untrained subjects. Appl. Physiol. Nutr. Metab. 38, 341–344. doi: 10.1139/apnm-2012-0176