Calculating Set-Volume for the Limb Muscles with the Performance of Multi-Joint Exercises: Implications for Resistance Training Prescription.

Brad Schoenfeld,Jozo Grgic,Cody Haun,Takahiro Itagaki,Eric Helms

doi:10.3390/sports7070177

Brad Schoenfeld, Jozo Grgic + Show 3 more

Open Access

https://doi.org/10.3390/sports7070177

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Abstract

Resistance training volume, determined by the number of sets performed (set-volume) is considered one of the key variables in promoting muscle hypertrophy. To better guide resistance exercise prescription for weekly per-muscle training volume, the purpose of this paper is to provide evidence-based considerations for set-volume ratios between multi-joint (MJ) and single-joint (SJ) exercises so that practitioners can better manage prescription of training volume in program design. We analyzed this topic from three primary areas of focus: (1) biomechanical and physiological factors; (2) acute research; and (3) longitudinal research. From a biomechanical and physiological standpoint, when considering force production of different muscle groups, the moment arm of a given muscle, “motor abundance”, the link between biomechanics and exercise-induced fatigue, as well as the amount of time in voluntary muscle activation, a logical rationale can be made for SJ exercises producing greater hypertrophy of the limb muscles than MJ exercises (at least from specific exercises and under certain conditions). This would mean that sets for a MJ exercise should be counted fractionally for select muscles compared to an SJ exercise (i.e., less than a 1:1 ratio) when prescribing set-volumes for given muscles. When considering results from acute studies that measured muscle activation during the performance of SJ and MJ exercises, it seems that MJ exercises are not sufficient to maximize muscle activation of specific muscles. For example, during performance of the leg press and squat, muscle activation of the hamstrings is markedly lower than that of the quadriceps. These results suggest that a 1:1 ratio cannot be assumed. Current longitudinal research comparing the effects of training with MJ vs. SJ or MJ + SJ exercises is limited to the elbow flexors and the evidence is somewhat conflicting. Until more research is conducted to derive stronger conclusions on the topic, we propose the best advice would be to view set-volume prescription on a 1:1 basis, and then use logical rationale and personal expertise to make determinations on program design. Future research should focus on investigating longitudinal hypertrophic changes between MJ and SJ in a variety of populations, particularly resistance-trained individuals, while using site-specific measures of muscle growth to more systematically and precisely compute effective individualized set-volumes.

Highlights

During exercise, muscles produce forces that act on bony levers to carry out given movement patterns
Given that multiple muscles are acting across a joint during MJ exercises, and given that these muscles may be functioning at different sarcomere lengths, it is conceivable that one or more muscles may be stretched or shortened to a length where active forces are minimal to nonexistent [7]
Based on the current literature, it would seem that hypertrophy of some limb muscles may be similar to the isolated performance of single joint (SJ) or MJ movements, while for other muscles, additional hypertrophic benefits might be attained from SJ

Summary

Introduction

Muscles produce forces that act on bony levers to carry out given movement patterns. A recent meta-analysis endeavored to quantify the optimal number of sets per muscle per week (i.e., set-volume) for maximizing muscle hypertrophy [2] In making their recommendations, muscle groups deemed prime movers during MJ and SJ were classified the same from a set standpoint. While it appears clear that substantial hypertrophy of the limbs can be achieved by only performing MJ exercises, it remains equivocal whether additional benefits can be derived from SJ movements It remains unclear whether both MJ and SJ exercises should be counted or differentially when providing recommendations for set-volume per muscle. This is a relevant metric to establish given that set-volume seems to be one of the most important training variables in resistance exercise prescription, both for muscle hypertrophy and health-related outcomes [5,6]. We attempted to draw conclusions by triangulating evidence from the following three primary areas of focus: biomechanical and physiological factors, acute research, and longitudinal research

Biomechanical and Physiological Considerations

Acute Studies

Longitudinal Studies

Additional Considerations

Findings

Conclusions