Rosa, Avery BSc; Vazquez, Gregory BSc; Grgic, Jozo PhD; Balachandran, Anoop T. PhD; Orazem, John PhD; Schoenfeld, Brad J. PhD

Strength and Conditioning Journal 45(1):p 49-57, February 2023. | DOI: 10.1519/SSC.0000000000000720

PURPOSE:

A systematic review and meta-analysis compared the effects of single-joint (SJ) and multi-joint (MJ) resistance exercises on limb muscle hypertrophy.

PROCEDURES:

A direct comparison of hypertrophic changes between SJ and MJ resistance exercises, as well as combinations of the two, as it related to healthy adults. Seven studies met inclusion criteria, comprising 10 nested comparisons.

CONCLUSIONS:

o Meta-analysis indicated a trivial standardized point estimate with a relatively moderate precision for  

   the confidence interval estimate.

o Subgroup analyses showed no effect on results when stratifying studies according to combined SJ + 

   MJ versus MJ training alone, as well as under volume-equated or non-equated conditions.

o However, scrutiny of individual studies in conjunction with related indirect evidence collectively 

   indicate that SJ exercise may provide the ability to preferentially hypertrophy muscular subdivisions, 

   potentially promoting more complete muscle development.

o In short, it was concluded that current evidence indicates similar whole muscle hypertrophy between 

   MJ and SJ training and there may be added benefit to combining SJ and MJ exercises for targeting 

   individual aspects of a given muscle, although this hypothesis remains understudied.

 

o Future studies are needed to explore the effects of SJ and MJ exercises in resistance training on 

   regional muscle hypertrophy.

IN PLAIN ENGLISH:

o Provided high mechanical tension occurs in the targeted muscles, it will improve the chances of 

   inducing hypertrophy in the individual muscle fibers.

o Some exercises better target more muscle fibers – such as single-joint leg extensions that better 

   recruit the rectus femoris – thus there is an advantage of SJ vs. MJ. Also, the hamstrings are a 

   synergist in MJ lower body exercises (i.e., the barbell squat), but are better isolated in single joint leg 

   curls and Romanian dead lifts.

o Much depends on one’s goal: is it to become stronger in a multi-muscle involved multi-joint movement 

   or in an isolated SJ movement?