This systematic review with meta-analysis grouped studies investigating the influence of resistance training proximity-to-failure on muscle hypertrophy into three broad themes based on the definition of set failure used (and therefore the specific research question being examined), to improve the validity of the meta-analyses.

Based on the limited available literature, our main findings show (i) no evidence to support that resistance training performed to momentary muscular failure is superior to non-failure resistance training, (ii) that higher velocity loss thresholds, and thus, theoretically closer proximities-to-failure, elicit greater muscle hypertrophy in a non-linear manner and (iii) no moderating effect of either volume load or relative load on muscle hypertrophy when resistance training was performed using any definition of set failure versus non-failure.

These findings provide evidence for a potential non-linear relationship between proximity-to-failure and muscle hypertrophy, but current set termination methods used during non-failure resistance training conditions limit insight into the actual proximity-to-failure achieved and pose a challenge for deriving practical recommendations for manipulating resistance training proximity-to-failure to achieve desired outcomes.