Effects of variable resistance training versus conventional resistance training on muscle hypertrophy: a systematic review

PurposeVarious training factors in combination with high intensity methodologies and techniques have been extensively investigated, with the intention of increasing anabolic, endocrine responses and subsequent structural adaptations. Variable resistance training allows the demands of an exercise to be matched to the muscle's ability to exert force. The aim of this article is to examine whether variable resistance training produces significant gains in muscle mass compared to conventional resistance training.MethodsA literature search was performed via PubMed, Web of Science, Cochrane and Scopus with search terms including "variable resistance", "accommodating resistance", "flywheel resistance", "bands resistance", "eccentric overloading resistance", "isokinetic resistance", "elastic resistance", "variable cam", "chain loaded resistance training", "hypertrophy", "resistance training", strength training" and "power training" in July 2023. Inclusion criteria were studies that measured direct data related to muscle hypertrophy, compared variable resistance training and conventional resistance training and measured body composition using tape measures, ultrasound, dual-energy X-ray absorptiometry (DXA), magnetic resonance imaging and bioimpedance metres.ResultsOur search identified a total of 528 articles, and 12 studies met the inclusion criteria. The results of the studies analysed show that similar improvements occur, with no significant differences between the two training protocols.ConclusionThis systematic review revealed that variable resistance training does not produce a greater gain in muscle mass compared to conventional training over a short-medium period of time and with untrained subjects. Therefore, it is necessary to compare these two training methods over longer training periods and with subjects with more experience in resistance training.