Effect of free-weight vs. machine-based strength training on maximal strength, hypertrophy and jump performance – a systematic review and meta-analysis

Abstract

Background The efectiveness of strength training with free-weight vs. machine equipment is heavily debated. Thus, the purpose of this meta-analysis was to summarize the data on the efect of free-weight versus machine-based strength training on maximal strength, jump height and hypertrophy. Methods The review was conducted in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, and the systematic search of literature was conducted up to January 1st, 2023. Studies that directly compared free-weight vs. machine-based strength training for a minimum of 6 weeks in adults (18–60 yrs.) were included. Results Thirteen studies (outcomes: maximal strength [n=12], jump performance [n=5], muscle hypertrophy [n=5]) with a total sample of 1016 participants (789 men, 219 women) were included. Strength in free-weight tests increased signifcantly more with free-weight training than with machines (SMD: -0.210, CI: -0.391, -0.029, p=0.023), while strength in machine-based tests tended to increase more with machine training than with free-weights (SMD: 0.291, CI: -0.017, 0.600, p=0.064). However, no diferences were found between modalities in direct comparison (free-weight strength vs. machine strength) for dynamic strength (SMD: 0.084, CI: -0.106, 0.273, p=0.387), isometric strength (SMD: -0.079, CI: -0.432, 0.273, p=0.660), countermovement jump (SMD: -0.209, CI: -0.597, 0.179, p=0.290) and hypertrophy (SMD: -0.055, CI: -0.397, 0.287, p=0.751). Conclusion No diferences were detected in the direct comparison of strength, jump performance and muscle hypertrophy. Current body of evidence indicates that strength changes are specifc to the training modality, and the choice between free-weights and machines are down to individual preferences and goals.