Effect of free-weight vs. machine-based strength training on maximal strength, hypertrophy and jump performance - a systematic review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of comparative training trials
PubMed 37582807 · doi:10.1186/s13102-023-00713-4
What was done
A systematic review and meta-analysis adhering to PRISMA guidelines was conducted to evaluate the effects of free-weight versus machine-based strength training. Literature searches were conducted up to January 1, 2023. Included studies directly compared free-weight and machine-based training for a minimum duration of 6 weeks in adults aged 18 to 60 years.
What was found
Thirteen studies comprising 1,016 participants (789 men, 219 women) were included. Free-weight training resulted in significantly greater strength increases on free-weight tests compared to machine training (SMD: -0.210, 95% CI: -0.391 to -0.029, p = 0.023). Machine training showed a non-significant trend toward greater strength on machine-based tests (SMD: 0.291, 95% CI: -0.017 to 0.600, p = 0.064). No statistically significant differences were observed between modalities for dynamic strength (SMD: 0.084, 95% CI: -0.106 to 0.273, p = 0.387), isometric strength (SMD: -0.079, 95% CI: -0.432 to 0.273, p = 0.660), countermovement jump performance (SMD: -0.209, 95% CI: -0.597 to 0.179, p = 0.290), or muscle hypertrophy (SMD: -0.055, 95% CI: -0.397 to 0.287, p = 0.751).
Why it matters
These findings suggest that muscle growth and functional power development are not inherently superior with either free weights or machines. Strength adaptations primarily follow training specificity, allowing practitioners to select equipment based on individual goals, preferences, and equipment availability.
Limits
The total participant pool was disproportionately male (789 men vs. 219 women). The number of studies analyzing jump performance (n = 5) and muscle hypertrophy (n = 5) was relatively small compared to maximal strength (n = 12). The analysis was restricted to adults aged 18–60 years, limiting generalizability to youth or older populations.
Cited by
- supports Meta-analyses demonstrate that muscle hypertrophy outcomes are equal when comparing machine-based exercises to free weights.
- supports Resistance training using machines produces equivalent muscle hypertrophy compared to training with free weights.