The Claim

Free-weight and machine-based training are associated with similar changes in muscle hypertrophy, with an effect size of -0.01 and a 95% confidence interval ranging from -0.525 to 0.545, indicating that neither modality has a clear advantage for increasing muscle size.

Source: Machines and free weight exercises: a systematic review and meta-analysis comparing changes in muscle size, strength, and power.

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
33score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Correlation
1 study reviewed
In plain English

Lifting free weights and using weight machines both help you build muscle in about the same way—neither one is clearly better than the other.

See the scientific wording

Free-weight and machine-based training are associated with similar changes in muscle hypertrophy (effect size: -0.01; 95% CI: -0.525, 0.545), indicating that neither modality has a clear advantage for increasing muscle size.

What the research says

1 study

  1. Study: Machines and free weight exercises: a systematic review and meta-analysis comparing changes in muscle size, strength, and power.

    This study found that lifting free weights and using machines both make your muscles grow about the same amount—neither one is better than the other for building muscle size.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

Fit Body Science verdict — we translate health claims into clear verdicts backed by peer-reviewed research.

Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.