Free Weight vs Machine Training for Muscle Size and Strength: An 8-Week RCT
Schwanbeck SR, Cornish SM, Barss T, Chilibeck PD
Evidence is still building up
Summary
In 46 recreationally trained participants (26 women, mean age 22) training for 8 weeks, increases in muscle thickness were similar between free-weight and machine groups, and strength gains were largely specific to the equipment used.
Key findings
- 1
Increases in muscle thickness were similar between the two groups
- 2
Machine bench press 1RM improved +13.9% in the machine group vs +8.6% in the free-weight group (interaction p=0.05), indicating strength gains were largely specific
- 3
Training was 2–3 times per week, 3–4 sets of 4–10 reps per exercise
- 4
Single RCT with n=46 over 8 weeks, so scale and duration are limited; confidence is moderate
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