Free Weights vs. Machines: Which Builds More Muscle?
Effects of Training With Free Weights Versus Machines on Muscle Mass, Strength, Free Testosterone, and Free Cortisol Levels.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Free weights caused significantly greater acute testosterone spikes in men—but not in women—and had no effect on cortisol.
Many assume free weights are universally more 'anabolic' due to instability and muscle recruitment, but this effect was only seen in men and only as a short-term spike—not linked to greater muscle growth.
Practical Takeaways
If your goal is to get stronger on a specific machine, train on that machine. If you want general strength and muscle growth, free weights and machines are equally effective.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Free weights caused significantly greater acute testosterone spikes in men—but not in women—and had no effect on cortisol.
Many assume free weights are universally more 'anabolic' due to instability and muscle recruitment, but this effect was only seen in men and only as a short-term spike—not linked to greater muscle growth.
Practical Takeaways
If your goal is to get stronger on a specific machine, train on that machine. If you want general strength and muscle growth, free weights and machines are equally effective.
Publication
Journal
Journal of strength and conditioning research
Year
2020
Authors
Shane Schwanbeck, S. Cornish, Trevor S. Barss, P. Chilibeck
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Claims (3)
When men lift weights with dumbbells or barbells instead of using machines, their bodies produce more of the hormone testosterone right after the workout—so free weights might give a bigger hormonal boost.
If you're a young adult and you lift weights for 8 weeks—whether you use free weights like dumbbells or machines at the gym—you'll end up with about the same muscle growth and strength gains in your arms and legs, no matter which one you pick.
If you lift weights using machines, you'll get stronger on those machines more than if you use free weights—your strength gains depend on what equipment you train with.