How Wobbly Weights and Benches Change Your Muscles' Work
Muscle Activation Patterns While Lifting Stable and Unstable Loads on Stable and Unstable Surfaces
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Triceps worked *less* on unstable surfaces and with unstable loads, even though the exercise felt harder.
Many assume that instability forces all muscles to work harder, but this shows prime movers actually engage less—contradicting common fitness marketing claims.
Practical Takeaways
Stick to stable benches and barbells for overhead pressing if your goal is strength or muscle growth.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Triceps worked *less* on unstable surfaces and with unstable loads, even though the exercise felt harder.
Many assume that instability forces all muscles to work harder, but this shows prime movers actually engage less—contradicting common fitness marketing claims.
Practical Takeaways
Stick to stable benches and barbells for overhead pressing if your goal is strength or muscle growth.
Publication
Journal
Journal of Strength and Conditioning Research
Year
2010
Authors
J. M. Kohler, S. Flanagan, W. Whiting
Related Content
Claims (4)
If you're used to lifting weights and do shoulder presses on a bouncy ball instead of a bench, your lower back muscles have to work harder to keep you stable — even though you're probably lifting less weight.
If you're already strong and used to lifting, doing overhead presses with shaky weights or on wobbly surfaces probably won't help you build more muscle or get stronger — and you'll likely end up lifting less weight overall.
If you're used to lifting weights and do shoulder presses sitting down, using an unstable weight or an unstable surface means you won't be able to lift as much weight.
If you're used to lifting weights, your triceps work harder during shoulder presses when you use a barbell on a solid bench than when you use dumbbells on a wobbly ball — the more stable the setup, the more your main muscles have to engage.