Key Takeaway
Flywheel training significantly increases both muscle volume and maximal force output, confirming it as an effective hypertrophy and strength stimulus.
Summary
This meta-analysis by Nuñez and Sáez de Villarreal (2018) in the Journal of Strength and Conditioning Research synthesized the available evidence on whether flywheel (isoinertial) training improves muscle volume and force production. By pooling data across multiple controlled studies, the authors found statistically significant improvements in both muscle hypertrophy and maximal force following flywheel-based training programs. The flywheel paradigm generates resistance through rotational inertia rather than gravity, allowing coupled concentric-eccentric actions where the eccentric phase can exceed the concentric load. This eccentric overload stimulus is thought to preferentially activate fast-twitch motor units and trigger greater mechanical tension at longer muscle lengths — both potent drivers of hypertrophy. The meta-analytic results confirm that flywheel training is not merely an alternative to traditional loading but a genuinely effective method for building muscle size and strength, with applications across sport and rehabilitation settings.