# Rate of force development (RFD)

Rate of force development (RFD) is the change in muscle force per unit of time (in N/s). It captures how fast you can express maximal force, which is a key part of power, distinct from peak force alone. Early-phase RFD (0 to 50 ms) reflects your neural drive, motor-unit synchronization, and Type II fiber recruitment. Late-phase RFD (100 to 200 ms) depends more on your muscle's cross-sectional area and fiber composition. RFD declines with age faster than maximal strength does. And it is closely tied to your ability to prevent falls, your functional power, and your reactive balance. That is because most protective everyday moves (catching a stumble, rising from a chair) happen within 100 to 200 ms. Power-focused and plyometric training preferentially improve RFD.

## Sources

- Aagaard P, Simonsen EB, Andersen JL, Magnusson SP, Dyhre-Poulsen P. (2002). Increased rate of force development and neural drive of human skeletal muscle following resistance training. Journal of Applied Physiology. https://doi.org/10.1152/japplphysiol.00283.2002
- Maffiuletti NA, Aagaard P, Blazevich AJ, Folland J, Tillin N, Duchateau J. (2016). Rate of force development: physiological and methodological considerations. European Journal of Applied Physiology. https://doi.org/10.1007/s00421-016-3346-6

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_Canonical: https://longevity-switzerland.com/en/glossary/rate-of-force-development · Part of Longevity Cities · Updated 2026-06-22_