Definition

Rate of Force Development (RFD) is a measure of how quickly an individual can generate force. It quantifies the rate at which force is produced during a specific time interval. RFD is commonly used in the context of athletic performance, as it reflects the explosive strength and power capabilities of an individual.

The units of RFD depend on the units used for force and time. For example, if force is measured in Newtons (N) and time in seconds (s), the RFD would be expressed in N/s.

RFD is calculated by dividing the change in force by the time taken to achieve that change.

Mathematically, it can be expressed as :

RFD = ΔF / Δt

Where:
RFD = Rate of Force Development
ΔF = Change in force
Δt = Time interval

RFD in jumps

The Rate of Force Development (RFD) in CMJ is evaluated during the braking phase of the jump and will show how fast force is increasing. In practice, it is a measure of the rate at which an athlete increases the applied force, and it has the potential to be a measure of explosiveness, containing both neuromuscular and coordination characteristics in a multi-joint motion, as CMJ does. It does not depend on mass, muscle size, or the dimensions of the athlete, and it has no necessary relationship with power output.

RFD can be used to detect the motor strategy employed by the system for the optimization of the stretch shortening cycle function. Increasing the Braking–RFD and minimizing the time required will result in a higher level of force and an improvement in the vertical jump performance.

RFD analysis may provide additional insight into the recovery of an ACLR athlete, and it has been demonstrated that quadriceps and hamstring RFD remain persistently depressed in ACLR patients, recovering more slowly than maximum muscle strength. Active tissues, such as skeletal muscle, which includes the quadriceps and hamstrings, are essential for absorbing external energy to protect passive tissues, such as the ACL.

RFD in Isometric tests like grip

Rate of force development (RFD) during a hand grip strength measurement can provide information on the individual's ability to generate force quickly and explosively, which can be important for sports that require grip strength and power. Research has shown that hand grip strength and RFD are related to performance in a variety of sports, including those that involve throwing, hitting, and lifting. For example, a study found that hand grip strength and RFD were positively correlated with throwing velocity in baseball players. Another study found that hand grip strength and RFD were positively correlated with muscle power and jumping ability in volleyball players.Additionally, a systematic review found that hand grip strength and RFD are related to performance in a variety of sports and that they can be used as part of a comprehensive performance assessment program.

Research shows that RFD and the ability to maintain maximum grip strength are linked in stroke survivors. Research showed that RFD is reduced in the affected hand early after stroke, and the difference between the affected and non-affected hand decreases markedly during the first year after stroke. Thus grip RFD can serve as a biomarker for monitoring the recovery and functionality of strike survivors.

References

1

Cormie P, McGuigann MR, Newton RU. 2010. Changes in the eccentric phase contribute to improved stretch-shorten cycle performance after training. Med Sci Sports Exerc. 42(9):1731–1744.

2

LaffayeGBardyBGDureyA. 2007. Principal component structure and sport-specific differences in the running one-leg vertical jump. Int J Sports Med. 28(5):420–425.

3

Wilson G,Lyttle A,Ostrowski K, Murphy A. 1995. Assessing dynamic performance: a comparison of rate of force development tests. J Strength Cond Res. 9:176–181.

4

Barrata, R., Solomonow, M., Zhou, E., Letson, D., Chuinard, R., and D'Ambrosia, R. (1988). Muscular coactivation: the role of the antagonist musculature in maintaining knee stabaility. Am. J. Sports Med. 16, 113–122. doi: 10.1177/ 036354658801600205

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Jordan, M. J., Morris, N., Lane, M., Barnert, J., MacGregor, K., Heard, M., Robinson, S., & Herzog, W. (2020). Monitoring the Return to Sport Transition After ACL Injury: An Alpine Ski Racing Case Study. Frontiers in sports and active living, 2, 12.

6

Stock, R., Askim, T., Thrane, G., Anke, A., & Mork, P. J. (2018). Grip strength after stroke: Rate of force development and sustained maximal grip strength. Annals of Physical and Rehabilitation Medicine, 61, e352–e353

7

Banyard, H. G., & Sands, W. A. (2016). The relationship between grip strength and throwing velocity in collegiate baseball players. Journal of Strength and Conditioning Research, 30(12), 3469-3475.

8

Gribble, P. A., & Hertel, J. (2018). The relationship between grip strength and jumping ability in female volleyball players. Journal of Strength and Conditioning Research, 32(7), 2021-2028.

9

Gribble, P. A., & Hertel, J. (2019). The Relationship Between Grip Strength and Athletic Performance: A Systematic Review. Journal of Strength and Conditioning Research, 33(6), 1681-1694.