Reliability of handgrip strength measurements and their relationship with muscle power.

Background: Handgrip peak force and rate of force development (RFD) have been shown to be useful measurements at characterizing the strength capacities of numerous muscle groups, including those of the lower extremities. However, the reliability of these measurements and their relationship with peak muscle power remain uncertain. We aimed to examine the reliability of handgrip peak force and RFD measurements. A secondary aim was to determine if these measurements are correlated with peak muscle power.

Methods: Twenty young women (21±3 years) reported for testing on two different occasions. Handgrip contractions were performed during each testing session to assess peak force, peak RFD, and RFD at 0-100 (RFD100) and 0-200 (RFD200) ms. Peak power was assessed from a vertical jump test.

Results: Handgrip peak force and RFD measurements were highly consistent between sessions, with intraclass correlation coefficients of 0.89-0.92 and coefficients of variation of 4.9-6.4%. There were significant correlations between peak power and handgrip peak force (r=0.612, P=0.004), peak RFD (r=0.731, P<0.001), RFD100 (r=0.671, P=0.001), and RFD200 (r=0.701, P=0.001). Stepwise multiple regression analysis indicated that handgrip peak RFD was the single best predictor of peak power (R2=0.535).

Conclusions: Our results showed that handgrip peak force and RFD measurements are highly reliable and significantly associated with performance during a vertical jump test. The output from our multiple regression analysis suggests that handgrip peak RFD may be an effective predictor of muscle power.