A novel equation that incorporates the linear and hyperbolic nature of the force-velocity relationship in lower and upper limb exercises.

The purpose of this study is to provide a force-velocity (F-V) equation that combines a linear and a hyperbolic region, and to compare its derived results to those obtained from linear equations. A total of 10 cross-training athletes and 14 recreationally resistance-trained young men were assessed in the unilateral leg press (LP) and bilateral bench press (BP) exercises, respectively. F-V data were recorded using a force plate and a linear encoder. Estimated maximum isometric force (F 0 ), maximum muscle power (P max ), and maximum unloaded velocity (V 0 ) were calculated using a hybrid (linear and hyperbolic) equation and three different linear equations: one derived from the hybrid equation (linear hyb ), one applied to data from 0 to 100% of F 0 (linear 0-100 ), and one applied to data from 45 to 100% of F 0 (linear 45-100 ). The hybrid equation presented the best fit to the recorded data (R 2  = 0.996 and 0.998). Compared to the results derived from the hybrid equation in the LP, significant differences were observed in F 0 derived from linear 0-100 ; V 0 derived from linear hyb , linear 0-100 and linear 45-100 ; and P max derived from linear hyb and linear 45-100 (all p < 0.05). For the BP, compared to the hybrid equation, significant differences were found in F 0 derived from linear 0-100 ; and V 0 and P max derived from linear hyb , linear 0-100 and linear 45-100 (all p < 0.05). An F-V equation combining a linear and a hyperbolic region showed to fit adequately recorded F-V data from ~ 20 to 100% of F 0 , and overcame the limitations shown by linear equations while providing relevant results.