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Yousefian Molla R, Ardigò L P, Fatahi A, Khezri D, Pardos E M, Nobari H. Phase Characteristics of Rate of Force Development in Vertical Jump Performance: A Regression-based Analysis. PTJ 2026; 16 (4) :373-382
URL: http://ptj.uswr.ac.ir/article-1-828-en.html

Purpose: The rate of force development (RFD) is widely used as an indicator of explosive strength and is associated with athletic performance. However, the extent to which RFD and other force-time characteristics contribute to vertical jump performance remains unclear, particularly when the eccentric and concentric phases of the countermovement jump (CMJ) are considered separately. Therefore, this study aimed to investigate the relationships between RFD, power-related and temporal kinetic variables, and CMJ height during the eccentric and concentric phases of the CMJ in professional male volleyball players.
Methods: Fifteen male professional volleyball players participated in this study. Each participant performed maximal CMJs on a force platform under standardized testing conditions. Forcetime data were recorded and analyzed separately for the eccentric and concentric phases of the movement. The variables extracted from the force-time curve included average power, peak power (PP), time to PP, maximum RFD, average RFD, and peak RFD. CMJ height was used as the primary performance criterion. Pearson correlation coefficients were calculated to examine the relationships between kinetic and temporal variables and CMJ height. Regression coefficients were also determined to assess the extent to which force-related variables were associated with jump height. Statistical significance was set at P<0.05.
Results: The analysis revealed no significant correlations between the examined force-related variables and CMJ height during either the eccentric or concentric phases of the movement (P>0.05). Similarly, the regression analyses did not demonstrate a significant association between the assessed force-production characteristics and vertical jump height. These findings indicate that RFD, average and PP, and other force-time characteristics measured during the CMJ may not independently explain differences in jump performance among professional volleyball players. These results suggest that vertical jump performance is a multifactorial outcome that may depend on the interaction between contractile and non-contractile factors, including anthropometric characteristics, neuromuscular coordination, movement strategy, and biomechanical factors.
Conclusion: The present findings suggest that RFD should be interpreted cautiously when used as an indicator of explosive performance during the CMJ. Although RFD provides valuable information regarding rapid force generation, it may not be a reliable standalone predictor of CMJ height in professional volleyball players. Therefore, the assessment of jump performance may benefit from a multidimensional approach incorporating force-time characteristics alongside biomechanical, neuromuscular, and anthropometric variables.