An Investigation into the Relationship between Maximum Isometric Strength and Vertical Jump Performance

Research has shown a clear association between dynamic strength and vertical jump performance; however, the relationship of isometric strength and vertical jump performance has been studied less extensively. The aim of this study was to determine the relationship between isometric strength and performance during the squat jump (SJ) and countermovement jump (CMJ). Twenty-two male collegiate athletes (mean ± SD; age = 21.3 ± 2.9 years; height = 175.63 ± 8.23 cm; body mass = 78.06 ± 10.77 kg) performed isometric mid-thigh pulls (IMTP) to assess isometric peak force (IPF), maximum rate of force development (mRFD) and impulse (I100, I200, and I300). Force time data, collected during the vertical jumps, was used to calculate peak velocity (PV), peak force (PF), peak power (PP), and jump height. Absolute IMTP measures of IMP showed the strongest correlations with VJ PF(r = 0.43 – 0.64, p ≤ 0.05), and VJ PP (r = 0.38 – 0.60, p ≤ 0.05). No statistical difference was seen in CMJ height (0.33 ± 0.05 m vs. 0.36 ± 0.05 m; p = 0.19; ES = -0.29) and SJ height performance (0.29 ± 0.06 m vs. 0.33 ± 0.05 m vs.; p = 0.14; ES = -0.34) when comparing stronger to weaker athletes. The results of this study show that absolute IPF and IMP are associated with VJ PF and PP, but not VJ height. As stronger athletes did not jump higher than weaker athletes, dynamic strength tests may be more practical methods of assessing the relationships between relative strength levels and dynamic performance in collegiate athletes.