Pre-season isokinetic knee extensor total work at high speeds correlate to vertical jump height in Costa Rican professional soccer players

Abstract

Purpose: The aim was to determine the relationship between pre-season isokinetic strength and vertical jump performance in professional soccer players. Methods: Sixty-three players were tested for isokinetic strength of the knee extensor and flexor muscles at angular velocities of 60°/s and 240°/s (Biodex 2), and peak countermovement vertical jump (VJ) height. Pearson product-moment correlations were conducted to determine the relationship among variables. Results: Mean age, height, weight, and VO max were 24.3±4.1 y, 176.8±5.5 cm, 72.9±7.14 kg, and 57.6±6.9 ml·kg−1·min−1, respectively. A moderate correlation was found between total work for the knee extensor muscles at 240°/s and VJ (r=0.31, p=0.02). Conclusion: During pre-season, high-speed knee extensor total work was associated to jump performance. These results showed the important contribution of this muscle group on this particular multi-articular power-related task, especially at higher speeds. Total work may better predict jump performance than peak torque values. Other studies [Özçakar et al., (2007); Saliva & Hrysomalils, (2001)] have shown significant correlations between knee strength (peak torque values) and jump height during the competitive phase, whereas no correlations existed during preseason [Malliou et al., (2003)].