Rapid hamstrings/quadriceps strength capacity in professional soccer players with different conventional isokinetic muscle strength ratios

Muscle strength imbalance can be an important factor in hamstrings muscle strain. a hamstrings/quadriceps (h/q) strength ratio based on concentric peak torque values (h con:q con) has traditionally been used to describe the potential for knee-joint destabilization. because certain standard actions in soccer are explosive,the analysis of the h/q strength ratio based on the rate of torque development (h rtd:q rtd) might also be useful in the evaluation of joint stability. the objective of this study was to compare the h rtd:q rtd between professional soccer players with heterogeneous values of h con:q con. thirty-nine professional soccer players took part in the following procedures on different days: 1) familiarization session with the isokinetic dynamometer,and 2) two maximal isometric actions and five maximal concentric actions at 60°·s-1 for hamstrings (h) and quadriceps (q). participants were ranked according to their h con:q con ratio. the median third was excluded to form a high torque group (htg),and a low torque group (ltg). peak isometric (h) and concentric (h and q) torques and rate of torque development (h) were significantly greater in the htg group. similarly,h con:q con (0.68 ± 0.02 vs. 0.52 ± 0.03) and h rtd:q rtd (0.54 ± 0.12 vs. 0.43 ± 0.16) were significantly greater in the htg group than in the ltg group. there was no significant correlation between h con:q con and h rtd:q rtd. it can be concluded that h con:q con and h rtd:q rtd are determined,but not fully defined,by shared putative physiological mechanisms. thus,the physiologic and clinical significance of h con:q con and h rtd:q rtd to an athlete's individual evaluation might be different. © journal of sports science and medicine (2012).