Muscle function and muscle balance in lower limbs are not impaired in individuals with general joint hypermobility

The generalized joint hypermobility (GJH) syndrome is a condition characterized by a connective tissue disorder that may negatively affect the muscle function and muscle balance in the lower limbs. The aim of study was to compare isometric and dynamic maximal strength, total work, active optimum angle, electromyographic activity strategy, and the muscle imbalance of the knee extensors and flexors using the hamstrings/quadriceps ratio (H:Q) in individuals with GJH and without GJH (NGJH). Forty healthy untrained men and women (20 with GJH and 20 without GHJ) participated in the study. Dynamic, isometric (30° and 60°) peak torque, total work, active optimum angle, and agonist and antagonist muscle activation of knee extensors and flexors were obtained. The conventional and functional H:Q ratio were calculated using peak torque, rate of torque development, muscle activation, and total work. The dynamic and isometric peak torque, total work, active optimum angle, and agonist and antagonist muscle activation were not different between GJH and NGJH (p > 0.05). Conventional and functional H:Q ratios calculated using the different neuromuscular parameters were considered below the normative values for both groups, with no difference between groups (p > 0.05). The lack of difference between groups suggests that hypermobility does not have a greater influence on maximal strength and in underlying mechanisms related to knee extensors and flexors muscle activation and muscle balance in the knee joint.