Generalized joint hypermobility and perceived harmfulness in healthy adolescents; impact on muscle strength, motor performance and physical activity level.

Objective: The first aim of this study was to determine whether adolescents with asymptomatic Generalized Joint Hypermobility (GJH) have a lower level of physical functioning (physical activity level, muscle strength and performance) compared to non-hypermobile controls. Secondly, to evaluate whether the negative impact of perceived harmfulness on physical functioning was more pronounced in adolescents with asymptomatic GJH.Methods: Cross-sectional study. Sixty-two healthy adolescents (mean age 16.8, range 12-21) participated. Hypermobility (Beighton score), perceived harmfulness (PHODA-youth) and muscle strength (dynamometry), motor performance (Single-Leg-Hop-for-Distance) and physical activity level (PAL) (accelerometry) were measured. Hierarchical regression analyses were used to study differences in physical functioning and perceived harmfulness between asymptomatic GJH and non-hypermobile controls.Results: Asymptomatic GJH was associated with increased knee extensor muscle strength (peak torque/body weight; PT/BW), controlled for age and gender (dominant leg; ß = 0.29; p = .02). No other associations between asymptomatic GJH and muscle strength, motor performance and PAL were found. Perceived harmfulness was not more pronounced in adolescents with asymptomatic GJH.Conclusions: Adolescents with asymptomatic GJH had increased knee extensor muscle strength compared to non-hypermobile controls. No other differences in the level of physical functioning was found and the negative impact of perceived harmfulness was not more pronounced in adolescents with asymptomatic GJH.