Reliability of isokinetic hip abductor and adductor strength measurements: A systematic review and meta-analysis

The aims of this study were to: (I) examine the reliability of the abduction and adduction isokinetic strength measurements in healthy subjects and athletes; (II) determine which position is the most valid and reliable for strength measurement; and (III) determine the most reliable velocity to assess hip abductor and adductor strength. The databases used were Web of Science, SCOPUS, MedLine and PubMed. The metafor package of R software was used to conduct meta-analysis. A total of 767 studies were identified through a search of electronic databases, of which 10 were included in this meta-analysis. The main finding of the study revealed; (I) the reliability of isokinetic force measurement is good in abduction (ICC = 0.83) and adduction (ICC = 0.81); (II) standing position presents good reliability in abduction (ICC = 0.83) and adduction (ICC = 0.79); (III) the lateral position presents good reliability in abduction (ICC = 0.83) and adduction (ICC = 0.82); (IV) the velocity of 60°/s (ICC = 0.84), 90°/s (ICC = 0.84) and 120°/s (ICC = 0.86) show good reliability for abduction, and; (V) the velocity of 30°/s (ICC = 0.76), 60°/s (ICC = 0.83), and 120°/s (ICC = 0.89) show good reliability for adduction. Many factors influence the reliability of isokinetic assessments of the hip abductors and adductors, the best known of which are body position, isokinetic velocity, and type of muscle contraction. And although most of the researchers opt for the evaluation in lateral position, and at low velocities, our results conclude that the standing position, at a velocity of 120°/s is a better alternative to evaluate these movements (ABD-ADD), and not only because of its good reliability, but also because of the similarity of the evaluation with the gestures developed within the sport.