Isokinetic hip muscle strength: a systematic review of normative data

The aim of this study was to conduct a systematic review to determine the quality of evidence of studies assessing isokinetic hip muscle strength in adult non-injured individuals. We also aimed to summarise and pool data of normative values for hip muscle strength. The influence of methodological and participant-related factors on hip strength performance was explored as well. Guidelines proposed in the PRISMA were used to undertake a search strategy involving the keyword 'hip' associated with a set of keywords reflecting muscle strength. Five databases were searched: ProQuest, PubMed, Science Direct, Scopus and Web of Science. From the 2,939 records initially retained, 28 articles were included in this systematic review. Eight articles were classified as high quality. This systematic review exposed the methodological fragility of most studies assessing hip strength in non-injured adult population. Only data from studies with a small number of participants are available to be used as reference. A few individual studies suggest no differences in torque parameters between dominant and non-dominant lower limbs; differences in torque parameters between age groups; and between male and female participants. Overall, reference values for hip muscle performance in isokinetic tests are mostly unclear.