Can hip muscle strengthening interventions improve lower extremity kinematics among healthy subjects? A systematic review of randomized controlled trials

Purpose Poor lower extremity kinematics have been linked with lower extremity injuries. One of the main contributing factors in the development of poor lower extremity kinematics is hip muscle weaknesses. This systematic review aimed to summarize the literature related to the effects of hip muscle strengthening on lower extremity kinematics among healthy subjects. Methods A search for randomized controlled trials (RCTs) was conducted using the following databases: Cochrane, Web of Science, MEDLINE, PEDro and EBSCO. The selected studies had to distinguish the effects of hip muscle strengthening in healthy subjects, as compared to non-intervention or other kinds of intervention, and investigate at least one of the lower extremity kinematic factors. Two researchers performed study screening for obtaining the quality assessment scores in each included study using the PEDro scale. Statistical heterogeneity was tested using the Chi 2 test and I 2 statistic. Results Five studies were entered to review. There was level 1b or moderate evidence based on one “high” quality study that demonstrated hip muscle strengthening intervention was effective in the improvement of lower extremity kinematics. Conclusion It is difficult to make any definitive conclusions based on the results of this review and further research is needed. However, it should be considered that prescription hip muscle strengthening interventions alone maybe has a small effect on lower extremity kinematics in healthy subjects.