Degree and evolution of functional and structural lower limb asymmetry with a possible link to injury (risk) prevention and running performance in healthy novice and highly distance runners: A PhD project

Introduction: Running is an endurance sport that is often associated with high injury rates. Injuries have a multifactorial aetiology in which interlimb asymmetry has been shown to play a role. Daily activities and sport practice can further accentuate such differences between body sides, resulting in both functional (e.g., unequal strength) and structural (e.g., dissimilar lean mass) asymmetry. Besides its link with injury, interlimb asymmetry has also been associated with impaired physical and/or sports performances. Given that the literature on the degree and evolution of functional and structural lower limb asymmetry in running is scarce, this project aims to gain comprehensive knowledge on the topic among novice and highly-trained distance runners. Methods: The project’s target populations include healthy 20-50 y/o age- and sex-matched novice runners, (i.e., no running experience for ≥5 years), highly-trained runners (i.e., running >150km/month) and a control group of non-runners (i.e., <75min of moderate-to-vigorous intensity physical activity per week). First, a reliability study will be conducted to ensure the reliability of a functional test battery (N=54). Secondly, the link between the degree and evolution in lower limb asymmetries, injury and running performance will be assessed using a 30-week prospective study, in which participants (N=69) will be monitored regarding training exposures and potential injuries. They will also be measured on 4 test occasions at 10-week intervals to assess the degree of functional and structural asymmetry. Finally, an experimental crossover study will be conducted in which only highly-trained runners (N=42) will be measured on three test occasions at 10-week intervals. In this study, a supervised strength programme will be imposed to examine its effect on the link between running economy and changes in functional and structural asymmetry. Conclusion: This project will identify the extent and evolution of lower limb asymmetries and their possible role in view of injury (risk) prevention and running performance.