Functional and structural lower limb asymmetry in novice and highly trained recreational distance runners:
A prospective approach with a possible link to injury (risk) prevention and running performance
Running is a popular and accessible endurance sport commonly practiced by a large part of the population. Although regular (aerobic) physical activity and exercise are strongly recommended by the World Health Organization, recreational distance running is frequently associated with high injury rates. Injuries have a multifactorial etiology in which interlimb asymmetry has been shown to play a role. Daily activities as well as 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 performance. Given that the literature on the degree and evolution of both structural and functional lower limb asymmetry as well as their link with injury and sports performance is very scarce, we aim to gain comprehensive knowledge on the topic among both novice and highly trained adult recreational distance runners through (1) a test-retest reliability study, (2) a prospective longitudinal cohort study, and (3) a randomized experimental cross-over study. As such, this innovative project will provide greater insight in the existence of structural and functional asymmetry and its role regarding injuries and running performances. The fundamental and novel knowledge to be gained can serve future sports practitioners with evidence-based (training) recommendations.