The Magnitude of Inter-limb Asymmetry and Its Assocation with Inter-limb Asymmetry in Distance Runners and Non-runners

Distance running is one of the most popular and most accessible ways to engage in physical activity. Although distance running offers numerous health-related benefits and protects against noncommunicable diseases (e.g., type 2 diabetic, obesity, hypertension), research has indicated a high prevalence of running-related injuries with a more pronounced incidence among novice runners (i.e., 17.8 injuries per 1000h) compared to their highly trained peers (i.e., 7.2 injuries per 1000h). Interlimb asymmetry has previously been related to higher injury risk as well as to impaired sports performances. Nevertheless, to date, research on the degree and evolution of functional asymmetry (e.g., unequal strength between limbs) in distance runners is scarce and the role of functional asymmetries in running performance and running-related injuries remains unclear. Moreover, and despite the great number of unilateral tests available in the literature, there currently exists no reliable and run-specific field-based test battery to examine the degree of lower limb asymmetry in distance runners. Therefore, this study aims to assess the test-retest, intra- and inter-rater reliability of a newly created running-specific field-based test battery to assess the presence and degree of functional lower limb asymmetry among novice, moderatly and highly trained distance runners as well as a control group of non-athletes. The second objective is to assess the association between inter-limb asymmetry and running performance.