Differences in kinetic asymmetry between injured and noninjured novice runners: A prospective cohort study

•Natural levels of asymmetry of kinetic factors in running were high.•Differences in asymmetry of impact peak and contact time were significant, but these variables did not remain significant in multifactorial analysis.•There were no differences in asymmetry of kinetic and spatio-temporal variables between injured and noninjured runners in this prospective study.

PurposeThe purpose of this prospective study was to describe natural levels of asymmetry in running, compare levels of asymmetry between injured and noninjured novice runners and compare kinetic variables between the injured and noninjured lower limb within the novice runners with an injury.MethodsAt baseline vertical ground reaction forces and symmetry angles (SA) were assessed with an instrumented treadmill equipped with three force measuring transducers. Female participants ran at 8 and 9 km h−1 and male runners ran at 9 and 10 km h−1. Participants were novice female and male recreational runners and were followed during a 9-week running program.ResultsTwo hundred and ten novice runners enrolled this study, 133 (63.3%) female and 77 (36.7%) male runners. Thirty-four runners reported an RRI. At baseline SA values varied widely for all spatio-temporal and kinetic variables. The inter-individual differences in SA were also high. No significant differences in SA were found between female and male runners running at 9 km h−1. In injured runners the SA of the impact peak was significantly lower compared to noninjured runners.ConclusionsNatural levels of asymmetry in running were high. The SA of impact peak in injured runners was lower compared to noninjured runners and no differences were seen between the injured and noninjured lower limbs.