Symmetry and reproducibility of kinematic parameters during various running techniques.

PURPOSE This study examined the validity of the assumption of lower-extremity kinematic parameter reproducibility and symmetry during running with different velocities and stride frequencies. METHODS Each of 12 female long-distance runners ran on a treadmill in combinations of three different velocities (2.5, 3.0, and 3.5 m.s-1) and three different stride frequencies (preferred and +/- 10% from preferred). The left and right sides of the athletes were filmed using video cameras placed orthogonally to the sagittal plane. A total number of three step cycles for each running condition were recorded (250 Hz). For each side of the body, 19 sagittal kinematic parameters from the lower extremity were evaluated. RESULTS Intraclass correlation coefficients (ICC) for both legs were high (generally > 0.80). Only the angular velocity parameters demonstrated correlation values below 0.70. The symmetry index for the linear and angular displacement parameters and the contact times during all running techniques were less than 8%, whereas those for the angular velocity parameters and flight times were higher than 15%. CONCLUSION The present results suggested that the degree of reproducibility and symmetry of kinematic data do not vary with a deliberate change in running technique but rather depend on the parameter itself. With respect to the economy of data analysis, the present findings indicate that recording a single monolateral trial would provide reproducible and symmetric values for most kinematic parameters.