Load effects of thigh wearable resistance on angular and linear kinematics and kinetics during non-motorised treadmill sprint-running.

The aim of this study was to investigate the load effects of thigh attached wearable resistance (WR) on linear and angular kinematics and linear kinetics during sprint-running. Fourteen recreational active subjects performed a series of maximal sprints with and without WR of 1%, 2%, and 3% body mass (BM) in a randomised order. Sprints were performed on a non-motorised treadmill that collected velocity, and linear step kinematics and kinetics. Angular kinematics of the thigh were collected from an inertial measurement unit attached to the left thigh. Trivial decreases were found in peak velocity with all WR loads (-0.9 to -.2.4%, effect size [ES] 0.09-0.17, p  > .05). The WR conditions resulted in significantly decreased average step frequency (-2.0% to -3.0%, ES = 0.35-0.44, p  < .05) with loads of ≥2% BM, whereas average step length was statistically unchanged (1.9-2.8%, ES = 0.20-0.33). Average angular displacement was significantly decreased (-7.0% to -10.3%, ES = 0.88-1.10, p  = 0.00-0.03) with loads of ≥2% BM. Average angular flexion velocity (-10.2%, ES = 1.07, p  = .02) and extension velocity (-12.0%, ES = 0.85, p  = .01) were significantly decreased with 3% BM. Trivial to small ES changes ( p  > .05) were found in the linear kinetic measures of interest. Thigh WR provides a sprint-specific rotational form of resistance resulting in greater changes to angular kinematics than linear properties of sprint-running. For practitioners who wish to target thigh angular kinematics and step frequency without decreasing step length, thigh WR of ≥2% BM offers a sprint-specific resistance training tool.