Forearm wearable resistance effects on sprint kinematics and kinetics.

OBJECTIVES: Arm swing is a distinctive characteristic of sprint-running with the arms working in a contralateral manner with the legs to propel the body in a horizontal direction. The purpose of this study was to determine the acute changes in kinematics and kinetics when wearable resistance (WR) of 1kg (equivalent to ∼1% body mass) was attached to each forearm during over ground short distance (20m) maximal sprint-running.

DESIGN: Cross-sectional study.

METHODS: Twenty-two male amateur rugby athletes (19.4±0.5years; 97.0±4.8kg; 180.4±7.2cm) volunteered to participate in the study. Radar and Optojump were used to examine kinematic and kinetics between WR and unloaded sprint-running conditions.

RESULTS: No significant (p<0.05) differences were found at 2m or 5m between conditions, however, the WR condition resulted in a significant increase in 10m, 20m and 10-20m split time (all, ∼2%, small effect size) compared to the unloaded condition. Significant decreases were also found in theoretical maximum velocity (V0 ) (-1.4%, small effect size) and relative peak horizontal power production (Pmax ) (-5.5%, small effect size). Step length (2.1%, small effect size) and contact time (6.5%, medium effect size) were significantly increased, while step frequency (-4.1%, small effect size) and flight time (-5.3%, medium effect size) were significantly decreased.

CONCLUSIONS: WR forearm loading provides a movement specific overload of the arms which significantly alters step kinematics and sprint times ≥10m.