"Arm swing is a distinctive characteristic of sprint-running with the arms working in a con-tralateral 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 1 kg was attached to each forearm (equivalent to ∼2% body mass) during over ground short distance (20 m) maximal sprint-running.
WR forearm loading provides a movement specific overload of the arms which significantly alters step kinematics and sprint times ≥10 m.
The principle of specificity provides insight into how loading and training stimuli can be applied to optimise transference to the activ- ity/sport of interest. In this regard it is desirable that the contraction forces, movement velocities, and technical demands simulate the activity of interest. From this study loads in the proximity of 1 kg per limb were found to significantly increase contact time and step length whilst decreasing flight time, step frequency, and horizontal power.
Even though the changes were statistically significant the effects were deemed small or medium and so may be interpreted as appropriate loading to overload the sprint start i.e. not major disruptions to technique. The small increases in step length were interesting and were assumed to be the result of arm loading resulting in similar ground reaction force magnitudes applied over a longer contact time i.e. greater horizontal impulse.
However, whether such assumptions are correct would need force plates to quantify the vertical as well as the horizontal ground reaction forces used in tandem with motion capture to capture changes in joint angle positions."
- Given the results we speculate that WR forearm loading pro- vides a training means that may potentially improve arm drive mechanics significantly overloading step frequency and ground contact forces, however, further research is needed to verify such a contention.
- Forearm WR causes an acute overload resulting in a small but significant increase in sprint times for distances ≥10 m.
- During the start phase forearmWR can increase step length (2.1%) which may be due to the longer ground contact time (6.5%) i.e. potentially greater impulses.
Paul Macadam, Kim D. Simperingham, John B. Cronin
Sports Performance Research Institute New Zealand (SPRINZ) at AUT Millennium, Auckland University of Technology, New Zealand School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Australia
E-mail address: firstname.lastname@example.org (P. Macadam).
1440-2440/© 2018 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.