Kinetic Contributions of the Upper Limbs During Counter-Movement Vertical Jumps With and Without Arm Swing
This study examined the kinetic contributions of the upper extremities during counter-movement vertical jumps (CMVJ) while using arm swing (AS) or no-arm swing (NAS) conditions. Fourteen healthy men (X¯±SD; age = 24.1±3.9 yrs) volunteered for this investigation. Subjects performed in random order a total of 6 jumps consisting of 3 AS and 3 NAS CMVJ. A motion capture system was used to analyze the kinetic data. Paired samples t-tests were used to examine the subjects’ mean differences in the AS and NAS CMVJ trials (p<0.05). Results for all subjects were determined for each jump performed, with statistical analyses performed on mean values for all three jumps per subject. The AS significantly increased the vertical jump height (VJH) by an average of 0.07±0.03 m (3.0±1.3 in). DXA scans determined the upper limbs were 12.0% of the total body mass. Movement of the upper limbs during the AS CMVJ produced 32.2±7.0% of the total mean ground reaction force (GRF), and 11.3±2.2% during the NAS CMVJ. The enhancement of performance when jumping using an AS resulted in a 13.6% increase in VJH. The contribution of the upper limbs during the AS CMVJ averaged 31.5% of the peak GRF which occurred immediately before takeoff. The upper extremities can greatly influence vertical jump performances and the accompanying kinetics. When analyzing jump GRFs, one must be aware of how much the upper limbs contribute to these forces. Additionally, proper arm swing mechanics must be emphasized when instructing correct jump technique.