Dallas Johnson, Russell Lowell, Zachary Gillen. Mississippi State University, Mississippi State, MS.

BACKGROUND: The countermovement jump (CMJ) is a common assessment of vertical jump capabilities and overall athletic performance. In research studies and in clinical settings, the CMJ is commonly performed without the use of an arm swing (hands placed on hips) to control for the effects of upper-body movement on vertical jump performance. However, in field-based settings, such as during an exercise routine, an arm swing is commonly employed during the CMJ, which may augment overall performance. While jumping with no arm swing may allow for more precise, controlled assessments of lower-body performance, integrating the use of arm swing may yield more sport-specific results. The purpose of this study was to compare the effects of arm swing (AS) and no arm swing (NAS) on CMJ performance. METHODS: Ten recreationally trained males and females (age=23±2 yrs, height=171±7 cm, body mass=72±12 kg) participated. Participants completed six total CMJs, three with AS and three with NAS, in random order. Ground reaction forces were collected during all CMJ attempts to quantify unweighting, braking, propulsive, and performance metrics. Dependent samples t-tests were used to examine differences for all unweighting, braking, propulsive, and performance metrics. RESULTS: The NAS condition resulted in greater braking phase metrics, such that force at the low position of the countermovement and braking eccentric force were greater than the AS (p≤0.020). The AS condition resulted in greater propulsive and performance metrics, such that peak propulsive power and jump height were greater than the NAS (p≤0.024) CONCLUSIONS: The present study demonstrates that braking phase metrics may be superior when no arm swing is employed during the CMJ, however, it does appear that propulsive power production and vertical jump performance are positively affected by using an arm swing during the jump even with lower braking phase metrics. Although prohibiting an arm swing during the CMJ may allow greater isolation of lower-body performance, which can be beneficial in research and/or clinical settings when experimental control is a priority, it may be suggested that permitting the use of an arm swing could potentially allow a more holistic examination of overall athletic performance and sport-specific capabilities during jumping movements, which may prove beneficial in sports performance settings.

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