Proximal-to-Distal Sequencing in Vertical Jumping With and Without Arm Swing

Chiu, LZF, Bryanton, MA, and Moolyk, AN. Proximal-to-distal sequencing in vertical jumping with and without arm swing. J Strength Cond Res 28(5): 1195-1202, 2014-Vertical jumping performance is dependent on muscle strength and motor skill. An understanding of motor skill strategies and their influence on jumping mechanics provides insight into how to improve performance. This study aimed to determine whether kinematic sequencing strategy influenced jump height, the effect of sequencing on jumping mechanics, and whether arm swing influences sequencing strategy. Women volleyball players (n = 16) performed vertical jumps with and without arm swing on force platforms while recorded with a 6-camera motion capture system. Sequencing strategy was determined as the relative time delay between pelvis and knee extension. A long time delay indicated a proximal-to-distal strategy, whereas no time delay represented a simultaneous strategy. Longer relative time delay was correlated with higher jump height in jumps with (r = 0.82, p < 0.001) and without arm swing (r = 0.58, p = 0.02). Longer relative time delay and higher jump height were associated with greater hip extensor and ankle plantar flexor net joint moments (NJM), and greater ratio of concentric to eccentric knee extensor NJM (p <= 0.05). Longer relative time delay and higher jump height were correlated with greater thigh and leg angular accelerations (p <= 0.05). These kinetic and kinematic variables, along with relative time delay and jump height were greater in jumps with arm swing than without (p <= 0.05), indicating arm swing promotes use of a proximal-to-distal strategy. Use of a proximal-to-distal strategy is associated with greater NJM and segment accelerations, which may contribute to better vertical jump performance.