Author(s): MURAKAMI, T., OKUDA, Y., FUJITA, K., YANASE, K., Institution: DOSHISHA UNIVERSITY, Country: JAPAN, Abstract-ID: 1961

INTRODUCTION:
Human spine consists of cervical, thoracic, lumbar, and pelvis regions. In the sagittal plane, there are arranged physiological curvature, and each spine part interacts with one another (1). In general, the posture is believed to affect sports performance, for example, excessive anterior or posterior pelvic tilt postures have negative effects on sprint. However, there have been no studies examining the relationship between postures and sports performance, such as sprint. The purpose of this study was to clarify the effect of different sagittal postural alignment on floor reaction force during sprint start.
METHODS:
Participants were 25 healthy young males (21.0 ± 0.8 years, 173.0 cm ± 5.2 cm, 50.2 kg ± 5.0 kg).
The participants were instructed to run as fast as they could a distance of 2.5m toward. They performed to step their right limb first, and kick the floor strongly with the left foot. The participants conducted three different postures at sprint start: the natural posture (NP), intentional　maximum anterior tilt posture(AP), and intentional maximum posterior tilt posture (PP). Spine angles in sagittal plane were measured just before the sprint start using Spinal Mouse (Index Ltd., Tokyo, Japan). The order was performed randomly, and each trial was performed twice. Floor reaction forces of lift limb were measured during the sprint start by a force plate. The peak forces of horizontal direction, vertical direction, and total force were measured. A one-way repeated measures analysis of variance (ANOVA) and Friedman test were used to compare spine angles in three postures. Additionally, these same tests were performed to compare for each peak force among the three postures.

RESULTS:
The thoracic and sacral angles in sagittal plane were significantly different among postures. The thoracic extension angles were greater in the order of AP, NP, and PP, and the sacral anterior tilt angles were greater in the same order. The lumbar extension angles showed no significant differences among the postures. The ANOVAs showed main effects for all forces among the postures. Both the vertical and total forces of NP and PP were significantly greater than those of AP. The horizontal force of NP was significantly greater than that of AP.
CONCLUSION:
Our results of this study suggest the NP are appropriate sprint start positions compared with AP. In near future, there is a need to analyze reaction times, sprint speeds, and other sprint factors between different postures.

References:
1) Kim et al, Clin Spine Surg. 2016

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