Affiliations: [a] Centre de Recherches du Service de Santé des Armées, Département des Facteurs Humains, La Tronche – Grenoble, France | [b] Laboratoire Sport et Performance Motrice, Université Joseph Fourier, Grenoble, France
Correspondence:
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Corresponding author: Corinne Cian, CRSSA, Département des facteurs humains, BP 87 – 38702 La TRONCHE Cedex, France. Tel.: +33 4 76 63 69 81; Fax: +33 4 76 63 69 87; E-mail: corinnecian@compuserve.com
Abstract: The purpose of this study was to examine whether an over-stimulation of the vestibular system, induced by thousands of time saccadic head stimulations, affects the vestibular sensitivity, and consequently if such a phenomenon could contribute to the deterioration of postural stability observed after a long distance running exercise. Eighteen athletic subjects performed a 20.5 km over ground race with an average speed of 15 km.h−1, corresponding roughly to 7,500 strides shocks with associated saccadic accelerations transmitted to the head. A preliminary validation of the exercise protocol was realized to confirm the effect of the sustained exercise on body balance by recording standard postural parameters. A visually perceived eye level (VPEL) task was used to indirectly assess otolithic sensitivity motionless or undergoing low centrifugation conditions, before and after exercise. Results obtained from body balance analysis confirmed a decreased postural stability illustrated by increased postural oscillations after the 20.5 km run. Under low centrifugation conditions, results showed a lowering of the VPEL with the increase of the gravito-inertial acceleration in accordance with the literature. However, no significant change in the VPEL after a sustained running exercise was observed. In conclusion, the vestibular sensitivity at the otolithic level does not seem to be altered by an intensive running exercise and then failed to play a key role in the post-exercise deterioration of postural stability.
Keywords: active head movement, body sway, centrifuge, human, linear acceleration, otolithic organs, position of gaze, vestibular adaptation
