Effects of experience within a dynamic environment on postural control

Dale W Chapman ^1*, Kale J Needham ², Gary T Allison ³, Brendan Lay ⁴ and Dylan J Edwards ⁵

¹ School of Exercise, Biomedical and Health Sciences. Edith Cowan University, Australia
² 2. School of Human Movement and Exercise Science, University of Western Australia., Australia
³ 3. Centre for Musculoskeletal Studies , University of Western Australia., Australia
⁴ 2. School of Human Movement and Exercise Science, University of Western Australia, Australia
⁵ 1. School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Australia

^* To whom correspondence should be addressed. E-mail: d.chapman{at}ecu.edu.au.

Accepted 5 May 2007

Abstract

Objectives: Surfing is a balance-reliant, open-skill performed in a dynamic environment rich in visual, somatosensory and vestibular information. The purpose of this study was to evaluate adaptations to the postural control system by surfing experience.

Methods: Postural control was assessed in an upright bipedal stance in 60 male volunteers (elite surfers: n=21, intermediate level surfers: n=20 and control: n=19) using various closed stance positions. Six tasks were performed with two trials including a cognitive task, in the following order; eyes open head in a neutral position (EO1), eyes closed head in a neutral position (EC), eyes closed head back (ECHB), eyes open head in a neutral position: cognitive task 1 (EOC1), eyes open head in a neutral position: cognitive task 2 (EOC2), eyes open head in a neutral position (EO2). Dependent variables were area of 95th percentile ellipse (AoE) and sway path length (SPL).

Results: All participants showed systematic increases in SPL and AoE in EC and ECHB trials. Expert surfers displayed significantly (p<0.05) increased SPL but not AoE when sharing attention with both concurrent mental tasks compared to controls. Controls showed a mild, non-significant change in postural control when attending to concurrent mental tasks, of reduced SPL and AoE.

Conclusions: These findings indicate that standard postural sway indices are not able to elucidate whether expertise in surfing facilitates adaptations to the postural control system. However concurrent mental task findings illustrate that systematic difference between expert surfers and controls on balance abilities may exist.

Key Words: Balance, Stroop test, stability testing, training adaptations

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