Yasunori Watanabe¹, Kohji Wakayoshi¹, Teruo Nomura², Masanobu Tachi³

¹Biwako Seikei Sport College (Shiga, Japan)
²Kyoto Institute of Technology (Kyoto, Japan)
³Nara University of Education (Nara, Japan)

THE EFFECT OF BREATHING ON THE DISTANCE BETWEEN CENTER OF BUOYANCY AND CENTER OF MASS IN COMPETITIVE SWIMMERS

Sport Mont 2014, XII(40-41-42), 98-104

Abstract

Introduction: Buoyancy is an important parameter in swimming. Previous studies suggested that gender, arm position, and lung volume influence natural buoyancy characteristics (Gagnon & Montpetit, 1981; McLean & Hinrichs, 2000). However, these data have not fully described the changes in natural buoyancy. For example, most previous studies measured center-of-buoyancy when participants held their breath. The purpose of this study was to examine the effect of breathing on the distance (d) between Center-of-buoyancy (CB) and Center-of-mass (CM), and its relation to glide-swimming performance. Method: The participants of this study were 14 male and 22 female Japanese Junior elite competitive swimmers. A reaction board (Hay, 1993) was used to locate CM for each participant while they lay in prone position with both arms held above the head (a streamline posture). The participant submerged and took the same posture for the measurement of CB. In both measurements, the changes of CM and CB were measured in relation to the changes of the lung volume which was measured by a flow instrument. The distance covered by glide-swimming was measured with the participant pushing off from the wall. Results: The result of d showed significant differences (p<.05) between the male (1.93 ± 0.21 cm) and the female swimmers (1.36 ± 0.17 cm) during hovering position (a neutral buoyancy). However there was no significant difference during full inspiration (male: 2.28 ± 0.44 cm, female: 2.01± 0.35 cm). The distance of the glide-swimming was not significantly different between the male and the female swimmers. Discussion: The results of this study showed that the change of CB with breathing was larger for the female swimmers than for the male swimmers. Also, the distance between CB and CM became smaller in the female swimmer during neutral buoyancy. These results indicated that the female swimmers have a potential to use buoyancy more effectively and could maintain a better horizontal streamline position. References: Gagnon M, Montpetit R (1981). Journal of Biomechanics, 14, 235-41. McLean SP, Hinrichs RN (2000). Research Quarterly for Exercise and Sport, 71(2), 182-9.

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