Effect of Additional Buoyancy Swimsuits on Performance of Competitive Swimmers

Shin-Ichiro Moriyama1, *, Yasunori Watanabe2, Tsubasa Kurono3, Jorge E. Morais4, 5, Daniel A. Marinho5, 6, Kohji Wakayoshi7
1 Department of Health & Sports Sciences, Tokyo Gakugei University, Tokyo, Japan
2 Department of Sports Science, Sendai University, Miyagi, Japan
3 Warashikonokai, Tokyo, Japan
4 Department of Sport Sciences, Polytechnic Institute of Bragança, Bragança, Portugal
5 Research Centre in Sports, Health and Human Development (CIDESD), University of Beira Interior, Covilhã, Portugal
6 Department of Sport Sciences, University of Beira Interior, Covilhã, Portugal
7 Department of Human Sciences, Osaka University of Economics, Osaka, Japan

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© 2021 Moriyama et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Health and Sports Sciences, Faculty of Education, Tokyo Gakugei University, 4-1-1, Nukuikita-machi, Koganei-shi, Tokyo 184-8501, Japan; Tel/Fax: +81-42-329-7731;



When in water, the Centers of Buoyancy (CoB) and Mass (CoM) of the human body are positioned cranially and caudally, respectively. With increasing distance between these centers, the sinking torque of the lower limbs increases, with a subsequent decrease in swimming performance due to increased drag.


To clarify the effect of additional buoyancy swimsuits on swimming performance.


The subjects were eight competitive male swimmers of mean ±SD age 21±2 years. Swimming performance was compared between Conventional (CS) and Additional Buoyancy Swimsuits (ABS). CoM and CoB were identified on land and in water, respectively, with the swimmers maintaining a horizontal posture. CoM was measured by the reaction board method. CoB was calculated as the force exerted in the vertical direction accompanied by changes in inspiratory volume. Swimming velocity and Blood Lactate (BL) concentration value during 200 m front crawl in trials at four different speeds (curve test) were recorded as swimming performance.


No significant difference in inspiratory volume was observed between CS and ABS (small effect size, d=0.28). The distance between CoM and CoB was significantly shorter for CS than ABS (p < 0.001; large effect size, d=1.08). Both swimming velocity at BL of 4 mmol·L-1 and maximal effort were significantly faster for ABS (p < 0.042; 0.008), with large effect size (d=0.91; 0.98). However, there was no significant difference in maximal BL between CS and ABS (small effect size, d=0.37).


ABS improves swimming performance by streamlining the horizontal posture.

Keywords: Swimming velocity, Horizontal posture, Blood lactate, Center of mass, Center of buoyancy, Water resistance.