Four years ago the author noted that few people of African origin excel in water sports, swimming in particular. Although the primary reason for this is probably in social differences and attitudes, hence, motivation; the problem of buoyancy may also affect the Africans' performance in swimming, especially over long distances. This factor may also play a critical role in learning to swim, and in water safety. In a theoretical discussion, the author pointed out that, as a rule, the buoyancy of the African was less than that of people of European or Asian origin-not taking into account the interindividual differences within the group. Buoyancy will be affected by three principal factors: a) the ratio of fat to fat-free body-mass; b) the ratio of volume to weight or density; and c) the relative volume of the lungs (residual volume as well as total lung volume). The two first factors have been discussed in detail in a paper presented at the First Symposium of Biomechanics in Swimming (1971). The author is not aware of any study comparing the relative density of Negro to white, as could be measured by underwater weighing techniques. (Fat percentage, assessed by anthropometric methods; skinfold thickness, for example, rarely exceeds 10 to 11 percent of total body weight, among the people in Zaire). However, the reader's attention should be directed to the relative size of lung volumes and their influence upon swimming performance. Differences in Negro-white lung volumes are by no means a new discovery. Shortly after the invention of a practical spirometer by Hutchinson in 1846, these differences were reported by Gould in 1869, who found smaller vital capacity among Negroes as compared to whites by as much as 11 percent (height taken into account) in his famous study on Civil War soldiers.
© Copyright 1975 Swimming II: Proceedings of the Second International Symposium on Biomechanics in Swimming, Brussels, Belgium. Published by University Park Press. All rights reserved.