Eventually, bodysuits do absorb water, which displaces some trapped air. That bodysuits, their fabrics and coatings, assist in floatation in a manner similar to a thin wetsuit, is indisputable. What should be of concern to anyone who cares about the sport of swimming and the conduct of fair competitions, is that these suits are even allowed . What should be of concern is the amount of floatation a bodysuit's covering provides relative to the size of the swimmer. Some examples that illustrate this subtle point that will affect swimming race outcomes are as follows.
Thin swimmers have smaller body surface areas than do fuller swimmers.
They sink lower in the water because they are denser. Thus, the amount of bodysuit floatation for a thin swimmer will be less than the amount for a stockier swimmer because, for the latter, the amount of fabric to swimmer height will be proportionally larger. The larger a swimmer, the greater will be the body surface area and the amount of bodysuit fabric needed to cover it. Those swimmers will derive a greater floatation benefit. Coaches have verified this reasoning by noting that thin swimmers do not seem to get as much benefit from bodysuits as do thicker swimmers.