Taimura, A., & Matsunami, M. (2006). Effect of swimsuits and water temperature on thermal responses during submaximal swimming. Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 2055.

This study was conducted to clarify thermal responses to swimming while wearing bodysuits in water temperatures of 28.9°C and 30.2°C. Male competitive college swimmers (N = 12) served as Ss. Ss swam 1,500 m at submaximal effort using front crawl stroke wearing both types of competitive swimsuits (bodysuits and regular swimsuits ) in water temperatures of 28.9°C and 30.2°C. Temperature loggers were attached to a swimmer's calf, thigh, abdomen, chest, and forearm and the skin temperatures of those locations measured throughout the swim at one minute intervals. Oral temperature, rating of perceived exertion, and thermal sensation of the head and body were measured upon completion of the swim.

Swimming time, heart rate, rating of perceived exertion and weight loss were similar for both forms of suit in both water temperatures. There were no significant differences in oral temperatures after wearing the suits. In 30.2°C water, there were significant differences in thermal sensations in the body and head caused by increases when wearing bodysuits. However, there were no significant differences in thermal sensations in the body and head in 28.9°C water.

Implication. There is a critical water temperature in competitive swimming (>29°C) when bodysuits cause increased thermal sensations of the body and head. Increased temperatures cause performance to decline. Wearing bodysuits in distance swimming races in warm water is inadvisable because of their detrimental effect on performance, which is likely to be far more significant than any hypothesized ("marketed") physical benefit of the garments. The thermal responses to swimming wearing the bodysuits were significantly higher than wearing the regular swimsuits in the water temperature of 30.2°C and not in water of 28.9°C.

[Editor's note: Grant Hackett set his world-record for 1,500 m at Fukuoka in 2001 wearing only a lower-body suit. Since changing to a full bodysuit (ostensibly for fiduciary gain), he has not approached his world record, although he has set the world-record for the "softer" event of 800-m freestyle. After completing a major 1,500-m event, Grant Hackett displays symptoms of mild heat stress, which would produce a performance decrement. It would be interesting to see how much better he would swim 1,500 m if he returned to lower-body suits or even a regulation suit. It is unlikely he will break the 1,500 m world record again if he persists with wearing full bodysuits in that event. As with most performance principles, there is considerable individual variation in factors between individuals. Although the above study showed that 28.9°C water did not promote bodysuits to cause heat stress symptoms, there are likely to be a number of individuals who will react adversely even at that temperature. A coach needs to monitor heat-stress reactions in each swimmer if they insist on wearing the bodysuit in distance races. Any symptom of heat-stress should be sufficient to decide not to wear a full bodysuit again in such races.]

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