The primary objective of this investigation was to determine the thermal and metabolic effects of wearing a rubberized wet suit (WS) while swimming for 30 min in 20.1, 22.7, and 25.6 degrees C water. Metabolic and body temperature measurements were recorded in each water temperature with subjects wearing either a WS or a competitive swimming suit (SS). Immediately after each swim the subjects cycled for 15 min on a stationary cycle ergometer. Energy expenditure (VO2), heart rate, post-swim blood lactate, work completed on the cycle ergometer, and rating of perceived exertion (RPE) were similar in all trials. Mean (+/- SE) core temperature (Tc) during swimming in the SS trials increased 0.56 (+/- 0.33), 0.48 (+/- 0.20), and 1.22 (+/- 0.24) degrees C, whereas in the WS trial Tc rose 0.62 (+/- 0.22), 1.02 (+/- 0.15), and 0.89 (+/- 0.13) degrees C in the 20.1, 22.7, and 25.6 degrees C treatments, respectively. Following swimming many of the subjects experienced a decrease in Tc, but it was significantly elevated above preimmersion by the end of cycling in all trials except the SS 20.1 degrees C trial. Mean trunk temperatures (Ttr) during swimming in the WS trials were 4.32 +/- 0.16 (20.1 degrees C), 3.90 +/- 0.25 (22.7 degrees C), and 3.21 +/- 0.20 (25.6 degrees C) degrees C warmer than in the SS. Ttr rose after the subjects exited the water, but remained significantly below baseline throughout cycling in all trials.(ABSTRACT TRUNCATED AT 250 WORDS)