No difference in core temperature or thermal sensation in male and female scuba divers using wetsuits or semi-drysuits in 22.6°C sea water

Introduction: Scuba diving in water below thermoneutral temperature (< 30°C) can reduce core temperature and impair comfort and performance. Semi-drysuits are presumed superior to wetsuits because they presumably limit water entry into the suits, but changes in core temperature and thermal sensation have not been previously published in males and females wearing semi-drysuits. This study assessed the influence of anthropometrics and thermal protection from wetsuits and semi-drysuits on core temperature and thermal sensation in males and females performing recreational scuba dives. Methods: Core temperature (telemetric pill) and thermal sensation (Young's scale) were measured in 39 recreational divers (17 females) wearing wetsuits (mean 6 [SD 1] mm thickness, n = 19, 6 females) or semi-drysuits (7 [1] mm, n = 20, 11 females) during a 45-minute dive in mean 22.6 (1.1)°C water. Results: The wetsuit group had approximately 2 mm thinner suits (P < 0.001) and a 0.2 m² greater body surface area (P = 0.035), while age, body mass index, body fat percentage, and water temperature did not differ between groups. No significant differences were observed between suit types for absolute core temperature change or thermal sensation. In semi-drysuit divers, body fat percentage negatively correlated with the change in temperature per minute of dive time (rate of temperature change, R² = 0.29, P = 0.014). However, when anthropometric values were multiplied by suit thickness, there were no significant correlations with the rate of temperature change in either suit type. Conclusions: Semi-drysuits did not confer superior thermal protection in 22.6°C water during recreational scuba diving activities.