Abstract
Purpose: Laboratory studies have demonstrated that manual dexterity decreases with increasing cold, which may adverselyaffect performance. Dexterity may be impaired by cooling of the hand, cooling of the lower motor neurons, and cognitiveimpairment. Wetsuits are commonly used in open-water swimming and are mandated in some situations. This study investigatesthe effects of cold-water wetsuited swimming on dexterity. Methods: Five male and 4 female trained swimmers were recruited forthis cohort crossover study. Following dual-energy X-ray absorptiometry scans to determine body composition, they swam in afreshwater lake on 7 occasions with water temperatures between 24.5 °C and 8.4 °C. Dexterity was measured preswim andpostswim with a “nut–washer–bolt assembly time test” and cognition with a Stroop test. Core and peripheral body temperatureswere continuously monitored. Effects were analyzed by linear mixed-model regression. Results: Pre–post swim difference intime to complete the nut–bolt assembly increased as water temperatures decreased (1.0 s, 95% CI, 0.5–1.5 per 1 °C, P < .0001;R2 = .456), to a maximum of 14.7 seconds (95% CI, 3.3–26.0). This represented a 47.5% increase in assembly time from 24.5 °Cto 8.4 °C, which we consider to be of practical significance. Decreased dexterity was associated with decreased forearm andscapular temperature and decreased cognitive function. Body composition did not affect dexterity, cognitive function, or bodytemperature during swims. Water temperature did not affect swim speed. Conclusions: Despite the use of wetsuits, manualdexterity decreased with cold-water swimming. Swimmers, triathletes, and event organizers should consider the implications forsafety, performance, and equipment utilization.