The effect of clothing on "diving bradycardia" in man during submersion in cold water.
Eighteen healthy male volunteers undertook three seated submersions into stirred water at 5 degrees C. Whilst submerged, the subjects attempted to hold their breath for 20 s. They wore a different clothing assembly for each submersion, viz: a cotton overall assembly, a "wet suit" assembly and a "dry suit" assembly. During the experiments the breath-hold time, heart rate, skin and rectal temperatures of the subjects were recorded. The results showed that significantly (P less than 0.05) more subjects developed a diving bradycardia--defined as five or more consecutive R-R intervals of over 1.2 s--when wearing the dry suit. It is concluded that increasing the cold stress experienced by individuals during cold-water submersion decreases the incidence of diving bradycardia but not the magnitude of the bradycardia when it occurs.
Tipton
M
M
Institute of Naval Medicine, Gosport, Hants, UK.
D000293:Adolescent; D000328:Adult; D001831:Body Temperature; D001919:Bradycardia / Q000503:physiopathology*; D003020:Clothing; D003080:Cold Temperature; D004242:Diving; D006339:Heart Rate; D006801:Humans; D007101:Immersion; D008297:Male; D013997:Time Factors