Effectiveness of Glycerol Ingestion for Enhanced Body Water Retention during Cold Water Immersion

Abstract

SUMMARYThe efficacy of ingesting an aqueous glycerol (GLY) solution to reduce diuresis and enhance body water retention during prolonged cold water dives was evaluated. Nine Navy divers 131 ± 5 years, height 175.0 ± 4.5 centimeters (cm), weight 78.9 ± 9.5 kilograms (kg), and 16 ± 2 percent (%) body fat] performed three-hour dives at 5 feet fresh water (FFW) maintained at 13*C.Divers wore thermal undergarments and dry suits and used a closed-circuit (MK-15) rebreathing unit. Six subjects were assigned to either a water treatment (VT) or glycerol treatment (GT) group. Three other divers performed a repeated measures design with dives separated by a day of nondiving. Statistical analyses of data from repeated and nonrepeated subjects consistently revealed no significant differences between and within these groups of subjects. Data were thus pooled into two treatment groups (VT . 6) and (GT -6).During the predive period, Serum glucose (sCLU) and serum lactate (sLAC) did not differ between treatments or times, but sLAC was significantly lover (P < 0.02) for both treatments at PD than at PH. Serum free fatty acids (sFFA) at PD for both treatments were significantly higher (P < 0.2) than at PRH and PH. Serum glycerol (sGLY) values for GT were 200 times above PRH at PH and 100 times ahn,'e PRH at PD. The amount of urinary glycerol (uGLY) rolected during the hyperhydration period (PRH to PH) and the thr'ýc-hotr dive periods accounted for 2 4.1Z and 10.3Z, respectively, of the total GLY ingested.Urine electrolyte values did not differ between treatments, except GT lost significantly (P < 0.02) more sodium (Na) [53.7 + 9.9 versus 21.6 + 6.2 milliequivalent per liter (meq/1)] during the PH period. Hyperhydratien with GLY (1.2 ml/kg LBM) mixed in 2 liters of water and consumed over 30 minutes appears ineffective in significantly reducing body water loss in divers under the stress of prolonged cold water immersion. It may be that altering the timing and/or concentration of the GLY doses will produce a significant effect under these test conditions.