Effects of carbohydrate-electrolyte content of beverages on voluntary hydration in a simulated industrial environment

This study examined the effects of ingesting beverages of varying electroly te-carbohydrate (ECHO) composition on hydration, sensory response, physiolo gical function, and work performance during 4 hours of simulated industrial work for subjects wearing impermeable protective clothing (PC). Male subje cts (N=18) completed four separate work sessions. Each session consisted of 30 min of treadmill walking with intermittent arm curls at 300 kcal per ho ur (moderate work rate), followed by 30 min of rest, for a total of 4 hours at 33 degreesC wet-bulb globe temperature. Excessive physiological strain prevented only four subjects from completing the 4-hour protocol. A differe nt beverage was provided for consumption ad libitum for each work trial in a repealed measures, double-blind design. The beverages included lime color ed water (W), lemon-lime placebo (P), lemon-lime ECHO with 18 mEq/L NaCl (E CHO18), and lemon-lime ECHO with 36 mEq/L NaCl (ECHO36). There was no diffe rence in sweat production among the four trials (p = 0.61). Mean (standard deviation [SD]) fluid consumption was significantly greater for the ECHO36 [771 (+/-264) mt per hour] as compared with the W [630.6 (+/-234) mt per ho ur] and the P [655.2 (+/-228) mt per hour] (p<0.05), but not significantly greater than the ECHO18 [740.4 (+/-198) mt per hour]. Also, consumption of the ECHO18 was significantly greater than the W. Mean (SD) weight change, e xpressed as a percentage of total body weight (pre minus post), was -0.55(/-0.8) for W, -0.31(+/-1.0) for P, -0.01(+/-1.1) for ECHO18, and +0.11(+/-1 .1) for ECHO36 (p = 0.06). Subjects drank less and tended to experience gre ater weight loss in trials in which W or P were provided compared with tria ls in which either ECHO was provided. Thus, ECHO beverages, when provided a d libitum to workers wearing PC in a hot environment, produced better hydra tion than water.