DRINKING BEHAVIOR AND EXERCISE-THERMAL STRESS - ROLE OF DRINK CARBONATION

This study investigated the influence of drink carbonation and carbohy drate content on ad libitum drinking behavior and body fluid and elect rolyte responses during prolonged exercise in the heat. Eight competit ive male runners completed three 2-hr treadmill runs at 60% VO2max in an environmental chamber maintained at 30-degrees-C and 40% RH. Three test drinks were used: 8% carbohydrate, low carbonation (8%-C); 8% car bohydrate, noncarbonated (8%-NC), and water (0%-NC). Blood samples wer e taken preexercise (0), at 60 and 120 min of exercise, and at 60 min of recovery (+60 min). The data suggest that while reports of heartbur n tend to be higher on 8% carbohydrate drinks than on 0%-NC, this does not appear to be a function of drink carbonation. Similarly, the incr eased frequency of heartburn did not significantly reduce fluid consum ption either during exercise or during a 60-min recovery period. Impor tantly, no differences were observed between fluid and electrolyte, or thermoregulatory responses to the three sport drinks. Thus, consumpti on of low-carbonation beverages does not appear to significantly influ ence drinking behavior or the related physiological responses during p rolonged exercise in the heat.