Could Kool Aid be Better Than IV Rehydration in Dehydrated Athletes?
June 1, 2000 3 minutes read
Could Kool Aid be Better Than IV Rehydration in Dehydrated Athletes?
Abstract & Commentary
Synopsis: No specific differences in performance between IV and oral rehydration were identified. However, some physiological parameters were maintained better in the oral rehydration group.
Source: Casa DJ, et al. Intravenous versus oral rehydration during a brief rest period: Responses to subsequent exercise in the heat. Med Sci Sports Exerc 2000;32:124-133.
This is a prospective, randomized study using eight endurance-trained male cyclists from the University of Connecticut cycling club with an average age of 24, body fat of 13.5%, and peak O2 uptake of 61.4 mL/kg min. The purpose of the study was to assess whether a brief period of rehydration, either by intravenous (IV) or oral methods, affects cardiovascular, thermoregulatory, and performance factors during an exhaustive exercise in the heat.
Baseline studies included sitting in an environmental chamber, weight measurement, and labs in a normal hydration state tested by urine specific gravity. Dehydration occurred by overnight fluid restriction and exercise until 4% body weight loss was obtained. The IV (0.45 NS) and oral rehydration (Kool Aid mix without sugar in 0.45 NS solution) occurred over a 20-minute period and replaced 2% of the lost body weight. The exercise testing was performed on a cycle ergometer and was terminated if voluntary exhaustion was reached, if a rectal temperature higher than 39.5° was recorded, or if other signs of heat intolerance were identified. The time to exhaustion was 34.5 minutes for the oral group and 29.5 minutes in the IV group (not statistically significant at P = 0.07). A lower plasma lactate, greater heart rate control, and lower rectal temperature were noted in the oral vs. IV group. (All significant at P < 0.05.)
The study concluded that no performance differences were identified between the IV and oral groups. However, significant physiological benefits were identified in the oral replacement group.
Comment by James R. Slauterbeck, MD
Sports medicine physicians are faced with a short period to rehydrate athletes between periods. Many high-caliber athletes are requesting IV rehydration to get fluid in fast and many physicians (me included) have assisted athletes with IV rehydration. Although this study does not answer all the questions in rehydration of athletes, it does help in many areas.
The shortcomings in this article are well overcome by the stringent methodology. For example, the dehydration and rehydration states are well controlled. Although my goals are to completely rehydrate my athletes between periods, this study used only 50% rehydration for the athletes. The 50% rehydration state may have been chosen because the true volume of fluids needed to fully resuscitate a 4% weight loss may be prohibitive in a 20-minute period. In addition, athletes (not in this study) are encouraged to drink continually during the sporting event to stay as hydrated as possible and not to forcibly dehydrate themselves either during the activity or overnight. It is also unsafe for athletes to intentionally dehydrate themselves overnight prior to competition.
Despite these technical difficulties and design choices, this study clearly standardizes and reproduces the dehydration and rehydration conditions and tests the athletes on a cycle that they are accustomed to riding. Additionally, a partial dehydration state is probably a true state many athletes are competing in as a game advances. Therefore, I like this study. Certain athletes are competing when sick and other athletes simply cannot drink fluids because of cramping and bloating. For these athletes, IV rehydration may be the method of choice. This project clearly shows that oral rehydration of a partially rehydrated athlete has physiologic benefits. I believe this is important and should be stressed to our athletes and trainers. Oral rehydration with an inexpensive homemade Kool Aid solution effectively rehydrates athletes, improves physiological parameters, and shows a trend to increase performance.
Oral rehydration is significantly better than IV rehydration because:
a. the oral rehydration group had a significantly lower time to exhaustion compared to the IV rehydration group.
b. the oral rehydration group had a significantly lower plasma lactate level, better heart rate control, and lower rectal temperature than the IV rehydration group.
c. the oral rehydration group had a significantly higher time to exhaustion compared to the IV rehydration group.
d. no significant differences were seen between the IV and oral groups.
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