Fluid Retention Properties of Carbohydrate/Protein and Carbohydrate-Only Sports Drinks
Seifert John G, Harmon Joseph, DeClercq Patti
Human Performance Laboratory, St Cloud State University, St Cloud, MN USA Introduction
Nose et al. (1988) reported that beverage osmolality, and ultimately serum osmolality, is one of the key factors in determining fluid retention rates during rehydration. Previous investigations have focused on the role of carbohydrate and sodium to aid fluid retention during rehydration. Makers of sports drinks tout their products as better fluid replacement beverages than plain water because of the combination of water, carbohydrate, and sodium. However, other compounds may also influence osmolality, and ultimately, fluid retention. The purpose of this study was to compare two popular sports drinks, a carbohydrate + protein and a carbohydrate-only beverages, and water in fluid retention following 2% BW loss. Methods
Following approval from the IRB, data collection began with 13 subjects. Subjects cycled at 25C to dehydrate to 2% of starting BW during three trials. They then ingested a fluid, within 20 minutes, at a volume equal to BW loss. Subjects ingested a 6% CHO + 1.5% protein + 24 mEq/kg sodium sports drink (CP, Accelerade„¥, PacificHealth Labs), a 6% CHO + 20 mEq/kg sports drink (CHO, Gatorade„¥, PepsiCo), or plain water (WA) during a three hour recovery period. Average beverage osmolality for CP was 305 mOsm/kg water, 285 mOsm/kg for CHO, and 4 mOsm/kg for WA. Blood samples, urine samples and volume, and BW were measured at seven time points during each trial. Results
Subjects averaged 1.74 kg weight loss (2.5 +.06 %) from exercise. Fluid retention was significantly (p=.000) greater for CP (88 +1.3%) than CHO (75 +4%) and WP (53 +4.5%). Average serum osmolality was greater (p=.000) for CP (284.7 +1.4 mOsm/kg) than CHO (282.6 +1.4 mOsm/kg) and WA (280.6 +1.7 mOsm/kg). Consequently, average urine osmolality was also greater (p=.001) for CP (569.4 +43.5 mOsm/kg) than CHO (472.9 +31 mOsm/kg) and WA (303.7 +42 mOsm/kg). Serum protein was lower for CP (7.39 +.3 g/L) and CHO (7.33 +.2 g/L) than WA (7.63 +.2 g/L). Discussion/Conclusion
Results indicate that a CP may be a preferable choice when fluid retention is a concern. Fluid retention for CP was 15% greater than CHO and 40% greater than WA. It is apparent that CP maintained a slightly higher serum osmolality during fluid replacement that resulted in fluid retention being improved over CHO and WA during a three-hour recovery period. It is not possible, however, to discern if it was the protein, sodium, or combination that added to the osmolality that significantly increased fluid retention with CP compared to CHO. Plain water ingestion, however, led to a significant dilution of the serum that resulted in only 53% fluid retention. References
Nose H et al. (1988). J Appl Physiol 65:325-31. My own thoughts: In the past, heavy sweaters have attempted hyperhydration only to elevate risk for hyponatremia (water intoxication), ingest glycerol as means to improve fluid uptake only to experience diarrhea, and increase salt intake as means to absorb fluid better only to become puffy so if a carb/protein solution does, indeed, help with fluid absorption or retention as this study suggests, this nutritional practice could be highly beneficial to those of you athletes who tend to lose more than 2% of your body weight during training/racing. Accelerade was used in this particular study but there are countless other sports drinks that provide the protein option: Powerbar Recovery, InfinIT customized sports drinks (www.infinitnutrition.com), Spiz (www.spiz.com), among more. Healthy trails, Kim Mueller-Brown, MS, RD
Sports Nutritionist
www.kbnutrition.com
Are you just getting on this train?
I join in when I can ( :
.
No she is just advertising herself more. See Gordo’s forum for the amount of “helpful advice” she gives.
She is the Tom Demerly of nutrition.
You have seen the other studies though–to same effect. In one they used soldiers in boot camp–after the training, some got water, some got a carbo-hydrate drink and some got a carbo and protein drink. Not only did they recover faster, the trips to the infirmary were cut down dramatically.
Who was faster than whom?