Carbohydrate supplementation stabilises plasma sodium during training with high intensity
Investigations of the effect of beverages containing carbohydrates, only, on the sodium and fluid balance during intermittent exercise of high intensity are rare. Therefore, we compared the effects of water and carbohydrate supplementation on plasma, blood volume, and electrolyte shifts during intermittent exercise.
Ten male subjects performed an intermittent exercise test twice. In one trial, tap water (4 ml/kg/15 min) was consumed (Plac trial). In the other trial, the same amount of water supplemented with maltodextrin to achieve a 9.1 % carbohydrate solution (CHO trial) was ingested. Training schedule: warm-up at 50 % for 15 min. Afterwards, power changed between 100 % of the maximum power from a previous incremental test minus 10 and 10 W for each 30 s. Venous blood was sampled to measure electrolytes, osmolality, [protein], hct, [Lactate], [glucose], [Hb] and catecholamines. Hydration status was evaluated by BIA before and after exercise.
After beverage ingestion [glucose] was significantly higher in CHO until the end of the trial. Starting with similar resting values, osmolality increased significantly more during CHO (p = 0.002). PV decreased by 5 % under both conditions, but recovered partly during exercise under Plac (p = 0.002). [Na+] and [Cl−] decreased with Plac during exercise (both p < 0.001) but remained constant during exercise with CHO.
Sole carbohydrate supplementation seems to stabilise plasma [Na+]. This cannot be explained simply by a cotransport of glucose and [Na+], because that should lead to a recovery of the blood and plasma volume under CHO. In contrast, this was found during exercise with Plac.
KeywordsIntermittent exercise Carbohydrate supplementation Hyponatremia Hydration status
Capillary concentration of…
Venous concentration of…
Analysis of variance
Bio impedance analysis
Continuous endurance training
High-intensity high-volume training
High-intensity interval training
Placebo = water
Total body water
We thank Hannelore Konrad for her invaluable technical support.
Compliance with ethical standards
Conflict of interest
The authors report that there were no conflicts of interest during this study.
- Burge CM, Skinner SL (1995) Determination of hemoglobin mass and blood volume with CO: evaluation and application of a method. J ApplPhysiol (1985) 79:623–631Google Scholar
- Clausen T (2010) Hormonal and pharmacological modification of plasma potassium homeostasis. FundamClin Pharmacol 24:595–605Google Scholar
- Coyle EF, Hamilton MT, Alonso JG, Montain SJ, Ivy JL (1991) Carbohydrate metabolism during intense exercise when hyperglycemic. J Appl Physiol (1985) 70:834–840Google Scholar
- Maassen N, Vardaxoglou KFM (2006) The impact of highly intensive interval like training on respiration. European College of Sport Science, 11th Annual Congress, LausanneGoogle Scholar
- Maassen N, Weis T, Schneider G, Schmidt W (1995) Carbohydrate rich beverages reduce plasma volume decrease during endurance exercise. Dehydration, rehydration and exercise in the heat. An International Conference, Nottingham, England. Abstracts of Poster Presentations, 15Google Scholar
- Maassen N, Foerster M, Mairbaurl H (1998) Red blood cells do not contribute to removal of K+ released from exhaustively working forearm muscle. J Appl Physiol (1985) 85:326–332Google Scholar
- Maassen M, Kummer O, Chouchakov VMN (2007) Die Wirkung von Kohlenhydratgaben während hochintensiver Intervallarbeit auf den Energiestoffwechsel und den Wasserhaushalt. Kummer O Chouchakov V, Maassen N. 7/8. 2007. Deutsche Zeitschrift für SportmedizinGoogle Scholar
- Murray B, Stofan J, Eichner E (2003) Hyponatremia in athletes. Sports Sci Exch Gatorate Sports Sci Ins 16:88Google Scholar
- Noakes TD, Sharwood K, Speedy D, Hew T, Reid S, Dugas J, Almond C, Wharam P, Weschler L (2005) Three independent biological mechanisms cause exercise-associated hyponatremia: evidence from 2,135 weighed competitive athletic performances. Proc Natl Acad Sci USA 102:18550–18555CrossRefPubMedPubMedCentralGoogle Scholar
- Shushakov V, Stubbe C, Peuckert A, Endeward V, Maassen N (2007) The relationships between plasma potassium, muscle excitability and fatigue during voluntary exercise in humans. ExpPhysiol 92:705–715Google Scholar
- Sjogaard G (1990a) Exercise-induced muscle fatigue: the significance of potassium. Acta Physiol ScandSuppl 593:1–63Google Scholar
- Vrijens DM, Rehrer NJ (1999) Sodium-free fluid ingestion decreases plasma sodium during exercise in the heat. J Appl Physiol (1985) 86:1847–1851Google Scholar