title: Carbohydrate supplementation stabilises plasma sodium during training with high intensity.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Institute of Sports Medicine, Hannover Medical School, Carl-Neuberg-Str.1, 30625, Hannover, Germany. maik-g-schrader@gmx.de.
authors.forename: M
authors.initials: M
authors.lastname: Schrader
authors.affiliation: Institute of Sports Medicine, Hannover Medical School, Carl-Neuberg-Str.1, 30625, Hannover, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Treff
authors.affiliation: Institute of Sports Medicine, Hannover Medical School, Carl-Neuberg-Str.1, 30625, Hannover, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Sandholtet
authors.affiliation: Institute of Sports Medicine, Hannover Medical School, Carl-Neuberg-Str.1, 30625, Hannover, Germany.|Institute of Sports Science, Leibniz University Hannover, Am Moritzwinkel 6, 30167, Hannover, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Maassen
authors.affiliation: Institute of Sports Medicine, Hannover Medical School, Carl-Neuberg-Str.1, 30625, Hannover, Germany.|Institute of Sports Science, Leibniz University Hannover, Am Moritzwinkel 6, 30167, Hannover, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Shushakov
authors.affiliation: Data Input, Lindenberg 7, 82343, Pöcking, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Kaesebieter
authors.affiliation: Institute of Sports Medicine, Hannover Medical School, Carl-Neuberg-Str.1, 30625, Hannover, Germany.|Institute of Sports Science, Leibniz University Hannover, Am Moritzwinkel 6, 30167, Hannover, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Maassen
mesh_terms: D000328:Adult; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000378:metabolism*; D019587:Dietary Supplements; D000072696:High-Intensity Interval Training / Q000379:methods*; D006801:Humans; D008297:Male; D064797:Physical Conditioning, Human / Q000379:methods; D010807:Physical Endurance / Q000187:drug effects / Q000502:physiology*; D005082:Physical Exertion / Q000187:drug effects / Q000502:physiology; D012964:Sodium / Q000097:blood*; D014882:Water-Electrolyte Balance / Q000187:drug effects / Q000502:physiology*
chemical_list: D004040:Dietary Carbohydrates; D012964:Sodium
keywords: Carbohydrate supplementation; Hydration status; Hyponatremia; Intermittent exercise