title: Effect of varying the concentrations of carbohydrate and milk protein in rehydration solutions ingested after exercise in the heat.
abstract: The present study investigated the relationship between the milk protein content of a rehydration solution and fluid balance after exercise-induced dehydration. On three occasions, eight healthy males were dehydrated to an identical degree of body mass loss (BML, approximately 1·8%) by intermittent cycling in the heat, rehydrating with 150% of their BML over 1 h with either a 60 g/l carbohydrate solution (C), a 40 g/l carbohydrate, 20 g/l milk protein solution (CP20) or a 20 g/l carbohydrate, 40 g/l milk protein solution (CP40). Urine samples were collected pre-exercise, post-exercise, post-rehydration and for a further 4 h. Subjects produced less urine after ingesting the CP20 or CP40 drink compared with the C drink (P<0·01), and at the end of the study, more of the CP20 (59 (SD 12)%) and CP40 (64 (SD 6)%) drinks had been retained compared with the C drink (46 (SD 9)%) (P<0·01). At the end of the study, whole-body net fluid balance was more negative for trial C (- 470 (SD 154) ml) compared with both trials CP20 (- 181 (SD 280) ml) and CP40 (2107 (SD 126) ml) (P<0·01). At 2 and 3 h after drink ingestion, urine osmolality was greater for trials CP20 and CP40 compared with trial C (P<0·05). The present study further demonstrates that after exercise-induced dehydration, a carbohydrate--milk protein solution is better retained than a carbohydrate solution. The results also suggest that high concentrations of milk protein are not more beneficial in terms of fluid retention than low concentrations of milk protein following exercise-induced dehydration.
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough LE11 3TU, UK.
authors.forename: Lewis J
authors.initials: LJ
authors.lastname: James
authors.forename: Gethin H
authors.initials: GH
authors.lastname: Evans
authors.forename: Joshua
authors.initials: J
authors.lastname: Madin
authors.forename: Darren
authors.initials: D
authors.lastname: Scott
authors.forename: Michael
authors.initials: M
authors.lastname: Stepney
authors.forename: Russell
authors.initials: R
authors.lastname: Harris
authors.forename: Robert
authors.initials: R
authors.lastname: Stone
authors.forename: David J
authors.initials: DJ
authors.lastname: Clayton
mesh_terms: D000328:Adult; D001642:Bicycling; D003681:Dehydration / Q000178:diet therapy*; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000494:pharmacology; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000494:pharmacology; D004311:Double-Blind Method; D005440:Fluid Therapy / Q000379:methods*; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008894:Milk Proteins / Q000008:administration & dosage* / Q000494:pharmacology; D012016:Reference Values; D014882:Water-Electrolyte Balance / Q000187:drug effects; D055815:Young Adult
chemical_list: D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D008894:Milk Proteins