None listed
Conditions
Brief summary
The major aim of this study is to assess whether rehydration in athletes can be improved by the use of intravenous fluids and/or oral glycerol, compared to oral fluids alone. It was hypothesised that both intravenous fluids or oral glycerol would improve rehydration, but that a combination of intravenous fluids and oral glycerol together would improve rehydration more than either of the interventions alone.
Interventions
All subjects completed all four experimental trials in a randomised crossover sequence: (1) 100% oral fluid without glycerol (oral); (2) 100% oral fluid with oral glycerol (oral with glycerol); (3) 50% oral fluid, 50% intravenous (IV) fluid (0.9% NaCl), without glycerol (IV); and (4) 50% oral fluid, 50% intravenous fluid (0.9% NaCl) with oral glycerol (IV with oral glycerol). Trials were conducted at least two weeks apart.
In each experimental trial, subjects were initially dehydrated via cycli
All subjects completed all four experimental trials in a randomised crossover sequence: (1) 100% oral fluid without glycerol (oral); (2) 100% oral fluid with oral glycerol (oral with glycerol); (3) 50% oral fluid, 50% intravenous (IV) fluid (0.9% NaCl), without glycerol (IV); and (4) 50% oral fluid, 50% intravenous fluid (0.9% NaCl) with oral glycerol (IV with oral glycerol). Trials were conducted at least two weeks apart. In each experimental trial, subjects were initially dehydrated via cycling exercise in the heat (35oC, 70% relative humidity) to -4% bodyweight. The interventions (oral [control trial], oral with glycerol, IV and IV with oral glycerol) were then provided during rehydration over a two hour period. The total volume of rehydration was 150% of the bodyweight lost. In the first hour, subjects were given 100% of the bodyweight lost, with a further 50% provided in the second hour of rehydration. Glycerol (1.5 g/kg bodyweight) was provided orally in a sports drink (Gatorade) solution during two hours of rehydration (after being dehydrated by -4% bodyweight) in the oral with glycerol and IV with glycerol trials. The overall dose was provided in two fluid boluses containing 1.0 g/kg and 0.5 g/kg during the first and second hours of rehydration, respectively. Intravenous fluids (0.9% NaCl) were administered in the IV and IV with oral glycerol trials. In these trials, half the rehydration volume was IV fluid and the other half was oral fluid.
Sponsors
University of Queensland
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Treatment
Masking
Blinded (masking used)
Eligibility
Sex/Gender
Male
Age
18 Years to 40 Years
Healthy volunteers
Yes
Inclusion criteria
1) male aged 18 – 40 yrs; 2) experienced cyclist; 3) high endurance training status (V•O2max > 55 mL · kg-1 · min-1); and 4) consistently high training volumes for at least the preceding two months
Exclusion criteria
1) a history of current or previous renal, hepatic, cardiovascular, thermoregulatory or endocrine disorders; 2) contraindications to exercising in the heat; 3) any current or chronic health problems or injuries; 4) the use of any diuretic during the preceding four weeks; and 5) having made a blood donation in the preceding three months
Outcome results
None listed