Healthy
Conditions
Brief summary
This study will evaluate the effects manipulating ingested fluids can have on hydration status and cycling performance. There will be 4 different conditions.
Detailed description
Being dehydrated can decrease endurance exercise performance. The investigators wish to test which of three drinks is most effective at re-hydrating cyclists and if this affects performance. Subjects will undertake 4 tests: once dehydrated, once hydrated with water, once hydrated with a sports-specific drink, and once with an altered sports drink. Blood samples will be taken and expired gasses will be sampled at various time points throughout the tests for later analysis. A small amount of labelled water will be consumed with each drink, a technique which will allow us to quantify the absorption of each of the drinks.
Interventions
Sponsors
University of Exeter
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Investigator)
Masking description
Doubly-blinded & randomised using an online randomisation website.
Eligibility
Sex/Gender
ALL
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
* Highly trained cyclists (vo2max \>55 ml/kg/min, PPO (peak power output) \> 4 w/kg) * Training at least 4 times a week * Females must be taking an oral contraceptive, or using the contraceptive implant
Exclusion criteria
* Recent history of musculoskeletal injury * Diagnosed cardiovascular disease * Regular use of nutritional supplements that may interfere with the protocol
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Absorption of fluid through the gut | To begin 10 minutes after the completion of the 90 minute steady-state cycle | Absorption of drinks through the gut will be measured using 2 boluses of deuterated water. This will be consumed alongside 2 of the drinks, and blood samples will be used to quantify enrichment. Total body water calculations are required to provide corrections in equations related to D2O. H218O will be consumed in order to quantify total body water: this will be provided in a single bolus before each trial. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Work done (kJ) during 15 minute cycling time-trial | Throughout the 90 minute steady-state cycle & the 15 minute time trial. | Subjects will perform a cycle ergometer protocol that has been shown to be reproducible in athletes. Subjects will complete the time trial on a Lode Excalibur cycling ergometer. Software linked to this software will record work done and power output. |
Other
| Measure | Time frame | Description |
|---|---|---|
| Heart rate | Throughout the 90 minute steady-state cycle and time-trial | Heart rate will be measured throughout with the use of a heart rate monitor. |
| Substrate utilisation | Throughout the 90 minute steady-state cycle | Substrate utilisation will be calculated from data collected through a metabolic cart and its software. It will be measured during the 90-minute steady-state cycle for 4 periods of 3 minutes. Carbohydrate and lipid oxidation rates will be calculated using equations by Jeukendrup & Wallis (2005). |
| Core body temperature | Throughout the 90 minute steady-state cycle and time-trial | Core temperature will be measured throughout with the use of an ingestible core-body temperature pill (HQ Inc, FL, USA). |
| RPE (rating of perceived exertion) | Throughout the 90 minute steady-state cycle and time-trial | RPE will be measured using the Borg Scale. |
| Plasma metabolites | Throughout the 90 minute steady-state cycle and time-trial | A cannula will be used to draw blood from subjects at several time points. Whole blood samples will be analysed immediately for plasma glucose, plasma lactate, haemoglobin content, haematocrit and plasma volume. Remaining whole blood will be centrifuged immediately and its plasma split into aliquots and stored in a -20°C freezer. At the end of the trial, plasma samples will be moved to a -80°C freezer for later analysis for sodium, glycerol, and NEFA. |
Countries
United Kingdom
Outcome results
None listed