Hydration and Exercise Performance in Cycling

How Does Altering the Composition of Ingested Fluids Affect Hydration Status Whilst Cycling?

This study will evaluate the effects manipulating ingested fluids can have on hydration status and cycling performance. There will be 4 different conditions.

Study Overview

• Status: Completed
• Conditions: Healthy
• Intervention / Treatment: Dietary supplement: Placebo; Other: Dehydrated; Dietary supplement: Hypotonic; Dietary supplement: Isotonic

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.

• Study Type: Interventional
• Enrollment (Actual): 15
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Devon
    • Exeter, Devon, United Kingdom, EX1 2LU
      • School of Sports and Health Sciences

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 50 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Dehydrated; 90 minutes cycling, without the ingestion of any fluids, followed by a 15 minute cycling time trial test	Other: Dehydrated; N/A: see arm description
Experimental: Hypotonic; 90 minutes cycling, with the ingestion of six 250 ml carbohydrate (6g sucrose, 3g glucose) drinks, followed by a 15 minute cycling time trial test	Dietary supplement: Hypotonic; N/A: see arm description
Experimental: Isotonic; 90 minutes cycling, with the ingestion of six 250 ml carbohydrate (6g glucose, 3g fructose) drinks, followed by a 15 minute cycling time trial test	Dietary supplement: Isotonic; N/A: see arm description
Experimental: Placebo; 90 minutes cycling, with the ingestion of six 250 ml taste-matched water drinks, followed by a 15 minute cycling time trial test	Dietary supplement: Placebo; N/A: see arm description

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Absorption of fluid through the gut	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.	To begin 10 minutes after the completion of the 90 minute steady-state cycle

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Work done (kJ) during 15 minute cycling 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.	Throughout the 90 minute steady-state cycle & the 15 minute time trial.

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Substrate utilisation	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).	Throughout the 90 minute steady-state cycle
Plasma metabolites	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.	Throughout the 90 minute steady-state cycle and time-trial
Heart rate	Heart rate will be measured throughout with the use of a heart rate monitor.	Throughout the 90 minute steady-state cycle and time-trial
RPE (rating of perceived exertion)	RPE will be measured using the Borg Scale.	Throughout the 90 minute steady-state cycle and time-trial
Core body temperature	Core temperature will be measured throughout with the use of an ingestible core-body temperature pill (HQ Inc, FL, USA).	Throughout the 90 minute steady-state cycle and time-trial

Collaborators and Investigators

• Sponsor: University of Exeter
• Investigators: Principal Investigator: Andrew D Davenport, MSc, The University of Exeter

Study record dates

Study Major Dates

• Study Start (Actual): September 11, 2017
• Primary Completion (Actual): June 1, 2018
• Study Completion (Actual): June 1, 2018

Study Registration Dates

• First Submitted: September 13, 2017
• First Submitted That Met QC Criteria: October 2, 2017
• First Posted (Actual): October 6, 2017

Study Record Updates

• Last Update Posted (Actual): October 12, 2018
• Last Update Submitted That Met QC Criteria: October 11, 2018
• Last Verified: October 1, 2018

More Information

Terms related to this study

• Other Study ID Numbers: 170614/A/01

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No