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Trial registered on ANZCTR


Registration number
ACTRN12621001331820
Ethics application status
Approved
Date submitted
19/08/2021
Date registered
29/09/2021
Date last updated
7/06/2024
Date data sharing statement initially provided
29/09/2021
Type of registration
Prospectively registered

Titles & IDs
Public title
Can hyperhydration improve half-marathon time-trial performance in hot conditions?
Scientific title
Can hyperhydration improve half-marathon time-trial performance in hot conditions?
Secondary ID [1] 305078 0
None
Universal Trial Number (UTN)
N/A
Trial acronym
N/A
Linked study record
N/A

Health condition
Health condition(s) or problem(s) studied:
Dehydration 323308 0
Condition category
Condition code
Diet and Nutrition 320873 320873 0 0
Other diet and nutrition disorders

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
In a randomized and cross-over fashion, participants will complete either a hyperhydration protocol or a control protocol before completing a half-marathon under race conditions in the field (i.e., outside the laboratory), in hot ambient conditions.

The hyperhydration protocol involves ingestion 1.2 g/kg of body mass (BM) of glycerol + 7.5 g/L of sodium chloride with a large bolus of fluid totalling 25 ml/kg BM. The fluid bolus is an artificially sweetened beverage made to the manufacturers instructions.

The sodium will be orally consumed using opaque coloured, dissolvable tablets to protect from the salty taste. Glycerol will be orally ingested and mixed in with the large bolus of fluid.

Each intervention will be orally ingested in 4 equal portions over a 60 minute period (i.e., minute 0, 20, 40 and 60). Although the intervention treatment is consumed at different time points, these are not independent interventions. The entire treatment is split into doses to manage the potential gastrointestinal discomfort that may occur with ingesting large amounts of fluid. Participants will be instructed to consume their bolus at each time point within five minutes and will be monitored by the research team to ensure adherence. As this is a cross-over trial, each trial will be completed with a wash-out period of at least 14 days.
Intervention code [1] 321481 0
Prevention
Intervention code [2] 321643 0
Treatment: Other
Comparator / control treatment
The control condition in this study will require participants to ingest the large bolus of fluid with no nutritional supplement added. The same dosage and timing of fluid ingestion will be used for the control trial as for the intervention trials.

The control fluid is an artificially sweetened beverage which aims to mask the sweet taste of glycerol. In addition, opaque dissolvable tablets containing an inert substance will be administered in place of the sodium chloride filled tablets in the intervention trial.
Control group
Placebo

Outcomes
Primary outcome [1] 328668 0
Exercise performance. Calculated as the time taken to complete a half-marathon. Recorded using a digital stopwatch.
Timepoint [1] 328668 0
End of the half-marathon time-trial.
Secondary outcome [1] 399882 0
Fluid retention. Calculated as the total amount of fluid ingested minus the total amount of urine produced. Urine will be collected using large urine volume containers and weighed, minus the mass of an empty bottle. Fluid ingestion calculated as = 25 ml x Body mass in kg.
Timepoint [1] 399882 0
Fluid retention will be calculated at the 180 min point of the hyperhydration/control protocol.
Secondary outcome [2] 400762 0
Urine volume. Calculated as the total amount of urine produced. Urine will be collected in large urine volume containers and weighed using calibrated food scales. The mass of an empty urine volume container will be taken to calculate urine volume.
Timepoint [2] 400762 0
Urine volume will be calculated at every 20 min of the hyperhydration/control protocol.
Secondary outcome [3] 400763 0
Urine specific gravity. Recorded using a digital refractometer.
Timepoint [3] 400763 0
Every 20 min during the hyperhydration/control protocol.
Secondary outcome [4] 400764 0
Urine colour. Assessed using a 1-8 adapted urine colour scale.
Timepoint [4] 400764 0
Every 20 min during the hyperhydration/control protocol.
Secondary outcome [5] 400765 0
Heart rate. Recorded using a heart rate strap and synced watch. Mean and peak heart rate will be recorded.
Timepoint [5] 400765 0
Both mean and peak heart rate will be recorded during the half-marathon time-trial.
Secondary outcome [6] 400766 0
Core temperature. Recorded using an ingestible core temperature monitoring pill
Timepoint [6] 400766 0
Both mean and peak core temperature will be recorded during the half-marathon time-trial.
Secondary outcome [7] 400767 0
Plasma osmolality. Assessed using a calibrated osmometer.
Timepoint [7] 400767 0
Recorded at minute 0, 60, 120 and 180 of the hyperhydration/control protocol.

Eligibility
Key inclusion criteria
The inclusion criteria for this study is: trained males and females, aged 18-45 years. To be classified as 'trained', potential participants must be completing running based trained greater than or equal to 3 times per week and greater than or equal to 5 hours per week as per published criteria for participants completing exercise-based studies.
Minimum age
18 Years
Maximum age
45 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Exclusion criteria includes any abnormal renal function, use of diuretics or creatine in the previous eight weeks as these factors can effect the body's fluid retention capability. Participants that have previously suffered from heat illness and those that have an impairment that affects thermoregulation will also be excluded.

Participants will be excluded if they answer 'Yes' to any of the first six questions in stage one of the Exercise and Sport Science pre-screening tool. Participants will also complete stage 2 of the Exercise and Sport Science pre-screening tool, those that have multiple (i.e., 2 or more) risk factors will be asked to seek medical advice before participating in this project.

Participants must not have sustained a lower limb injury in the previous six months and have no current injury that will impair their ability to complete the exercise protocol.

Participants will also be excluded if they have a history of migraines, chronic headaches or liver disease as it is recommended that these populations avoid glycerol ingestion.

Participants who are allergic to the nutritional aids used in the study (i.e., glycerol or sodium chloride) will also be excluded.

Study design
Purpose of the study
Prevention
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Numbered containers for beverages and numbered sealed bags for sodium chloride tablets. Please note that tablets are opaque in colour.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Computerised sequence generation
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s


Intervention assignment
Crossover
Other design features
N/A
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
The primary outcome variable in this study was the difference in TT performance between interventions. A sample size was calculated using a within-factors, repeated measures analysis of variance (ANOVA) using statistical software (G*Power; version 3.1.9.7). It was determined that, with a coefficient of variation (CV) of 2.9% (within-subject CV for faster half-marathon runners), alpha set at 0.05 and beta set at 0.8, a sample size of 12 participants would be required to detect a mean difference of 2.5% in exercise performance. Statistical analyses were completed using Stata v17.0 (StataCorp LLC, Texas, United States). Descriptive data are presented as mean ± standard deviation (SD). Linear mixed models were used to analyse data with treatment and time as fixed effects and participant as a random effect. Where significant time, condition or interaction effects were detected, post-hoc comparisons were made using the Benjamini-Hochberg procedure. Mean differences and 95% confidence intervals (CIs) are reported were significant differences between conditions were observed. Statistical significance was accepted at p < 0.05.

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
1/11/2021
Actual
1/12/2021
Date of last participant enrolment
Anticipated
31/01/2023
Actual
1/01/2023
Date of last data collection
Anticipated
28/02/2023
Actual
11/03/2023
Sample size
Target
12
Accrual to date
Final
13
Recruitment in Australia
Recruitment state(s)
ACT,VIC
Recruitment postcode(s) [1] 35042 0
2601 - Canberra
Recruitment postcode(s) [2] 42706 0
3206 - Albert Park

Funding & Sponsors
Funding source category [1] 309478 0
University
Name [1] 309478 0
Deakin University
Country [1] 309478 0
Australia
Primary sponsor type
University
Name
Deakin University
Address
221 Burwood Highway, Burwood, VIC, 3125
Country
Australia
Secondary sponsor category [1] 310461 0
None
Name [1] 310461 0
Address [1] 310461 0
Country [1] 310461 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 309265 0
Deakin University Human Research Ethics Committee
Ethics committee address [1] 309265 0
221 Burwood Highway, Burwood, VIC, 3125
Ethics committee country [1] 309265 0
Australia
Date submitted for ethics approval [1] 309265 0
25/08/2021
Approval date [1] 309265 0
29/11/2021
Ethics approval number [1] 309265 0

Summary
Brief summary
Exercise performance is impaired in hot conditions compared with temperate conditions. During exercise in such thermally stressful conditions, fluid loss through sweat production to liberate heat from the body is accelerated, which can adversely impact cardiovascular and thermoregulatory function and ultimately hinder exercise performance. To increase the total fluid pool available for sweat production, ingestion of nutritional aids such as glycerol and sodium prior to exercise may increase total body water above normal body water levels (i.e., euhydration) prior to exercise, which is known as hyperhydration. This topic requires further investigation to determine if hyperhydration is a viable preparation strategy for endurance running in hot conditions. The hypothesis for this study is that the combined ingestion of glycerol and sodium will result in a significantly greater fluid retention than the control and this will improve half-marathon time-trial performance in hot ambient conditions.
Trial website
N/A
Trial related presentations / publications
N/A
Public notes
N/A

Contacts
Principal investigator
Name 113550 0
Dr Amelia Carr
Address 113550 0
Deakin University, Faculty of Health, School of Exercise and Nutrition Sciences, Centre for Sport Research, 221 Burwood Highway, Burwood, VIC, 3125
Country 113550 0
Australia
Phone 113550 0
+613 9251 7309
Fax 113550 0
N/A
Email 113550 0
[email protected]
Contact person for public queries
Name 113551 0
William Jardine
Address 113551 0
Deakin University, Faculty of Health, School of Exercise and Nutrition Sciences, Centre for Sport Research, 221 Burwood Highway, Burwood, VIC, 3125
Country 113551 0
Australia
Phone 113551 0
+61 429489126
Fax 113551 0
N/A
Email 113551 0
[email protected]
Contact person for scientific queries
Name 113552 0
William Jardine
Address 113552 0
Deakin University, Faculty of Health, School of Exercise and Nutrition Sciences, Centre for Sport Research, 221 Burwood Highway, Burwood, VIC, 3125
Country 113552 0
Australia
Phone 113552 0
+61 429489126
Fax 113552 0
N/A
Email 113552 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
Yes
What data in particular will be shared?
All of the individual participant data collected during the trial, after de-identification.
When will data be available (start and end dates)?
Immediately following publication and ending 5 years following main results publication.
Available to whom?
Researchers wishing to access it.
Available for what types of analyses?
Any purpose.
How or where can data be obtained?
Access subject to approvals by the principal investigator or the contact person for public queries.
Email addresses:
[email protected]
[email protected]


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.