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Trial registered on ANZCTR
Registration number
ACTRN12621000750886
Ethics application status
Approved
Date submitted
4/05/2021
Date registered
15/06/2021
Date last updated
15/06/2021
Date data sharing statement initially provided
15/06/2021
Type of registration
Prospectively registered
Titles & IDs
Public title
Does increasing sodium concentration impact plasma sodium and volume with ad libitum drinking in healthy, trained males?
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Scientific title
Does increasing sodium concentration impact plasma sodium and volume with ad libitum drinking in healthy, trained males?
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Secondary ID [1]
304124
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none
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Universal Trial Number (UTN)
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Trial acronym
Na60 Ad Lib
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Linked study record
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Health condition
Health condition(s) or problem(s) studied:
hyponatraemia
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Condition category
Condition code
Diet and Nutrition
319535
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0
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Other diet and nutrition disorders
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Metabolic and Endocrine
319837
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0
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Other metabolic disorders
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Intervention/exposure
Study type
Interventional
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Description of intervention(s) / exposure
Ad libitum ingestion of a commercially available sports drink (Gatorade Lemon-Lime) with added sodium chloride to achieve 60 mmol sodium/L during 3 h of cycling (55% VO2max) in the heat (34 C, 65%RH). This will be a cross-over experiment with each condition conducted one time, at least one week apart. At least one of named researchers and a technician or assistant will be on site at all time. Cycle ergometer set at a given workload equivalent to 55% VO2max (determined in pre-trial). Trials conducted in a climate controlled chamber.
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Intervention code [1]
320458
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Treatment: Other
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Comparator / control treatment
The control is the ad libitum consumption of a a commercially available sports drink (Gatorade Lemon-Lime) that has a sodium concentration typical of sports drinks (21 mmol sodium/L).
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Control group
Dose comparison
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Outcomes
Primary outcome [1]
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Change in plasma sodium concentration
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Assessment method [1]
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Timepoint [1]
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Plasma sodium will be measured at baseline and every 30 min throughout exercise and upon completion of exercise at 3 h (or exhaustion),
Outcome will be analysed two ways, 1) as difference from baseline to end (3h or exhaustion), and 2) as change over time across the exercise duration including all measurements: at baseline, every 30 min, and upon completion of 3 h exercise or exhaustion..
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Secondary outcome [1]
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Change in plasma volume as calculated from haemoglobin and haematocrit according to Dill & Costill, 1974.
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Assessment method [1]
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Timepoint [1]
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Haematocrit and haemoglobin will be measured at baseline and every 30 min throughout exercise and upon completion of exercise at 3 h (or exhaustion). Plasma volume change from baseline will be calculated for every 30 min throughout exercise and upon completion of exercise at 3 h (or exhaustion),
Outcome will be analysed two ways, 1) as difference from baseline to end (3h or exhaustion), and 2) as change over time across the exercise duration including all measurements: at baseline, every 30 min, and upon completion of 3 h exercise or exhaustion..
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Eligibility
Key inclusion criteria
Healthy males, Maximal oxygen consumption (VO2max) > 50 ml/kg/min
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Minimum age
18
Years
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Maximum age
60
Years
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Sex
Males
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Can healthy volunteers participate?
Yes
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Key exclusion criteria
Fail to pass a questionnaire to assess readiness to participate in physical activity Physical Activity Readiness Questionnaire (PAR-Q); any chronic diseases (e.g. diabetes, heart problems, high blood pressure, etc.) or be on any prescription medications (except for nutritional supplements).
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Study design
Purpose of the study
Prevention
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Allocation to intervention
Randomised controlled trial
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Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Sodium content of beverage unknown to researchers and participants, allocated by a third party. Containers with sports drink powder will have a code A or B and the allocation will only be known by the third party.
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Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Random number generator (computer)
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Masking / blinding
Blinded (masking used)
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Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
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Intervention assignment
Crossover
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Other design features
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Phase
Not Applicable
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Type of endpoint/s
Efficacy
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Statistical methods / analysis
Data will be analysed by linear mixed effects model analysis of variance for data collected over time and for those variables only measured at one time point in two conditions, or in one condition before and after exercise, by paired t-tests, (significance at P<0.05).
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Recruitment
Recruitment status
Not yet recruiting
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Date of first participant enrolment
Anticipated
21/06/2021
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Actual
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Date of last participant enrolment
Anticipated
30/12/2022
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Actual
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Date of last data collection
Anticipated
31/01/2023
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Actual
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Sample size
Target
11
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Accrual to date
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Final
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Recruitment outside Australia
Country [1]
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New Zealand
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State/province [1]
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Otago
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Funding & Sponsors
Funding source category [1]
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University
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Name [1]
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School of Physical Education, Sport & Exercise Science
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Address [1]
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University of Otago
PO Box 56
Dunedin 9054
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Country [1]
308502
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New Zealand
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Primary sponsor type
University
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Name
School of Physical Education, Sport & Exercise Science
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Address
University of Otago
PO Box 56
Dunedin 9054
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Country
New Zealand
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Secondary sponsor category [1]
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None
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Name [1]
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Address [1]
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Country [1]
309354
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Ethics approval
Ethics application status
Approved
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Ethics committee name [1]
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Human Research Ethics Committee, University of Otago
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Ethics committee address [1]
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University of Otago PO Box 56 Dunedin 9054
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Ethics committee country [1]
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New Zealand
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Date submitted for ethics approval [1]
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02/03/2021
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Approval date [1]
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01/04/2021
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Ethics approval number [1]
308463
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HE21/001
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Summary
Brief summary
The role of sodium ingestion on the development of exercise associated hyponatremia (EAH) is uncertain (Hew-Butler, Loi, Pani, & Rosner, 2017). There is, however, evidence from controlled, long lasting exercise trials in the heat to indicate that sodium intake, both acutely (Vrijens & Rehrer, 1999) and chronically (Koenders, Franken, Cotter, Thornton, & Rehrer, 2017), can significantly affect plasma sodium concentration during exercise. Sodium balance is important not only with respect to risk of hyponatremia, but also with respect to retaining water and reinstating hydration after significant sweat losses (Merson, Maughan, & Shirreffs, 2008; Shirreffs, Taylor, Leiper, & Maughan, 1996). In most sport drinks, beverage sodium concentration is considerably less (Chatterjee & Abraham, 2019), than the typical sweat sodium concentration (Baker, 2017). In previous research (Rehrer, Wijering, & Cotter, 2017) we have shown that with prescribed drinking volume to replace losses a beverage of 60 mmol/L sodium maintains both plasma sodium and plasma volume better than the same beverage but with 21 mmol/L. But to test the ecological validity we need to see if drinking ad libitum will give similar results or not. Thus, the purpose of this study is to find out if ad libitum consumption of a beverage with ~ 3 times that normally in sports drinks will maintain plasma sodium and volume better than a typical sports drink, during 3 h of exercise in the heat, as is observed when the volume of beverage is prescribed. The hypothesis is that ad libitum ingestion of a beverage with 60 mmol/L of sodium during 3 h of cycling in the heat will result in better maintenance of plasma sodium concentration and plasma volume than a typical sports drink with 21 mmol/L sodium.
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Trial website
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Trial related presentations / publications
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Public notes
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Contacts
Principal investigator
Name
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A/Prof Nancy J Rehrer
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Address
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School of Physical Education Sport & Exercise Sciences
University of Otago PO Box 56
Dunedin 9054
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Country
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New Zealand
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Phone
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+64 34799128
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Fax
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Email
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[email protected]
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Contact person for public queries
Name
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Nancy J Rehrer
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Address
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School of Physical Education Sport & Exercise Sciences
University of Otago PO Box 56
Dunedin 9054
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Country
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New Zealand
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Phone
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+64 34799128
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Fax
110775
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Email
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[email protected]
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Contact person for scientific queries
Name
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Nancy J Rehrer
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Address
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School of Physical Education Sport & Exercise Sciences
University of Otago PO Box 56
Dunedin 9054
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Country
110776
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New Zealand
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Phone
110776
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+64 34799128
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Fax
110776
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Email
110776
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[email protected]
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Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
Yes
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What data in particular will be shared?
Main outcome variables, plasma sodium and volume change treatment means and SD and individual VO2max data.
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When will data be available (start and end dates)?
As soon as possible after publication for at least 5 years
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Available to whom?
Case by case basis by PI discretion
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Available for what types of analyses?
For meta analyses
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How or where can data be obtained?
By emailing PI
[email protected]
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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.
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