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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?
Scientific title
Does increasing sodium concentration impact plasma sodium and volume with ad libitum drinking in healthy, trained males?
Secondary ID [1] 304124 0
none
Universal Trial Number (UTN)
Trial acronym
Na60 Ad Lib
Linked study record

Health condition
Health condition(s) or problem(s) studied:
hyponatraemia 321809 0
Condition category
Condition code
Diet and Nutrition 319535 319535 0 0
Other diet and nutrition disorders
Metabolic and Endocrine 319837 319837 0 0
Other metabolic disorders

Intervention/exposure
Study type
Interventional
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.
Intervention code [1] 320458 0
Treatment: Other
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).
Control group
Dose comparison

Outcomes
Primary outcome [1] 327399 0
Change in plasma sodium concentration
Timepoint [1] 327399 0
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..
Secondary outcome [1] 394959 0
Change in plasma volume as calculated from haemoglobin and haematocrit according to Dill & Costill, 1974.
Timepoint [1] 394959 0
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..

Eligibility
Key inclusion criteria
Healthy males, Maximal oxygen consumption (VO2max) > 50 ml/kg/min
Minimum age
18 Years
Maximum age
60 Years
Sex
Males
Can healthy volunteers participate?
Yes
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).

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)
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.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Random number generator (computer)
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s

Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
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).

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
21/06/2021
Actual
Date of last participant enrolment
Anticipated
30/12/2022
Actual
Date of last data collection
Anticipated
31/01/2023
Actual
Sample size
Target
11
Accrual to date
Final
Recruitment outside Australia
Country [1] 23670 0
New Zealand
State/province [1] 23670 0
Otago

Funding & Sponsors
Funding source category [1] 308502 0
University
Name [1] 308502 0
School of Physical Education, Sport & Exercise Science
Country [1] 308502 0
New Zealand
Primary sponsor type
University
Name
School of Physical Education, Sport & Exercise Science
Address
University of Otago
PO Box 56
Dunedin 9054
Country
New Zealand
Secondary sponsor category [1] 309354 0
None
Name [1] 309354 0
Address [1] 309354 0
Country [1] 309354 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 308463 0
Human Research Ethics Committee, University of Otago
Ethics committee address [1] 308463 0
University of Otago
PO Box 56
Dunedin 9054
Ethics committee country [1] 308463 0
New Zealand
Date submitted for ethics approval [1] 308463 0
02/03/2021
Approval date [1] 308463 0
01/04/2021
Ethics approval number [1] 308463 0
HE21/001

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.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 110774 0
A/Prof Nancy J Rehrer
Address 110774 0
School of Physical Education Sport & Exercise Sciences
University of Otago PO Box 56
Dunedin 9054
Country 110774 0
New Zealand
Phone 110774 0
+64 34799128
Fax 110774 0
Email 110774 0
[email protected]
Contact person for public queries
Name 110775 0
Nancy J Rehrer
Address 110775 0
School of Physical Education Sport & Exercise Sciences
University of Otago PO Box 56
Dunedin 9054
Country 110775 0
New Zealand
Phone 110775 0
+64 34799128
Fax 110775 0
Email 110775 0
[email protected]
Contact person for scientific queries
Name 110776 0
Nancy J Rehrer
Address 110776 0
School of Physical Education Sport & Exercise Sciences
University of Otago PO Box 56
Dunedin 9054
Country 110776 0
New Zealand
Phone 110776 0
+64 34799128
Fax 110776 0
Email 110776 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?
Main outcome variables, plasma sodium and volume change treatment means and SD and individual VO2max data.
When will data be available (start and end dates)?
As soon as possible after publication for at least 5 years
Available to whom?
Case by case basis by PI discretion
Available for what types of analyses?
For meta analyses
How or where can data be obtained?
By emailing PI
[email protected]


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

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