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Trial registered on ANZCTR

Registration number

ACTRN12615001332516p

Ethics application status

Submitted, not yet approved

Date submitted

30/11/2015

Date registered

4/12/2015

Date last updated

4/12/2015

Type of registration

Prospectively registered

Titles & IDs

Public title

Effect of sodium bicarbonate and sodium phosphate supplementation on cycling performance

Scientific title

Sodium bicarbonate and sodium phosphate supplementation: effect on blood buffering capacity, 2, 3-diphosphoglycerate and cycling power output, in well-trained cyclists.

Secondary ID [1]

None known

Universal Trial Number (UTN)

U1111-1177-0531

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Cycling performance

Condition category

Condition code

Diet and Nutrition

Other diet and nutrition disorders

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

Two safe and legal supplements (sodium phosphate and sodium bicarbonate) will be administered to well-trained cyclists, prior to performing a cycling-based performance test in the laboratory.

Participants' performance will be compared to their own baseline performance, and also to the placebo condition. There will be four treatment groups:
1) Sodium phosphate supplementation - requiring participants to ingest sodium phosphate for the six days prior to the second cycling performance test, and a placebo on the day of the second performance test.
2) Sodium phosphate and sodium bicarbonate supplementation - requiring participants to ingest sodium phosphate for the six days prior to the second performance test, and sodium bicarbonate on the day of the second performance test.
3) Sodium bicarbonate supplementation - requiring participants to ingest a placebo for the six days prior to the second performance test, and sodium bicarbonate on the day of the second performance test.
4) Placebo - requiring participants to ingest a placebo for the six days prior to the second performance test, and also ingest a placebo on the day of the second performance test.

The sodium bicarbonate will be administered at a dose of 300 mg per kg of the participants' body mass, and will be ingested in capsule form, 90 min prior to the start of the second cycling performance test. The sodium bicarbonate will be ingested in the laboratory, on the day of the second cycling performance test, under the supervision of staff.

The sodium phosphate will be administered at a dose of 50 mg per kg of participants' fat free mass (as determined by a DEXA scan), and will be ingested as a solution (sodium phosphate powder mixed with sports drink powder, and then dissolved in water). The sodium phosphate dosage will be provided to participants after they perform their baseline test, and they will be instructed to ingest the sodium phosphate daily for the six days prior to the second cycling performance test. Participants will be asked to verbally confirm that they have ingested the sodium phosphate as instructed.

There will be one week between the baseline and post-intervention cycling tests. The cycling test comprises six sets of repeated sprints and time trials, and is 43 min in total duration. The performance test has previously been used in a previous study (Brewer et al., 2015). This reference has now been attached to the application. To summarise the performance test, the first set comprises 6 x 15 second sprints, with 45 seconds active recovery between each sprint. The second set comprises 6 x 15 second sprints, with 15 seconds of active recovery between each sprint. The third set comprises a continuous, 5 min time trial. The fourth set again comprises 6 x 15 second sprints with 45 seconds active recovery, the fifth set is 6 x 15 second sprints with 15 seconds active recovery, and the sixth set is a continuous, 5 min time trial. A 3 minute active recovery at a minimum power output of 100 watts is performed after the first 5 sets, and the test concludes at the end of the sixth set.

Performance will be measured in comparison to baseline performance on the same cycling performance test.

Intervention code [1]

Treatment: Other

Comparator / control treatment

The placebo used for the sodium bicarbonate supplement comprises gluten free cornflour encased in opaque gelatine capsules, while the placebo used for the sodium phosphate supplement will be a mixture of glucose and salt, to be dissolved in water.

Control group

Placebo

Outcomes

Primary outcome [1]

Cycling performance, measured in power.

Timepoint [1]

Throughout the cycling performance test, peak power, mean power and total work will be measured. Specifically, these measures will be recorded throughout each of the six sets in the performance test.

Secondary outcome [1]

Blood buffering capacity will be measured, via the analysis of capillary blood samples to determine blood pH and blood bicarbonate concentration.

Timepoint [1]

Blood buffering capacity will be determined via the change between baseline and experimental trials.

Capillary blood samples will be taken during participants' second and third visits to the laboratory (baseline and experimental testing sessions). A capillary blood sample will be taken upon participants' arrival at the laboratory, as well as approximately 1 minute prior to the start of the performance test. Further capillary blood samples will also be taken immediately after completion of the six sets included in the cycling performance test.

Secondary outcome [2]

Blood 2,3-diphosphoglycerate and phosphate content will be determined via the analysis of venous blood samples.

Timepoint [2]

Venous blood samples will be taken upon participants' arrival in the laboratory (for their second and third laboratory visits), and 1 minute after the completion of the cycling performance test.

Eligibility

Key inclusion criteria

Male and female, well trained cyclists. Cyclists will need to demonstrate evidence of participation in a recent Criterium (short road race).

Minimum age

18 Years

Maximum age

40 Years

Sex

Both males and females

Can healthy volunteers participate?

Yes

Key exclusion criteria

Children under 18 years of age, as well as pregnant women.

Study design

Purpose of the study

Educational / counselling / training

Allocation to intervention

Non-randomised trial

Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)

Allocation is not concealed.

Methods used to generate the sequence in which subjects will be randomised (sequence generation)

For this trial, each participant will complete two cycling performance tests. The first test for each participant will be their baseline trial, and the second test for each participant will be their experimental trial.

The allocation of participants to one of the four experimental groups will not be randomised; rather four equal groups will be selected by the researchers, on the basis of participants’ gender, age, current training and competition status (as reported in the questionnaire answered by participants), and VO2max (measured in participants' first visit to the laboratory).

Masking / blinding

Blinded (masking used)

Who is / are masked / blinded?

The people receiving the treatment/s

Intervention assignment

Parallel

Other design features

Phase

Not Applicable

Type of endpoint/s

Efficacy

Statistical methods / analysis

A one-way ANOVA will be used to assess the differences between the four protocols, for the key variables.

The total number of participants to be recruited will be 120.

A sample size estimate was performed, based on the results of a similar, previous study (Brewer et al., 2015), where the standard deviation for total work (for cycling performance, in the experimental trial - placebo condition) was 78kJ, and the smallest worthwhile change was deemed to be 17kJ. The smallest worthwhile change was calculated as 0.2 of the between-subject standard deviation at baseline, in the placebo condition (0.2 x 75kJ).

The calculation indicated that a sample size of 81 participants would be required (approximately 2o participants in each of the four groups). In the present study, 30 participants will be recruited for each group, to allow adequate statistical power in the even of participant drop out throughout the course of the study.

Recruitment

Recruitment status

Not yet recruiting

Date of first participant enrolment

Anticipated

7/11/2016

Actual

Date of last participant enrolment

Anticipated

31/12/2016

Actual

Date of last data collection

Anticipated

Actual

Sample size

Target

120

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

VIC

Recruitment postcode(s) [1]

3125 - Burwood

Recruitment postcode(s) [2]

3207 - Port Melbourne

Recruitment postcode(s) [3]

3182 - St Kilda

Recruitment postcode(s) [4]

3206 - Albert Park

Recruitment postcode(s) [5]

3187 - Brighton East

Recruitment postcode(s) [6]

3186 - Brighton

Funding & Sponsors

Funding source category [1]

University

Name [1]

School of Exercise and Nutrition Sciences, Deakin University

Address [1]

221 Burwood Highway
Burwood Vic 3125

Country [1]

Australia

Primary sponsor type

Individual

Name

Dr Amelia Carr

Address

School of Exercise and Nutrition Sciences
Deakin University
221 Burwood Highway
Burwood Vic 3025

Country

Australia

Secondary sponsor category [1]

Other

Name [1]

Australian Institute of Sport

Address [1]

Leverrier St
Bruce ACT
2617

Country [1]

Australia

Ethics approval

Ethics application status

Submitted, not yet approved

Ethics committee name [1]

Deakin Unviersity Human Reseach Ethics Committee

Ethics committee address [1]

Human Research Ethics Office
Deakin Research Integrity
Deakin University
221 Burwood Hwy
Burwood VIC 3125

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

09/09/2015

Approval date [1]

Ethics approval number [1]

Summary

Brief summary

Background:
Sodium bicarbonate is a compound often used in food and baking, and has been associated with improvements in high intensity exercise of different modalities, including running, swimming and cycling (Burke and Pyne, 2007). Ingestion of sodium bicarbonate results in an increased blood alkalosis (measured via blood pH and blood bicarbonate concentration), which can aid in buffering hydrogen ions, and act to delay the onset of fatigue in high-intensity exercise (Carr et al., 2011). Sodium bicarbonate is most often ingested at a dose of 0.3 grams per kilogram of participants’ body mass, a dose that has been found to have the greatest effect on performance (McNaughton et al., 1992).
Phosphate is an essential mineral that is obtained in the diet, and is a component of phosphocreatine and adenosine triphosphate, important components in oxygen transport within the red blood cell (Brewer et al., 2013). Phosphate can be ingested in the form of sodium phosphate, which has been associated with enhancements in endurance exercise performance (Cade et al., 1984) and peak aerobic capacity (Folland et al., 2008). The recommended dose of sodium phosphate is 50 mg per kg of participants’ fat free mass. Mechanisms associated with sodium phosphate supplementation include an increase in 2,3-diphosphoglycerate content in the blood, which can aid with the release of oxygen to the muscle, as well as an increased buffering capacity (Brewer et al., 2014). 

Participants:
One hundred and twenty well-trained, male and female cyclists will be recruited to complete this study.

Experimental Design:
Experimental Testing Overview:
Participants will visit the laboratory on three occasions. The first visit to the laboratory will require participants to complete a DEXA scan and simple anthropometric measures (height, mass and sum of 7 skin folds) to assess body composition, as well as a graded exercise test to determine maximal oxygen consumption (VO2max), and a familiarisation with the cycling performance test. The remaining two visits will require participants to complete cycling performance trials. For the second laboratory visit, participants will complete a baseline cycling performance test. The third laboratory visit will require participants to complete the same cycling performance test, under one of four supplementation conditions, assigned in a parallel groups design. The four experimental conditions are:
1) sodium phosphate and placebo, 
2) sodium phosphate and sodium bicarbonate, 
3) sodium bicarbonate and placebo, 
4) placebo and placebo. 
Capillary and venous blood samples will also be taken during the second and third laboratory visits.

Trial website

Trial related presentations / publications

Public notes

Attachments [1]

/AnzctrAttachments/369701-Brewer et al., 2015.pdf

Contacts

Principal investigator

Name

Dr Amelia Carr

Address

School of Exercise and Nutrition Sciences
Deakin University
221 Burwood Highway
Burwood Vic 3025

Country

Australia

Phone

+61 3 9251 7309

Fax

amelia.carr@deakin.edu.au

Contact person for public queries

Name

Amelia Carr

Address

School of Exercise and Nutrition Sciences
Deakin University
221 Burwood Highway
Burwood Vic 3025

Country

Australia

Phone

+61 3 9251 7309

Fax

amelia.carr@deakin.edu.au

Contact person for scientific queries

Name

Amelia Carr

Address

School of Exercise and Nutrition Sciences
Deakin University
221 Burwood Highway
Burwood Vic 3125

Country

Australia

Phone

+61 3 9251 7309

Fax

amelia.carr@deakin.edu.au

No information has been provided regarding IPD availability

What supporting documents are/will be available?

No Supporting Document Provided

Results publications and other study-related documents

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No additional documents have been identified.

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