Trial Review

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Trial registered on ANZCTR


Registration number
ACTRN12625001030460
Ethics application status
Approved
Date submitted
22/08/2025
Date registered
17/09/2025
Date last updated
17/09/2025
Date data sharing statement initially provided
17/09/2025
Type of registration
Retrospectively registered

Titles & IDs
Public title
The effect of running distance on physiological outcomes in hot conditions
Scientific title
The effect of running distance on physiological outcomes in trained runners during hot conditions
Secondary ID [1] 315206 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Heat illness 338652 0
Condition category
Condition code
Injuries and Accidents 334945 334945 0 0
Other injuries and accidents

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Materials and procedures:
-Once enrolled into the study, participants will complete one familiarisation session and three experimental trials in an environmental chamber. Every session will involve only an individual participant completing the trials.

-Each experimental session will take approximately 2 to 4 hours and are undertaken 3-7 days apart.

-The familiarisation session will occur 3-7 days prior to the first experimental session and take approximately 3 hours and requires participants to complete an incremental test to exhaustion and a 5 km time trial on the treadmill. The incremental test to exhaustion will be conducted in temperate conditions (22°C and 50% relative humidity) on a calibrated motorised treadmill at 1% incline with a metabolic cart to measure gas exchange. The test will consist of initial four minute submaximal steady state exercise intensities, followed by the speed of the treadmill increasing by 1 km/h every minute until volitional exhaustion.

- The three experimental sessions require the participant to complete a running self-paced time trial on a treadmill across three distances (one per session) in warm and humid conditions (28.5°C and 76 % relative humidity);
- 5 km
- 10 km
- Half marathon

Running economy will be assessed before and after each time-trial. The minimum period of days that the intervention can be completed over is 18 days. A study calendar will be used to manage adherence to the study sessions.

The 5 km, 10 km and 21.1 km were chosen as these are sanctioned World Athletics distances and are popular community-run distances

Who will deliver:
A sport science graduate will lead data collection, and the remainder of the team are experienced researchers with 10-30 years of academic experience.

Mode:
In-person testing of individual participants

Location:
Environmental chamber at the Mile End campus of Adelaide University.
Intervention code [1] 331820 0
Prevention
Comparator / control treatment
Whilst the crossover design means that participants act as their own control (i.e. "Active" control group), there is no true 'reference' trial as all trials are compared equally to each other.
Control group
Active

Outcomes
Primary outcome [1] 342576 0
Core temperature (directly measured)
Timepoint [1] 342576 0
Monitored continuously during the entire duration of each time trial across the experimental sessions. An ingestible sensor is consumed 6-8 prior to each session.
Secondary outcome [1] 451357 0
Heart rate
Timepoint [1] 451357 0
Fitted within 15 minutes prior to the time-trial or incremental test to exhaustion, and then monitored continuously during the entire duration of each exercise activity during all sessions.
Secondary outcome [2] 451358 0
Thermal sensation
Timepoint [2] 451358 0
Baseline (start of each time trial), every 1 km, and at each 25% distance completion point of all time trials.
Secondary outcome [3] 451359 0
Thermal discomfort
Timepoint [3] 451359 0
Baseline (start of each time trial), every 1 km, and at each 25% distance completion point of all time trials.
Secondary outcome [4] 451360 0
Rating of perceived exertion (RPE)
Timepoint [4] 451360 0
Baseline (start of each time trial), every 1 km, and at each 25% distance completion point of all time trials. Also checked during the incremental test to exhaustion at each change in workload.
Secondary outcome [5] 451361 0
Skin temperature
Timepoint [5] 451361 0
Fitted within 30 minutes prior to each time-trial and then monitored continuously during the entire duration.
Secondary outcome [6] 451362 0
Whole body sweat loss
Timepoint [6] 451362 0
Before and after all time trials in each session.
Secondary outcome [7] 451363 0
Hydration status
Timepoint [7] 451363 0
30 minutes prior to each time trial for the three experimental sessions
Secondary outcome [8] 451364 0
Time trial performance
Timepoint [8] 451364 0
End of each time trial
Secondary outcome [9] 451365 0
Blood pressure
Timepoint [9] 451365 0
Measured at rest during the baseline session and at the end of each time trial
Secondary outcome [10] 451366 0
Participant wellness
Timepoint [10] 451366 0
Completed at the start of each session
Secondary outcome [11] 451368 0
Maximal oxygen consumption (VO2max)
Timepoint [11] 451368 0
During the incremental test to exhaustion
Secondary outcome [12] 451878 0
Core temperature (estimated)
Timepoint [12] 451878 0
Fitted within 15 minutes prior to each time-trial and then monitored continuously during the entire duration of each time-trial.
Secondary outcome [13] 451881 0
Running economy
Timepoint [13] 451881 0
Before and after each time-trial.

Eligibility
Key inclusion criteria
Trained long-distance runners who are: males and females aged between 18-55 and are training at least three times per week with local level representation
Minimum age
18 Years
Maximum age
55 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Not passing Stage 1 of the ESSA pre-exercise screening tool.

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)
No allocation concealment
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Since the study is a crossover design, participants are not randomly allocated to groups, but randomly allocated the trial order via blocked randomisation. Blocked randomisation (without blinding) by the lead data collector
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
1) Null hypothesis testing to compare the participant responses during the three time trials using common statistical approaches to the Sport Science literature.

2) Comparison of physiological outcomes during each time trial condition against known thresholds that represent biological risk and intensity.

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
Actual
4/08/2025
Date of last participant enrolment
Anticipated
1/06/2026
Actual
Date of last data collection
Anticipated
31/07/2026
Actual
Sample size
Target
14
Accrual to date
6
Final
Recruitment in Australia
Recruitment state(s)
SA

Funding & Sponsors
Funding source category [1] 319776 0
University
Name [1] 319776 0
Adelaide University
Country [1] 319776 0
Australia
Primary sponsor type
University
Name
Adelaide University
Address
Country
Australia
Secondary sponsor category [1] 322289 0
None
Name [1] 322289 0
Address [1] 322289 0
Country [1] 322289 0
Other collaborator category [1] 283626 0
University
Name [1] 283626 0
Waseda University
Address [1] 283626 0
Country [1] 283626 0
Japan

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 318334 0
University of South Australia Human Research Ethics Committee
Ethics committee address [1] 318334 0
Ethics committee country [1] 318334 0
Australia
Date submitted for ethics approval [1] 318334 0
04/05/2023
Approval date [1] 318334 0
23/07/2025
Ethics approval number [1] 318334 0
205513

Summary
Brief summary
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 143846 0
Dr Samuel Chalmers
Address 143846 0
Adelaide University, Level 2, SASI Building, 145B Railway Terrace, Mile End SA 5031.
Country 143846 0
Australia
Phone 143846 0
+61 08 8302 1307
Fax 143846 0
Email 143846 0
[email protected]
Contact person for public queries
Name 143847 0
Mikayla Vidmar
Address 143847 0
Adelaide University, Level 2, SASI Building, 145B Railway Terrace, Mile End SA 5031.
Country 143847 0
Australia
Phone 143847 0
+61 08 8302 1307
Fax 143847 0
Email 143847 0
[email protected]
Contact person for scientific queries
Name 143848 0
Samuel Chalmers
Address 143848 0
Adelaide University, Level 2, SASI Building, 145B Railway Terrace, Mile End SA 5031.
Country 143848 0
Australia
Phone 143848 0
+61 08 8302 1307
Fax 143848 0
Email 143848 0
[email protected]

Data sharing statement
Will the study consider sharing individual participant data?
Yes
Will there be any conditions when requesting access to individual participant data?
Persons/groups eligible to request access:
• Researchers
Conditions for requesting access:
• Yes, conditions apply:
• Requires review on a case-by-case basis by the trial custodian, sponsor or data sharing committee
What individual participant data might be shared?
• De-identified individual participant data:
• Published results
What types of analyses could be done with individual participant data?
• Systematic reviews and meta-analyses
When can requests for individual participant data be made (start and end dates)?
From:
After publication of main results
To:
5 years

Where can requests to access individual participant data be made, or data be obtained directly?
• Email of trial custodian, sponsor or committee: [email protected]

Are there extra considerations when requesting access to individual participant data?
No


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.