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Trial registered on ANZCTR


Registration number
ACTRN12620000669998
Ethics application status
Approved
Date submitted
21/11/2019
Date registered
11/06/2020
Date last updated
22/10/2021
Date data sharing statement initially provided
11/06/2020
Type of registration
Retrospectively registered

Titles & IDs
Public title
What role does heat play in exercise? Part 1: Resistance exercise.
Scientific title
Determining the role of exercise-induced heat in resistance exercise conditioning
Secondary ID [1] 299868 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Exercise-mediated adaptations 315278 0
Condition category
Condition code
Physical Medicine / Rehabilitation 313575 313575 0 0
Other physical medicine / rehabilitation

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Using a within-subjects design, each participant will undertake a training intervention with one upper limb randomly assigned to cool resistance training. Cool training will attenuate exercise-induced heat accumulation with immersion in cool water (14°C) preceding (10 min) and interspersed between exercise sets (cool-trained limb is immersed in the cold water for ~2 min between sets). The contralateral (control) upper limb will train the same but without cooling.
The intervention consists of 6 weeks of training with each limb training 3 times per week (~30 min each session), supervised by Masters and Honours research students. The upper limb will perform unilateral bicep curls (six sets of 4 repetitions at ~85% of 1 Repetition Maximum (1RM), spaced 3 min apart) with exercise loads being progressed during the 6-week period, increasing ~5% 1RM when arms were able to complete more than 4 repetitions on the final set.

Measurements:
Pre- and post-intervention: Testing will take place before the initiation of training and at least 48 hours after completing training, respectively, using 4 assessments. First, dynamic strength will be assessed by the 1RM across a full range of motion. The 1RM will also be used to provide relative training intensities. Second, isometric torque will be assessed using a Maximial Voluntary Contraction (MVC) at a standardised joint angle with the elbow joint at 90° flexion. This static method of strength assessment is less impacted by improved coordination in dynamic 1RM tests. Third, twitch interpolation will be done in the same position (90° flexion) to determine physical contractile characteristics of the muscle (i.e., rate of force development and decay). Fourth, force production will be assessed also using isokinetic dynamometry (60°/s) at the elbow joint to determine the general ability to produce force during elbow flexion.

Anthropometry will be assessed to measure tissue adaptations to exercise training. This entails (i) eight-electrode multi-frequency bioelectric impedance analysis, (ii) girth and skinfold thickness of limb segments at the point of maximal circumference and ultrasound assessment of each upper arm, and (iii) dual-energy X-ray absorptiometry as an additional measure of change in upper limb muscle mass and whole-body composition.

Acute Training: Blood flow measures (duplex ultrasound and near-infrared spectroscopy), perceptual measures, including rating of perceived exertion, perceived body temperature and associated thermal comfort will be assessed in both the warm and the cool arms during training. This is to determine the physiological and perceived strain of training with and without exercise induced heat strain.
Intervention code [1] 316132 0
Treatment: Other
Comparator / control treatment
Please see above. i.e., adaptive responses to training with cool muscles will be compared to normal exercise-induced warming responses (= control), Adaptive responses to cool training will be expressed as a proportion of baseline, as will those from warm/control training, and the extent of change will be formally compared against each other.
Control group
Active

Outcomes
Primary outcome [1] 322031 0
Change (%) in bicep curl 1 RM over the course of the resistance training programme in both warm and cool training conditions. This is assessed using dumbells of increasing weight (smallest adjustment of 0.5 kg) following a standardised protocol of 3 priming sets: the first primer of 5-10 reps of a weight deemed 'easy', following a 1-minute rest, a second priming set at an increased weight (5-10% increase) is completed for 3-5 repetitions and after a 2 minute rest and another 5-10% weight increase, the third priming set of 2-3 repetitions is completed. Following the 3 priming sets on each arm, 1RM attempts will be made on each arm by incrementally increasing the weight by 2.5-5% and having 2-4 minute rest periods between attempts until each arm reaches failure.
Timepoint [1] 322031 0
The measures of 1RM will be completed both before and after (~48 hours following the final training) the 6-week training period.
Secondary outcome [1] 377078 0
A composite secondary outcome is the change (%) in functional testing results of force generation over the course of the resistance training programme in both warm and cool training conditions. Elbow flexion MVC with electrically evoked twitch, in which rates of force development and decay are recorded in response to a supramaximal stimulus. The parameters for this outcome are peak torque, contraction time (time to peak torque) and half relaxation time. Elbow flexion peak isokinetic force at 60 deg/s is the other secondary functional outcome.
Timepoint [1] 377078 0
The measures of MVC with twitch interpolation and isokinetic force will be completed both before and after (~48 hours following the final training) the 6-week training period.
Secondary outcome [2] 377079 0
A composite secondary outcome is the change in lean mass within each training limb. Dual energy x-ray absorptiometry, bioelectrical impedance analysis and limb girths corrected to skinfolds will be assessed to provide an estimation of structural/tissue responses to the resistance training programme.
Timepoint [2] 377079 0
Dual energy x-ray absorptiometry, bioelectrical impedance analysis and limb girths corrected to skinfolds will be completed in the same session both before and after (~48 hours following the final training) the 6-week training period.
Secondary outcome [3] 377080 0
Acute responses of tissue oxygenation will be measured in cool and warm arms to determine differences between training stimuli.
Timepoint [3] 377080 0
Tissue oxygenation will be continuously measured using near-infrared spectroscopy in both warm and cool arms during a training session.
Secondary outcome [4] 377099 0
Ultrasound assessment of blood flow in the brachial artery will be done in the cool and warm arms on separate training sessions (to minimise impact on cooling/recovery time) to determine differences between training stimuli.
Timepoint [4] 377099 0
Blood flow measures will be taken at baseline, after precooling, and in response to individual sets as well as after the completion of the workout.
Secondary outcome [5] 377100 0
A composite secondary outcome is perceptions of whole and regional body temperature during training; these will be assessed using a 1-13 scale in an individual training session.
Timepoint [5] 377100 0
Perceptual measures whole and regional body temperature will be taken at baseline, at the beginning and end of precooling, and before and after the 1st, 3rd and 6th sets.
Secondary outcome [6] 377584 0
Perceptions of thermal comfort will be assessed for the whole body and for each arm using a 1-5 scale in an individual training session.
Timepoint [6] 377584 0
Perceptual measures of thermal comfort will be taken at baseline, at the beginning and end of precooling, and before and after the 1st, 3rd and 6th sets.
Secondary outcome [7] 377587 0
Rating of perceived exertion will be assessed in each arm using Borg’s 6-20 scale within an individual training session.
Timepoint [7] 377587 0
Perceived exertion will be taken for each arm following the 1st, 3rd and 6th set of the training session.

Eligibility
Key inclusion criteria
Volunteers may participate if they are not on any medication (besides oral contraceptives), not have a known or identifiable disease state, have a BMI <30 kg/m2 (for thermal reasons), and be physically capable of participating in physical activity. Individuals will be excluded if they are highly resistance-trained (e.g. resistance exercise strenuously each week for more than 3 hours per week) or if they experience heat exposure (sauna/spa bathing) or cold exposure (sea swimming or cold bathing) on a regular basis (> once/week).
Minimum age
18 Years
Maximum age
55 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Contraindication to exercise, as indicated by PARQ(+)

Study design
Purpose of the study
Educational / counselling / training
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation not concealed
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using coin toss for first participant's arm allocation, then alternated thereafter; stratified by sex.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Other
Other design features
All participants receive both interventions during the same time span of the study. Using a contralateral limb design, each arm is trained in parallel, within participants. Assignment of the cool training condition to either the dominant or non-dominant arm is determined by simple randomisation, and the contralateral arm receives the warm (control) condition.
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
Mixed models analysis

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
Actual
14/10/2019
Date of last participant enrolment
Anticipated
1/07/2020
Actual
20/10/2020
Date of last data collection
Anticipated
31/08/2020
Actual
16/12/2020
Sample size
Target
14
Accrual to date
Final
10
Recruitment outside Australia
Country [1] 22133 0
New Zealand
State/province [1] 22133 0
Otago

Funding & Sponsors
Funding source category [1] 304330 0
University
Name [1] 304330 0
University of Otago
Country [1] 304330 0
New Zealand
Primary sponsor type
Individual
Name
Prof Jim Cotter
Address
School of Physical Education, Sport and Exercise Sciences,
University of Otago
PO Box 56
Dunedin 9054
Country
New Zealand
Secondary sponsor category [1] 304575 0
Individual
Name [1] 304575 0
Dr Kate Thomas
Address [1] 304575 0
Department of Surgical Sciences Dunedin School of Medicine University of Otago PO Box 56 Dunedin 9054
Country [1] 304575 0
New Zealand
Other collaborator category [1] 281049 0
Individual
Name [1] 281049 0
Dr Ashley Akerman
Address [1] 281049 0
Montpetit Hall,
University of Ottawa,
125 Universite Pvt,
Ottawa,
Ontario K1N 6N5,
Canada
Country [1] 281049 0
Canada
Other collaborator category [2] 281050 0
Individual
Name [2] 281050 0
Ben Smith
Address [2] 281050 0
School of Physical Education, Sport and Exercise Sciences,
University of Otago
PO Box 56
Dunedin 9054
Country [2] 281050 0
New Zealand
Other collaborator category [3] 281052 0
University
Name [3] 281052 0
Mr Ashton Tourell
Address [3] 281052 0
School of Physical Education, Sport and Exercise Sciences,
University of Otago
PO Box 56
Dunedin 9054
Country [3] 281052 0
New Zealand
Other collaborator category [4] 281053 0
Individual
Name [4] 281053 0
Ms Natasha Burton
Address [4] 281053 0
School of Physical Education, Sport and Exercise Sciences,
University of Otago
PO Box 56
Dunedin 9054
Country [4] 281053 0
New Zealand
Other collaborator category [5] 281054 0
Individual
Name [5] 281054 0
Mr Tom de Hamel
Address [5] 281054 0
School of Physical Education, Sport and Exercise Sciences,
University of Otago
PO Box 56
Dunedin 9054
Country [5] 281054 0
New Zealand

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 304781 0
University of Otago Human Research Ethics Committee (Health)
Ethics committee address [1] 304781 0
University of Otago PO Box 56 Dunedin 9056
Ethics committee country [1] 304781 0
New Zealand
Date submitted for ethics approval [1] 304781 0
06/05/2019
Approval date [1] 304781 0
21/05/2019
Ethics approval number [1] 304781 0
H19/056

Summary
Brief summary
This study is part of the second of two approved within this ethics application. The first was a pilot study, aimed at determining (i) the muscle, core and skin temperature responses arising from resistance and high-intensity interval exercise, and (ii) how much cooling was required to prevent such rises exceeding baseline temperatures. This study aims to elucidate the role of exercise-induced heat strain in exercise related adaptations for resistance exercise. The adaptive role of exercise-induced heat will be assessed by preventing any heat strain/gain during resistance exercise training, and comparing this to training in which heat is allowed to accumulate. It is hypothesised that resistance training with heat prevention/removal will attenuate hypertrophic and strength adaptations when compared to matched training with exercise-induced heat accumulation.
To address this question, limbs will complete unilateral bicep curls for resistance training with manipulation of muscle temperature by immersion in cool water allowing for each limb to train in different thermal states.
Trial website
Nil
Trial related presentations / publications
N/A
Public notes
Thermal energy (~heat) is an inevitable outcome of exercise, and may contribute to its adaptive effects/signal, as is evident from passive heat alone being able to induce many exercise-related adaptations. We are interested in the role that muscle-generated heat has in driving exercise adaptations, and therefore whether heat is a key factor in driving such adaptations.

Contacts
Principal investigator
Name 98178 0
Prof Jim Cotter
Address 98178 0
School of Physical Education, Sport and Exercise Science University of Otago PO Box 56 Dunedin 9056
Country 98178 0
New Zealand
Phone 98178 0
+64 3 479 9109
Fax 98178 0
+64 3 479 8309
Email 98178 0
[email protected]
Contact person for public queries
Name 98179 0
Jim Cotter
Address 98179 0
School of Physical Education, Sport and Exercise Science University of Otago PO Box 56 Dunedin 9056
Country 98179 0
New Zealand
Phone 98179 0
+64 3 479 9109
Fax 98179 0
+64 3 479 8309
Email 98179 0
[email protected]
Contact person for scientific queries
Name 98180 0
Jim Cotter
Address 98180 0
School of Physical Education, Sport and Exercise Science University of Otago PO Box 56 Dunedin 9056
Country 98180 0
New Zealand
Phone 98180 0
+64 3 479 9109
Fax 98180 0
+64 3 479 8309
Email 98180 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?
After de-identification, individual participant data underlying published results only
When will data be available (start and end dates)?
Immediately following publication, ending 10 years following main results publication.
Available to whom?
Only researchers who provide a methodologically sound proposal
Available for what types of analyses?
IPD meta-analyses
How or where can data be obtained?
access subject to approvals by Principal Investigator ([email protected])


What supporting documents are/will be available?

Doc. No.TypeCitationLinkEmailOther DetailsAttachment
5790Ethical approval  [email protected]



Results publications and other study-related documents

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