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Trial registered on ANZCTR

Registration number

ACTRN12616001459415

Ethics application status

Approved

Date submitted

17/10/2016

Date registered

19/10/2016

Date last updated

16/04/2018

Type of registration

Retrospectively registered

Titles & IDs

Public title

The thermoneutral zone- Can we use ambient temperature to aid health

Scientific title

Investigation into the effect of mild cold exposure and temperature variations on energy expenditure in healthy adults- Determining the Thermoneutral Zone.

Secondary ID [1]

none

Universal Trial Number (UTN)

U1111-1175-3074

Trial acronym

Linked study record

Health condition

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

Thermoregulation

Metabolism

Condition category

Condition code

Metabolic and Endocrine

Normal metabolism and endocrine development and function

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

The intervention in this research program is the ambient temperature to which participants will be exposed. Two separate protocols will be investigated:
1. Ambient temperature will begin at 23 degrees, and over the course of 90 minutes, will either be increased to 35 degrees or decreased down to 11 degrees. These temperature ramps will be linear and controlled with automatic feedback loop programs within the environmental simulation suite. The cooling and warming exposures will both be carried out by the same participants but on separate days. To allow for further clarification of the thermo-neutral zone (TNZ), participants will have these expired gases measured with indirect hood calorimetry throughout the exposure. Participants will be asked to wear scrubs and sit in a semi-reclined position.
2. During the second protocol, participants will visit the environmental simulation suite for three sessions. Whilst wearing standardised scrubs, they will be asked to live and work inside the room calorimeter for 8 hours in an effort to replicate a normal office day experience. For the control condition, temperature will be kept at the thermo-neutral temperature of 23 degrees. The two intervention exposures will lower the temperature to 18 degrees for the 8 hour exposure or fluctuate the temperature between 23 and 18 throughout the exposure. Indirect room calorimetry will be collected throughout the exposure so that the energy expenditure response to temperature changes may be monitored.
For both protocols, a DXA scan will be performed to gain accurate anthtropometry measurements for subsequent analysis with the calorimetry data. Testing for both protocols will be performed in the Global Energetic Environmental Simulation Suite (GEnESiS), which is situated in the Centre for Translational Physiology at the University of Otago Wellington. Set up and observation will be performed by Mr. Terry O'Donnell, who established the GEnESiS at the centre, and has a history of research and publication in the relationship of metabolism and environment. Due to the cross over design of both protocols, at least a 2 day wash our period will be implemented between exposures.

Intervention code [1]

Lifestyle

Comparator / control treatment

Participants will serve as their own controls for both protocols with the control conditions being set at 23 degrees. This is a temperature commonly used in the literature by previous studies and has been shown to be in the thermoneutral zone for most participants.

Control group

Active

Outcomes

Primary outcome [1]

Changes in energy expenditure as measured with indirect calorimetry

Timepoint [1]

This will be continuously measured throughout the exposure interventions.

Secondary outcome [1]

Thermal comfort scales will be sought from participants

Timepoint [1]

This will be assessed every 15 minutes during protocol 1 and every 30 minutes during protocol 2

Secondary outcome [2]

Satiety measures will be sought from participants via questionnaires in protocol two. This questionnaire was designed within our lab, and amended and abridged to be appropriate for this particular study.

Timepoint [2]

Questionnaires will be supplied immediately prior to meals (pre-prandial), and thirty minutes post-meals (post-prandial), and at the end of the exposures in protocol two.

Secondary outcome [3]

Heart rate will be monitored using the ECG capabilities of the Equivital life sign monitor in protocol one and two .

Timepoint [3]

This measures will be taken continuously within each exposure for both protocols.

Secondary outcome [4]

Biomarkers of satiety/appetite (ghrelin and des-acyl ghrelin) in blood plasma obtained by venous-puncture blood-draw.

Timepoint [4]

Bloods will be taken before and after each exposure in protocol two.

Secondary outcome [5]

Breathing rate will be monitored using the expansion-detecting capabilities of the Equivital life sign monitor in protocol one and two.

Timepoint [5]

Breathing rate will be monitored continuously within each exposure in protocol two.

Secondary outcome [6]

Movement will be assessed using the Equivital life sign monitors tri-axial accelerometer

Timepoint [6]

Movement is monitored continuously within each exposure in protocol one and two.

Secondary outcome [7]

Skin temperature will be assessed using the Equivital life sign monitor.

Timepoint [7]

Skin temperature will be monitored continuously within each exposure for protocol one and two.

Eligibility

Key inclusion criteria

Aged 18-60 years old
Healthy Male or Female
BMI of 18-30

Minimum age

18 Years

Maximum age

60 Years

Sex

Both males and females

Can healthy volunteers participate?

Yes

Key exclusion criteria

Major cardiovascular diseases
Obesity (BMI >30)
Pregnant woman (due to DXA scan)
Diabetes
Prescription medications which may affect autonomic function

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)

Allocation not concealed.

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

Order of exposures will be selected by random number generator

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

Multivariable-adjusted general linear models (GLM) will be used to quantify the environmental condition differences in total energy expenditure and the changes in total energy expenditure. In the latter GLM for analysis of changes, covariates will include baseline total energy expenditure and other variables known to be associated with this outcome variable. These covariates will include body composition, neuroendocrine function, gender, age and both peripheral and core temperature. The precise relationship between total energy expenditure and body mass will be identified with an allometric model rather than simple ratio normalisation.

Recruitment

Recruitment status

Recruiting

Date of first participant enrolment

Anticipated

1/11/2016

Actual

29/09/2016

Date of last participant enrolment

Anticipated

20/09/2019

Actual

Date of last data collection

Anticipated

27/09/2019

Actual

Sample size

Target

Accrual to date

Final

Recruitment outside Australia

Country [1]

New Zealand

State/province [1]

Wellington

Funding & Sponsors

Funding source category [1]

Charities/Societies/Foundations

Name [1]

Wellington Medical Research Foundation

Address [1]

PO BOX 51211
Tawa
Wellington 5249

Country [1]

New Zealand

Primary sponsor type

Individual

Name

Terry O'Donnell

Address

University of Otago Wellington
Centre for Translational Physiology
23A Mein Street
Newtown 6021

Country

New Zealand

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Central Health and Disability Ethics Committee

Ethics committee address [1]

Ministry of Health
Freyberg Building
20 Aitken Street
PO BOX 5013
Wellington 6011

Ethics committee country [1]

New Zealand

Date submitted for ethics approval [1]

01/10/2015

Approval date [1]

11/12/2015

Ethics approval number [1]

15/CEN/177

Summary

Brief summary

Our energy expenditure has three major components; the thermic effect of physical activity, the thermic effect of feeding, and the resting metabolic rate (RMR). This RMR is a basal use of energy for the body to maintain basic functions, such as homeostatic mechanisms.

There is a long-established relationship between ambient temperature and energy expenditure. The range of temperatures where the body naturally maintains its optimum temperature is the thermo-neutral zone (TNZ). This is said to be around 22 °C when light clothing is taken into consideration, and within the individual is determined by insulation, body composition, genetics, and long-term residential environment. Thermo-regulation - an active homeostatic mechanism by which optimum body temperature is maintained - must be employed outside of the TNZ. Previously, mild cold exposure (19 °C) has been shown to induce a ~6% increase in energy expenditure compared to the thermo-neutral (24 °C) control[1]. This corresponded to ~120 kcal/day increase; similar prolonged changes in energy balance have been shown to effect gradual weight change[2].

Modern lifestyle, often revolving around office environments and related environmental control, limit exposures to temperature ‘extremes’ outside of the TNZ. This could limit energy expenditure, complicating weight management in already low-ambulatory jobs. Similarly, increased energy expenditure hypothesized to occur in cold or poorly insulated housing could drive compensatory increases in appetite and subsequent weight management issues.

This study aims to define the TNZ of New Zealand based individuals (protocol one). The TNZ will be used to establish the effect and feasibility of minor decreases or fluctuations in ambient temperature as an intervention to increase energy expenditure and aid in weight management (protocol two). This is pertinent as the only alternative, safe way of increasing energy expenditure is increased physical activity, which is not always an option. Along with continuous physiological measures and body composition information, we may also be able to establish models to determine individual TNZ ranges and energy expenditure under known conditions.

This study will provide potential interventions regarding the obesity epidemic and weight management with New Zealand specific parameters, and suggest a method for its application elsewhere. It may also advise the public health sector as to a further effect of cold housing on physical health.

[1] Celi FS, Brychta RJ, Linderman JD, Butler PW, Alberobello AT, Smith S, Courville AB, Lai EW, Costello R, Skarulis MC, Csako G. Minimal changes in environmental temperature result in a significant increase in energy expenditure and changes in the hormonal homeostasis in healthy adults. European journal of endocrinology. 2010 Dec 1;163(6):863-72.
[2] Hill JO, Wyatt HR, Reed GW, Peters JC. Obesity and the environment: where do we go from here?. Science. 2003 Feb 7;299(5608):853-5.

Trial website

Trial related presentations / publications

Public notes

Contacts

Principal investigator

Name

Mr Terry O'Donnell

Address

University of Otago Wellington
Centre for Translational Physiology
23A Mein Street
Newtown
Wellington 6021

Country

New Zealand

Phone

+64 4 8061504

Fax

terry.odonnell@otago.ac.nz

Contact person for public queries

Name

Terry O'Donnell

Address

University of Otago Wellington
Centre for Translational Physiology
23A Mein Street
Newtown
Wellington 6021

Country

New Zealand

Phone

+64 4 8061504

Fax

terry.odonnell@otago.ac.nz

Contact person for scientific queries

Name

Terry O'Donnell

Address

University of Otago Wellington
Centre for Translational Physiology
23A Mein Street
Newtown
Wellington 6021

Country

New Zealand

Phone

+64 4 8061504

Fax

terry.odonnell@otago.ac.nz

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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Documents added automatically

No additional documents have been identified.

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