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Trial registered on ANZCTR


Registration number
ACTRN12619000461190
Ethics application status
Approved
Date submitted
25/02/2019
Date registered
20/03/2019
Date last updated
2/03/2020
Date data sharing statement initially provided
20/03/2019
Type of registration
Retrospectively registered

Titles & IDs
Public title
Respiratory responses to exercise in older and younger adults
Scientific title
Mechanical and neural respiratory responses to exercise in older and younger adults
Secondary ID [1] 296270 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Respiratory ageing 311743 0
Condition category
Condition code
Respiratory 308770 308770 0 0
Normal development and function of the respiratory system

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Participants will attend the laboratory on three separate occasions. Visits 2 is generally 1-2 weeks after visit 1, while the second and third visits will be separated by at least 24 hours and completed within 1 week. Each visit will be held at approximately the same time of day. All aspects of the intervention will be administered by university research students or university researchers. There is no difference in experimental procedure for the control and intervention group (we are reviewing whether they respond differently to the same stimulus).

During visit 1, participants will complete their medical and consent forms. Participants will then be asked to self-report on their dyspnoea using the Medical Research Council dyspnoea scale. Following this their height, body mass and lung function will be measured. Subsequently, participants will have an electrocardiogram (ECG) at rest which will be sent to a cardiologist for review. Participants will not be permitted to participate in the project without the permission of the cardiologist. Participants will subsequently be familiarised with all the other experimental procedures required for testing.

During visit 2, participants will complete maximal inspiratory and expiratory mouth pressure manoeuvres, as well as forced vital capacity and inspiratory capacity manoeuvres. Maximal inspiratory pressure manoeuvre require participants to breath out fully, before breathing in maximally against an occluded mouthpiece. Maximal expiratory manoeuvre requires participants to take a full breath in and then then breath out maximally against an occluded mouthpiece. Forced vital capacity manoeuvre requires participants to take a maximally deep breath in, followed by a maximally forceful breath out which is sustained for 6 second. Inspiratory capacity manoeuvre requires participants to inspire maximally at the end of a normal breath out. Participants will then complete an incremental cycling test (Corival; Lode, Groningen, Netherlands) to the limit of volitional tolerance. The cycling test commences with exercise at either 60, 80 or 100 W with increases of 20 W in two minute stages. The starting power depends on self-reported participant fitness (Coffman, Carlson, Miller, Johnson, & Taylor, 2017).

During visit 3, participants will again perform forced vital capacity and inspiratory capacity manoeuvres as well as supramaximal cervical and thoracic magnetic stimulation (delivered using Magstim 90mm remote coil and Magstim BiStim2 set to single pulse). The stimulations are carried out as so, participants have a magnetic stimulator placed over the cervical vertebrae and a magnetic stimulation is delivered. Thoracic stimulation is carried out similarly, except the stimulator is placed over the thoracic vertebrae. Stimulation duration's are approximately 1-2ms. Stimulations are performed before the exercise tolerance test, immediately after the test, 15minutes after the test and 30 minutes after the test. After the first set of stimulations are complete participants will undertake the exercise tolerance test (cycling at 85% of their maximum power output until the limit of volitional tolerance). Immediately, 15 and 30min post test participants will complete further sets of stimulations.

Each cycling test will begin with 5 minutes of steady state rest (the participant will be seated on the bike and undertaking no activity), followed by a 1 minute warm up of unloaded pedalling (self-paced cycling with at 0 W). During visits 2 and 3, participants will have the catheter inserted and positioned in their oesophagus and stomach. The participants will then be connected to an electrocardiogram (ECG) monitoring system and a pulse oximeter, as well as having electromyography (EMG) electrodes attached to their scalene and parasternal muscles. The ECG and pulse oximetry signals will be monitored during the exercise to minimise chances of participants experiencing a cardiac event. At rest, every 2 minutes, and at the end of the exercise tests, participants will complete inspiratory capacity manoeuvres for EMG normalisation and to calculate end-expiratory and end-inspiratory lung volumes (operating lung volumes). At the same time points, rating of perceived exertion (RPE) for leg and breathing discomfort will be assessed using Borgs CR10 scale. Additionally, at the end of exercise, participants will be asked to: state their primary reason for stopping exercise (e.g., leg discomfort or breathing discomfort); give and RPE value for leg and breathing discomfort (Borg Scale); and complete the qualitative descriptors of dyspnea at symptom limitation questionnaire.

The comparator (65-84 years) and control group (18-35 years) follow the same intervention procedure (i.e., both groups follow the procedure described above).
Intervention code [1] 313767 0
Treatment: Other
Comparator / control treatment
Healthy younger adults aged 18-35 years (male and female participants).
Control group
Active

Outcomes
Primary outcome [1] 307747 0
Transdiaphragmatic pressure. Transdiaphragmatic pressure is measured using an oesophageal catheter integrated with two pressure transducers (one oesophageal and one gastric).
Timepoint [1] 307747 0
Visit 3
Before exercise induced by cervical magnetic stimulation (CMS)
During exercise (dynamic measurements)
Immediately post exercise by CMS
15 minutes post exercise by CMS
30 minutes post exercise by CMS
Primary outcome [2] 307748 0
Abdominal pressure. Measured using an oesophageal catheter integrated with two pressure transducers (one oesophageal and one gastric).
Timepoint [2] 307748 0
Visit 3
Before exercise induced by abdominal magnetic stimulation (AMS)
During exercise (dynamic measurements)
Immediately post exercise by AMS
15 minutes post exercise by AMS
30 minutes post exercise by AMS
Primary outcome [3] 307749 0
VO2 Maximum. Assessed using a Vyntus™ CPX Metabolic Cart.
Timepoint [3] 307749 0
Visit 2 and 3
Evaluated during exercise
Secondary outcome [1] 352770 0
Dyspnea and leg fatigue (Borg Scale)
Timepoint [1] 352770 0
Visit 2 and 3
Before exercise
At 2 min intervals during exercise
Immediately post exercise
Secondary outcome [2] 352771 0
Forced vital capacity
Assessed using a Hans Rudolph 800 L/min Heated Pneumotachometer with heat controller.
Timepoint [2] 352771 0
Visit 2 and 3.
Forced vital capacity measured prior to exercise.
Secondary outcome [3] 352772 0
Mouth pressure is assessed using a Memscap SP844 pressure transducer with the inlet attached to a facemask worn during exercise.
Timepoint [3] 352772 0
Visit 2 and 3. Measured dynamically pre-exercise and during exercise. No measurements taken post exercise.
Secondary outcome [4] 352773 0
Electromyography of the diaphragm to assess diaphragmatic fatigue.
Timepoint [4] 352773 0
Visit 2 and 3. Measured prior to exercise, during exercise and post exercise
Secondary outcome [5] 352774 0
Exploratory electromyography of the parasternals, sternocleidomastoid and abdominals. EMG of the diaphragm is also recorded so that other calculations such as neuro-mechanical coupling (a combination of transdiaphragmatic pressure and diagram EMG recordings) can be calculated post-hoc.
Timepoint [5] 352774 0
Visit 2 and 3. Measured prior to exercise, during exercise and post exercise
Secondary outcome [6] 352776 0
Qualitative descriptors of dyspnea at symptom limitation (Ramsook et al, 2016) and Medical Research Council Dyspnoea Scale.
Timepoint [6] 352776 0
Visit 2 and 3
Collected post exercise.
Secondary outcome [7] 368312 0
Tidal Volume.
Assessed using a Hans Rudolph 800 L/min Heated Pneumotachometer with heat controller.
Timepoint [7] 368312 0
Visit 2 and 3. During exercise.
Secondary outcome [8] 368313 0
Inspiratory capacity.
Assessed using a Hans Rudolph 800 L/min Heated Pneumotachometer with heat controller.
Timepoint [8] 368313 0
Inspiratory capacity is measured prior to exercise (during the 5 minute rest period) and during exercise at 2 min intervals.

Eligibility
Key inclusion criteria
18-35 years or 65-84 years of age.
Minimum age
18 Years
Maximum age
84 Years
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
1. Aged under 18 years; 36 to 64 years; or over 84 years
2. Epilepsy
3. Diabetes
4. Cardiac conditions
5. Respiratory conditions
6. Coagulation abnormalities
7. Oesophageal varices or strictures
8. Dysphagia (difficulty swallowing)
9. Reactions to medical adhesives
10. Restrictive equipment inhibiting effective breathing
11. Implanted medical device/s or cardiac pacemaker
12. Medical condition or surgical procedure involving the nose, throat, diaphragm, lungs or stomach
13. Stroke
14. Recent banding of oesophageal strictures
15. Surgical procedures affecting the nose, throat, stomach, diaphragm or lungs
16. History of head, facial or airway trauma
17. Currently pregnant or having given birth in the previous 12 months
18. Blood thinners, anticoagulants or fish oils
19. Known reactions to medications
20. Currently taking medication

Study design
Purpose of the study
Diagnosis
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint(s)
Efficacy
Statistical methods / analysis
A power analysis of other published works and our own pilot data indicated that a sample size of 12 should be sufficient to identify significant differences in pressure and electromyogram data within each of our two groups (older and younger) (Johnson, Babcock, Suman, & Dempsey, 1993; Jolley et al., 2009; Polkey et al., 1997; Ramsook et al., 2016).

Statistical analyses will be performed using SPSS for Windows (IBM, Chicago, IL). Normality of the data will be assessed by inspection of histograms. In addition, skewness and kurtosis scores will be converted to Z-scores by dividing them by their standard error. Within day reliability of the measurements will be assessed using the intraclass correlation coefficient. The data will be analysed using a two-way ANOVA to determine the effects of ‘age’ and ‘training status’. Statistical significance will be set at P < 0.05. Results will be presented as means ± SD.

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
QLD
Recruitment postcode(s) [1] 24370 0
4305 - Ipswich
Recruitment postcode(s) [2] 24371 0
4350 - East Toowoomba
Recruitment postcode(s) [3] 24372 0
4405 - Dalby
Recruitment postcode(s) [4] 24373 0
4000 - Brisbane

Funding & Sponsors
Funding source category [1] 300863 0
University
Name [1] 300863 0
University of Southern Queensland
Address [1] 300863 0
USQ Ipswich Campus, 11 Salisbury Rd, Ipswich QLD 4305
Country [1] 300863 0
Australia
Primary sponsor type
University
Name
University of Southern Queensland
Address
USQ Ipswich Campus, 11 Salisbury Rd, Ipswich QLD 4305
Country
Australia
Secondary sponsor category [1] 300419 0
None
Name [1] 300419 0
Address [1] 300419 0
Country [1] 300419 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 301638 0
USQ Human Research Ethics Committee
Ethics committee address [1] 301638 0
USQ Ipswich Campus, 11 Salisbury Rd, Ipswich QLD 4305
Ethics committee country [1] 301638 0
Australia
Date submitted for ethics approval [1] 301638 0
19/09/2017
Approval date [1] 301638 0
19/12/2017
Ethics approval number [1] 301638 0
H17REA261

Summary
Brief summary
Respiratory limitations to exercise such as reduced oxygen in the blood, fatigue of the muscles used in breathing and the resulting impact on blood supply to the limb muscles, pressure effects on heart output, increased energy spent on breathing and breathlessness are well researched in younger adults, athletes and clinical patients. However, little is known about whether age related changes in respiratory structure and function, fatigue of muscles used in breathing and the electrical activation of these muscles by the nervous system, limit exercise tolerance in apparently healthy older adults. This research aims to identify if these changes limit exercise tolerance in older adults.

The aim of this project is to compare the energy spent on breathing, fatigue of muscles used in breathing (specifically the diaphragm and abdominals), exercise tolerance (time to exhaustion) and breathlessness in older (65 to 84 years) and younger (18 to 35 years) adults in response to exercise. This data will then be analysed against age and fitness to look for differences. This analysis will identify the effect that training has on work of breathing, respiratory muscle fatigue and dyspnoea, and whether these effects are identical in younger and older adults. We will also determine whether fitter older adults reach their respiratory limits more quickly than less fit older adults, potentially resulting from the increased demands that their 'stronger' muscles place on the respiratory system. We hypothesise that older adults may experience hyperinflation of the lung during exercise (i.e., air is increasingly trapped in the lungs with each respiratory cycle), will fatigue sooner during exercise and demonstrate greater rates of diaphragm and abdominal fatigue post exercise, than younger adults.

Ultimately, we hope this project will lead to future research focussed on reducing respiratory limitations to exercise, thereby improving exercise tolerance and physical activity levels in older adults. We believe this project is worthwhile as increased participation in physical activity has benefits such as reduced mortality, improved mental health, improved cognition, reduced disease progression, symptoms reductions in many diseases, improved quality of life and reduced medical costs.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 87622 0
Mr William MacAskill
Address 87622 0
USQ Ipswich Campus, 11 Salisbury Rd, Ipswich QLD 4305
Country 87622 0
Australia
Phone 87622 0
+61 7 3812 6161
Fax 87622 0
Email 87622 0
Billy.MacAskill@usq.edu.au
Contact person for public queries
Name 87623 0
Mr William MacAskill
Address 87623 0
USQ Ipswich Campus, 11 Salisbury Rd, Ipswich QLD 4305
Country 87623 0
Australia
Phone 87623 0
+61 7 3812 6161
Fax 87623 0
Email 87623 0
Billy.MacAskill@usq.edu.au
Contact person for scientific queries
Name 87624 0
Mr William MacAskill
Address 87624 0
USQ Ipswich Campus, 11 Salisbury Rd, Ipswich QLD 4305
Country 87624 0
Australia
Phone 87624 0
+61 7 3812 6161
Fax 87624 0
Email 87624 0
Billy.MacAskill@usq.edu.au

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
Yes
What data in particular will be shared?
All of the individual participant data collected during the trial, after de-identification;
When will data be available (start and end dates)?
Immediately following publication with no end date determined.
Available to whom?
Case-by-case basis at the discretion of the University of Southern Queensland.
Available for what types of analyses?
Case-by-case basis at the discretion of the University of Southern Queensland.
How or where can data be obtained?
Case-by-case basis at the discretion of the University of Southern Queensland.
What supporting documents are/will be available?
No other documents available
Summary results
No Results