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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
Comparing the effect of self-paced interval cycling and continuous cycling on energy expenditure and enjoyment of exercise in healthy pregnant women
Scientific title
Enhancing energy expenditure and enjoyment of exercise during pregnancy through the addition of brief higher intensity intervals to traditional continuous moderate intensity cycling
Secondary ID [1] 289182 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Pregnancy 298736 0
Physical inactivity 298737 0
Condition category
Condition code
Reproductive Health and Childbirth 298782 298782 0 0
Normal pregnancy

Study type
Description of intervention(s) / exposure
This study was conducted at a single-centre, with two sessions of acute, laboratory based intervention using a counterbalanced Latin square design. The sessions are one continuous cycling session and one interval cycling session performed within a two week period with at least two days between sessions.

On two separate occasions, each participant individually completed 30 minutes of cycling on the stationary cycle ergometer commencing and ending with a 5-minute warm up and cool down at 30 W. This ensured that exercise performance was self-paced and not affected by the presence or pace of other exercisers. The 20-minute conditioning phase between the warm up and cool down consisted of the following performed in a counterbalanced order 1) continuous cycling (CONT) at a steady power output equivalent to 65% HRmax or 2) interval cycling (INTV) consisting of continuous cycling at the same power output as CONT, but with the addition of six 15-second self-paced higher intensity efforts repeated every three minutes, performed with the same instructions as familiarisation. All sessions held in the Alan Morton laboratory at the School of Sport Science Exercise and Health, UWA and were supervised by the main investigator.
Intervention code [1] 294714 0
Comparator / control treatment
The two experimental trials (continuous cycling vs interval cycling) were compared against each other. The participants were their own controls
Control group

Primary outcome [1] 298253 0
Enjoyment of Exercise measured using the Physical Activity Enjoyment Scale (PACES)
Timepoint [1] 298253 0
PACES was administered within 15 min of completing cycling trial
Primary outcome [2] 298254 0
Heart rate during trial measured using Polar heart rate monitors & Rate of Perceived Exertion (RPE: Borg 6-20 scale). This is a composite primary outcome.
Timepoint [2] 298254 0
Measured at 5 min-intervals during the entire 30 minute of cycling exercise
Primary outcome [3] 298255 0
Oxygen consumption was measure to calculate energy expenditure of each trial. Between the 20th to 25th min of cycling exercise when steady state was established, expired air was collected using a computerised gas analysis system. The system consisted of a ventilometer (Universal ventilation meter, VacuMed, Ventura, California USA) that was calibrated prior to each trial as per manufacturer specifications, using a one litre syringe; and gas analysers (Ametek Applied Electrochemistry S-3A/1 and CD-3A, AEI Technologies, Pittsburgh, USA) that were calibrated using standard a reference gas of a known physiological concentration.
Timepoint [3] 298255 0
Raw data collection performed from 20-25th min of exercise trial
Secondary outcome [1] 323689 0
Capillary blood samples were taken and analysed for glucose concentration.
Timepoint [1] 323689 0
Samples was taken before and immediately after each exercise trial

Key inclusion criteria
Healthy, non-smoking, recreationally active women with uncomplicated singleton pregnancies were recruited upon entering their third trimester at 28 weeks of gestation.
Minimum age
18 Years
Maximum age
40 Years
Can healthy volunteers participate?
Key exclusion criteria
1. Multiple pregnancy
2. Highly trained (physically) pregnant women (i.e athlete)
3. Smoker
4. Less than 28 weeks pregnant
5. Has pregnancy complications

Study design
Purpose of the study
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
allocation was not concealed as participants underwent both trials for comparison.
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
Other design features
a counterbalanced Latin square design
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
One-way repeated measures analysis of variance (ANOVA) - Heart rate, cycling power output, energy expenditure, oxygen consumption, RPE and PACES (enjoyment).
Two-way (time x condition) repeated measure ANOVA - blood glucose response to exercise.
This sample size is based on a previous study by our laboratory comparing similar variables (energy expenditure, heart rate, and enjoyment) between different modes of exercise in women in late pregnancy (Halse, Wallman, Newnham, Guelfi, Pregnant women exercise at a higher intensity during 30min of self-paced cycling compared with walking during late gestation, Metabolism, 2013:62;801-807). It was anticipated that 12 participants would be required to detect an effect size of 0.8 (one-tailed; p < 0.05; power of 0.8) using a repeated measures design.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment postcode(s) [1] 13230 0
6009 - Broadway Nedlands

Funding & Sponsors
Funding source category [1] 293566 0
Government body
Name [1] 293566 0
National Health and Medical Research Council
Address [1] 293566 0
National Health and Medical Research Council GPO Box 1421 Canberra ACT 2601
Country [1] 293566 0
Primary sponsor type
School of Sport Science Exercise & Health, The University of Western Australia
M408, 35 Stirling Hwy,
Nedlands WA 6009
Secondary sponsor category [1] 292385 0
Name [1] 292385 0
Address [1] 292385 0
Country [1] 292385 0

Ethics approval
Ethics application status
Ethics committee name [1] 295009 0
The University of Western Australia (UWA) Human Ethics Committee
Ethics committee address [1] 295009 0
M459, 35 Stirling Highway
Crawley WA 6009
Administration Building
North Wing
2nd Floor
Ethics committee country [1] 295009 0
Date submitted for ethics approval [1] 295009 0
Approval date [1] 295009 0
Ethics approval number [1] 295009 0

Brief summary
Many women fail to achieve the current exercise guidelines for pregnancy which recommend that pregnant women without contraindications engage in 20-30 minutes or more of moderate intensity exercise on most days of the week. As exercise enjoyment is an important factor which affects exercise adherence, it is important to determine the optimal format of exercise which promotes enjoyment. Interval type exercise has been reported to be more enjoyable in the non-pregnant population but no study had investigated this format of exercise in pregnancy. Thus, this trial investigated the effects of adding brief higher intensity intervals to moderate intensity continuous cycling on the overall energy expenditure and intensity of exercise and the enjoyment of exercise. It was hypothesised that the addition of brief higher intensity intervals to moderate intensity continuous cycling will increase the overall energy expenditure and intensity of exercise, at the same time as enhancing enjoyment. The trial of interval cycling was found to increased energy expenditure by 28% when compared to the continuous cycling trial. At the same time, the interval cycling trial significantly enhanced the enjoyment of exercise in late pregnancy. Importantly, the findings was specific to recreationally active women only, but this study provides a rationale for future studies to examine the physiological and psychological responses to regular interval training during pregnancy to optimise exercise prescription.
Trial website
Trial related presentations / publications
Ong MJ, Wallman KE, Fournier PA, Newnham JP, Guelfi KJ. Enhancing energy expenditure and enjoyment of exercise during pregnancy through the addition of brief higher intensity intervals to traditional continuous moderate intensity cycling. BMC Pregnancy and Childbirth.
Publication pending trial registration.
Public notes

Principal investigator
Name 65766 0
Dr Ming Jing Ong
Address 65766 0
School of Sport Science, Exercise and Health
The University of Western Australia
M408, 35 Stirling Hwy
Nedlands WA 6009
Country 65766 0
Phone 65766 0
Fax 65766 0
Email 65766 0
Contact person for public queries
Name 65767 0
Dr Ming Jing Ong
Address 65767 0
School of Sport Science, Exercise and Health
The University of Western Australia
M408, 35 Stirling Hwy
Nedlands WA 6009
Country 65767 0
Phone 65767 0
Fax 65767 0
Email 65767 0
Contact person for scientific queries
Name 65768 0
Dr Ming Jing Ong
Address 65768 0
School of Sport Science, Exercise and Health
The University of Western Australia
M408, 35 Stirling Hwy
Nedlands WA 6009
Country 65768 0
Phone 65768 0
+61 8 6488 8003
Fax 65768 0
Email 65768 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary