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Trial registered on ANZCTR

Registration number

ACTRN12614000737639

Ethics application status

Approved

Date submitted

3/07/2014

Date registered

11/07/2014

Date last updated

2/10/2018

Type of registration

Prospectively registered

Titles & IDs

Public title

The interacting effects of breaking up prolonged sitting with a single bout of exercise, plus regular short intervals of exercise, on blood flow to the brain and cognitive function in overweight adults

Scientific title

Taking a break for brain health: Interacting effects of exercise bouts with breaks in sitting time on cognitive and cerebrovascular function in overweight adults

Secondary ID [1]

Nil known

Universal Trial Number (UTN)

U1111-115716981

Trial acronym

Brain Breaks

Linked study record

Health condition

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

Cognitive Function

Condition category

Condition code

Mental Health

Studies of normal psychology, cognitive function and behaviour

Public Health

Health promotion/education

Metabolic and Endocrine

Normal metabolism and endocrine development and function

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

We propose a randomised cross-over trial in 48 sedentary and overweight adults aged between 55-80 years, to be undertaken (using a balanced orthogonal design) in two testing sites. The study will involve three acute experimental conditions (each of one day duration), separated by a minimum 7-day washout period to account for any residual physiological effects of acute exercise that may persist for up to 72 hours. To eliminate bias, the order in which participants undertake the three experimental conditions will be determined from a computer-generated, randomised sequence. Each experimental condition (detailed below) will be conducted in a controlled, laboratory setting to minimise the potential confounding influences and the inherent variability of less-controlled and more-variable ‘real-world’ settings. In all experimental conditions participants will arrive, having fasted for 10 hours, and be seated in a comfortable lounge-chair and instructed to minimise excessive movement and avoid all activities requiring cognitive engagement (eg: cross-words, Sudoku).
1) Uninterrupted Sitting: Participants will sit quietly for eight hours, with breakfast and lunch provided during this period.
2) Continuous Exercise + Uninterrupted Sitting: After sitting quietly for 1 hour (steady state) participants will complete a 30 minute bout of continuous moderate-intensity exercise on a motorised treadmill , at a predetermined power output corresponding to a range of between 65% -75% of maximal heart rate. Following this participants will sit quietly for the remaining 6 1/2 hours.
3) Continuous Exercise + Interrupted Sitting: Identical procedure to condition 2, however, after the continuous exercise bout, participants will remain seated for a further 30 minutes before completing a three-minute bout of light-intensity walking on a motorised treadmill at 3.2km.hr-1. They will then return to the seated position. This procedure will be repeated on 12 occasions every 30 minutes for a total of 36 minutes of light-intensity activity. The scientific rationale for the utilisation of the proposed protocol has been deliberately guided by our recently published findings (2min every 20min, total 28min) but modified slightly to accommodate the appropriate timing of the proposed testing procedures.
The research group consisting of the coordinator, research nurse and assistant will be responsible for monitoring adherence to the interventions

Intervention code [1]

Lifestyle

Intervention code [2]

Behaviour

Intervention code [3]

Prevention

Comparator / control treatment

One day of prolonged sitting without activity breaks: Participants will sit quietly in a comfortable chair for an 8-hour period.

Control group

Active

Outcomes

Primary outcome [1]

Cognitive function: Measured using a computerized battery of tests (CogState - www.cogstate.com.au) that has been specifically developed for brief repeated testing of cognitive performance in clinical and research trials, with good acceptability, efficiency and stability, and minimisation of practice effects. The test battery will cover multiple cognitive domains with a primary focus on executive function (most likely to be influenced by acute exercise). The battery will comprise: 1) Identification task to assess visual attention and vigilance; 2) N-back to assess attention and working memory; 3) Groton Maze Learning to assess executive function including spatial problem solving; 4) Detection task to assess psychomotor function and speed of processing; and 5) One card learning task to assess visual learning and memory; for a total administration time of approximately 25 minutes.

Timepoint [1]

4 times over 8 hours, including baseline during the first hour after arrival, and at +95 mins, +185 mins and + 395 minutes after the start of the exercise bout.

Secondary outcome [1]

Blood measurements: Venous blood samples will be collected by a trained nurse via an in-dwelling catheter in the antecubital vein. Between 6mL- 20mL (0.4 - 1.3 tablespoons) will be collected on each occasion, of which a fraction will be sent immediately to Alfred Pathology (for the Baker IDI site) or University of Western Australia (UWA) for that site, for analysis of glucose, triglycerides, full blood evaluation and lipid profile. The remaining blood will be centrifuged and the plasma fraction removed and frozen at at -80°C for later analysis related to this trial. The cannula will be flushed with normal saline following every blood draw to maintain its patency.

Timepoint [1]

A total of 13 blood draws will be done across the experimental day. Time points include baseline, +30 mins, +60 mins, +90 mins, +120 mins, +150 mins, +180 mins, +220 mins, +270 mins, +300 mins, +330 mins, +360 mins and +420 minutes after the breakfast meal.

Secondary outcome [2]

Blood pressure: Hourly resting brachial arterial blood pressure will be taken after a five minute rest period, three times, at one-minute intervals, using an automated oscillometric blood pressure monitor 10 (Dinamap Vital Signs Monitor 18465X, Criticon, Florida, USA).

Timepoint [2]

At baseline , +30 mins, + 90 mins, + 150 mins, + 210 mins, + 270 mins, + 330 mins, +390 mins and + 420 mins after the start of the exercise bout.

Eligibility

Key inclusion criteria

BMI equal or greater than 25 kg/m2 but less than 45 kg/m2 and English-speaking

Minimum age

55 Years

Maximum age

80 Years

Sex

Both males and females

Can healthy volunteers participate?

Key exclusion criteria

Pregnancy; employment in a non-sedentary occupation; currently watching less than 3 hours of television per day; regularly engaged in moderate-intensity exercise equal or greater than 150 min/week for longer than 3 months; cognitive impairment as evaluated during screening via mini-mental exam; diagnosed diabetes; use of glucose/lipid lowering medication, antidepressant medications, beta blockers; anti anxiety medication, peri-menopausal or menopausal women; excessive alcohol consumption; known physical activity contraindications, major illness/physical problems (acute or chronic) that may limit their ability to perform the exercise or activity bouts.

Study design

Purpose of the study

Treatment

Allocation to intervention

Randomised controlled trial

Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)

Interested volunteers will receive written information about the study in lay terms and a full description of the inclusion/exclusion criteria. After obtaining informed consent and background information, the potential participants will be screened to confirm eligibility. Once a potential subject has been deemed eligible, the subject will be randomised to the order of experimental conditions. The method for allocation concealment is closed envelopes. The allocation information will be placed in numbered envelopes (1 allocation per envelope) by an independent researcher. After a subject has been enrolled in the study, the study co-ordinators will contact an independent staff member to ask for the sequence of experimental conditions. The independent staff member will keep a log of the date and time the envelope was opened, the envelope number, the initials and gender of the participant and the order of experimental conditions. The study co-ordinator will also keep a record of this information.

Using the randomization schedule, the independent researcher will, after data collection, create a dataset containing outcome, other relevant variables and the random unique code but will not include overt information on the experimental conditions, subject initials, and date of data collection. Data collected under the experimental conditions will be assigned a code (e.g., 0 and 1) unknown to the data analyst and the research team (they would be blinded to the randomization process and condition). Once the data are analysed, the experimental-condition codes will be revealed and the dataset will be checked for errors.

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

The randomisation allocation sequence will be generated using computer-generated random numbers in a Latin-square experimental design.

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

Power calculations have been made in relation to the primary outcome measures of cognitive function and reflect the cross-over design of the study. Based on recent evidence we estimate the effect sizes (Cohen‘s d for repeated measures; ES) of additional exposure to light-intensity breaks (as compared to sole exposure to a moderate-intensity exercise bout) would be ~0.40 for executive function tasks, which is similar to the effect size previously-observed effects sizes for glucose, insulin, systolic blood pressure and diastolic blood pressure. The estimated ES of a moderate-intensity exercise bout as compared to the prolonged sitting is 0.7717. Sample size calculations indicate that 52 subjects would be needed to detect an ES of 0.40 based on one baseline and one post assessment per experimental condition. However, the proposed trial will include three post assessments per experimental condition, which gives 3 x subjects data points per condition. Assuming a within-subject, within-condition correlation between assessments of 0.6, the effective sample size per condition is [3 x subjects]/[1+(3-1)*0.6] = [3 x subjects]/2.2. To achieve an effective sample size of 52, we need 52*(2.2/3) ~ 40 subjects. Thus, the sample size needed to detect an ES of 0.40 with a power of 0.80 and a two-tailed probability of 0.05 is 40 (with three post-assessment measures per person and experimental condition). In a recent trial adopting a similar design, we achieved a 15% attrition rate. However, as a safeguard, assuming a conservative attrition rate of ~20%, we will aim to recruit 48 participants (24 per site).

Recruitment

Recruitment status

Completed

Date of first participant enrolment

Anticipated

27/08/2014

Actual

19/02/2015

Date of last participant enrolment

Anticipated

Actual

11/07/2017

Date of last data collection

Anticipated

Actual

10/08/2017

Sample size

Target

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

WA,VIC

Funding & Sponsors

Funding source category [1]

Government body

Name [1]

National Health and Medical Research Council (NHMRC)

Address [1]

National Health and Medical Research Council
GPO Box 1421
Canberra
ACT 2601

Country [1]

Australia

Primary sponsor type

Other

Name

Baker IDI Heart and Diabetes Institute

Address

Baker IDI Heart and Diabetes Institute
Physical Activity Laboratory
Level 4
The Alfred Centre
75 Commercial Road
Melbourne
VIC 3004

Country

Australia

Secondary sponsor category [1]

University

Name [1]

University of Western Australia (UWA)

Address [1]

School of Sport Science, Exercise and Health M408
University of Western Australia
35 Stirling Highway
Parkway Entrance 3
Nedlands
WA 6009

Country [1]

Australia

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Alfred Hospital Ethics Committee (EC00315)

Ethics committee address [1]

Office of Research Governance
Ground Floor Linay Pavilion
The Alfred
55 Commercial Road
Melbourne
VIC 3004

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

Approval date [1]

04/06/2014

Ethics approval number [1]

181/14

Summary

Brief summary

In recent years the, role of physical activity in healthy brain ageing has also been a major topic of investigation. Observational studies have shown that adults who are physically active are more likely to have better performance on several cognitive test tasks, including those involving higher order executive functions. Regular physical activity during midlife has also been associated with a significantly slower rate of cognitive decline and reduced risk of developing dementia in later adulthood. Such evidence has prompted calls to investigate the potential role of regular exercise as a protective factor against cognitive decline and dementia.

Traditionally, the physical activity public health focus has been directed at purposeful exercise for health benefits, at a moderate to vigorous-intensity. Emerging evidence suggests that targeting the adoption of moderate to vigorous exercise in the population should not be the only consideration; a focus on reducing sedentary behaviour may be equally important for health outcomes. Previous work has provided epidemiological and experimental evidence on the independent associations of sedentary behaviour with metabolic health.

Together, with The University of Western Australia, we propose to undertake a randomised cross-over trial in 48 older overweight adults involving three experimental conditions. All participants will complete each of the three (one-day) experimental conditions, separated by a 7-day washout period to account residual physiological effects of the acute exercise. We will examine whether, compared to uninterrupted sitting, there are acute effects of a single bout of moderate-intensity exercise, with or without intermittent (3 min) light-intensity activity breaks from prolonged sitting, on cognitive function and metabolic function in overweight adults aged between 55 and 80 years of age. We hypothesise that (1) a continuous 30 minute bout of moderate-intensity exercise will lead to improvements in cognitive function relative to uninterrupted sitting, and (2) that the magnitude of the improvement in cognitive function resulting from the exercise bout, compared to uninterrupted sitting, will be greater when an exercise bout is combined with a series of brief intermittent light-intensity breaks from prolonged sitting. Furthermore, we aim to examine an exploratory hypothesis that the improvement in cognitive function associated with both the continuous 30 minute bout of exercise and the brief intermittent breaks from prolonged sitting will be associated with mechanisms which increase cerebral blood flow and glucose uptake.

Trial website

Trial related presentations / publications

Public notes

Contacts

Principal investigator

Name

A/Prof David Dunstan

Address

Physical Activity Laboratory
Baker IDI Heart and Diabetes Research Institute
Level 4, Alfred Centre
99 Commercial Road
Melbourne
VIC 3004

Country

Australia

Phone

+61 3 8532 1873

Fax

+61 3 8532 1150

David.Dunstan@bakeridi.edu.au

Contact person for public queries

Name

David Dunstan

Address

Physical Activity Laboratory
Baker IDI Heart and Diabetes Research Institute
Level 4, Alfred Centre
99 Commercial Road
Melbourne
VIC 3004

Country

Australia

Phone

+61 3 8532 1873

Fax

+61 3 8532 1150

David.Dunstan@bakeridi.edu.au

Contact person for scientific queries

Name

David Dunstan

Address

Physical Activity Laboratory
Baker IDI Heart and Diabetes Research Institute
Level 4, Alfred Centre
99 Commercial Road
Melbourne
VIC 3004

Country

Australia

Phone

+61 3 8532 1873

Fax

+61 3 8532 1150

David.Dunstan@bakeridi.edu.au

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

Documents added manually

No documents have been uploaded by study researchers.

Documents added automatically

Source	Title	Year of Publication	DOI
Embase	Effect of morning exercise with or without breaks in prolonged sitting on blood pressure in older overweight/obese adults: Evidence for sex differences.	2019	https://dx.doi.org/10.1161/HYPERTENSIONAHA.118.12373
Embase	Combined effects of continuous exercise and intermittent active interruptions to prolonged sitting on postprandial glucose, insulin, and triglycerides in adults with obesity: a randomized crossover trial.	2020	https://dx.doi.org/10.1186/s12966-020-01057-9

N.B. These documents automatically identified may not have been verified by the study sponsor.

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