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Br J Sports Med. 2019 Apr 29. pii: bjsports-2018-100168. doi: 10.1136/bjsports-2018-100168. [Epub ahead of print]

Distinct effects of acute exercise and breaks in sitting on working memory and executive function in older adults: a three-arm, randomised cross-over trial to evaluate the effects of exercise with and without breaks in sitting on cognition.

Author information

1
School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Perth, Western Australia, Australia michael.wheeler@baker.edu.au.
2
Physical Activity, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia.
3
School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Perth, Western Australia, Australia.
4
Academic Unit for Psychiatry of Old Age, Department of Psychiatry, University of Melbourne, Melbourne, Victoria, Australia.
5
Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Victoria, Australia.
6
School of Public Health, The University of Hong Kong, Hong Kong, Hong Kong.
7
Turku PET Centre, University of Turku, Turku, Finland.
8
Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.
9
Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital, Hvidovre, Denmark.
10
Centre for Demographic and Ageing Research (CEDAR), Umeå University, Umeå, Sweden.
11
Iverson Health Innovation Research Institute and School of Health Science, Swinburne University of Technology, Melbourne, Victoria, Australia.
12
Department of Psychiatry, University of Melbourne, Melbourne, Victoria, Australia.
13
Metabolic and Vascular Physiology Laboratory, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia.
14
Behavioural Epidemiology, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia.
15
Centre for Urban Transitions, Swinburne University of Technology, Melbourne, Victoria, Australia.

Abstract

BACKGROUND:

Sedentary behaviour is associated with impaired cognition, whereas exercise can acutely improve cognition.

OBJECTIVE:

We compared the effects of a morning bout of moderate-intensity exercise, with and without subsequent light-intensity walking breaks from sitting, on cognition in older adults.

METHODS:

Sedentary overweight/obese older adults with normal cognitive function (n=67, 67±7 years, 31.2±4.1 kg/m2) completed three conditions (6-day washout): SIT (sitting): uninterrupted sitting (8 hours, control); EX+SIT (exercise + sitting): sitting (1 hour), moderate-intensity walking (30 min), uninterrupted sitting (6.5 hours); and EX+BR (exercise + breaks): sitting (1 hour), moderate-intensity walking (30 min), sitting interrupted every 30 min with 3 min of light-intensity walking (6.5 hours). Cognitive testing (Cogstate) was completed at four time points assessing psychomotor function, attention, executive function, visual learning and working memory. Serum brain-derived neurotrophic growth factor (BDNF) was assessed at six time points. The 8-hour net area under the curve (AUC) was calculated for each outcome.

RESULTS:

Working memory net AUC z-score·hour (95% CI) was improved in EX+BR with a z-score of +28 (-26 to +81), relative to SIT, -25 (-79 to +29, p=0.04 vs EX+BR). Executive function net AUC was improved in EX+SIT, -8 (- 71 to +55), relative to SIT, -80 (-142 to -17, p=0.03 vs EX+SIT). Serum BDNF net AUC ng/mL·hour (95% CI) was increased in both EX+SIT, +171 (-449 to +791, p=0.03 vs SIT), and EX+BR, +139 (-481 to +759, p=0.045 vs SIT), relative to SIT, -227 (-851 to +396).

CONCLUSION:

A morning bout of moderate-intensity exercise improves serum BDNF and working memory or executive function in older adults, depending on whether or not subsequent sitting is also interrupted with intermittent light-intensity walking.

TRIAL REGISTRATION NUMBER:

ACTRN12614000737639.

KEYWORDS:

ageing; brain; exercise; sedentary

Conflict of interest statement

Competing interests: None declared.

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