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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
  1. Michael J Wheeler1,2,
  2. Daniel J Green1,
  3. Kathryn A Ellis3,
  4. Ester Cerin4,5,
  5. Ilkka Heinonen1,6,
  6. Louise H Naylor1,
  7. Robyn Larsen2,
  8. Patrik Wennberg7,
  9. Carl-Johan Boraxbekk8,9,
  10. Jaye Lewis,
  11. Nina Eikelis2,10,
  12. Nicola T Lautenschlager11,
  13. Bronwyn A Kingwell12,
  14. Gavin Lambert10,
  15. Neville Owen13,14,
  16. David W Dunstan2,4
  1. 1School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Perth, Western Australia, Australia
  2. 2Physical Activity, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
  3. 3Academic Unit for Psychiatry of Old Age, Department of Psychiatry, University of Melbourne, Melbourne, Victoria, Australia
  4. 4Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Victoria, Australia
  5. 5School of Public Health, The University of Hong Kong, Hong Kong, Hong Kong
  6. 6Turku PET Centre, University of Turku, Turku, Finland
  7. 7Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden
  8. 8Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital, Hvidovre, Denmark
  9. 9Centre for Demographic and Ageing Research (CEDAR), Umeå University, Umeå, Sweden
  10. 10Iverson Health Innovation Research Institute and School of Health Science, Swinburne University of Technology, Melbourne, Victoria, Australia
  11. 11Department of Psychiatry, University of Melbourne, Melbourne, Victoria, Australia
  12. 12Metabolic and Vascular Physiology Laboratory, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
  13. 13Behavioural Epidemiology, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
  14. 14Centre for Urban Transitions, Swinburne University of Technology, Melbourne, Victoria, Australia
  1. Correspondence to Mr Michael J Wheeler, School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Perth, WA 6009, Australia; michael.wheeler{at}baker.edu.au

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.

  • sedentary
  • exercise
  • brain
  • ageing
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Footnotes

  • Contributors MJW, DJG, KAE, EC, LHN, RL, PW, C-JB, NTL, BK, GL, NO and DWD contributed to the design of the study. MJW coordinated the trial and data collection and is the study guarantor. IH and JL assisted with recruitment and data collection. NE assisted with biochemical analysis. MJW and EC wrote the statistical analysis plan. MJW, DJG and DWD wrote the paper. KAE, EC, IH, LHN, RL, PW, C-JB, JL, NE, NTL, BAK, GL and NO reviewed and edited the paper. All authors approved the final version of the manuscript.

  • Funding This work was funded by a project grant from the National Health and Medical Research Council of Australia (1062338) and supported in part by the Victorian Government’s OIS Program. MJW is supported by The University of Western Australia and the Baker Heart and Diabetes Institute. DJG is supported by an NHMRC Principal Research Fellowship (APP1080914). EC is supported by an ARC Future Fellowship (ARC FT140100085). IH is supported by the University of Turku, Hospital District of Southwest Finland and the Juho Vainio Foundation. DD is supported by an NHMRC Senior Research Fellowship (NHMRC APP1078360). GL is supported by an NHMRC Senior Research Fellowship (APP1042492). The laboratory of GL has recently received research funding from Medtronic, Abbott (formerly Solvay) Pharmaceuticals, Servier Australia and Allergan. GL has acted as a consultant for Medtronic.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval Ethical approval was obtained from the Alfred Hospital Ethics Committee (181-14) and The University of Western Australia Human Research Ethics Committee (RA/4/1/6990).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement The data that support the findings of this study are available from the corresponding author upon reasonable request.

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