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Agyapong-Badu S1, Bostock E2, Whittaker A1,3, Jackson T3,4, Chastin S5,6, Skelton DA5, Greig C1,3,7
1School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom, 2Centre for Health, Exercise and Active Living, Manchester Metropolitan University, Manchester, United Kingdom, 3MRC-Arthritis Research Centre for Musculoskeletal Ageing Research, Birmingham, United Kingdom, 4Institute of Inflammation and Ageing, University of Birmingham, Birmingham, United Kingdom, 5School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, United Kingdom, 6Department of Movement and Sport Science, Ghent University, Ghent, Belgium, 7NIHR Birmingham BRC Inflammation, University of Birmingham, Birmingham, United Kingdom
Background: Epidemiological studies have identified sedentary behaviour as an independent risk factor leading to adverse health outcomes such as metabolic disease and mortality, even when meeting recommended physical activity guidelines. Older people are most sedentary and also spend very little time taking part in physical activity, with a reported 67% of older adults being sedentary for more than 8.5 hours daily.
Purpose: Although there is evidence supporting the longer-term detrimental health effects of prolonged bouts of sedentary behaviour (sitting) across the age range, there is a need to investigate the acute dose response effects of uninterrupted sitting on physiological measures such as muscle power and cardiovascular function in healthy older people. Thus, this study aimed to identify key physiological outcomes influenced by acute periods of inactivity.
Methods: This experimental study utilised a randomised cross-over design to recruit n=55 healthy community-dwelling older adults over 70 years (mean age 78 ± 7.5 years; 73% women). Participants completed sitting times of 1, 2 and 4 hours on separate days at the same start time of day, and were permitted to watch television, knit or read but not allowed to sleep. The sitting times corresponded to a brief control period of sitting (1hour), moderately sedentary (2-4hours per day) and sedentary (>4hours per day). Overall participants completed over 360 hours of sedentary time. The primary outcome measure was lower limb explosive power using the Nottingham Power Rig (Watts/kg) and the secondary outcome measure was blood pressure using Welch Allyn Sphygmomanometer (mmHg). Assessments were made before and after each period of sitting time in a temperature-controlled room. Differences between the pre and post measurements were analysed using repeated measure ANOVA with SPSS 22.
Results: Leg power did not change significantly (p=0.26) following the 1h (pre1.59±0.6, post 1.61±0.6 Watt/kg), 2h (pre 1.54±0.7, post 1.53±0.6 Watt/kg) and 4h (pre 1.56±0.6, post 1.56±0.6 Watt/kg) sitting times. A significant increase in systolic and diastolic blood pressure was recorded following the 2h (systolic pre 141±13, post 145±14 mmHg; p 0.001; diastolic pre 75±10, post 77±10mmHg; p 0.001) and 4h sitting times (systolic pre 140±14, post 155±14 mmHg; p 0.001; diastolic pre 74±10, post 81±10 mmHg; p 0.001). Mean arterial pressure also significantly increased after the 2 (pre 97± 9, post 99± 10 mmHg; p=0.02) and 4 hour (pre 95± 10, post 104± 10 mmHg; p 0.001) periods of sitting.
Conclusion(s): The data indicate that sitting for over 2 hours may have adverse effects on blood pressure in healthy older adults.
Implications: These observed changes (2-9%) in the cardiovascular response to acute sedentary behaviour highlight the need to further investigate the observed phenomenon mechanistically, alongside well-established practical recommendations for reducing sedentary behaviour in older adults.
Keywords: sedentary behaviour, acute effects, , blood pressure
Funding acknowledgements: This study was funded by the Dunhill Medical Trust.
Purpose: Although there is evidence supporting the longer-term detrimental health effects of prolonged bouts of sedentary behaviour (sitting) across the age range, there is a need to investigate the acute dose response effects of uninterrupted sitting on physiological measures such as muscle power and cardiovascular function in healthy older people. Thus, this study aimed to identify key physiological outcomes influenced by acute periods of inactivity.
Methods: This experimental study utilised a randomised cross-over design to recruit n=55 healthy community-dwelling older adults over 70 years (mean age 78 ± 7.5 years; 73% women). Participants completed sitting times of 1, 2 and 4 hours on separate days at the same start time of day, and were permitted to watch television, knit or read but not allowed to sleep. The sitting times corresponded to a brief control period of sitting (1hour), moderately sedentary (2-4hours per day) and sedentary (>4hours per day). Overall participants completed over 360 hours of sedentary time. The primary outcome measure was lower limb explosive power using the Nottingham Power Rig (Watts/kg) and the secondary outcome measure was blood pressure using Welch Allyn Sphygmomanometer (mmHg). Assessments were made before and after each period of sitting time in a temperature-controlled room. Differences between the pre and post measurements were analysed using repeated measure ANOVA with SPSS 22.
Results: Leg power did not change significantly (p=0.26) following the 1h (pre1.59±0.6, post 1.61±0.6 Watt/kg), 2h (pre 1.54±0.7, post 1.53±0.6 Watt/kg) and 4h (pre 1.56±0.6, post 1.56±0.6 Watt/kg) sitting times. A significant increase in systolic and diastolic blood pressure was recorded following the 2h (systolic pre 141±13, post 145±14 mmHg; p 0.001; diastolic pre 75±10, post 77±10mmHg; p 0.001) and 4h sitting times (systolic pre 140±14, post 155±14 mmHg; p 0.001; diastolic pre 74±10, post 81±10 mmHg; p 0.001). Mean arterial pressure also significantly increased after the 2 (pre 97± 9, post 99± 10 mmHg; p=0.02) and 4 hour (pre 95± 10, post 104± 10 mmHg; p 0.001) periods of sitting.
Conclusion(s): The data indicate that sitting for over 2 hours may have adverse effects on blood pressure in healthy older adults.
Implications: These observed changes (2-9%) in the cardiovascular response to acute sedentary behaviour highlight the need to further investigate the observed phenomenon mechanistically, alongside well-established practical recommendations for reducing sedentary behaviour in older adults.
Keywords: sedentary behaviour, acute effects, , blood pressure
Funding acknowledgements: This study was funded by the Dunhill Medical Trust.
Topic: Health promotion & wellbeing/healthy ageing; Older people
Ethics approval required: Yes
Institution: University of Birmingham, Birmingham, UK
Ethics committee: NHS Health Research Authority, NRES Committee West Midlands, South Birmingham
Ethics number: 15/WM/0260
All authors, affiliations and abstracts have been published as submitted.
