- Title
- Breaking up prolonged sitting time after stroke
- Creator
- Mackie, Paul Ian
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2021
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Background: Living a sedentary lifestyle (particularly spending excessive time in prolonged sitting) significantly increases the risk of developing cardiovascular disease and having a subsequent cardiovascular event, such as a stroke. Although promotion of regular physical activity is fundamental in the management of cardiovascular diseases, many stroke survivors are unable to meet physical activity recommendations, and spend large portions of the day sitting. The time spent in prolonged sitting is a health risk for stroke survivors with already comprised cardiovascular health, and is likely a significant contributing factor to the risk of recurrent stroke after the initial event. Experimental evidence has indicated that interrupting prolonged sitting time with bouts of physical activity or standing (active interruptions) has substantial cardio-metabolic health benefits in those with type 2 diabetes, or who are overweight or obese. In stroke survivors, interrupting prolonged sitting time with light-intensity standing-based exercises appears to be beneficial for decreasing systolic blood pressure, but not postprandial glucose. However, it is unknown in stroke survivors if less frequent standing-based exercises provide similar cardio-metabolic health benefits as more frequent bouts, and if the effects are sustained under free-living conditions. Objectives: The first aim of this thesis was to identify the acute effects of interrupting prolonged sitting time on first and recurrent stroke risk factors. The second aim was to investigate the dose-response effect of frequent bouts of light-intensity exercises while standing (STAND-EX) in stroke survivors, which: a. Reduces blood pressure immediately and for 24 hours following experimental conditions b. Are tolerable and feasible at the most beneficial dose of STAND-EX c. Reduces postprandial glucose during experimental conditions. Methods: To address the aims of this thesis, I undertook a scoping review and an experimental trial: Scoping review (aim 1): Five databases were searched for experimental trials that interrupted prolonged sitting time with frequent bouts of physical activity or standing. Experimental trials included were conducted under supervised conditions and were compared to bouts of prolonged, uninterrupted sitting. Experimental trial (aim 2): This trial was a within participant, laboratory-based, dose-escalation trial conducted in community dwelling stroke survivors. Participants completed three 8-hour experimental conditions, involving a control condition (prolonged sitting) and two experimental conditions that interrupted prolonged sitting. Experimental conditions included light-intensity standing-based exercises that increased by 2 × 5 min bouts until a dose-limiting threshold was obtained. The dose-limiting threshold was the inability of participants to accomplish ≥ 80% of time in standing-based exercises, and ≥ 70% of the cohort attaining the dose-limiting threshold. The primary outcome was systolic blood pressure and the secondary outcome was postprandial glucose. Results: Scoping review: The scoping review included 30 trials, of which 50% included individuals characterised at risk of first stroke. Only one trial included stroke survivors. Trials included measurements of hypertension, dysglycaemia, hypercholesterolemia and anthropometric factors, with the majority of trials (26 of 30) measuring markers associated with dysglycaemia. Interrupting prolonged sitting time with physical activity or standing bouts appeared to improve markers of hypertension and dysglycaemia in those at risk of a first stroke or recurrent stroke. Experimental trial: Twenty-nine stroke survivors (aged 66 years) completed the trial. The dose-limiting threshold was not reached and therefore three experimental conditions were completed (2 × 5 min condition, 4 × 5 min condition and 6 × 5 min condition). Interrupting 8 hours of prolonged sitting with 4 × 5 min and 6 × 5 min bouts of light-intensity standing-based exercises significantly decreased systolic blood pressure by -2.1 mmHg (95% CI -3.6, -0.6) and -2.3 mmHg (95% CI -4.2, -0.5), respectively. Diastolic blood pressure decreased significantly by -1.4 mmHg (95% CI - 2.7, -0.2) following 6 × 5 min bouts of light-intensity standing-based exercises, compared to prolonged sitting. Twenty-four hour systolic blood pressure significantly increased by 6.9 mmHg (95% CI 3.1, 10.6) following the 2 × 5 min condition. In addition, interrupting 8 hours of prolonged sitting with 4 × 5 min bouts of light-intensity standing-based exercises significantly decreased postprandial glucose (iAUC; -1.1 mmol/L.7 hour [95% CI -2.0, -0.1]), compared with prolonged sitting. Exploratory analysis found decreases in postprandial glucose during the morning period (08:00 – 11:00) in the 4 × 5 min condition (iAUC; -0.8 mmol/L.3 hours [95% CI -1.3, -0.3]) and 6 × 5 min condition (iAUC; -0.8 mmol/L.3 hours [95% CI -1.5, -0.2]), compared with prolonged sitting. All doses of light-intensity standing-based exercises were safe and feasible for stroke survivors. Conclusion: The scoping review demonstrated that experimental trials that investigate the acute effects of interrupting prolonged sitting have a limited focus in stroke, with only one trial involving stroke survivors. Interrupting 8 hours of prolonged sitting time with 4 × 5 min and 6 × 5 min bouts (equating to one bout every 60 to 90 min, respectively) of light-intensity standing-based exercises decreased blood pressure and postprandial glucose responses in stroke survivors. Future trials should investigate the feasibility of implementing frequent bouts of standing-based exercises in care facilities and real world settings, and over longer-time periods in stroke survivors.
- Subject
- sitting time; stroke; light-intensity; physical activity; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1442899
- Identifier
- uon:41830
- Rights
- Copyright 2021 Paul Ian Mackie
- Language
- eng
- Full Text
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| View Details Download | ATTACHMENT01 | Thesis | 3 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 167 KB | Adobe Acrobat PDF | View Details Download |