ORCID Profile
0000-0002-7404-7069
Current Organisations
Deakin University
,
University of Melbourne
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Publisher: Wiley
Date: 22-12-2023
DOI: 10.1002/OBY.23637
Abstract: This study aimed to assess the impact of time‐restricted eating (TRE) on integrated skeletal muscle myofibrillar protein synthesis (MyoPS) rates in males with overweight/obesity. A total of 18 healthy males (age 46 ± 5 years BMI: 30 ± 2 kg/m 2 ) completed this exploratory, parallel, randomized dietary intervention after a 3‐day lead‐in diet. Participants then consumed an isoenergetic diet (protein: ~1.0 g/kg body mass per day) following either TRE (10:00 a.m. to 6:00 p.m.) or an extended eating control (CON 8:00 a.m. to 8:00 p.m.) protocol for 10 days. Integrated MyoPS rates were measured using deuterated water administration with repeated saliva, blood, and muscle s ling. Secondary measures included continuous glucose monitoring and body composition (dual‐energy x‐ray absorptiometry). There were no differences in daily integrated MyoPS rates (TRE: 1.28% ± 0.18% per day, CON: 1.26% ± 0.22% per day p = 0.82) between groups. From continuous glucose monitoring, 24‐hour total area under the curve was reduced following TRE (−578 ± 271 vs. CON: 12 ± 272 mmol/L × 24 hours p = 0.001). Total body mass declined (TRE: −1.6 ± 0.9 and CON: −1.1 ± 0.7 kg p 0.001) with no differences between groups ( p = 0.22). Lean mass loss was greater following TRE compared with CON (−1.0 ± 0.7 vs. −0.2 ± 0.5 kg, respectively p = 0.01). Consuming food within an 8‐hour time‐restricted period does not lower daily MyoPS rates when compared with an isoenergetic diet consumed over 12 hours. Future research should investigate whether these results translate to free‐living TRE.
Publisher: Springer Science and Business Media LLC
Date: 27-01-2022
Publisher: Springer Science and Business Media LLC
Date: 12-2020
DOI: 10.1186/S12966-020-01057-9
Abstract: Postprandial glucose, insulin, and triglyceride metabolism is impaired by prolonged sitting, but enhanced by exercise. The aim of this study was to assess the effects of a continuous exercise bout with and without intermittent active interruptions to prolonged sitting on postprandial glucose, insulin, and triglycerides. Sedentary adults who were overweight to obese ( n = 67 mean age 67 yr SD ± 7 BMI 31.2 kg∙m − 2 SD ± 4.1), completed three conditions: SIT: uninterrupted sitting (8-h, control) EX+SIT: sitting (1-h), moderate-intensity walking (30-min), uninterrupted sitting (6.5-h) EX+BR: sitting (1-h), moderate-intensity walking (30- min), sitting interrupted every 30-min with 3-min of light-intensity walking (6.5 h). Participants consumed standardized breakfast and lunch meals and blood was s led at 13 time-points. When compared to SIT, EX+SIT increased total area under the curve (tAUC) for glucose by 2% [0.1–4.1%] and EX+BR by 3% [0.6–4.7%] (all p 0.05). Compared to SIT, EX+SIT reduced insulin and insulin:glucose ratio tAUC by 18% [11–22%] and 21% [8–33%], respectively and EX+BR reduced values by 25% [19–31%] and 28% [15–38%], respectively (all p 0.001 vs SIT, all p 0.05 EX+SIT-vs-EX+BR). Compared to SIT, EX+BR reduced triglyceride tAUC by 6% [1–10%] ( p = 0.01 vs SIT), and compared to EX+SIT, EX+BR reduced this value by 5% [0.1–8.8%] ( p = 0.047 vs EX+SIT). The magnitude of reduction in insulin tAUC from SIT-to-EX+BR was greater in those with increased basal insulin resistance. No reduction in triglyceride tAUC from SIT-to-EX+BR was apparent in those with high fasting triglycerides. Additional reductions in postprandial insulin-glucose dynamics and triglycerides may be achieved by combining exercise with breaks in sitting. Relative to uninterrupted sitting, this strategy may reduce postprandial insulin more in those with high basal insulin resistance, but those with high fasting triglycerides may be resistant to such intervention-induced reductions in triglycerides. Australia New Zealand Clinical Trials Registry ( ACTRN12614000737639 ).
Publisher: Wiley
Date: 02-05-2017
Publisher: BMJ
Date: 02-2016
Publisher: Elsevier BV
Date: 09-2021
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.CCT.2017.10.015
Abstract: Physical activity is positively associated with survival and quality of life among breast cancer survivors. Despite these benefits, the majority of breast cancer survivors are insufficiently active. The potential health benefits of reducing sedentary behaviour (sitting time) in this population have not been extensively investigated. The ACTIVATE Trial will evaluate the efficacy of an intervention that combines wearable technology (the Garmin Vivofit2®) with traditional behavioural change approaches to increase physical activity and reduce sedentary behaviour performed by breast cancer survivors. This randomised controlled trial includes inactive, postmenopausal women diagnosed with stage I-III breast cancer who have completed their primary treatment. Participants are randomly assigned to the primary intervention group (Garmin Vivofit2® behavioural feedback and goal setting session and, five telephone-delivered health coaching sessions) or to the wait-list control group. The primary intervention is delivered over a 12-week period. The second 12-week period comprises a maintenance phase for the primary intervention group, and an abridged intervention (Garmin Vivofit2® only) for the wait-list control group. Moderate- to vigorous-intensity physical activity (MVPA) and sedentary behaviour are assessed by accelerometry at baseline (T1), end of intervention (T2), and end of maintenance phase (T3). The ACTIVATE Trial is one of the first studies to incorporate wearable technology into an intervention for cancer survivors. If the use of wearable technology (in combination with behaviour change strategies, or alone) proves efficacious, it may become an inexpensive and sustainable addition to the health promotion strategies available to health care providers in the cancer survivorship context. ACTRN12616000175471.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-2019
DOI: 10.1161/HYPERTENSIONAHA.118.12373
Abstract: Both exercise and breaks in prolonged sitting can reduce blood pressure (BP) in older overweight/obese adults. We investigated whether there is an additive hypotensive effect when exercise is combined with subsequent breaks in sitting. Sex differences and changes in plasma catecholamines as a potential candidate mechanism underlying BP responses were also examined. Sedentary older adults (n=67 67±7 years 31.2±4.1 kg/m 2 ) completed 3 conditions in random order—sitting (SIT): uninterrupted sitting (8 hours, control) exercise+sitting (EX+SIT): sitting (1 hour), moderate-intensity walking (30 minutes), uninterrupted sitting (6.5 hours) exercise+breaks (EX+BR): sitting (1 hour), moderate-intensity walking (30 minutes), sitting interrupted every 30 minutes with 3 minutes of light-intensity walking (6.5 hours). Serial BP and plasma epinephrine/norepinephrine measurements occurred during 8 hours. The 8-hour average systolic and diastolic BP (mm Hg 95% CI) was lower in EX+SIT −3.4 (−4.5 to −2.3), −0.8 (−1.6 to −0.04), and EX+BR −5.1 (−6.2 to −4.0), −1.1 (−1.8 to −0.3), respectively, relative to SIT (all P .05). There was an additional reduction in average systolic BP of −1.7 (−2.8 to −0.6) in EX+BR relative to EX+SIT ( P =0.003). This additional reduction in systolic BP was driven by women −3.2 (−4.7 to −1.7 P .001 EX+BR versus EX+SIT). Average epinephrine decreased in EX+SIT and EX+BR in women (−13% to −12%) but increased in men (+12% to +23%), respectively, relative to SIT ( P .05). No differences in average norepinephrine were observed. Morning exercise reduces BP during a period of 8 hours in older overweight/obese adults compared with prolonged sitting. Combining exercise with regular breaks in sitting may be of more benefit for lowering BP in women than in men. URL: www.anzctr.org.au . Unique identifier: ACTRN12614000737639.
Publisher: Springer International Publishing
Date: 2023
Publisher: American Diabetes Association
Date: 06-2021
DOI: 10.2337/DC20-1410
Abstract: To determine whether interrupting sitting with brief bouts of simple resistance activities (SRAs) at different frequencies improves postprandial glucose, insulin, and triglycerides in adults with medication-controlled type 2 diabetes (T2D). Participants (n = 23, 10 of whom were female, with mean ± SD age 62 ± 8 years and BMI 32.7 ± 3.5 kg · m−2) completed a three-armed randomized crossover trial (6- to 14-day washout): sitting uninterrupted for 7 h (SIT), sitting with 3-min SRAs (half squats, calf raises, gluteal contractions, and knee raises) every 30 min (SRA3), and sitting with 6-min SRAs every 60 min (SRA6). Net incremental areas under the curve (iAUCnet) for glucose, insulin, and triglycerides were compared between conditions. Glucose and insulin 7-h iAUCnet were attenuated significantly during SRA6 (glucose 17.0 mmol · h · L−1, 95% CI 12.5, 21.4 insulin 1,229 pmol · h · L−1, 95% CI 982, 1,538) in comparison with SIT (glucose 21.4 mmol · h · L−1, 95% CI 16.9, 25.8 insulin 1,411 pmol · h · L−1, 95% CI 1,128, 1,767 P & 0.05) and in comparison with SRA3 (for glucose only) (22.1 mmol · h · L−1, 95% CI 17.7, 26.6 P = 0.01) No significant differences in glucose or insulin iAUCnet were observed in comparison of SRA3 and SIT. There was no statistically significant effect of condition on triglyceride iAUCnet. In adults with medication-controlled T2D, interrupting prolonged sitting with 6-min SRAs every 60 min reduced postprandial glucose and insulin responses. Other frequencies of interruptions and potential longer-term benefits require examination to clarify clinical relevance.
Publisher: Springer Science and Business Media LLC
Date: 03-02-2022
Publisher: American Physiological Society
Date: 04-2019
DOI: 10.1152/JAPPLPHYSIOL.00001.2019
Abstract: Preventing declines in cerebral blood flow is important for maintaining optimal brain health with aging. We compared the effects of a morning bout of moderate-intensity exercise, with and without subsequent light-intensity walking breaks from sitting, on cerebral blood velocity over 8 h in older adults. In a randomized crossover trial, overweight/obese older adults ( n = 12, 70 ± 7 yr 30.4 ± 4.3 kg/m 2 ), completed three acute conditions (6-day washout) SIT: prolonged sitting (8 h, control) EX+SIT: sitting (1 h), moderate-intensity walking (30 min), followed by uninterrupted sitting (6.5 h) and EX + BR: sitting (1 h), moderate-intensity walking (30 min), followed by sitting (6.5 h) interrupted with 3 min of light-intensity walking every 30 min. Bilateral middle cerebral artery velocities (MCAv) were determined using transcranial Doppler at 13 time points across the day. The temporal pattern and average MCAv over 8 h was determined. The pattern of MCAv over 8 h was a negative linear trend in SIT ( P 0.001), but a positive quadratic trend in EX + SIT ( P 0.001) and EX + BR ( P 0.01). Afternoon time points in SIT were lower than baseline within condition ( P ≤ 0.001 for all). A morning dip in MCAv was observed in EX + SIT and EX + BR ( P 0.05 relative to baseline), but afternoon time points were not significantly lower than baseline. The average MCAv over 8 h was higher in EX + SIT than SIT ( P = 0.007) or EX + BR ( P = 0.024). Uninterrupted sitting should be avoided, and moderate-intensity exercise should be encouraged for the daily maintenance of cerebral blood flow in older adults. The clinical implications of maintaining adequate cerebral blood flow include the delivery of vital oxygen and nutrients to the brain. NEW & NOTEWORTHY This is the first study to measure the combined effects of an exercise bout with breaks in sitting on cerebral blood velocity in older adults. Using frequent recordings over an 8-h period, we have performed a novel analysis of the pattern of cerebral blood velocity, adjusting for concurrent measures of mean arterial pressure and other potential confounders in a linear mixed effects regression.
Publisher: BMJ
Date: 29-04-2020
DOI: 10.1136/BJSPORTS-2018-100168
Abstract: Sedentary behaviour is associated with impaired cognition, whereas exercise can acutely improve cognition. 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. Sedentary overweight/obese older adults with normal cognitive function (n=67, 67±7 years, 31.2±4.1 kg/m 2 ) 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. 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). 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. ACTRN12614000737639.
Publisher: American Physiological Society
Date: 2021
DOI: 10.1152/AJPHEART.00422.2020
Abstract: This is the first trial to examine both the effects of interrupting prolonged sitting on vascular function in type 2 diabetes and the effects of the frequency and duration of interruptions. Brief, simple resistance activity bouts every 30 min, but not every 60 min, increased mean femoral artery flow-mediated dilation over 7 h, relative to uninterrupted sitting. With further supporting evidence, these initial findings can have important implications for cardiovascular health in type 2 diabetes.
Publisher: Elsevier BV
Date: 10-2018
Publisher: Frontiers Media SA
Date: 26-03-2019
Publisher: American Physiological Society
Date: 12-2018
DOI: 10.1152/JAPPLPHYSIOL.00544.2018
Abstract: Prolonged sitting contributes to cardiovascular disease (CVD) risk. The underlying mechanisms are unknown but may include changes in arterial function and vasoactive mediators. We examined the effects of prolonged unbroken sitting, relative to regular active interruptions to sitting time, on arterial function in adults at increased CVD risk. In a randomized crossover trial, 19 sedentary overweight/obese adults (mean ± SD age 57 ± 12 yr) completed 2 laboratory-based conditions: 5 h uninterrupted sitting (SIT) and 5 h sitting interrupted every 30 min by 3 min of simple resistance activities (SRA). Femoral artery function [flow-mediated dilation (FMD)], blood flow, and shear rate were measured at 0 h, 30 min, 1 h, 2 h, and 5 h. Brachial FMD was assessed at 0 and 5 h. Plasma was collected hourly for measurement of endothelin-1 (ET-1), nitrates/nitrites, vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1). There was a significant decline in femoral artery FMD, averaged over 5 h in the SIT condition, relative to SRA ( P 0.001). Plasma ET-1 total area under the curve over 5 h increased in the SIT condition compared with SRA ( P = 0.006). There was no significant difference between conditions in femoral or brachial shear rate, brachial FMD, nitrates/nitrites, VCAM-1, or ICAM-1 ( P 0.05 for all). Five hours of prolonged sitting, relative to regular interruptions to sitting time, impaired femoral artery vasodilator function and increased circulating ET-1 in overweight/obese adults. There is the need to build on this evidence beyond acute observations to better understand the potential longer-term vascular-related consequences of prolonged sitting. NEW & NOTEWORTHY This is the first study to examine the effect of prolonged sitting on arterial function in adults at increased cardiovascular disease risk. We have shown that 5 h of prolonged sitting, relative to regular interruptions to sitting time, impaired femoral artery vasodilator function and increased circulating endothelin-1 in overweight/obese adults. There is now the need to build on this evidence beyond acute observations to better understand the potential longer-term vascular-related consequences of prolonged sitting.
No related grants have been discovered for Michael Wheeler.