None listed
Conditions
Brief summary
Prolonged periods of sitting are prevalent in the modern office workplace and adversely impact on cardiometabolic risk factors including blood glucose and insulin concentrations. Acute aerobic exercise can transiently improve these risk factors. Evidence suggests that the pattern of exercise accumulation throughout a day and the timing of exercise in relation to meals modulates the beneficial effects it has on these markers. However, the role of exercise timing throughout a day on cardiometabolic risk factors has not been evaluated. The aim of this study is to compare the impact of a morning and evening bout of aerobic exercise on blood glucose and insulin metabolism throughout a day of prolonged sitting. Young overweight or obese men and women with a familial history of type 2 diabetes will be recruited for this study. As this demographic are at an increased risk of developing type 2 diabetes they represent a relevant target population for the prevention of type 2 diabetes. We hypothesise that aerobic exercise performed in the morning, prior to a prolonged bout of sitting and the ingestion of meals will more effectively improve glycaemic control compared to an identical evening bout.
Interventions
This is a randomised, two-condition crossover trial where participants will undergo 2x ~48 h experimental conditions. Each condition will be separated by a minimum 7-day washout period
For both conditions participants will attend the laboratory at ~5 pm on the evening prior to the main experimental trial day (day one) for fitting of a continuous glucose monitoring system and receive a standardised take-home meal for dinner. Participants will also be fitted with an an accelerometer and an inclin
This is a randomised, two-condition crossover trial where participants will undergo 2x ~48 h experimental conditions. Each condition will be separated by a minimum 7-day washout period For both conditions participants will attend the laboratory at ~5 pm on the evening prior to the main experimental trial day (day one) for fitting of a continuous glucose monitoring system and receive a standardised take-home meal for dinner. Participants will also be fitted with an an accelerometer and an inclinometer for measurement of physical activity levels prior and during each experimental condition. Food and activity diaries will also be completed by participants prior to either experimental condition. On the main experimental trial day (day two) participants will arrive at the laboratory via taxi at ~0730 h. A catheter will be inserted in the antecubital vein of the non-dominant arm at 0800 h and remain in place until 1900 h. Participants will remain seated for the duration of the visit and blood samples will be collected at regular intervals. Identical meals will be provided at 0900 h, 1300 h and 1700 h. . Each meal will contain ~33% total energy intake for the day with a macronutrient profile of 50% from carbohydrates, 30% from fat and 20% from protein. Additionally, participants will perform 30 minutes of aerobic exercise at ~65% VO2max on a cycle ergometer. The timing of the exercise bout will depend on the experimental condition being undertaken. At 1900 h participants will return home via taxi and fast overnight. Condition A: Exercise will be performed at 0800 h, prior to breakfast. Condition B: Exercise will be performed at 1600 h, prior to dinner. Participants will then return to the lab for a follow up (day three) at ~0730 and remain seated for the duration of the visit. A catheter will be inserted in the antecubital vein of the non-dominant arm at 0800 h and remain until 1600 h for serial blood sampling. Participants will be provided identical meals to day two at 0900 h and 1300 h. At 1630 h all monitoring devices will be removed.
Sponsors
Professor John Hawley
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Prevention
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
18 Years to 30 Years
Healthy volunteers
No
Inclusion criteria
Sedentary overweight or obese [body mass index (BMI) > 25 kg/m2 but < 45 kg/m2] adults with a familial history of type 2 diabetes (diagnosis in a first or second degree relative).
Exclusion criteria
Pregnancy, use of carbohydrate or lipid-lowering medication, major illness/injury (acute or chronic), current smoker or use of nicotine replacement therapy or physical or major illness/physical problems (acute or chronic) that may limit their ability to participate in the intervention.
Outcome results
None listed