Cardiovascular Risk Factor, Endothelial Dysfunction
Conditions
Keywords
Flow mediated dilation, Reactive hyperaemia, Endothelial function, Paediatrics, Physical inactivity
Brief summary
This study aims to investigate the effect of interrupting a three hour bout of prolonged sitting with high intensity interval exercise on lower limb blood vessel function in adolescents before and after a mixed meal challenge.
Detailed description
Participants will be required to visit the laboratory on three separate occasions. The first of which will be a preliminary visit to collect anthropometric data (e.g. stature and body weight) and participants will complete a combined ramp-incremental and supra-maximal test to exhaustion on a cycle ergometer to determine the work rate for the exercise in the subsequent experimental visits. For the two experimental visits, participants will arrive to the laboratory after an overnight fast and an activPAL accelerometer will be attached to the midline of the participants' thigh for the duration of the visit to quantity sitting time. Lower limb macro and micro-vascular function will be assessed using a single protocol through flow mediated dilation of the popliteal artery and post-occlusive reactive hyperaemia in the capillaries of the calf. Participants will then either sit for three hours or have this three hour sitting period interrupted with high intensity interval cycling exercise at 30, 90 and 150 minutes. Vascular function will then be reassessed before participants will be given a mixed meal challenge (58.4 g fat and 53.4 g sugar) with a three hour postprandial period where the participants will remain seated for the duration. At the end of the postprandial period, vascular function will be reassessed. Blood pressure, heart rate and calf circumference will be assessed hourly throughout the experimental day. In addition, capillary blood samples will be collected at baseline, pre meal and each hour during the postprandial period and assessed for changes in plasma glucose, triglyceride, cholesterol and insulin concentrations. Participants will be transported to the toilet by wheelchair to limit the amount of walking undertaken during the sitting period and this activity will be quantified by the activPAL accelerometers.
Interventions
BEHAVIORALInterrupting 3 hours of prolonged sitting with high intensity interval exercise
Breaking up a prolonged bout of sitting in adolescents using high intensity interval exercise
BEHAVIORAL3 hours of prolonged sitting
Participants will be asked to remain seated for 3 hours and refrain from moving their lower limbs
Sponsors
University of British Columbia
University of Exeter
Study design
Allocation
NON_RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
12 Years to 15 Years
Healthy volunteers
Yes
Inclusion criteria
* Male and female adolescents * 12-15 years
Exclusion criteria
* Medications known to affect blood pressure, carbohydrate or fat metabolism * Allergies to the test meal e.g. dairy or gluten * Contraindications to exercise * Individuals with special educational needs that mean they are unable to fully comprehend the demands of the study procedures
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Popliteal macrovascular function | Before and after 3 hours of prolonged vs. interrupted sitting and after a subsequent 3 hour postprandial period | Flow mediated dilation will be used to assess changes in microvascular function of the popliteal artery |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Microvascular function in the capillaries of the calf | Before and after 3 hours of prolonged vs. interrupted sitting and after a subsequent 3 hour postprandial period | Microvascular function will be assessed using post occlusive reactive hyperaemia via laser Doppler flowmetry |
| Changes in plasma triglyceride concentration from a capillary sample | 6.5 hours | Changes in plasma triglyceride concentration will be assessed in response to the prolonged or interrupted sitting and after mixed meal |
| Changes in plasma insulin concentration from a capillary sample | 6.5 hours | Changes in plasma insulin concentration will be assessed in response to the prolonged or interrupted sitting and after mixed meal |
| Changes in plasma glucose concentration from a capillary sample | 6.5 hours | Changes in plasma glucose concentration will be assessed in response to the prolonged or interrupted sitting and after mixed meal |
| Blood pressure | 6.5 hours | Changes in blood pressure will be monitored hourly throughout the 3 hour sitting period and three hour postprandial period |
| Physical activity prior to the experimental visits | 48 hours prior to each visit | Participants will wear GENEactiv accelerometers to monitor their physical activity levels before the experimental visit |
| Sitting time during the experimental visits | 6 hours | Participants will wear an activPAL accelerometer on their thigh to quantify the amount of time they spend sitting, standing and cycling during the trials |
| Heart rate | 6.5 hours | Changes in heart rate will be monitored hourly throughout the 3 hour sitting period and three hour postprandial period |
| Calf circumference | 6.5 hours | Calf circumference will be monitored every hour throughout experimental visit to give an indication of venous pooling that may occur as a result of the prolonged sitting and be implicated in the potential decline in vascular function |
Other
| Measure | Time frame | Description |
|---|---|---|
| Participant Enjoyment During the High Intensity Interval Exercise | 3 hours | The enjoyment of the high intensity interval exercise will be assessed during the exercise bouts using the Exercise Enjoyment Scale (ESS) (Stanley & Cumming, 2010). The scale runs from 1 (not at all) to 7 (extremely) so a larger score indicates greater enjoyment. |
| Participant Enjoyment Post the High Intensity Interval Exercise | 3 hours | Participants will rate their enjoyment post exercise using the Physical Activity Enjoyment Scale (PACES) modified for adolescents (Motl et al., 2001). Participants rate how much they agree (1 = disagree a lot to 5 = agree a lot) with 16 statements about their feelings from the exercise. The combined enjoyment scale score can range from 16 to 80 with a higher score indicating greater perceived enjoyment. |
Countries
United Kingdom
Outcome results
None listed