Interrupting Sitting With High Intensity Exercise on Vascular Function in Adolescents Before and After a Mixed Meal

Study Overview
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Brief Summary
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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
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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.

Official Title
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The Effect of Prolonged vs. Interrupted Sitting With High Intensity Interval Exercise on Lower Limb Vascular Function in Adolescents Before and After a Mixed Meal

Conditions
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Cardiovascular Risk Factor, Endothelial Dysfunction

Intervention / Treatment
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* Behavioral: Interrupting 3 hours of prolonged sitting with high intensity interval exercise
* Behavioral: 3 hours of prolonged sitting


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 12 Years
Maximum Age: 15 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 3 hours of Prolonged Sitting<br>Participants will sit continuously for three hours before receiving a mixed meal challenge. | Behavioral: 3 hours of prolonged sitting<br>* Participants will be asked to remain seated for 3 hours and refrain from moving their lower limbs<br>|
| Experimental: 3 hours of interrupted sitting with hourly HIIE<br>Participants will have their three hour sitting period interrupted with high intensity interval cycling exercise (HIIE) at 30, 90 and 150 minutes into the intervention. In each exercise bout, they will cycle at 90% peak power for 3 x 60 second periods with 75 seconds of recovery in-between. | Behavioral: Interrupting 3 hours of prolonged sitting with high intensity interval exercise<br>* Breaking up a prolonged bout of sitting in adolescents using high intensity interval exercise<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Popliteal macrovascular function | Flow mediated dilation will be used to assess changes in microvascular function of the popliteal artery | Before and after 3 hours of prolonged vs. interrupted sitting and after a subsequent 3 hour postprandial period | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Microvascular function in the capillaries of the calf | Microvascular function will be assessed using post occlusive reactive hyperaemia via laser Doppler flowmetry | Before and after 3 hours of prolonged vs. interrupted sitting and after a subsequent 3 hour postprandial period | 
| Changes in plasma triglyceride concentration from a capillary sample | Changes in plasma triglyceride concentration will be assessed in response to the prolonged or interrupted sitting and after mixed meal | 6.5 hours | 
| Changes in plasma insulin concentration from a capillary sample | Changes in plasma insulin concentration will be assessed in response to the prolonged or interrupted sitting and after mixed meal | 6.5 hours | 
| Changes in plasma glucose concentration from a capillary sample | Changes in plasma glucose concentration will be assessed in response to the prolonged or interrupted sitting and after mixed meal | 6.5 hours | 
| Blood pressure | Changes in blood pressure will be monitored hourly throughout the 3 hour sitting period and three hour postprandial period | 6.5 hours | 
| Heart rate | Changes in heart rate will be monitored hourly throughout the 3 hour sitting period and three hour postprandial period | 6.5 hours | 
| Calf circumference | 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 | 6.5 hours | 
| Physical activity prior to the experimental visits | Participants will wear GENEactiv accelerometers to monitor their physical activity levels before the experimental visit | 48 hours prior to each visit | 
| Sitting time during the experimental visits | Participants will wear an activPAL accelerometer on their thigh to quantify the amount of time they spend sitting, standing and cycling during the trials | 6 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Flow mediated dilation, Reactive hyperaemia, Endothelial function, Paediatrics, Physical inactivity