Effects of Physical Inactivity on Insulin Sensitivity, Appetite, Energy Balance, and Cardiovascular Responses in Humans.

Study Overview
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Brief Summary
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Physical inactivity is a significant predictor of major non-communicable diseases such as type 2 diabetes (7%), cardiovascular disease (6%), musculoskeletal disorders and some cancers, and has been proposed to be the 4th leading cause of death worldwide. Reduced physical activity leads to an impaired function of the hormone insulin and increased adiposity. Thus, the elimination of physical inactivity would remove between 6% and 10% of the major non-communicable diseases and increase life expectancy. The aim of the study is to investigate the effects of a short-term (2-day) period of reduced physical activity, with and without a proportional decrease in energy intake, on the action of insulin to regulate blood sugar fluctuations, appetite, and cardiovascular parameters (heart rate, cardiac output, stroke volume, blood flow, arterial blood pressure, peripheral vascular resistance) in response to food ingestion.

Official Title
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Short-term Effects of Physical Inactivity on Insulin Sensitivity, Appetite, Energy Balance, and Cardiovascular Responses in Healthy Humans.

Conditions
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Sedentary Behavior

Intervention / Treatment
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* Other: Control
* Other: SIT+E
* Other: SIT=E


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Non-smoking Males and females Age (18-35 years old) Body mass index (BMI) of 18-27 kg/m2 Waist circumference <94cm for males and <80cm for females Ability to give informed consent Exclusion Criteria: Smoking Any metabolic (e.g. diabetes), endocrine (e.g. hyperthyroidism) or cardiovascular (e.g. heart or blood) abnormalities including hypertension or heart failure Clinically significant abnormalities on screening including ECG abnormalities Taking routine medication that may alter cardiovascular function and blood flow (e.g. blood pressure-lowering drugs or drugs that cause hypertension) Well trained individuals with PAL>2.00; on an energy-restricted diet or seeking to lose weight High alcohol consumption (<3-4 units/d for men; <2-3 units/d for women) Females who are pregnant or lactating; self-reported allergy, intolerance or strong dislike of foods or drinks to be offered for the test breakfast, pasta meal or during the intervention period Beck Depression Inventory score >10 and Eating Attitudes Test (EAT-26) score >20 as self-reported markers of symptoms and concerns characteristic of depression and eating disorders, respectively.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 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: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Control<br>2 consecutive days of standardised daily levels of moderate physical activity (PAL=1.85 reflecting their habitual levels), and matched energy (food) intake | Other: Control<br>* Normal physical activity and standard energy intake<br>|
| Experimental: SIT+E<br>2 consecutive days of reduced physical activity induced by prolonged periods of sitting (PAL=1.4) whilst maintaining the level of food intake prescribed in the Control trial, thus creating a positive energy balance | Other: SIT+E<br>* Reduced physical activity and standard energy intake<br>|
| Experimental: SIT=E<br>2 consecutive days of reduced physical activity induced by prolonged periods of sitting (PAL=1.4) whilst reducing food intake to match the reduction in energy expenditure induced by inactivity, thus maintaining energy balance | Other: SIT=E<br>* Reduced physical activity and reduced energy intake<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The incremental area under curve for Insulin | The incremental area under curve for Insulin will be calculated using samples collected at 20 minute intervals between baseline and three hours | Over three hours from baseline | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The incremental area under curve for arterialized whole blood glucose | The incremental area under curve for arterialized whole blood glucose will be calculated using samples collected at 10 minute intervals between baseline and four hours | Over four hours from baseline |