Muscle Blood Flow During Exercise

Study Overview
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Brief Summary
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Physical exercise triggers various physiological responses including a marked increase in muscle blood flow and oxygen delivery in order to support muscle activity. How muscle blood flow is controlled is currently unclear. The primary purpose of this study is to establish the respective contribution of metabolic (linked to energy requirements) and mechanical (linked to muscle tensions) signals in the exercise hyperemia and the possible role of the red blood cells. Vasodilation and muscle blood flow during exercise are controlled by ATP released in the plasma from the red blood cells in response to a combination of metabolic and mechanical signals applied on the vasculature.

Official Title
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Muscle Blood Flow Control During Exercise in Humans: Contribution From Mechanical and Metabolic Signals and Role of the Erythrocyte.

Conditions
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Skeletal Muscle Blood Flow

Intervention / Treatment
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* Other: Session 1-4
* Other: Session 4
* Other: Session 5


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Non smoker or having stopped smoking for at least 5 yr Practice sports: physical activity level will be evaluated with a questionnaire (de Baecke et coll., 1982) and will give an activity index greater than 6 together with a VO2max greater than 50 ml/kg/min Body mass index lower than 25 Registered to the French Social Security system Providing a written and informed consent to participate in the study Exclusion Criteria: History of venous or arterial thrombo-embolic events Bad perfusion from the cubital artery Unable to understand the information notice Subject exposed to law investigations or with financial dependancy Subjects feeling unwell whan seing blood. Subjects advised to not practice sport. Musculo-tendinous or articular issues with the lower leg Respiratory, cardiovascular or metabolic pathologies Current medical treatment that can not be stopped 7 days before the experiment.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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Male

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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Concentric vs eccentric<br>One arm study in which each subject will act as his own control. | Other: Session 1-4<br>* Familiarization sessions to knee-extensor exercise separated by 72h recovery<br>Other: Session 4<br>* After the last familiarization session, 1 maximal incremental test on a bicycle, followed by 72h rest<br>Other: Session 5<br>* 2 maximal incremental tests of knee-extension exercise (concentric vs eccentric), separated by 3h rest.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in leg blood flow during concentric and eccentric muscle work | Serial measures (9) of leg blood flow during concentric and eccentric muscle work are performed at the beginning of the exercise (t0), and then after 14 minutes (t14), after 18 minutes (t18), after 22 minutes (t22), after 26 minutes (t26), after 30 minutes (t30), after 33 minutes (t33), after 35 minutes (t35), and after 45 minutes (45) during each exercice, concentric and eccentric. | Leg blood flow measurements during exercises performed at the beginning, after 14 minutes, then after 18 min, 22 min, 26 min, 30 min, 33 min, 35 min and 45 min | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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red blood cell, knee extension exercise