Peripheral Arterial Disease
Conditions
Keywords
exercise, cardiovascular, normobaric hypoxia
Brief summary
The aim of this randomized controlled trial is to: Phase I: To explore, in a first pilot phase, the adequate combination of hypoxia severity and exercise intensity in patients with symptomatic lower extremity artery disease (LEAD). Acute walking performances and physiological responses (vascular and muscular) to a normobaric hypoxic exercise performed will be assessed at two different altitudes (1500 m and 2500 m).
Detailed description
The results of this first phase will then be used to determine the optimal hypoxic level for the exercise training program which will be assessed during the Phase II.
Interventions
OTHERExercise in hypoxia 1500m
Subjects will perform a 6-min treadmill exercise wearing an oronasal mask connected (through a hose) with a three-way valve to an altitude simulation device (Altitrainer; SMTech, Nyon, Switzerland). The ambient air will be mixed with nitrogen and inspired oxygen fraction will be reduced to 16%. The first 3 min will be performed at 70% of the mean speed calculated during a previous visit, and the last 3 min at an intensity between 12-14 on the Borg's scale.
OTHERExercise in hypoxia 2500m
Subjects will perform a 6-min treadmill exercise wearing an oronasal mask connected (through a hose) with a three-way valve to an altitude simulation device (Altitrainer; SMTech, Nyon, Switzerland). The ambient air will be mixed with nitrogen and inspired oxygen fraction will be reduced to 14%. The first 3 min will be performed at 70% of the mean speed calculated during a previous visit, and the last 3 min at an intensity between 12-14 on the Borg's scale.
OTHERExercise in normoxia
Subjects will perform a 6-min treadmill exercise wearing an oronasal mask connected (through a hose) with a three-way valve to an altitude simulation device (Altitrainer; SMTech, Nyon, Switzerland). For the exercise performed in normoxia conditions, subjects will breathe room air. The first 3 min will be performed at 70% of the mean speed calculated during a previous visit, and the last 3 min at an intensity between 12-14 on the Borg's scale.
Sponsors
Centre Hospitalier Universitaire Vaudois
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Subject)
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Patients with symptomatic LEAD (Fontaine stage ≥ IIa) * ABI ≤ 0.9 * TBI ≤ 0.6 if incompressible arteries (diabetes and renal insufficiency) * Signed written informed consent form
Exclusion criteria
* Neurological and neuromuscular disorders which can limit balance and walking * Any history of altitude-related sickness * Any health risks (assessed during clinical history) linked to hypoxia exposure * Acclimatization or exposure to hypoxia of more than 2000 m for more than 48 h during a period of 6 months before the study * Medication required for the treatment of migraines, claustrophobia that may interfere with the interpretation of the results * Obstructive sleep apnea (\> 25 Apnea-Hypopnea Index) * Prior leg/foot amputation * Pregnant women * Cardiac contraindication to exercise
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Pulse oxygen saturation | After each 6 min treadmill test performed under hypoxic condition (1500 and 2500 m) and under normoxic condition (i.e., average of 3 weeks; one condition per week) | Pulse oxygen saturation during the 6 min treadmill test |
| Pain free walking time | After each 6 min treadmill test performed under hypoxic condition (1500 and 2500 m) and under normoxic condition (i.e., average of 3 weeks; one condition per week) | Pain free walking time during the 6 min treadmill test |
| Muscle oxygenation during exercise | After each 6 min treadmill test performed under hypoxic condition (1500 and 2500 m) and under normoxic condition (i.e., average of 3 weeks; one condition per week) | Muscle oxygenation during the 6 min treadmill test (assessed by near-infrared spectroscopy) |
| Pulse wave velocity | Before and after each 6 min treadmill test performed under hypoxic condition (1500 and 2500 m) and under normoxic condition (i.e., average of 3 weeks; one condition per week) | Pulse wave velocity before and after the 6 min treadmill test |
| Flow-mediated dilation | Before and after each 6 min treadmill test performed under hypoxic condition (1500 and 2500 m) and under normoxic condition (i.e., average of 3 weeks; one condition per week) | Flow-mediated dilation before and after the 6 min treadmill test |
| Walking performance | After each 6 min treadmill test performed under hypoxic condition (1500 and 2500 m) and under normoxic condition (i.e., average of 3 weeks; one condition per week) | Total walking distance (in meters) during the 6 min treadmill test |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Toe-brachial index | Before and after each 6 min treadmill test performed under hypoxic condition (1500 and 2500 m) and under normoxic condition (i.e., average of 3 weeks; one condition per week) | Toe-brachial index before and after the 6 min treadmill test |
| Rate of perceived exertion | After each 6 min treadmill test performed under hypoxic condition (1500 and 2500 m) and under normoxic condition (i.e., average of 3 weeks; one condition per week) | Rate of perceived exertion (RPE) will be assessed using Borg's scale. RPE is a widely used and reliable indicator to monitor and guide exercise intensity. The scale allows individuals to subjectively rate their level of exertion during 6 min treadmill test. Patients will classify their RPE between 6 (light) and 20 (maximal). |
| Leg pain | After each 6 min treadmill test performed under hypoxic condition (1500 and 2500 m) and under normoxic condition (i.e., average of 3 weeks; one condition per week) | Leg pain during exercise will be measured with a 10-points (0: no pain and 10: worst imaginable pain) visual analogic scale (VAS). |
| Ankle-brachial index | Before and after each 6 min treadmill test performed under hypoxic condition (1500 and 2500 m) and under normoxic condition (i.e., average of 3 weeks; one condition per week) | Ankle-brachial index before and after the 6 min treadmill test |
Countries
Switzerland
Contacts
Primary ContactLucia Mazzolai, Prof
Outcome results
None listed