To our knowledge, the measurement of the transcutaneous oxygen pressure during walking is the only continuous method that estimates the importance of ischemia, bilaterally and segment of limb by segment of limb. The determination of the lactates concentration, with micro method from earlobe sampling, is very widely validated in physiology and exercise physiopathology; and it is widely used, by laboratories, for exercise investigation in athletes. We use it in routine to evaluate the presence of functional limitation during tcpO2 tests on a treadmill.

The present study hypothesises a significant relationship between lactatemia variation (difference between lactatemia after 3 minutes of recovery from walking and the value at rest) and tcpO2 "decrease from rest of oxygen pressure (DROP) values for patients with peripheral artery disease (PAD).

Lactates sample (100 microliter) will be collected at rest Ankle brachial index is measured at rest transcutaneous oxygen pressure is measured at the chest, calves and buttocks and results will be expressed as the minimal value of the DROP index (Limb changes minus chest changes) Patients walk on treadmill (2MPH 10% slope) until exertional limb pain. Lactates sample (100 microliter) will be collected at minute 3 of recovery from walking Correlation of lactate increase to the sum of DROP values wil be studied

Inclusion Criteria:

• Age > 18 years old
• Patient able to walk on a treadmill
• Patient covered by the French health insurance
• Patient able to understand the protocol
• Patient agrees to be involve in the protocol and sign the consent form

Exclusion Criteria:

• Patient refuses to participate at the this protocol
• Patient has a wash-out period for another clinical trial

Patient with peripheral artery disease