| Date : 01/10/2015 Intervenant : Marie Gernigon Affiliation : EuroMov, University of Montpellier |
| Résumé : An imbalance starts between the supply of oxygen to the engaged muscle lead to stop the exercise. The first part of the present work aims to assess the maximal oxygen uptake (V ̇O2max) that represents the integrated response of the cardiovascular, respiratory and muscular systems to take up, distribute and use oxygen during exercise to volitional exhaustion and is one of the most widely used diagnostic tests for both athletic and clinical population groups. A V ̇O2max is typically confirmed by the presence of a plateau despite the increase of exercise intensity. The V ̇O2max plateau results from an imbalance starts between the supply of oxygen to the engaged muscle during an incremental work load test. Despite the significance of the V ̇O2max plateau, there are profound variations in reported response rates. The aim of this first work aims to investigate the effect of exercise modality on the incidence of plateau responses at V ̇O2max. First, it appears that a prior priming exercise, a treadmill-based exercise as well as the prior knowledge of trial number promote an increased incidence of the plateau at V ̇O2max. Moreover, the incidence of plateau at V ̇O2max is unaffected by an acute blood donation. Indeed, there is no change in exercise time to exhaustion while a ~9 % reduction in blood O2-carrying capacity. The present studies strongly suggest that achieving a plateau at V ̇O2max is dependent on anaerobic substrate metabolism and hence the size of an individual’s anaerobic capacity. The second part of the present work aims to assess of the walking limitations in Peripheral Arterial Diseased (PAD) patients with symptoms of intermittent claudication (IC) resulting from ischemia induced by exercise. A revascularization is indicated below the cut-off point of 300 m. In clinical routine, the maximal walking distance (MWD) is usually assessed with clinical questionnaires, a highly subjective method, and with walking treadmill tests that are design-dependent and that hardly reproduce the usual leg pain of the patients during the walk. Therefore, the aim of this second work is to test the validity of innovative methodologies based on GPS and Transcutaneous Pressure in Oxygen (TcPO2) during a treadmill test with respect to the assessment of the functional limitation in PAD patients. First, it appears that scores of the Estimation of Ambulatory Capacity by History-Questionnaire and MWD that is declared by the patients are more related to the GPS-measured MWD (that reflects the spontaneous walking pattern) than to the scores of the Walking Impairment Questionnaire, the 6-min walking test, and the walking treadmill test. Moreover, the GPS is an acute and reliable tool to assess the effects of therapeutic management such as revascularization. In addition, it appears that the GPS average walking speed is a key marker to characterize the evolution of functional impairment in PAD patients with claudication. The last study evidences the relevance of the use of TcPO2 during a walking treadmill test in detecting ischemia during exercise among patients with normal ankle to brachial Index that report leg pain. |