Interaction between hypoxia and training on NIRS signal during exercise: Contribution of a mathematical model
| Autor: | Pascal Mollard, Nicolas Bourdillon, Michèle Beaudry, Jean-Paul Richalet, Murielle Letournel |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
Adult
Male Pulmonary and Respiratory Medicine medicine.medical_specialty Physiology chemistry.chemical_element Physical exercise Models Biological Oxygen Hemoglobins Young Adult Heart Rate Internal medicine medicine Humans Respiratory system Exercise physiology Hypoxia Exercise Spectroscopy Near-Infrared General Neuroscience Venous blood Models Theoretical Hypoxia (medical) Surgery Pulmonary Alveoli chemistry Multivariate Analysis Exercise Test Physical Endurance Exercise intensity Cardiology Arterial blood Blood Gas Analysis medicine.symptom |
| Zdroj: | Respiratory Physiology & Neurobiology. 169:50-61 |
| ISSN: | 1569-9048 |
| Popis: | Acute exposure to hypoxia provokes a decrease in peak oxygen consumption ( V(O)(2peak)). At and above 4000 m, the decrease in V(O)(2peak) is greater than expected from the decrease in arterial oxygen content (C(a)O(2)) suggesting the participation of other factors. We hypothesized that O(2) transfer within the active muscle may play a role. Therefore we used Near Infra Red Spectroscopy (NIRS) to assess oxy (O2Hb) and deoxyhemoglobin (HHb) concentration in the vastus lateralis of trained athletes (TA) and untrained subjects (US) exercising at various inspired oxygen pressure (PI(O)(2), 131.4, 107.3 and 87.0 mmHg). A mathematical model has been developed to compute: (i) the pulmonary (K(p)) and muscular (K(tm)) O(2) diffusion coefficients and (ii) the proportion of arteriolar:capillary:venous blood participating in the NIRS signal at every exercise intensity from rest to peak exercise in the normoxic and various hypoxic conditions. In TA, O2Hb decreased near maximal exercise at 2500 and 4000 m, while in US, altitude had no effect. In normoxia O2Hb was higher in TA than in US, the difference disappearing in hypoxia. K(tm) increased linearly with workload and altitude and was higher in TA than US while K(p) plateaued near maximal exercise, which was consistent with athletes' greater decrease in C(a)O(2). The greater participation of arterial blood in the NIRS signal in TA at altitudes account for their higher O2Hb values as well as the greater decrease they underwent in hypoxia. At 4000m, athletes loose their advantages of adaptation to training due to a reduced arterial content, and both from NIRS variables and model output, characteristics of O(2) transfer of TA converge toward those of US. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect