Ventilation response to CO2 and exercise-induced hypoxaemia in master athletes.
Exercise-induced hypoxaemia (EIH) in master athletes may be related to a diminished exercise hyperpnoea. The aim of this study was to determine whether EIH is associated with a change in the sensitivity of the ventilation response to activation of the central chemoreceptors. The ventilation response to CO2 was measured in nine elderly untrained men (UT) [mean age 66.3 (SEM 3.1) years] and nine master athletes (MA) [mean age 62.7 (SEM 0.8) years] at rest, during moderate exercise (40% maximal oxygen uptake, VO2max), and during strenuous exercise (70% VO2max) using the rebreathing method. Our results showed that the ventilation response to CO2 did not differ with endurance training and/or exercise, that the threshold of the CO2 response (Th) increased with exercise (P < 0.001), that the increase in Th in MA was higher than in UT between rest and moderate exercise [deltaTh(0-40): 8.55 (SEM 1.8) vs 3.06 (SEM 1.72) mmHg, P < 0.05], and that deltaTh(0-40) and Th during moderate exercise were negatively correlated with arterial O2 saturation during maximal exercise (r=0.50, P<O0.05). We concluded therefore that exercise-induced hypoxaemia in master athletes may not be due to a lower ventilation response to CO2, but may be partly related to a greater increase in Th during moderate exercise.
Mucci
P
P
Laboratoire de Physiologie des Interactions, Hôpital Arnaud de Villeneuve, Montpellier, France.
Prioux
J
J
Hayot
M
M
Ramonatxo
M
M
Préfaut
C
C
D000368:Aged; D002245:Carbon Dioxide / Q000008:administration & dosage* / Q000502:physiology*; D002628:Chemoreceptor Cells / Q000187:drug effects / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology; D006985:Hyperventilation / Q000209:etiology / Q000503:physiopathology; D000860:Hypoxia / Q000209:etiology* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D010108:Oxyhemoglobins / Q000378:metabolism; D010807:Physical Endurance / Q000502:physiology; D012119:Respiration / Q000187:drug effects* / Q000502:physiology*
D010108:Oxyhemoglobins; D002245:Carbon Dioxide; D010100:Oxygen