J. Prioux et al., Effect of ageing on the ventilatory response and lactate kinetics during incremental exercise in man, EUR J A PHY, 81(1-2), 2000, pp. 100-107
Citations number
49
Categorie Soggetti
Physiology
Journal title
EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY
We investigated the effects of age on breathing pattern, mouth occlusion pr
essure, the ratio of mouth occlusion pressure to mean inspiratory flow, and
venous blood lactate kinetics during incremental exercise. Mouth occlusion
pressure was used as an index of inspiratory neuromuscular activity, and i
ts ratio to mean inspiratory flow was used as an index of the "effective im
pedance" of the respiratory system. Nine elderly male subjects [mean (SD) a
ge: 68.1 (4.8) years] and nine young male subjects [mean (SD) age: 23.4 (1.
3) years] performed an incremental exercise test on a bicycle ergometer. Af
ter a warm-up at 30 W, the power was increased by 30 W every 1.5 min until
exhaustion. Our results showed that at maximal exercise, power output, brea
thing pattern, and respiratory exchange values, with the exception of tidal
volume and the "effective impedance" of the respiratory system, were signi
ficantly higher in the young subjects. The power output and oxygen consumpt
ion values at the anaerobic threshold were also significantly higher in the
young men. At the same power output, the elderly subjects showed significa
ntly higher values for minute ventilation, respiratory equivalents for oxyg
en uptake and carbon dioxide output ((V) over dot CO2), mean inspiratory Gl
ow, occlusion pressure and lactate concentration than the young subjects. A
t the same (V) over dot CO2 below the anaerobic threshold (0.5, 0.75, 1.00
and 1.251 . min(-1)), minute ventilation and lactate concentration were als
o significantly higher in the elderly subjects. We observed a significantly
higher minute ventilation at (V) over dot CO2 values of 0.5, 0.75, 1.00(P
< 0.001) and 1.25 l . min(-1) (P < 0.05) in the elderly men, and a signific
antly higher lactate concentration at (V) over dot CO2 values of 1.00 (P <
0.05) and 1.25 l . min(-1) (P < 0.01). In conclusion, the ventilatory respo
nse in elderly subjects is elevated in comparison with that in young subjec
ts, both below and above the anaerobic threshold. This study demonstrates f
or the first time that this ventilatory increase, both below and above the
threshold, is partly due to an increased lactate concentration.