Methods
We thus enrolled both inactive and active (endurancetrained)
healthy men to evaluate whether physical activity
and age were correlated with VC at rest and with the
increase in lung diffusion of CO (DLCO) on exercise.
Physical activity was evaluated using the French version
of the International Physical Activity Questionnaire
(IPAQ, long form) [8] that evaluates vigorous, moderate
and walking activity domains. The resting VC was calculated
using DLCO and lung diffusion of NO (DLNO)
measured simultaneously by the single-breath technique
(4 seconds breath-hold, corrected for haemoglobin, assuming
negligible erythrocyte resistance to NO [9], using
an automatic apparatus (MasterScreenBody, Jaeger), as
previously described [10]). VC measurements were also
obtained at two levels of exercise (warm-up period and
at 50% of the maximal work rate: see Figure 1, experimental
protocol) to calculate the slope of the DLCO/
work relationship as an index evaluating the dynamic capillary
blood volume recruitment/dilation on exercise.
The linearity of the relationship between power and
DLCO has been demonstrated for V_ 2 ≤60% of V_ O2;peak