Table 2.

Lung diffusing capacity and cardiac output

	Rest				Exercise at 90% of Wpeak
	Young	Young Highly Fit	Old	Old Highly Fit	Young	Young Highly Fit	Old	Old Highly Fit
DLCO, ml·min−1·mmHg	28 ± 4	33 ± 4	17 ± 3*†	23 ± 5†	47 ± 6	53 ± 7	25 ± 3*†	37 ± 10*†#
DLNO, ml·min−1·mmHg	101 ± 22	112 ± 16	67 ± 10*†	85 ± 18†	153 ± 16	171 ± 18	87 ± 7*†	122 ± 30*†#
DLNO/DLCO, unitless	3.6 ± 0.4	3.4 ± 0.4	4.0 ± 0.6	3.8 ± 0.4	3.3 ± 0.3	3.2 ± 0.2	3.6 ± 0.2	3.3 ± 0.2
DmCO, ml·min−1·mmHg	45 ± 10	50 ± 7	30 ± 4*†	37 ± 8†	71 ± 12	77 ± 10	39 ± 3*†	54 ± 13*†#
Vc, ml	82 ± 20	95 ± 14	44 ± 9*†	68 ± 20†	127 ± 30	149 ± 15	66 ± 10*†	110 ± 29†#
Q̇, l/min	5.6 ± 2.0	6.2 ± 1.1	3.5 ± 0.6*†	5.1 ± 1.0	17.3 ± 3.1	20.3 ± 2.2	10.3 ± 1.6*†	14.7 ± 3.5†#

Values are reported as means ± SD. DL_CO, lung diffusing capacity for carbon monoxide; DLNO, lung diffusing capacity for nitric oxide; Dm_CO, alveolar-capillary membrane conductance; V_C, pulmonary-capillary blood volume; Q̇, cardiac output. Significance set at P < 0.05:

^*significantly different vs. Young;

^†significantly different vs. Young Highly Fit; and

^#significantly different vs. Old.