Table 5.

Arterial and venous blood-gas responses at rest and with incremental exercise during normoxia and hypoxia in men and women

	Normoxia			Hypoxia
	Rest	10%	20%	Rest	10%	20%
Young adults
Men (n = 16)
SaO2, %	97 ± 0	97 ± 0	97 ± 0	81 ± 1*	82 ± 1*	82 ± 0*
PaO2, Torr	103 ± 2	104 ± 2	107 ± 2	46 ± 1*	47 ± 1*	48 ± 1*
PvO2, Torr	40 ± 3	28 ± 2†	28 ± 1†	29 ± 1*	24 ± 1*†	25 ± 1*
Arterial O2 content, ml/1	189 ± 4	189 ± 5	190 ± 4	157 ± 4*	161 ± 4*	165 ± 5*
Venous O2 content, ml/1	129 ± 8	85 ± 6†	88 ± 5†	95 ± 6*	74 ± 6*†	76 ± 7*†
a-v O2, ml/1	61 ± 6	104 ± 6	102 ± 6	63 ± 5	87 ± 7*	88 ± 6*
O2 consumption, ml/min	4.6 ± 0.7	26.2 ± 2.4†	42.9 ± 3.3†	5.1 ± 0.5	25.2 ± 2.4†	42.5 ± 3.7†
Normalized for FAV, ml×min−1×100 ml−1	0.37 ± 0.06	2.34 ± 0.19†	3.86 ± 0.27†	0.43 ± 0.05	2.26 ± 0.20†	3.84 ± 0.33†
Women (n = 15)
SaO2, %	97 ± 0	97 ± 0	97 ± 0	83 ± 1*	83 ± 1*	83 ± 1*
PaO2, Torr	109 ± 2	112 ± 2	110 ± 2	49 ± 1*‡	49 ± 1*	49 ± 1*
PvO2, Torr	39 ± 2	25 ± 1†	27 ± 1	30 ± 1*	23 ± 1*†‡	24 ± 1*†
Arterial O2 content, ml/1	160 ± 3‡	161 ± 3‡	161 ± 3‡	135 ± 3*‡	138 ± 2*‡	140 ± 2*‡
Venous O2 content, ml/1	108 ± 6‡	61 ± 3†‡	67 ± 3†‡	82 ± 3*	55 ± 3*†‡	54 ± 2*†‡
a-v O2, ml/1	52 ± 6	100 ± 3†	95 ± 3†	53 ± 4	83 ± 4*†	86 ± 3*†
O2 consumption, ml/min	2.0 ± 0.3‡	13.9 ± 1.3†‡	21.1 ± 2.1†‡	2.4 ± 0.3‡	14.0 ± 1.4†‡	23.4 ± 2.2*†‡
Normalized for FAV, ml×min−1×100 ml−1	0.27 ± 0.04	1.85 ± 0.17†	2.82 ± 0.30†‡	0.32 ± 0.04	1.87 ± 0.20†	3.13 ± 0.32*†
Older adults
Men (n = 5)
SaO2, %	97 ± 0	96 ± 0	96 ± 0	82 ± 1*	80 ± 1*	81 ± 1*
PaO2, Torr	101 ± 2	96 ± 1	97 ± 3	45 ± 1*	43 ± 1*	46 ± 1*
PvO2, Torr	38 ± 2	26 ± 2†	25 ± 1†	31 ± 2*	23 ± 1*†	22 ± 1*†
Arterial O2 content, ml/1	182 ± 5	191 ± 6	191 ± 5	153 ± 5*	154 ± 6*	161 ± 4*
Venous O2 content, ml/1	140 ± 13	89 ± 10†	80 ± 8†	115 ± 5*	73 ± 8*†	70 ± 5†
a-v O2, ml/1	51 ± 4	102 ± 9†	110 ± 7†	38 ± 6*	81 ± 5*†	91 ± 3*†
O2 consumption, ml/min	4.0 ± 0.4	26.4 ± 3.6†	46.5 ± 6.3†	3.2 ± 0.4	25.5 ± 3.3†	42.1 ± 5.7†
Normalized for FAV, ml×min−1×100 ml−1	0.40 ± 0.05	2.69 ± 0.53†	4.69 ± 0.83†	0.32 ± 0.19	2.59 ± 0.51†	4.21 ± 0.67†
Women (n = 6)
SaO2, %	97 ± 0	96 ± 0	96 ± 0	81 ± 1*	80 ± 1*	80 ± 1*
PaO2, Torr	99 ± 3	98 ± 3	96 ± 3	47 ± 1*	46 ± 1*‡	46 ± 2*
PvO2, Torr	36 ± 3	24 ± 2†	28 ± 4	31 ± 2*‡	22 ± 1*†	24 ± 1*†
Arterial O2 content, ml/1	161 ± 7‡	164 ± 8‡	168 ± 8‡	136 ± 7*‡	138 ± 5*‡	140 ± 7*‡
Venous O2 content, ml/1	108 ± 10	65 ± 7†	77 ± 18†	95 ± 14*‡	59 ± 1†	59 ± 7*†
a-v O2, ml/1	53 ± 10	99 ± 6†	91 ± 11†	41 ± 9*‡	80 ± 6*†	81 ± 5†
O2 consumption, ml/min	2.9 ± 0.6	16.5 ± 1.5†‡	23.1 ± 4.0†‡	2.3 ± 0.5	15.4 ± 1.5†‡	22.0 ± 2.0†‡
Normalized for FAV, ml×min−1×100 ml−1	0.43 ± 0.10	2.42 ± 0.25†	3.37 ± 0.58†	0.33 ± 0.19	2.24 ± 0.22†	3.18 ± 0.28†

Values are means ± SE; n, no. of subjects. Sa_O2, arterial O₂ saturation; Pa_O2, arterial Po₂; Pv_O2, venous Po₂; a-v, arterial-venous.

^*P < 0.05 vs. normoxia.

^†P < 0.05 vs. rest.

^‡P < 0.05 vs. men.