Table 2.

Blood variables at rest and during 6 min of low- (LI) and high-intensity (HI) knee-extensor exercise

	Low intensity					High intensity
	Rest	30 s	60 s	3 min	6 min	Rest	30 s	60 s	3 min	6 min
Blood lactate (mmol−1)
Artery	0.7 ± 0.0	0.7 ± 0.1	0.8 ± 0.1	0.9 ±0.1	0.9 ± 0.1	0.6 ± 0.1	0.7 ± 0.1	1.1 ± 0.1	2.4 ± 0.4#	3.3 ± 0.6#
Vein	0.7 ± 0.1	0.9 ± 0.1	0.9 ± 0.1	0.9 ± 0.1	0.8 ± 0.1	0.7 ± 0.1	1.6 ± 0.1#	2.5 ± 0.3#	4.2 ± 0.7#	5.3 ± 0.9#
Blood pH (−log H+)
Artery	7.40 ± 0.01	7.38 ± 0.01	7.38 ± 0.01	7.37 ± 0.01	7.38 ± 0.01	7.38 ± 0.01#	7.38 ± 0.01	7.36 ± 0.00#	7.35 ± 0.01#	7.35 ± 0.01#
Vein	7.34 ± 0.01	7.36 ± 0.01	7.33 ± 0.01	7.31 ± 0.01	7.30 ± 0.01	7.35 ± 0.01	7.34 ± 0.01	7.27 ± 0.01#	7.21 ± 0.01#	7.19 ± 0.01#
Blood (mmHg)
Artery	41.6 ± 0.7	43.8 ± 0.9	43.0 ± 0.5	43.6 ± 0.8	43.3 ± 1.3	42.4 ± 0.7	41.4 ± 0.6	42.9 ± 0.3	42.0 ± 0.6	38.6 ± 0.3#
Vein	57.2 ± 2.5	52.3 ± 1.4	57.2 ± 1.7	60.8 ± 2.1	63.8 ± 1.9	51.1 ± 1.3#	50.3 ± 0.7	60.6 ± 1.5	73.6 ± 2.8#	74.5 ± 3.1#
Blood HCO3− (mmol l−1)
Artery	24.5 ± 0.3	25.0 ± 0.4	24.4 ± 0.3	24.5 ± 0.4	24.4 ± 0.7	24.0 ± 0.2	23.6 ± 0.2	23.7 ± 0.2	22.3 ± 0.1#	20.6 ± 0.2#
Vein	28.6 ± 0.9	27.7 ± 0.4	28.7 ± 0.6	29.0 ± 0.6	29.7 ± 0.7	26.5 ± 0.4	28.7 ± 1.5	27.1 ± 0.2#	27.1 ± 0.3#	26.1 ± 0.3#
Plasma K+ (mmol l−1)
Artery	4.0 ± 0.0	4.1 ± 0.1	4.2 ± 0.0	4.3 ± 0.1	4.2 ± 0.0	4.2 ± 0.1	4.3 ± 0.1	4.6 ± 0.0#	4.9 ± 0.1#	5.0 ± 0.1#
Vein	4.1 ± 0.0	4.7 ± 0.1	4.8 ± 0.1	4.8 ± 0.1	4.7 ± 0.0	4.3 ± 0.1	5.3 ± 0.1#	5.4 ± 0.1#	5.7 ± 0.1#	5.6 ± 0.1#
Hb (g dl−1)
Artery	9.2 ± 0.1	9.0 ± 0.2	9.1 ± 0.1	9.1 ± 0.2	9.1 ± 0.2	8.8 ± 0.1	8.9 ± 0.1	8.9 ± 0.1	9.0 ± 0.1	9.1 ± 0.2
Vein	9.1 ± 0.2	9.2 ± 0.2	9.2 ± 0.2	9.2 ± 0.1	9.2 ± 0.1	8.8 ± 0.1	8.9 ± 0.1	9.0 ± 0.1	9.1 ± 0.1	9.2 ± 0.2

Data are presented as means ± SEM.

^#Denotes significant difference from LI.