Table 3.

A, Blood flow per unit mass of muscle (ml min⁻¹ (100 g)⁻¹) and B, total muscle blood flow (ml min⁻¹) in the exercising (left) knee extensor muscles at the beginning and end of fatiguing contractions across force and position tasks

	Beginning, blood flow, ml min−1 (100 g)−1, mean ± s.d.		End, blood flow, ml min−1 (100 g)−1, mean ± s.d.
	Young men	Old men	Young men	Old men
A
Knee extensors	6.64 ± 2.03	9.76 ± 5.34†	9.83 ± 3.86§	13.76 ± 7.27†§
Rectus femoris	6.33 ± 2.41	7.90 ± 6.02	9.09 ± 3.49	12.21 ± 7.61
Vastus lateralis	6.21 ± 1.96	8.77 ± 6.27	9.77 ± 3.82‡	11.12 ± 7.33
Vastus medialis	5.66 ± 1.38	8.08 ± 2.6*	7.80 ± 3.00	12.13 ± 5.11*
Vastus intermedius	8.37 ± 1.29	14.27 ± 3.32†	12.66 ± 3.82§	19.59 ± 6.44*‡
B
Knee extensors	83.9 ± 17.9	82.5 ± 22.8	124.3 ± 39.5‡	116.6 ± 35.2‡
Rectus femoris	13.1 ± 5.3	7.6 ± 5.5	18.9 ± 8.0	13.4 ± 11.6
Vastus lateralis	22.5 ± 7.5	20.6 ± 13.8	35.2 ± 12.9‡	26.4 ± 17.5
Vastus medialis	21.6 ± 7.1	23.1 ± 10.5	29.8 ± 13.9	33.0 ± 10.6
Vastus intermedius	26.2 ± 6.6	32.5 ± 7.4	39.7 ± 13.5‡	44.0 ± 9.9‡

Muscle volumes of the left extensors were converted from cm³ into weight (g) by multiplying by an estimated density of 1.04 g ml⁻¹ to calculate total muscle blood flow (ml min⁻¹).

^*P < 0.05 and

^†P < 0.01 between young and old men.

^‡P < 0.05 and

^§P < 0.01 between the beginning and end of tasks within a group.