Tilted and non-tilted postischaemic exercise peak flow in the legs of normal human subjects.

Peak flow was measured by radioactive xenon in fifteen normal subjects in the anterior tibial muscle after maximal ischaemic exercise. The postischaemic exercise peak flow was 75 +/- 13 ml/100 g muscle/min (mean +/- SD), when the test was performed while the subjects rested in the horizontal position. When the same test was performed with the subjects resting in a 45 degrees feet down tilted position, the peak flow increased very much, about 65%, and averaged 125 +/- 17 ml/100 g muscle/min. The increased peak flow in the feet tilted position is explained by passive dilatation of the vessels due to increased hydrostatic pressure. It is suggested, that measurement of maximal ischaemic exercise blood flow in the tilted position may be a more sensitive procedure for detection of minimal vascular changes due to the very high blood flow obtained.