Does limb angular motion raise limb arterial pressure?

AIM

Mechanical factors such as the muscle pump have been proposed to augment flow by several mechanisms. The potential for limb angular motion to augment local perfusion pressure (pressure = (1/2)rhor(2)omega(2), where rho is the fluid density, r the radius and omega the angular velocity) has been overlooked. We sought to test the hypothesis that limb angular motion augments limb arterial pressure.

METHODS

Nine human subjects performed horizontal shoulder flexion ( approximately +/-90 degrees at 0.75 Hz for 30 s). We measured finger arterial pressure (photoplethysmography) in the moving (Trial 1) and non-moving arm (Trial 2) in separate trials along with the pressure (strain gauge) generated at the fingers within a length of water-filled tubing mounted on the moving arm in both trials.

RESULTS

Arm swinging raised (P < 0.05) the mean pressure measured in the tubing by 11 +/- 2 and 14 +/- 2 mmHg (Trials 1 and 2 respectively). In response to exercise, the rise in mean finger arterial pressure in the swinging limb (18 +/- 3 mmHg, Trial 1) exceeded (P < 0.05) the rise in the resting limb (8 +/- 2 mmHg, Trial 2) by an amount similar to the 11 mmHg rise in pressure generated in the tubing in Trial 1.

CONCLUSIONS

We conclude that the swinging of a limb creates centrifugal force (a biomechanical centrifuge) which imparts additional pressure to the arteries, but not the veins owing to the venous valves, which further widens the arterial-venous pressure difference.