MUSCLE OXYGEN SUPPLY AND OXYGENATION IN FOREARM AREA DURING SUSTAINED ISOMETRIC CONTRACTION

The muscle oxygen supply is determined by many factors; vasoconstriction, driving forces, vasodilation, mechanical factors.

PURPOSE

In order to identify the mechanism of peripheral circulation, we measured the blood vessel structure and muscle oxygen status in the forearm area during a high intensity of static handgrip exercise.

METHODS

The artery diameter (Di) and mean blood flow velocity (MBV) in the ulnaris and radial arteries were measured by an ultrasound Doppler imaging device. Muscle HbO2 values (o.d.) were determined in the flexor carpi ulnaris and brachioradialis muscles using a multiple continuous near infrared imaging device. Seven healthy subjects performed the 1min-sustained isometric handgrip exercise without thumb at 60%MVC.

RESULTS

During the trial, there were no significant differences in Di between the two arteries. The MBV in the ulnaris and radial arteries were similar during muscle contraction (3.8 vs. 3.6cm/sec, n.s.). During recovery, the MBV in the ulnaris artery was significantly higher compared with the radial artery (14.5 vs. 10.0cm/sec, p < 0.05). The flexor carpi ulnaris muscle had a larger deoxygenation (−0.25 vs. −0.11 o.d., p < 0.05) during contraction and it has a larger re-oxygenation (0.12 vs. 0.05 o.d., p < 0.05) during recovery compared with the brachioradialis muscle.

CONCLUSION

Although the ulnaris artery diameter and flow velocity did not change during higher muscle contraction, the higher blood flow velocity and greater re-oxygenation during recovery suggested that a larger circulatory compromise occurred in capillary beds in the ulnaris area compared with the brachioradialis area.