Blood flow in the triceps brachii muscle in humans during sustained submaximal isometric contractions

The main purpose of this study was to determine the extent to which blood f low through the profunda artery within the triceps brachii muscle may be co mpromised during maintained low-force isometric fatiguing contractions. Dop pler ultrasound techniques were used to record mean blood velocity and arte rial diameter of the profunda brachii artery during sustained isometric con tractions of 20% maximal voluntary contraction. The arterial diameter did n ot change throughout the contraction. Thus, blood velocity was considered t o be an indicator of blood flow. The mean blood velocity increased initiall y and then remained constant during the contraction period. When compared t o rest [0.06 (SD 0.03)m s(-1)] mean blood velocity was significantly larger at the start of the contraction [0.13 (SD 0.07) m s(-1)] and larger yet du ring recovery following the contraction [0.30 (SD 0.14)m s(-1)]. Although b lood flow through the conduit artery did not drop during the contraction, t he post-contraction hyperaemia suggested that circulatory compromise might have occurred at the level of the capillary beds.