Abstract

10 healthy males performed single (<1 s), sustained and intermittent plantarflexions (up to 40 s) of one foot in sitting exercise position. 2 different absolute forces were applied: 5-10 and 25-30 MVC. Blood velocity was continuously recorded in the proximal a. femoralis by Doppler technique. Heart rate (HR) and blood pressure (BP) were simultaneously determined by ECG and FINAPRES-tm method. Despite the distance between the proximal a. femoralis and the exercising muscle Doppler data showed: effects of single contractions on individual Doppler data, the influence of consecutive contractions, variiation with exercise intensity and differences between sustained and intermittent contractions. In all tests there was an immediate increase in blood velocity at onset of exercise. The major part (52-73) of the response to the 40 s tests was seen during the first 6 s. It was followed by a second phase of adjustment which depended on the type of exercise and exercise intensity. The single plantarflexion provoked increases in blood velocity for about 20 s. Comparison of HR and BP tracings with Doppler data demonstrated the importance of local mechanical factors for the perfusion of the exercising muscle. The early adjustment of muscle perfusion were not correlated to the systemic blood pressure and appeared to be related to muscle pump effects. The subsequent flow values were influenced by passive vessel compression and changes in local vasomotor tone. Fast withdrawal of vessel compression determined post-exercise flow kinetics. Verf.-Ref.