Cardiovascular effects of static and dynamic exercise

The cardiovascular response to static exercise has often been quantified on the basis of a comparison between static handgrip and dynamic cycling exercise. It is then difficult to make precise comparisons because the physical units of work are not compatible. If the data from dynamic exercise can be used to predict the cardiovascular response to zero movement (static exercise) this would suggest that static exercise is not fundamentally different from dynamic exercise. Using leg extension exercise which lasted for 1 min, a set of weights was lifted repeatedly 50 times/min, through three different distances. On each occasion, the heart rate, systolic time intervals (STI) and systemic arterial blood pressure were monitored non-invasively. Regression analysis of heart rate (HR) or blood pressure (BP) against the distance moved by the weights was used to predict the heart rate or blood pressure that would be expected for static exercise. In addition the same responses were measured following 1 min of static exercise during which the weights were held up but not moved. Five subjects, trained in leg extension exercise, completed the four exercise sessions in a random order. A constant force was produced in each variant of the protocol and in the static exercise it amounted to 50% maximal voluntary contraction (MVC). The forces developed and the distance the weights were lifted were monitored. During this sustained static exercise at relatively low intensity the cardiovascular changes could be predicted from the responses induced by dynamic exercise. It is suggested that other factors are important in determining the cardiovascular response to exercise, not simply the mode.