Intra- and extravascular volume changes in the human forearm after static hand grip exercise.

Studies have been conducted to evaluate intra- and extravascular volume changes and blood flow in the exercising human forearm by means of (1) combining plethysmographic and scintigraphic methods, (2) an indirect procedure using the relationship of blood flow and volume change from reactive hyperemia. A static hand grip exercise of 60% maximal voluntary contraction and 30 s duration increased the forearm volume by 3.03 +/- 0.65 ml/100 ml soft tissue, involving both the intra- and extravascular volume components. There is a quantitative and qualitative difference in the time course of change in these components, showing an extravascular part of about 50% for the 2-min post-exercise value and a substantially slower rate of recovery. Experiments involving muscle work at intervals (50% maximal voluntary contraction, 30 s duration, 2-min intervals) caused a further increase in extravascular volume. Furthermore, the study suggests that the flow-volume relationship from reactive hyperemia may be considered to be available for the determination of local blood volume changes in exercise hyperemia. The results are discussed in connection with the influence of anaerobic muscle metabolism and conclusions referring to this are drawn about the use of plethysmographic methods.