CARDIOVASCULAR-RESPONSES TO SUSTAINED MAXIMAL ISOMETRIC CONTRACTIONS OF THE FINGER FLEXORS

This study investigated cardiovascular responses to 2 min sustained su bmaximal (20% MVC) and maximal (100% MVC) voluntary isometric contract ions of the finger flexors in healthy young women. Cardiovascular vari ables investigated were: heart rate (f(c)), mean arterial pressure (P( a)BAR), and stroke volume (SV). Doppler echocardiography was used to e stimate SV from measures of aortic diameter (AD) and time-velocity int egrals. Preliminary studies indicated that AD did not change significa ntly after 2 min sustained 100% MVC. Therefore, pre-exercise AD values were used to calculate SV before, during and after exercise. During t he 2-min 100% MVC period, f(c) and P(a)BAR increased significantly dur ing the first 30 s of contraction. f(c) then remained constant during the remainder of the 2-min contraction period, while P(a)BAR continued to rise. SV did not change significantly during the 100% MVC task but increased significantly during recovery from sustained 100% MVC. The data suggest that the magnitude of cardiovascular responses to isometr ic exercise is dependent on the specific task performed, and that ther e is a different pattern of response for f(c), P(a)BAR, and SV during 20% and 100% MVC tasks. Unlike f(c) and P(a)BAR, SV did not change sig nificantly during isometric exercise, but increased significantly afte r sustained 100% MVC.