Cardiovascular responses to sustained maximal isometric contractions of the finger flexors.
This study investigated cardiovascular responses to 2 min sustained submaximal (20% MVC) and maximal (100% MVC) voluntary isometric contractions of the finger flexors in healthy young women. Cardiovascular variables investigated were: heart rate (fc), mean arterial pressure (Pa), and stroke volume (SV). Doppler echocardiography was used to estimate SV from measures of aortic diameter (AD) and time-velocity integrals. Preliminary studies indicated that AD did not change significantly after 2 min sustained 100% MVC. Therefore, pre-exercise AD values were used to calculate SV before, during and after exercise. During the 2-min 100% MVC period, fc and Pa increased significantly during the first 30 s of contraction. fc then remained constant during the remainder of the 2-min contraction period, while Pa 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 isometric exercise is dependent on the specific task performed, and that there is a different pattern of response for fc, Pa, and SV during 20% and 100% MVC tasks. Unlike fc and Pa, SV did not change significantly during isometric exercise, but increased significantly after sustained 100% MVC.
Smith
D L
DL
Department of Physical Education and Dance, Skidmore College, Saratoga Springs, NY 12866.
Misner
J E
JE
Bloomfield
D K
DK
Essandoh
L K
LK
D000328:Adult; D001011:Aorta / Q000033:anatomy & histology; D001794:Blood Pressure; D002320:Cardiovascular Physiological Phenomena; D015150:Echocardiography, Doppler; D005260:Female; D005385:Fingers; D006339:Heart Rate; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D007700:Kinetics; D013318:Stroke Volume