Hemodynamic Responses to Isometric Contractions of the Finger Flexor and Leg Extensor Muscle Groups in Men 18-30 and 50-70 Years of Age
Van Loan, Marta Diane
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https://hdl.handle.net/2142/71876
Description
Title
Hemodynamic Responses to Isometric Contractions of the Finger Flexor and Leg Extensor Muscle Groups in Men 18-30 and 50-70 Years of Age
Author(s)
Van Loan, Marta Diane
Issue Date
1985
Department of Study
Physical Education
Discipline
Physical Education
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Education, Physical
Abstract
The central circulatory responses of individuals 18-30 and 50-70 years of age were assessed while performing isometric hand-grip and isometric leg extension tests. The object was to ascertain which cardiovascular variables(s), heart rate, stroke volume, cardiac output, total peripheral resistance, systolic blood pressure, diastolic blood pressure, pulse pressure, and mean arterial pressure demonstrated significantly different responses to isometric exercise between the two age groups. Twenty-four, normal, healthy males, 18-30 years of age, and twenty-four, normal healthy males, 50-70 years of age served as subjects. Each subject performed four hand-grip and four leg extension tests at 15, 30, 45 and 60% of their maximal voluntary contraction (MVC) capacities. Heart rate and stroke volume were recorded continuously for the twenty-five second pre-exercise rest period and for the forty-five second contraction period. Systolic and diastolic blood pressures were recorded once during the pre-exercise rest period and twice, at twenty second intervals, during the contraction period. All four variables were measured immediately upon cessation of the contraction and at thirty second intervals for a two minute recovery period. Analysis of variance indicated a significant group affect for systolic (p < .005) and diastolic (p < .001) blood pressure. The older subjects demonstrated higher blood pressures during exercise than did the young subjects. The average increase in systolic pressure, during all contractions, for the young subjects was 22 mmHg compared to a change of 27 mmHg for the older subjects. Diastolic blood pressure also showed a difference between the two groups, with an increase of 15 mmHg for the young subjects and 17 mmHg for the older subjects. Heart rate, stroke volume, cardiac output and total peripheral resistance demonstrated a significant group affect during exercise (p < .000). The young subjects had higher heart rates, stroke volumes, cardiac outputs and lower total peripheral resistance than did the older subjects. A difference was demonstrated between the main affect of arm and leg isometric contractions for heart rate (p < .000), stroke volume (p < .000), cardiac output (p < .001), systolic pressure, (p < .001), and diastolic blood pressure. Hand-grip exercises elicited significantly lower responses in heart rate, stroke volumes, systolic pressures and diastolic pressures as compared to the observed responses during isometric leg extension exercises. Discriminant analysis indicated that stroke volume was the variable that best distinguished between the two age groups.
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