Year

1996

Degree Name

Master of Science (Hons.)

Department

Department of Biomedical Science

Abstract

Cardiovascular responses of trained male Cyclists (20.30 ±1.11 years; n=10), trained Runners (26.20 ±1.10 years; n=10), and fit but untrained Controls (22.00 ±0.75 years; n=10) were examined at supine and upright rest, and during passive cycle exercise. Mean maximal aerobic power of Cyclists (76.25 ±1.44 ml.kg-1.min-1) and Runners (65.50 ±2.16 ml.kg-1.min-1 was significantly higher (p<0.05) than that of Controls (46.31 ±2.36 ml.kg -1.min-1. Resting heart rate of Cyclists (58.43 ±2.69 b.min-1), Runners (57.21 ±3.47 b.min-1, and Controls (65.38 ±2.93 b.min-1) was not significantly different (p>0.05). Impedance cardiography was used to examine the response of heart rate, stroke volume, cardiac output, contractility of the heart, and arteriolar resistance, during passive cycle exercise at three different intensities (30 rpm, 60 rpm, and 80 rpm). Blood pressure and rate pressure product were measured throughout exercise. The vagal influence on the heart was assessed through time series analysis of heart rate variability at low (0.07-0.11 Hz) and high frequencies (0.12-0.40 Hz). Electromyography was used to ensure that passively moved muscles did not contract. Cardiovascular response was compared for all subjects combined and between the three groups (Cyclists, Runners, and Controls).

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