Cardiac Responses of Young Women to Conditioning for a 10 Kilometer Race

Abstract

Seven previously sedentary women (mean age, 19 yrs) participated in an 11-week running program (4-5 sessions/week) in preparation for a 10 km race. Training intensity was 80-85% of maximum heart rate reserve. Exercise duration began at 20 minutes/session and was lengthened 5 minutes/session every 2 weeks. A control group consisting of 4 women was also evaluated. Maximal oxygen uptake (V̇O₂max, ml/kg/min) increased 11% in the trained group and decreased 6% in the control group during the study (p < 0.05). Oxygen uptake, cardiac output (Q), and stroke volume (SV) increased significantly (p < 0.05) in the trained group during each of 3 levels of steady state cycle ergometer exercise (heart rate targets: 115, 135 and 155 beats/min, respectively). Arteriovenous oxygen difference (a- V̄O₂ diff) was not increased significantly after training. Resting left ventricular dimensions and performance evaluated by echocardiography also did not change significantly after training. It was concluded that short-term conditioning in this population results in an increased exercise Q without concomitant increases in left ventricular dimensions or arteriovenous oxygen difference.

Key words

Endurance training - women - cardiac output - echocardiography - left ventricle