Effect of Endurance Training on Cardiovascular Response to Static Exercise Performed with Untrained Muscles*

Eighteen male volunteers (20-23 years) were submitted to 13 weeks of training consisting of 30 min of exercise (at 50%-75% VO2max) on a bicycle ergometer, performed three times a week. Every 4 weeks the heart rate (HR), blood pressure (BP), and systolic time interval (STI) responses to the static handgrip (at 30% MVC) were examined. Before and after 13 weeks of training echocardiograms were recorded in seven subjects at rest and during the handgrip. Significant decreases in HR and BP responses to static exercise were found already after 4 weeks of training. Resting STI and left ventricular dimensions were not affected by training, but during the static exercise the pre-ejection period (PEP) and isovolumic contraction time interval (ICT) at the corresponding HR were significantly shortened after 8 weeks of training. The values of echocardiographic indices of left ventricular function obtained during exercise after training did not differ significantly from those found before training. It is concluded that endurance training of moderate intensity improves cardiac function during static exercise performed with untrained muscles.