Comparison of Hemodynamic and Left Ventricular Responses to Increased After-Load in Healthy Males and Females

Abstract

Hemodynamic and left ventricular responses were studied echocardiographically in 20 males (31.5 +/- 4.5 yrs) and 20 females (30.4 +/- 4.3 yrs) at rest and during 3 min of isometric deadlift exercise at 30% of maximum voluntary contraction. Maximal tension exerted was significantly (P less than .001) lower in the female group (87.4 +/- 8.1 kg) compared with the male group (127.3 +/- 15 kg). Significant (P less than .001) increases in heart rate and contractility index were noted in both groups during exercise compared to the resting values. Mean arterial blood pressures were significantly (P less than .05) higher in the males at rest and during exercise. Ejection fraction and fractional shortening, both at rest and during exercise, differed significantly (P less than .05) between the two groups. It was raised by exercise only in the males (from 62 +/- 5% to 65 +/- 5% and 32 +/- 4% to 35 +/- 4%, respectively) but remained unchanged in the females. No significant changes in end diastolic dimension and stroke volume were observed in either group during exercise. End systolic dimension was significantly (P less than .001) lower during exercise in females and males (from 3.25 +/- .23 to 3.1 +/- .26 and 3.12 +/- .33 to 3.00 +/- .32 cm, respectively). These data indicate that hemodynamic and left ventricular function in normal male and female subjects were augmented during submaximal isometric exercise. However, females do so with lower after-load than males.