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.

The effect of gender on left ventricular function immediately after the wingate test

“…These left ventricular responses were similar to those observed during isometric exercise (Bryg et al 1989;Sagiv et al 1985). During isometric exercise, it has been reported that afterload is elevated while stroke volume does not increase; rather a marked increase in heart rate has been noted as the factor for maintaining adequate cardiac output (Hossack and Bruce 1982;Sagiv et al 1991). The results for the Doppler derived indices and blood pressure response in the present study were similar to those seen during isometric exercise.…”

“…It is well-established that maximal aerobic power (watts) is highly correlated with the mass of skeletal tissue that is active during the exercise (Fagard et al 1995). It has been found that both body mass and lean body mass tend to be lower in women than men (Sagiv et al 1991) and thus, maximal aerobic power would be expected to be lower in the average woman than in the average man as reported previously (Fagard et al 1995;Sagiv et al 1991). However, in the present study, body mass and lean body mass were similar, and because all the subjects were exercised to a level of severe fatigue, it seems that the dierences were due to gender dierences and not to lack of motivation on the part of the women.…”

“…During isometric exercise the left ventricular contractile state has not been demonstrated to dier signi®cantly between sedentary male and female subjects, although end-diastolic dimension was lower in women than in men. This dierence has been attributed to the smaller heart size of women (Sagiv et al 1991). It has been suggested that this dierence may bring about a failure in the performance of the female heart under elevated pressure loads (Higginbotham et al 1984).…”

What Maintains the Metabolic Cost at Peak Aerobic Exercise in End Stage Renal Disease Patients?

“…All measurements were compared to norms for young adults [13,14]. The subjects' hematological profiles are given in Table 1.…”

Factors mediating the pressor response to isometric muscle contraction: An experimental study in healthy volunteers during lower body negative pressure

“…It remains debatable whether the pressor response is due to increases in cardiac output (CO) [5][6][7][8][9], total peripheral resistance (TPR) [10][11][12][13][14] or both [15][16][17][18]. CO changes during IHG is primarily driven by an elevated heart rate (HR), whilst the stroke volume (SV) is slightly reduced due to the tachycardia and increased afterload, or even maintained following both augmented ventricular contractility [19,20] and constant or elevated preload via central blood volume mobilization [21].…”