Cardiovascular responses to various autonomic tests in males and females.

The results of cardiovascular autonomic reflex tests on 224 healthy, randomly selected subjects were analysed to study possible sex differences in the autonomic responses. The heart rate response to the Valsalva manoeuvre (Valsalva ratio) was greater in females over 50 years than in males of the same age (1.58 +/- 0.34 vs. 1.44 +/- 0.30, p < 0.05). The heart rate response to deep breathing (E/I ratio) was higher in females under 50 years than in males under 50 years (1.37 +/- 0.17 vs. 1.34 +/- 0.18, p < 0.001). The diastolic blood pressure response to isometric handgrip was higher in males under 50 years than in females of the same age (p < 0.05). Although there were sex differences in the magnitude of the responses, the effect of age was similar in males and females and accelerated attenuation of the autonomic responses could not be demonstrated with increasing age. It can be concluded that significant sex differences exist in cardiovascular autonomic responses. The implication of such differences need consideration.