Aerobic fitness impact on autonomic BP control varies by age in women
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Aerobic exercise may have little or no part in parasympathetic BP control among fit postmenopausal women, according to research published in Hypertension.
In contrast, researchers did find a relationship between aerobic fitness and parasympathetic BP control in premenopausal women.
Researchers assessed aerobic fitness (maximal oxygen consumption), muscle sympathetic nerve activity, heart rate and beat-by-beat BP in 13 fit premenopausal women (mean age, 28 years; BMI, 23 kg/m2) and 13 fit postmenopausal women (mean age, 58 years; BMI, 23 kg/m2). Participants then underwent pharmacological blockade of the autonomic ganglia using trimethaphan camsylate, and measurements were repeated. Baseline resting BP did not differ between the two groups.
Investigators found a relationship between aerobic fitness and the change in BP of the younger women during ganglionic blockade (r = 0.761; P = .003). However, among older women, there was no association observed between aerobic fitness and change in BP during ganglionic blockade (r = 0.106; P = .73).
Moreover, among younger women, heart rate variability was associated with aerobic fitness (r = 0.713; P = .006), but the same was not true in older women (r = 0.172; P = .575).
“Together, these data suggest greater parasympathetic tone in young, fit women contributes to a smaller decrease in blood pressure during ganglionic blockade,” Sarah E. Baker, PhD, professor of physiology at Mayo Clinic, and colleagues wrote. “In contrast, older women (regardless of fitness level) have low parasympathetic tone and, thus, are unable to elicit a significant rise in heart rate. As a result, blood pressure decreases more significantly in older women compared with younger women.”
In other findings, researchers observed a relationship between cardiac output and maximal oxygen consumption among young women (r = 0.634, P = .02). This relationship demonstrated that younger women with higher aerobic fitness were able to increase cardiac output in response to ganglionic blockade, according to the study.
“Taken together, enhanced aerobic fitness contributes to greater vagal tone in younger women, but not older women,” the researchers wrote. “Elevated vagal tone attenuates sympathetic nervous system response in cardiovascular regulation. These data have important implications for the effect of aerobic fitness on blood pressure regulation.” – by Scott Buzby
Disclosures: The authors report no relevant financial disclosures.
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