Normotensive individuals with exaggerated exercise blood pressure response have increased cardiac vagal tone

Abstract

Background: Exaggerated systolic blood pressure (SBP) levels during a maximal cardiopulmonary exercise test (CPET) are classically considered as inappropriate and associated with a higher risk for the development of cardiovascular diseases. It is known that the autonomic nervous system modulates the BP during exercise. However, the behavior of the cardiac vagal tone (CVT) has not been fully established in healthy individuals with an exaggerated BP response to CPET.

Objective: To analyze the behavior of the CVT in healthy adult males presenting an exaggerated BP response to CPET.

Methods: Of the 2,505 cases evaluated between 2002-2009, 154 cases were thoroughly identified, consisting of healthy male normotensive subjects aged 20-50 years. The evaluation included clinical assessment, anthropometric measurements, 4-second exercise test (cardiac vagal tone) and cardiopulmonary exercise test (CPET) performed in a cycle-ergometer, with BP measurements being taken every minute through auscultation. Based on the maximum SBP value obtained at the CPET, the sample was divided in tertiles, comparing CVT, maximum workload and VO2 max.

Results: The CVT results differed between individuals in the lower tertile and upper tertile for the SBP response to the CPET, respectively: 1.57 +/- 0.03 and 1.65 +/- 0.04 (mean +/- standard error of mean) (p = 0.014). The two tertiles also differed regarding the VO2 max (40.7 +/- 1.3 vs 46.4 +/- 1.3 ml/kg(-1) x min(-1); p = 0.013) and the maximum workload (206 +/- 6.3 vs 275 +/- 8.7 watts; p < 0.001).

Conclusion: An increased BP response during the CPET in healthy adult males is accompanied by indicators of good clinical prognosis, including higher levels of aerobic fitness and cardiac vagal tone.