Exercise-induced exaggerated blood pressure response in men with the metabolic syndrome: the role of the autonomous nervous system

Introduction Abnormalities in the autonomic nervous system in the presence of insulin resistance may be involved in the pathophysiology of obesity-associated hypertension. We evaluated the association between exercise-induced exaggerated blood pressure (BP) response [exercise-induced hypertension (EIH)] and heart rate variability (HRV) and insulin resistance in men with metabolic syndrome (MetS). Materials and methods Ninety-eight resting normotensive men with MetS underwent a maximal symptom-limited treadmill test. BP was measured after a 5-min rest (anticipatory BP) every 3 min during exercise and during the recovery period. EIH was defined as maximum systolic BP of 220 mmHg or higher and/or maximum diastolic BP of 100 mmHg or higher. Insulin resistance was estimated using HOMA-IR. Each participant underwent a 3-h oral glucose tolerance test (OGTT). HRV was derived from a 24-h Holter. Results About half of the participants (52%) presented EIH. Resting BPs at baseline were 125 +/- 10/83 +/- 7 mmHg in participants with EIH and 120 +/- 9/80 +/- 6 mmHg (P=0.01) in the group with normal BP response to exercise. OGTT glucose levels were higher in the group with EIH (all P < 0.04) as well as HOMA-IR compared with participants with normal BP response to exercise (P=0.03). In terms of HRV, 24-h standard deviation of the RR intervals (SDNN) was lower in participants with EIH (P=0.04) as well as 24-h daytime and night-time high frequency and low frequency (P < 0.05). Conclusion Normotensive men with MetS but with EIH have greater insulin resistance as well as lower HRV parasympathetic and sympathetic indices. These features may be involved in the pathophysiology of EIH.