ABSTRACT
Autonomic imbalance in hypertension induces excessive blood pressure (BP) elevation during exercise, thereby increasing left ventricular mass (LVM). Although muscle weakness enhances autonomic imbalance by stimulating muscle sympathetic activity during exercise, it is unclear whether muscle weakness is associated with an increase of LVM in patients with hypertension. This study aimed to investigate the relationships between muscle weakness, BP elevation during exercise, and LVM in these patients. Eighty-six hypertensive patients aged 69 ± 8 years with controlled resting BP (ie, < 140/90 mmHg) were recruited. Plasma brain natriuretic peptide (BNP), left ventricular mass index (LVMI), and knee extension muscle strength were measured. Changes in plasma noradrenaline (NORA) and brachial-ankle pulse wave velocity (ba-PWV) were assessed before and after an ergometer exercise test performed at moderate intensity (ΔNORA and ΔPWV, respectively). A difference between baseline and peak systolic BP during the exercise test was defined as BP elevation during exercise (ΔSBP). Relationships between muscle strength, ΔNORA, ΔPWV, ΔSBP, BNP, and LVMI were analyzed, and significant factors increasing LVM were identified using univariate and multivariate regression analyses. Muscle strength was negatively correlated with ΔNORA (r = -0.202, P = 0.048), ΔPWV (r = -0.328, P = 0.002), ΔSBP (r = -0.230, P = 0.033), BNP (r = -0.265, P = 0.014), and LVMI (r = -0.233, P = 0.031). LVMI was positively correlated with ΔPWV (r = 0.246, P = 0.023) and ΔSBP (r = 0.307, P = 0.004). Muscle strength was a significant independent factor associated with LVMI (ß = -0.331, P = 0.010). Our findings suggest that muscle weakness is associated with an increase of LVM through excessive BP elevation during exercise in patients with hypertension.
