Changes in autonomic regulation induced by physical training in mild hypertension.

Abstract

SUMMARY The adaptive effects of physical training on cardiovascular control mechanisms were studied in 11 subjects with mild hypertension. In these subjects we assessed the gain of the heart periodsystolic arterial pressure relationship in the unfit and the fit state by using 1) an open loop approach, whereby the gain is expressed by the slope of the regression of heart period as a function of systolic arterial pressure, during a phenylephrine-induced pressure rise and 2) a closed loop approach with proper simplification, whereby the gain is expressed by the index a, obtained through simultaneous spectral analysis of the spontaneous variabilities of heart period and systolic arterial pressure. Both methods indicated that training significantly increased the gain of the relationship between heart period and systolk arterial pressure at rest and reduced arterial pressure and increased heart period significantly. This gam was drastically reduced during bicycle exercise both in the unfit and fit state. In a second group of normotensive (u = 7; systolic pressure, 133 ± 3 mm Hg) and hypertensive (n -1; systolic pressure, 180 ± 10 mm Hg) subjects undergoing 24 -hour diagnostic continuous ekctrocardiographic and high fidelity arterial pressure monitoring, the index a was significantly reduced in the hypertensive group at rest. Furthermore, when analyzed continuously over the entire 24-hour period, this index underwent minute-to-minute changes with lower values during the day and higher values during the night. We propose the index a as a quantitative indicator of the changes in the gain of baroreceptor mechanisms occurring with physical training in mild hypertension and during a 24-hour period in ambulatory subjects. This raises the possibility of recommending physical training as part of the nonpharmacological treatment of hypertension.1 -2 The mechanisms underlying the observed cardiovascular changes are not yet understood but are likely to be quite complex; they may include metabolic, cardiovascular, and neural factors in addition to changes in skeletal muscle fiber type. Our study explored the hypothesis that training induces new operating conditions in the neural regulatory mechanisms. We compared

Exercise training favourably affects autonomic and blood pressure responses during mental and physical stressors in African-American men

“…These findings of significant improvements in BRS for all conditions emphasize the importance of baroreflex modulation following aerobic training, as the BRS plays a key role as a mediator of autonomic responses and overall cardiovascular morbidity and mortality. [14][15][16][17][18] Moreover, prior research has shown improved BRS after exercise training in hypertensive participants. [47][48][49] The improvement in BRS in this investigation could be in part due to a lesser sympathetic modulation and a well-known mediator of vascular stiffness.…”

“…[5][6][7] Favourable modifications in autonomic modulation and BP have been documented following endurance training in animals and humans. [8][9][10][11][12] Our prior study has demonstrated an augmentation in parasympathetic or vagal modulation and enhanced baroreflex sensitivity (BRS) and arterial compliance (AC) following aerobic training. [13][14][15][16][17][18][19][20][21] Not surprisingly, few of these studies assessed these effects in African-American men, not in populations other than whites.…”

Early autonomic dysfunction in type 1 diabetes: a reversible disorder?

“…BRS was determined from spontaneous fluctuations in the RR interval and SBP during the 15 and 6 breaths per minute recordings using the sequence method (BRS+/+, BRS−/−) [34], the alpha coefficient (Alpha low-frequency BRS) [35] and the transfer function technique (TF-BRS) [36]. In the sequence method, BRS was estimated by identifying spontaneously occurring sequences of three or more consecutive heartbeats in which both SBP and the subsequent RR intervals changed in the same direction.…”

Spectral analysis of heart rate variability in elderly non-dipper hypertensive patients

“…A subsequent report by Langewitz et al, 4 showed a reduction of parasympathetic tone as a significant new factor in hypertensive subjects with the index (␣). In normotensive and hypertensive subjects undergoing a 24-h continuous recording of ECG and arterial pressure, measured with a high-fidelity technique, the overall gain of the baroreceptive mech- anisms was evaluated through an invasive study 5 with an index (␣), a measure of autonomic activity. This index underwent a clear circadian variation which was smaller during the day and decreased at rest in hypertensive patients, thus confirming that neural buffering mechanisms appear attenuated in essential hypertension.…”