Exercise training reduces peripheral arterial stiffness and myocardial oxygen demand in young prehypertensive subjects

Abstract

Background: Large artery stiffness is a major risk factor for the development of hypertension and cardiovascular disease. Persistent prehypertension accelerates the progression of arterial stiffness.

Methods: Forty-three unmedicated prehypertensive (systolic blood pressure (SBP) = 120-139 mm Hg or diastolic blood pressure (DBP) = 80-89 mm Hg) men and women and 15 normotensive time-matched control subjects (NMTCs; n = 15) aged 18-35 years of age met screening requirements and participated in the study. Prehypertensive subjects were randomly assigned to a resistance exercise training (PHRT; n = 15), endurance exercise training (PHET; n = 13) or time-control group (PHTC; n = 15). Treatment groups performed exercise training 3 days per week for 8 weeks. Pulse wave analysis, pulse wave velocity (PWV), and central and peripheral blood pressures were evaluated before and after exercise intervention or time-matched control.

Results: PHRT and PHET reduced resting SBP by 9.6±3.6mm Hg and 11.9±3.4mm Hg, respectively, and DBP by 8.0±5.1mm Hg and 7.2±3.4mm Hg, respectively (P < 0.05). PHRT and PHET decreased augmentation index (AIx) by 7.5% ± 2.8% and 8.1% ± 3.2% (P < 0.05), AIx@75 by 8.0% ± 3.2% and 9.2% ± 3.8% (P < 0.05), and left ventricular wasted pressure energy, an index of extra left ventricular myocardial oxygen requirement due to early systolic wave reflection, by 573±161 dynes s/cm(2) and 612±167 dynes s/cm(2) (P < 0.05), respectively. PHRT and PHET reduced carotid-radial PWV by 1.02±0.32 m/sec and 0.92±0.36 m/sec (P < 0.05) and femoral-distal PWV by 1.04±0.31 m/sec and 1.34±0.33 m/sec (P < 0.05), respectively. No significant changes were observed in the time-control groups.

Conclusions: This study suggests that both resistance and endurance exercise alone effectively reduce peripheral arterial stiffness, central blood pressures, augmentation index, and myocardial oxygen demand in young prehypertensive subjects.

Keywords: arterial stiffness; augmentation index; blood pressure; exercise; hypertension; left ventricular wasted pressure energy; prehypertension..

Figure 1.

A typical central aortic pressure waveform synthesized from the radial artery pressure waveform using applanation tonometry, with superimposed waveform of aortic blood flow. The dotted line is representative of the theoretical aortic pressure waveform independent of wave reflection. The line labeled “flow” is a representative waveform of aortic blood flow. Augmentation index (AIx) is the ratio of augmented pressure (central aortic systolic blood pressure (CSBP) − pressure at the first inflection point marking the onset of reflected aortic pressure wave return from the periphery (P_i) and central aortic pulse pressure (CSBP − central aortic diastolic blood pressure (CDBP). Wasted left ventricular pressure energy (LVE_W) is directly related to augmented pressure (CSBP − P_i) and to the time duration of the reflected aortic pressure wave, (ejection duration (ED) − round trip travel time of the reflected pressure wave to the major peripheral reflecting site and back to the aorta (∆t_p). Abbreviations: ∆t_r, systolic duration of the reflected aortic pressure wave; ESP, end systolic pressure. Reproduced from reference 19 with permission of the Society for Experimental Biology and Medicine.

Figure 2.

Absolute values for augmentation index (AIx), AIx normalized to a heart rate of 75 beats per minute (AIx@75), and wasted left ventricular pressure energy (LVE_w) are presented. P values are from within-group repeated measures analysis of variance and Tukey post hoc analysis of between-group and between–time point differences in absolute values. * indicates statically significant differences (P < 0.05) between post-treatment and pretreatment values within each group; ** indicates statistically significant (P < 0.05) differences between prehypertensive subjects randomized to resistance training (PHRT), prehypertensive subjects randomized to endurance training (PHET), and prehypertensive subjects randomized to nonexercising time control (PHTC) groups vs. normotensive time-matched control subjects (NMTC) group at the same experimental time point. Data are expressed as mean ± SEM.

Figure 3.

Absolute values for carotid–radial, carotid–femoral, and femoral–distal pulse wave velocity are presented. P values are from within-group repeated measures analysis of variance and Tukey post hoc analysis of between-group and between-time point differences in absolute values. * indicates statically significant differences (P < 0.05) between post-treatment and pretreatment values within each group; ** indicates statistically significant (P < 0.05) differences between prehypertensive subjects randomized to resistance training (PHRT), prehypertensive subjects randomized to endurance training (PHET), and prehypertensive subjects randomized to nonexercising time control (PHTC) groups vs. normotensive time-matched control subjects (NMTC) group at the same experimental time point. Data are expressed as mean ± SEM.