Acute and chronic effects of resistance training on arterial stiffness in healthy adults

Exercise training has different effects on arterial stiffness according to training modalities. The optimal exercise modality for improvement of arterial function has not been well established. Resistance training could offer greater development of muscular strength, endurance and mass, however, its effect on arterial stiffness is less certain. The aim of this dissertation is to investigate the acute and long-term effect of resistance training on arterial stiffness. Firstly, we systematically searched the Pubmed and Web of Science database from 1985 until December 2013 for relevant randomized controlled trials (RCTs). The available evidence from 17 RCTs indicates that aerobic exercise tends to have a beneficial effect on arterial stiffness in normotensive and hypertensive patients, but does not affect arterial stiffness in patients with isolated systolic hypertension. Resistance exercise has differing effects on arterial stiffness depending on type and intensity. Vigorous resistance training is associated with an increase in arterial stiffness. There seem to be no unfavorable effects on arterial stiffness if the training is of low intensity, in a slow eccentric manner or with lower limb in healthy individuals. However, the existing evidence does not allow firm conclusions. The interpretation is hampered by the use of different measures of arterial stiffness, varying exercise programs, different population-based variables and several confounding factors (e.g. exercise induced weight loss, daily physical activity, diet, medication). Further longitudinal interventional studies are needed to definitively rule out the effects of confounding factors on arterial stiffness and give conclusive answers to the true effect of aerobic as well as resistance exercise training on arterial stiffness in individuals with and without hypertension. Arterial stiffness is as an emerging biomarker in the assessment of vascular health. However, if it is necessary to standardize the time of the day when performing these measurements is less certain. This dissertation then showed a methodological study which investigated the variation of the arterial stiffness during the daytime. We recruited males and females at a wide range of ages and involve both healthy individuals and patients with heart disease. We found that the novel method [cardio-ankle vascular index (CAVI)] and the traditional method [carotid-femoral pulse wave velocity (cfPWV)] were both repeatable. In this study, we demonstrated a lack of diurnal variation of cfPWV. However, there was shown to be a significant diurnal variation in CAVI, indicative of pronounced vascular stiffening in the morning in healthy young and elderly individuals and patients with heart disease. Therefore, this methodological study provides support to initiate the measurement around the same time of day in order to minimize the diurnal variations in longitudinal studies.
On the basis of the literature review and the methodological study, resistance exercise with lower body seems to have no adverse or even beneficial effect on arterial stiffness. Therefore, we apply an intervention study comparing the acute effect of lower body resistance training (LRT) versus upper body resistance training (URT) on arterial stiffness. Twenty healthy young men underwent LRT, URT and whole body resistance training (WRT). Before, immediately after as well as 20 min, 40 min and 60 min after each training, we measured the cardio-ankle vascular index (CAVI) and brachial-ankle pulse wave velocity (baPWV) using VaSera VS-1500N. We used mixed models for repeated measures to estimate the post exercise differences in CAVI and baPWV between the three resistance training modes. Compared with WRT, LRT induced a decrease and URT an increase in arterial stiffness across all time points. Our results suggest that LRT or WRT may be preferred over URT in individuals with impaired arterial stiffness. Study showed eccentric resistance training has a favorable effect on arterial stiffness, while concentric training increased arterial stiffness. Therefore, we believe that resistance training with a reduced or shorten concentric phase might be prospective from the cardiovascular perspective. Power resistance training, whose concentric phase is as fast as possible, might cause less or no impairment of arterial stiffness. Therefore, an explicit need of longitudinal randomized controlled studies for determining the effects of the high velocity resistance training on arterial stiffness. To conclude, resistance exercise training has favourable effects with training of low intensity, in a slow eccentric manner or using lower body only. Lower body or whole body resistance exercise is preferred over upper body resistance exercise in individuals with impaired arterial stiffness. Our findings contribute to the evidences for resistance exercise prescription from a cardiovascular perspective.