Effect of unilateral resistance training on arterial compliance in elderly men

The impact of the 24-h movement spectrum on vascular remodeling in older men and women: a review

Aging is associated with increased risk of cardiovascular and cerebrovascular events, which are preceded by early, negative remodeling of the vasculature. Low physical activity is a well-established risk factor associated with the incidence and development of disease. However, recent physical activity literature indicates the importance of considering the 24-h movement spectrum. Therefore, the purpose of this review was to examine the impact of the 24-h movement spectrum, specifically physical activity (aerobic and resistance training), sedentary behavior, and sleep, on cardiovascular and cerebrovascular outcomes in older adults, with a focus on recent evidence (<10 yr) and sex-based considerations. The review identifies that both aerobic training and being physically active (compared with sedentary) are associated with improvements in endothelial function, arterial stiffness, and cerebrovascular function. Additionally, there is evidence of sex-based differences in endothelial function: a blunted improvement in aerobic training in postmenopausal women compared with men. While minimal research has been conducted in older adults, resistance training does not appear to influence arterial stiffness. Poor sleep quantity or quality are associated with both impaired endothelial function and increased arterial stiffness. Finally, the review highlights mechanistic pathways involved in the regulation of vascular and cerebrovascular function, specifically the balance between pro- and antiatherogenic factors, which mediate the relationship between the 24-h movement spectrum and vascular outcomes. Finally, this review proposes future research directions: examining the role of duration and intensity of training, combining aerobic and resistance training, and exploration of sex-based differences in cardiovascular and cerebrovascular outcomes.

Following the Physical Activity Guidelines for Adults With Spinal Cord Injury for 16 Weeks Does Not Improve Vascular Health: A Randomized Controlled Trial

OBJECTIVE

To evaluate the effects of following the physical activity guidelines (PAG) for adults with spinal cord injury (SCI) for 16 weeks.

DESIGN

Randomized controlled trial.

SETTING

Community exercise program.

PARTICIPANTS

Individuals with SCI (N=23; neurological level of injury, C3-T11; American Spinal Injury Association Impairment Scale A-C; time postinjury, 12.0±9.9 y; age, 41.4±11.6 y).

INTERVENTIONS

Participants were randomly assigned to PAG training (n=12) or active control (n=11) groups. PAG training involved ≥20 minutes of moderate-vigorous aerobic exercise (rating of perceived exertion 3-6 on 10-point scale) and 3×10 repetitions of upper-body strengthening exercises (50%-70% 1 repetition maximum) 2 times per week. The control group maintained existing physical activity levels with no guidance on training intensity.

MAIN OUTCOME MEASURES

Outcome measures were obtained pre- and postintervention. Vascular health indicators included arterial stiffness via carotid distensibility and pulse wave velocity, and endothelial function via flow-mediated-dilation. Fasted blood samples were analyzed for markers of cardiovascular disease (CVD) risk. Body composition was assessed via anthropometrics and with dual-energy x-ray absorptiometry.

RESULTS

Twenty-one individuals completed the intervention (PAG=12, control=9). Group-by-time interactions were observed for whole-body mass (P=.03), whole-body fat (P=.04), visceral adipose tissue (P=.04), and carotid artery distensibility (P=.05), suggesting maintained body composition and carotid stiffness in the PAG group concurrent with declines in the control group. No changes were found in any other outcome measure.

CONCLUSIONS

While 16 weeks of adherence to the PAG in adults with SCI is insufficient to improve many markers of CVD risk, it may prevent declines in others. The PAG should continue to be promoted as a means to increase physical fitness and maintain body composition in individuals with SCI, but changes may be needed to achieve other health outcomes.

High-intensity endurance training results in faster vessel-specific rate of vasorelaxation in type 1 diabetic rats

This study examined the effects of 6 weeks of moderate- (MD) and high-intensity endurance training (HD) and resistance training (RD) on the vasorelaxation responsiveness of the aorta, iliac, and femoral vessels in type 1 diabetic (D) rats. Vasorelaxation to acetylcholine was modeled as a mono-exponential function. A potential mediator of vasorelaxation, endothelial nitric oxide synthase (e-NOS) was determined by Western blots. Vessel lumen-to-wall ratios were calculated from H&E stains. The vasorelaxation time-constant (τ) (s) was smaller in control (C) (7.2±3.7) compared to D (9.1±4.4) and it was smaller in HD (5.4±1.5) compared to C, D, RD (8.3±3.7) and MD (8.7±3.8) (p<0.05). The rate of vasorelaxation (%·s⁻¹) was larger in HD (2.7±1.2) compared to C (2.0±1.2), D (2.0±1.5), RD (2.0±1.0), and MD (2.0±1.2) (p<0.05). τ vasorelaxation was smaller in the femoral (6.9±3.7) and iliac (6.9±4.7) than the aorta (9.0±5.0) (p<0.05). The rate of vasorelaxation was progressively larger from the femoral (3.1±1.4) to the iliac (2.0±0.9) and to the aorta (1.3±0.5) (p<0.05). e-NOS content (% of positive control) was greater in HD (104±90) compared to C (71±64), D (85±65), RD (69±43), and MD (76±44) (p<0.05). e-NOS normalized to lumen-to-wall ratio (%·mm⁻¹) was larger in the femoral (11.7±11.1) compared to the aorta (3.2±1.9) (p<0.05). Although vasorelaxation responses were vessel-specific, high-intensity endurance training was the most effective exercise modality in restoring the diabetes-related loss of vascular responsiveness. Changes in the vasoresponsiveness seem to be endothelium-dependent as evidenced by the greater e-NOS content in HD and the greater normalized e-NOS content in the smaller vessels.

Blood flow restricted exercise and vascular function

It is established that regular aerobic training improves vascular function, for example, endothelium-dependent vasodilatation and arterial stiffness or compliance and thereby constitutes a preventative measure against cardiovascular disease. In contrast, high-intensity resistance training impairs vascular function, while the influence of moderate-intensity resistance training on vascular function is still controversial. However, aerobic training is insufficient to inhibit loss in muscular strength with advancing age; thus, resistance training is recommended to prevent sarcopenia. Recently, several lines of study have provided compelling data showing that exercise and training with blood flow restriction (BFR) leads to muscle hypertrophy and strength increase. As such, BFR training might be a novel means of overcoming the contradiction between aerobic and high-intensity resistance training. Although it is not enough evidence to obtain consensus about impact of BFR training on vascular function, available evidences suggested that BFR training did not change coagulation factors and arterial compliance though with inconsistence results in endothelial function. This paper is a review of the literature on the impact of BFR exercise and training on vascular function, such as endothelial function, arterial compliance, or other potential factors in comparison with those of aerobic and resistance training.

Progressive resistance training might improve vascular function in older women but not in older men

OBJECTIVES

Resistance exercise training increases strength and muscle mass in older adults however there is no consensus for its effect on arterial health. The aim of this study was to determine the effect of community based resistance training versus flexibility training on indicators of arterial stiffness and central blood pressure in healthy older adults and to test whether the effects of training are gender specific.

DESIGN

A randomised crossover intervention study.

METHODS

Forty-nine healthy elderly participants (23 males) aged 66.7±4.3 years (mean±SD) participated in this study which involved undertaking 16 weeks of resistance training and 16 weeks of flexibility training in a random order separated by a four week washout period of usual activity. Prior to and following each training protocol period, participants underwent testing of arterial stiffness as augmentation index; and central blood pressure.

RESULTS

When all participants were compared no changes in any measure of arterial stiffness or central blood pressure following resistance training compared to flexibility training were found. When male and female participants were analysed separately, a statistically significant decrease in augmentation index was observed in females (-5.28%; 95% CI: -10.29 to -0.26; p=0.04) but not males (+1.72%; 95% CI: -3.04 to 6.48; p=0.48).

CONCLUSIONS

Community based resistance exercise training does not adversely affect vascular function in apparently healthy older adults and may actually improve arterial function in females.

Muscular strength is inversely associated with aortic stiffness in young men

Muscular strength is associated with reduced mortality. Paradoxically, strength training may increase central artery stiffness, a predictor of cardiovascular morbidity and mortality. However, the relationship between muscular strength and central arterial stiffness has yet to be defined.

PURPOSE

The purpose of this study was to determine the relationship between muscular strength and central arterial stiffness in young men.

METHODS

Central and peripheral pulse wave velocity (PWV), augmentation index, muscular strength, and aerobic capacity (V O2peak) were measured in 79 young men (mean +/- SD, age = 23 +/- 4 yr). Height, weight, and brachial blood pressure were also recorded. Muscular strength was determined using a one-repetition maximum bench press and normalized to bodyweight. Spearman correlations were used to determine the relationships between relative strength, aerobic fitness, and hemodynamic/vascular measures.

RESULTS

There was a significant negative correlation between central PWV and strength (r = -0.222, P < 0.05). The relationship remained significant when controlling for aerobic fitness (r = -0.189, P < 0.05). Muscular strength was significantly higher (P < 0.05) in men with low central PWV (5.2 +/- 0.4 m.s) compared with men with high central PWV (6.6 +/- 0.4 m.s).

CONCLUSION

These results show that there is a significant inverse association between muscular strength and aortic stiffness independent of aerobic fitness.

Exercise and vascular adaptation in asymptomatic humans

Beneficial effects of exercise training on the vasculature have been consistently reported in subjects with cardiovascular risk factors or disease, whereas studies in apparently healthy subjects have been less uniform. In this review, we examine evidence pertaining to the impact of exercise training on conduit and resistance vessel function and structure in asymptomatic subjects. Studies of arterial function in vivo have mainly focused on the endothelial nitric oxide dilator system, which has generally been shown to improve following training. Some evidence suggests that the magnitude of benefit depends upon the intensity or volume of training and the relative impact of exercise on upregulation of dilator pathways versus effects of inflammation and/or oxidation. Favourable effects of training on autonomic balance, baroreflex function and brainstem modulation of sympathetic control have been reported, but there is also evidence that basal vasoconstrictor tone increases as a result of training such that improvements in intrinsic vasodilator function and arterial remodelling are counterbalanced at rest. Studies of compliance suggest increases in both the arterial and the venous sides of the circulation, particularly in older subjects. In terms of mechanisms, shear stress appears to be a key signal to improvement in vascular function, whilst increases in pulse pressure and associated haemodynamics during bouts of exercise may transduce vascular adaptation, even in vascular beds which are distant from the active muscle. Different exercise modalities are associated with idiosyncratic patterns of blood flow and shear stress, and this may have some impact on the magnitude of exercise training effects on arterial function and remodelling. Other studies support the theory that that there may be different time course effects of training on specific vasodilator and constrictor pathways. A new era of understanding of the direct impacts of exercise and training on the vasculature is evolving, and future studies will benefit greatly from technological advances which allow direct characterization of arterial function and structure.

Effects of acute resistance exercise on arterial stiffness in young men

Background and Objectives

Increased central arterial stiffness is an emerging risk factor for cardiovascular disease. Acute aerobic exercise reduces arterial stiffness, while acute resistance exercise may increase arterial stiffness, but this is not a universal finding. We tested whether an acute resistance exercise program was associated with an increase in arterial stiffness in healthy young men.

Subjects and Methods

Thirteen healthy subjects were studied under parallel experimental conditions on 2 separate days. The order of experiments was randomized between resistance exercise (8 resistance exercises at 60% of 1 repeated maximal) and sham control (seated rest in the exercise room). Carotid-femoral pulse wave velocity (PWV) and aortic augmentation index as indices of aortic stiffness were measured using applanation tonometry. Measurements were made at baseline before treatments, 20 minutes, and 40 minutes after treatments (resistance exercise and sham control).

Results

There was no difference in resting heart rate or in arterial stiffness between the two experimental conditions at baseline. At 20 minutes after resistance exercise, heart rate, carotid-femoral PWV and augmentation index@75(%) were significantly increased in the resistance exercise group compared with the sham control (p<0.05). Brachial blood pressure, central blood pressure and pulse pressure were not significantly increased after resistance exercise.

Conclusion

An acute resistance exercise program can increase arterial stiffness in young healthy men. Further studies are needed to clarify the effects of long-term resistance training on arterial stiffness.

Low-intensity resistance exercise with slow lifting and lowering does not increase noradrenalin and cardiovascular responses

The aim of this study was to investigate the effect of low-intensity resistance exercise with slow lifting and lowering (LSL) on plasma endothelin-1 (ET-1) and noradrenalin concentrations in young healthy adults. Eight healthy males participated in this study (age 19.0 +/- 0.5 years, mean +/- SD). The LSL performed the 10 repetitions with 3 s eccentric (lowering phase) and 3 s concentric (lifting phase) muscle actions. The high-intensity resistance exercise with normal lifting and lowering (HNL) performed the 10 repetitions with 1 s eccentric (lowering phase) and 1 s concentric (lifting phase) muscle actions. The load was set to 40% of one repetition maximal (1RM) for LSL and 80% of 1RM for HNL. Plasma ET-1 and noradrenalin concentrations were measured before and after each type of exercise. Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), pulse pressure (PP) and heart rate (HR) during LSL and HNL were measured. The rate-pressure product (RPP) was calculated from SBP and HR. There were no significant differences in the plasma ET-1 concentration between LSL and HNL. However, the plasma noradrenalin concentration was significantly increased after HNL, compared with LSL (P<0.001). SBP, DBP, PP, MAP, HR and RPP during LSL were significantly lower compared with HNL (P<0.05: PP and HR; P<0.01: RPP; P<0.001: SBP, DBP and MAP). These results suggested that LSL may suppress the increase in plasma noradrenalin concentrations and cardiovascular responses.