Effect of resistance training on arterial wave reflection and brachial artery reactivity in normotensive postmenopausal women

Large elastic artery stiffness increases with age and menopause is a mitigating factor in women. High-intensity resistance training (RT) increases arterial stiffness in young men and women. However, the effects of moderate intensity RT on central aortic pressure wave reflection in healthy postmenopausal women are unknown. Healthy sedentary normotensive postmenopausal women were randomly assigned to either 18 weeks (2 days/week) of RT (RES n = 13) or aerobic training (AER n = 10). Central aortic pressure wave reflection and brachial artery reactivity were assessed before and after training. Central aortic pressure wave reflection was evaluated by measuring aortic augmentation index (AI_a) and round trip travel time (Δt _p) of the reflected arterial pressure wave using applanation tonometry. Brachial artery reactivity was assessed using brachial artery flow mediated dilation (FMD). Eighteen weeks of RT did not change AI_a (28.9 ± 1.9 vs. 28.5 ± 1.9%; mean ± S.E.M.) or Δt _p (140.6 ± 2.4 vs. 141.2 ± 2.1 ms). In contrast, the AER group showed a decrease in AI_a from 28.8 ± 2.1 to 25.1 ± 1.4% (P < 0.05) and an increase in Δt _p from 137.3 ± 2.5 to 144.6 ± 2.9 ms (P < 0.05). Brachial FMD did not significantly change in either group following training. This prospective, randomized study demonstrated that moderate intensity whole body RT in previously sedentary, normotensive postmenopausal women does not alter central aortic pressure wave reflection.     

动脉硬化检测技术分析

动脉功能是心血管系统健康的重要指标之一,诊断和预测动脉硬化是当前活跃的研究领域.动脉硬化有着复杂的物理和生理过程,简述了动脉硬化的生理基础,论述了动脉硬化及结构变化检测方法,分析了最新的基于多信息融合技术的动脉硬化检测方法,并提出了动脉硬化检测的新思路.     

Effect of single-leg resistance exercise on regional arterial stiffness

To examine the effects of lower-limb unilateral resistance exercise on central and peripheral arterial stiffness, thirteen participants (7 male and 6 female, mean age = 21.5 ± 0.7 years) performed leg press exercise using their dominant leg. Pulse wave velocity (PWV) was used to measure central (carotid to femoral) and peripheral (femoral to dorsalis pedis of both legs) arterial stiffness before, 5 min post, and 25 min post exercise. No change was found in central PWV. A leg-by-time interaction was found as peripheral PWV in the non-exercised leg did not change (7.9 ± 0.3 m/s to 7.9 ± 0.3 m/s to 8.0 ± 0.3 m/s, P = 0.907) while peripheral PWV in the exercised leg significantly decreased from pre (8.7 ± 0.4 m/s) to 5 min post exercise (7.5 ± 0.3 m/s, P = 0.008) and 25 min post exercise (7.8 ± 0.3 m/s, P = 0.031). Systolic blood pressure (BP) increased significantly from pre (126.9 ± 3.4 mmHg) to 5 min post exercise (133.7 ± 4.3 mmHg, P = 0.023) and was not different than resting values 25 min post exercise (123.2 ± 3.1 mmHg). There was no change in diastolic BP. Compared to heart rate (HR) pre-exercise (55.4 ± 1.4 bpm), HR was significantly increased 5 min post exercise (70.7 ± 3.0 bpm, P = 0.001) and 25 min post exercise (69.1 ± 2.0, P = 0.001). Acute resistance exercise appears to decrease arterial stiffness in the exercised leg while having no effect on central arterial stiffness or arterial stiffness of the non-exercised leg. These findings suggest that regional changes rather than systemic alterations may influence arterial stiffness following acute resistance exercise.     

Hormone replacement therapy improves arterial stiffness in normotensive postmenopausal women

Objectives: Aortic stiffness, determined by the pulse wave velocity (PWV), is an independent marker of cardiovascular risk. PWV is mainly influenced by age-associated alterations of arterial wall structure and blood pressure (BP). To determine the impact of hormone replacement therapy (HRT) on arterial compliance in normotensive, postmenopausal women, we examined the effects of HRT on PWV. Methods: Fifty-six postmenopausal women aged 50–70 years were recruited into the present retrospective study from the patients visiting our menopause clinic. Twenty-seven women who were prescribed HRT (14 on estrogen alone and 13 on estrogen plus progestogen) for several months to 6 years and an age-matched group of 29 women not on HRT were studied (Study 1). Nine postmenopausal women were also studied before and at 4 weeks of the treatment of estrogen replacement therapy (ERT) (Study 2). Brachial to ankle PWV (baPWV), which is correlated with aortic PWV, was determined using an automatic device, BP-203PRE. Results: In Study 1, PWV was significantly correlated with age in both groups (controls: r=0.392, P=0.035; HRT group: r=0.471, P=0.013), and HRT significantly lowered the PWV value at all ages examined (Mean±S.D. of baPWV in controls: 1382.2±114.1; HRT: 1245.3±124.8, P=0.0001). In Study 2, baPWV decreased significantly after ERT (P<0.05), without a significant change in systolic BP (P=0.851). Conclusions: Estrogen appears to improve arterial compliance independently of BP within 4 weeks.     

Bone metabolism regulators and arterial stiffness in postmenopausal women

Background

Osteoprotegerin (OPG), osteopontin (OPN) and matrix Gla protein (MGP) are markers of bone metabolism but they are also involved in vascular calcification. However, their precise role is not completely understood. Arterial stiffness is considered an independent predictor of cardiovascular events and it may be one of the causes of the increased cardiovascular risk associated with postmenopausal status. Medial and intimal calcification may increase arterial stiffness. The aim of our study was to assess the relationship of OPG, OPN and MGP with aortic pulse wave velocity (aPWV) as a marker of arterial stiffness in postmenopausal women.

Materials and methods

Circulating OPG, OPN and serum total MGP were measured in 144 postmenopausal women using the enzyme-linked immunosorbent assay method. Aortic PWV was determined by an oscillometric method.

Results

Osteoprotegerin correlated with age (p < 0.001, r = 0.27), aPWV (p < 0.001, r = 0.32) and hypersensitive C reactive protein (hsCRP) (p < 0.001, r = 0.37), OPN correlated directly with hsCRP (p < 0.001, r = 0.39) and inversely with high density lipoprotein cholesterol (p = 0.02, r = −0.02). No significant association was found between total MGP and clinical, biochemical and vascular parameters. The correlation between OPG and aPWV persisted even after the adjustment for various potential confounders (p = 0.02, r = 0.19). In multiple regression analysis in the whole study population the most important predictors of aPWV were OPG (β = 0.230, p = 0.006), hsCRP (β = 0.212, p = 0.01) and systolic blood pressure (β = 0.163, p = 0.04). After exclusion of patients treated with statins the independent predictors were hsCRP (β = 0.275, p = 0.005) and OPG (β = 0.199, p = 0.04).

Conclusion

Circulating OPG, but not OPN and total MGP, is associated with aPWV and may be a marker of the increased arterial stiffness and cardiovascular risk in postmenopausal women.     

Effects of reduced frequency breathing on arterial hypoxemia during exercise

Summary It is uncertain that exercise with reduced frequency breathing (RFB) results in arterial hypoxemia. This study was designed to investigate whether RFB during exercise creates a true hypoxic condition in arterial blood by examining arterial oxygen saturation (SaO₂) directly. Six subjects performed ten 30 s periods of exercise on a Monark bicycle ergometer at a work rate of 210 W alternating with 30 s rest intervals. The breath was controlled to use 1 s each for inspiration and expiration, and two trials with different breathing patterns were used; a continuous breathing (CB) trial and an RFB trial consisting of four seconds of breath-holding at functional residual capacity (FRC). Alveolar oxygen pressure during exercise showed a slight but significant (p<0.05) reduction with RFB as compared to CB. However, a marked increase in alveolar-arterial pressure difference for oxygen (A-aDO₂) (p<0.05) with RFB over CB resulted in a marked (p<0.05) reduction in arterial oxygen pressure. Consequently, SaO₂ fell as low as 88.8% on average. Additional examination of RFB with breath-holding at total lung capacity showed no increases in A-aDO₂ in spite of the same amount of hypoventilation as compared with that at FRC. These results indicate that RFB during exercise can result in arterial hypoxemia if RFB is performed with breath-holding at FRC, this mechanism being closely related to the mechanical responses due to lung volume restriction.     

Postural control in elderly subjects participating in balance training

The changes in postural control in elderly people after an 8-week training course were characterized. Static postural stability was measured during standing on a single force platform first with the eyes open and then with the eyes closed. Body sway was analysed on a force plate in groups of elderly and of young subjects. Half of the elderly subjects then took part in the training course. The posturographic measurements were repeated after the course. The sway in anteroposterior (AP) and mediolateral (ML) directions was subjected to spectral analysis. The frequency spectrum of the platform oscillations was calculated by fast Fourier transformation in the intervals 0.1–0.3, 0.3–1 and 1–3 Hz. It was found that the sway path was longer and the frequency power was higher in the elderly group. The training caused a significant improvement in functional performance, but a significantly longer sway path was observed after the training in the ML direction. The frequency analysis revealed a significantly higher power after 8 weeks without visual control in the ML direction in the training group in the low and the middle frequency bands. The results suggest that the participants’ balance confidence and the control of ML balance improved in response to the training. The higher ML frequency power exhibited after the training may be indicative of a better balance performance. Thus, the increase in the sway path in this age group did not mean a further impairment of the postural control.     

Surface EMG and mechanomyogram disclose isokinetic training effects on quadriceps muscle in elderly people

Maximum voluntary contraction (MVC) and cross-sectional area (CSA) of fast and slow twitch fibers are reduced in the lower limb muscles of elderly subjects. Isokinetic training at medium and high velocities has been widely used to improve muscle performance and force in young as well as elderly subjects. EMG and mechanomyogram (MMG) are compound signals in which the electrical and mechanical activities of recruited motor units (MUs) are summated. The aim of the present study was to verify the hypothesis that isokinetic training in the elderly induces changes in EMG and MMG parameters, compatible with a functional retrieval of fast twitch fiber MUs. In ten sedentary males (62–78 years), the surface EMG and MMG were recorded from the vastus lateralis muscle during isometric contractions at 20, 40, 60, 80 and 100% of the MVC, before and after 12 weeks of isokinetic training (six series of ten repetitions, each at an angular velocity of 2.09 rad s^–1 and 4.19 rad s^–1, two times a week). With training: (a) MVC and CSA increased by about 35±5% and 8±1%, respectively (P<0.05); (b) the ratio MVC/CSA increased significantly in all subjects by 25±5%; (c) the EMG root mean square and MMG spectral mean frequency increased significantly at the highest workloads. In conclusion, our data indicate that isokinetic training in the elderly improved muscle size and performance significantly. The EMG and MMG changes suggest that these results may be due to a retrieval of the fast twitch fiber MUs, contributing to muscle action.     

Specificity of velocity in strength training

Summary Twenty-one male volunteers (ages 23–25 years) were tested pre- and post training for maximal knee extension power at five specific speeds (1.05, 2.09, 3.14, 4.19, and 5.24 rad·s⁻¹) with an isokinetic dynamometer. Subjects were assigned randomly to one of three experimental groups; group S, training at 1.05 rad·s⁻¹ (n=8), group I, training at 3.14 rad·s⁻¹ (n=8) or group F, training at 5.24 rad·s⁻¹ (n=5). Subjects trained the knee extensors by performing 10 maximal voluntary efforts in group S, 30 in group I and 50 in group F six times a week for 8 weeks. Though group S showed significant increases in power at all test speeds, the percent increment decreased with test speed from 24.8% at 1.05 rad·s⁻¹ to 8.6% at 5.24 rad·s⁻¹. Group I showed almost similar increment in power (18.5–22.4 at all test speeds except at 2.09 rad·s⁻¹ (15.4%). On the other hand, group F enhanced power only at faster test speeds (23.9% at 4.19 rad·s⁻¹ and 22.8% at 5.24 rad·s⁻¹).     

Urine 6-sulfatoxymelatonin levels are inversely associated with arterial stiffness in post-menopausal women

Object

The secretion of melatonin, a pleiotropic hormone mainly synthesized by the pineal gland, typically decreases with age and may be associated with the development of aging-related pathologic conditions such as cardiovascular disease. Atherosclerosis is an aging-related disease, the pathogenesis of which involves chronic inflammation and increased oxidative stress. Since melatonin has both anti-oxidant and anti-inflammatory properties, it may be associated with atherosclerosis. Therefore, we investigated the relationship between urine concentrations of 6-sulfatoxymelatonin (aMT6s) and arterial stiffness in post-menopausal women.

Methods

A total of 66 post-menopausal women participated in the study. Melatonin secretion was estimated by measuring aMT6s levels in first morning urine samples. The cardio-ankle vascular index (CAVI) was used as an indicator of arterial stiffness.

Results

Estimated mean CAVI decreased gradually with increasing aMT6s quartiles. The multivariate logistic regression analysis showed that the fourth aMT6s quartile was associated with a high CAVI with an adjusted odds ratio of 0.03 (95% confidence interval, 0.01–0.47).

Conclusion

Our study revealed an inverse relationship between urine aMT6s and arterial stiffness as determined by CAVI. Although it is impossible to determine causality, our results suggest that melatonin may have a beneficial role in the pathogenesis of atherosclerosis. Further prospective studies are required to establish the clinical significance of our study.     

踝关节等速肌力训练对老年脑卒中患者平衡功能的影响

目的　探讨应用等速肌力训练加强踝关节屈伸肌群的肌力,对老年脑卒中患者平衡功能的影响。 方法　选取40例老年脑卒中患者随机分为对照组（n=20）、治疗组（n=20）,对照组接受常规康复治疗,治疗组在对照组基础上,增加针对踝关节背伸与跖屈肌群的等速肌力训练。2组患者治疗前和治疗3周后均进行Berg平衡量表（Berg balance scale, BBS）;“起立-走”计时测试（Timed up and go test, TUGT）;以及ProKin平衡仪的评估,参数包括Y-COP标准差、运动轨迹长度、运动轨迹面积、踝关节背伸与跖屈肌群的等速峰力矩等平衡功能相关指标的测量。 结果　2组患者经过平衡训练后,平衡功能的各项指标均较治疗前有改善(P<0.05）;治疗组患者治疗后平衡功能与对照组比较,各项评估指标均优于对照组(P<0.05）。 结论　踝关节等速肌力训练,可以明显改善老年脑卒中患者踝关节背伸与跖屈肌群的肌力及平衡功能。     

Endurance training regimen based upon arterial blood lactate: Effects on anaerobic threshold

Summary The purpose of this investigation was to assess the effect of endurance training based upon the intensity as determined by the arterial blood lactate concentration (LA). Seven healthy male college students performed endurance training on a Monark bicycle ergometer for 15 min on 3 days/week for 8 weeks, at an intensity corresponding to 4 mmol·l⁻¹ arterial blood LA determined during an incremental exercise test (25 watts increment every minute on a bicycle at 50 rpm). Another six male students served as the control group. To assess the training effect, both an incremental exercise test and a submaximal exercise test were performed before and after the endurance training. In the incremental exercise test, at , anaerobic threshold (AT), and the onset of respiratory compensation for metabolic acidosis (RCMA) were measured. AT was determined as the point at which arterial LA rose above the resting value, and RCMA was determined as the point at which Paco₂ decreased during the incremental exercise test. After training, AT increased significantly (37% increment expressed in ,p<0.05). There was a significant increase (p<0.05) in RCMA (17%) and (14%). This training decreased (4%), (15%), heart rate (10%), respiratory exchange ratio (5%), and LA (23%) significantly (p<0.05) during the submaximal exercise test after training. On the other hand, there were no significant changes in the control group through the period when the training group performed their training. These results showed that the endurance training intensity corresponding to 4 mmol·l₋₁ arterial blood LA was effective for the improvement in AT as well as . It is suggested that the present training regimen could delay the onset of anaerobic glycolysis, thus shifting AT to the higher workload and decreasing LA at a given submaximal exercise after training.     

Role of inflammation in the pathogenesis of arterial stiffness

Increased arterial stiffness is an independent predictor of cardiovascular disease independent from blood pressure. Recent studies have shed new light on the importance of inflammation on the pathogenesis of arterial stiffness. Arterial stiffness is associated with the increased activity of angiotensin II, which results in increased NADPH oxidase activity, reduced NO bioavailability and increased production of reactive oxygen species. Angiotensin II signaling activates matrix metalloproteinases (MMPs) which degrade TGFβ precursors to produce active TGFβ, which then results in increased arterial fibrosis. Angiotensin II signaling also activates cytokines, including monocyte chemoattractant protein-1, TNF-α, interleukin-1, interleukin-17 and interleukin- 6. There is also ample clinical evidence that demonstrates the association of inflammation with increased arterial stiffness. Recent studies have shown that reductions in inflammation can reduce arterial stiffness. In patients with rheumatoid arthritis, increased aortic pulse wave velocity in patients was significantly reduced by anti tumor necrosis factor-α therapy. Among the major classes of anti hypertensive drugs, drugs that block the activation of the RAS system may be more effective in reducing the progression of arterial stiffness. Thus, there is rationale for targeting specific inflammatory pathways involved in arterial stiffness in the development of future drugs. Understanding the role of inflammation in the pathogenesis of arterial stiffness is important to understanding the complex puzzle that is the pathophysiology of arterial stiffening and may be important for future development of novel treatments.     

The effects of long-term low intensity aerobic training and detraining on serum lipid and lipoprotein concentrations in elderly men and women

The effects of long-term low intensity aerobic training and detraining on serum lipid and lipoprotein concentrations were examined in 30 elderly men and women. These subjects were randomly divided into two groups. The training group [n=15; 7 men and 8 women; mean age 75.5 (SD 5.6) years] agreed to take part in physical training using a treadmill with an exercise intensity at the blood lactate concentration threshold for 30 min 3–6 times a week for 9 months. The other group [n=15; 7 men and 8 women; mean age 73.7 (SD 4.4) years] did not perform any particular physical training and was followed as the control. Following this training period the high density lipoprotein-cholesterol (HDL-C) had increased significantly (P<0.01) while the total cholesterol (TC) : HDL-C ratio had decreased significantly (P<0.01) in the training group after 9 months but had not changed in the control group. The TC, triglyceride (TG) and low density lipoprotein-cholesterol (LDL-C) had not changed significantly in either group. No significant difference was seen between the groups throughout the period for TC, LDLC or TG. There was, however, a significant correlation between the initial TC:HDL-C ratio and the change in the TC:HDL-C ratio following 3 months of training (P <0.05). After 1 month of detraining in 5 patients, the HDL-C had decreased significantly (P < 0.05) while the TC:HDL-C had increased significantly in the training group (P<0.01). These results suggested that long-term low intensity aerobic training improved the profile of serum lipid and lipoprotein concentrations, while detraining returned the profile to that of the pretraining levels in elderly persons.     

Effects of 8 weeks' endurance training on skeletal muscle metabolism in 56–70-year-old sedentary men

Summary The effects of 8 weeks' endurance training on muscle metabolism at rest and after a submaximal bicycle ergometer exercise were studied in 31 previously sedentary men, aged 56–70. Training consisted of 3–5 one hour exercise bouts per week including walking-jogging, swimming, gymnastics and ball games. The effects of training were similar to those previously reported for younger men. Mean maximal oxygen uptake increased (11%), as did the resting values for muscle glycogen concentration, the enzymes representing aerobic energy metabolism (malate dehydrogenase, succinate dehydrogenase), and also some of the anaerobic enzymes (creatine phosphokinase, lactate dehydrogenase). Lactate production during submaximal work decreased. The enzyme activities were lower following acute exercise both before and after training.     

High versus low training frequency in cardiac rehabilitation using a systems model of training

No study has reported the long term effects of cardiac rehabilitation, concerning the duration of beneficial effects of training program. The present study analyzed the influence of training session frequency on long-term beneficial effects in patients with coronary artery disease (CAD) undergoing phase 2 cardiac rehabilitation. Four patients with CAD completed 20 training sessions. Two patients were assigned to low training frequency (LTF) and two to high training frequency (HTF): three and five sessions per week⁻¹, respectively. The method was based on the systems model of training and required training quantification and the assessment of real exercise tolerance. Convolution of training quantity with real exercise tolerance provided the model exercise tolerance for every patient. The model parameters, the magnitude factor (k), and the time constant of decay (τ), were fitted from real and model exercise tolerances by the least squares method. LTF and HTF resulted in similar increases in exercise tolerance (12–14%). A model with one-component (fitness) allowed fitting exercise tolerance in all patients with r ²=0.77, 0.79, 0.84, and 0.91, respectively (p<0.05). The addition of a second component did not improve the fit in any patient (p>0.05). The k value was about twice as high with LTF (0.13 and 0.16 AU) than with HTF (0.05 AU for the two patients), whereas the τ value was about twice as low with LTF (37 and 41 days) than with HTF (72 and 89 days). The long term beneficial effects estimated by 4τ, were twice as long with HTF (288 and 356 days) than with LTF (148 and 164 days). We concluded that exercise tolerance was similarly increased with HTF and LTF but HTF training induced beneficial effects which were sustained twice as long.     

Relationships between serum uric acid,adiponectin and arterial stiffness in postmenopausal women

Objectives

Cardiovascular disease (CVD) is a leading cause of death in postmenopausal women. Elevated serum uric acid levels, hypoadiponectinemia and arterial stiffness are strongly associated with cardiovascular diseases. We investigated the relationships among uric acid, adiponectin and arterial stiffness in postmenopausal women.

Study design

9555 subjects who had the routine health check-ups, 841 postmenopausal women aged 50 years or older who had not had a menstrual period for more than 12 consecutive months were included in this study.

Main outcome measures

BMI, WC, and serum concentrations of uric acid, adiponectin, glucose, lipids (total cholesterol, triglycerides, LDL cholesterol, and HDL cholesterol) were measured. Insulin resistance was estimated by the insulin resistance index of homeostasis model assessment (HOMA-IR). Pulse wave velocity (PWV) was evaluated to assess arterial stiffness.

Results

The subjects were stratified into three groups according to uric acid values. PWV values gradually increased and adiponectin level decreased with uric acid tertiles. Serum uric acid levels in postmenopausal women correlated significantly with age, BMI, WC, TG, HDL-C, insulin, HOMA-IR, adiponectin and PWV. Multiple regression analysis showed that WC (β = 0.141, P < 0.01), HOMA (β = 0.137, P < 0.01), adiponectin (β = −0.104, P < 0.01), and PWV (β = 0.129, P < 0.01) were independently correlated with uric acid levels. In multiple logistic regression analysis after adjusting for risk factors, uric acid was a significant contributor to increased PWV.

Conclusions

These findings indicate that serum uric acid is independently associated with adiponectin and arterial stiffness in postmenopausal women.     

A J-shaped association between plasma testosterone and risk of ischemic arterial event in elderly men: The French 3C cohort study

Objectives

Low plasma testosterone is associated with increased mortality in men. However, the relation between testosterone and cardiovascular disease is uncertain. We assessed the association of plasma sex hormones with the incidence of ischemic arterial disease (IAD) in elderly men.

Methods

We used data from the French Three-City prospective cohort study (3650 men aged >65 years). A case-cohort design was set up including a random sample of 495 men and 146 incident cases of first IAD event (112 coronary heart disease (CHD) and 34 strokes) after a 4-year follow-up. Plasma total and bioavailable testosterone, total estradiol and sex hormone-binding globulin (SHBG) were measured at baseline. Multivariate hazard ratios (HRs) and 95% confidence intervals for IAD were assessed using Cox model.

Results

After adjustment for cardiovascular risk factors, a J-shaped association between plasma total testosterone and IAD risk was found (p < 0.01). The HRs associated with the lowest and the highest total testosterone quintiles relative to the second quintile were 2.23 (95% CI: 1.02; 4.88) and 3.61 (95% CI: 1.55; 8.45) respectively. Additional analysis for CHD showed similar results (HR: 3.11, 95% CI: 1.27; 7.63 and HR: 4.75, 95% CI: 1.75; 12.92, respectively). Similar J-shaped association was observed between bioavailable testosterone and IAD risk (p = 0.01). No significant association of estradiol and SHBG with IAD was found.

Conclusion

High and low plasma testosterone levels are associated with an increased risk of IAD in elderly men. Optimal range of plasma testosterone may confer cardiovascular protection and these results may have clinical implications in the management of testosterone deficiency.