Skeletal muscle dysfunction in chronic renal failure: effects of exercise

Quality matters: chronic kidney disease progression is associated with reduced muscle strength independently of changes in skeletal muscle mass: an observational study

Background

Chronic kidney disease (CKD) is commonly associated with multifactorial neuromuscular impairments. Few studies have investigated CKD-induced changes in maximal voluntary force (MVF), and even fewer have longitudinal follow-up. The aim of this study is to investigate whether CKD progression modifies the relationship between skeletal muscle mass and force, and the prevalence of sarcopaenia and sarcopenic obesity.

Methods

The data used were prospectively collected during routine check-ups in a network of nutritional centres in Mexico and retrospectively analysed. From a dataset of 5430 patients, we selected 1098 patients with available anthropometric, kidney function, handgrip and bioimpedance data. The relationship between appendicular skeletal muscle mass (ASM) and MVF was investigated using mixed models and adjusted for age, sex, body mass index, physical activity level and CKD aetiology. Sarcopaenia prevalence were tested across period of follow-up using the Cochran-Mantel-Haenzen for repeated measures and across CKD stages using the Chi-2 test.

Results

After normalization with ASM, MVF was higher in CKD G1-G3 compared with G4 and G5 (P ≤ .001, Cohen's d = 0.270-0.576). Slopes between MVF and ASM were lower in CKD G3, G4 and G5 than in CKD G1-G2 [-2.268 (-3.927, -0.609), P  = .008; -2.694 (-4.593, -0.794), P  = .006; -3.675 (-5.326, -1.725), P  < .001, respectively]. The prevalence of sarcopaenia and sarcopaenic obesity did not differ across CKD stages, but recovery was most commonly observed in CKD G1-G2. Slope analysis showed an independent interaction between the slopes of kidney function and ASM on MVF evolution over time.

Conclusions

CKD negatively, progressively and independently affects the neuromuscular system, and force production is reduced for any given muscle mass as CKD progresses. While no association was found between CKD stage and prevalence of sarcopaenia, recovery was more frequent in the early CKD stages. These results suggest the importance of early rehabilitation programs to improve musculoskeletal health, quality of life and survival in CKD patients.

Evaluation of Factors Influencing Handgrip Strength Asymmetry in Older Peruvian Adults

BACKGROUND

Sarcopenia is a musculoskeletal disease involving the reduction of muscle mass, strength, and performance. Handgrip strength (HGS) measurements included in frailty assessments are great biomarkers of aging and are related to functional deficits. We assessed the association between potential influencing factors and HGS asymmetry in older Peruvian adults.

METHODS

We used a database of the Peruvian Naval Medical Center "Cirujano Santiago Távara" located in Callao, Peru. All the patients included were ≥60 years old and had an HGS measurement in the dominant and non-dominant hand.

RESULTS

From a total of 1,468 patients, 74.66% had HGS asymmetry. After adjustment, calf circumference weakness (adjusted prevalence ratio [aPR]=1.08; 95% confidence interval [CI], 1.01-1.15), falls risk (aPR = 1.08; 95% CI, 1.02-1.16), and an altered Lawton index (aPR=0.92; 95% CI, 0.84-0.99) were associated with HGS asymmetry.

CONCLUSION

Our findings suggest that HGS asymmetry should be measured along with other geriatric assessments used to evaluate health outcomes in the elderly to enhance health promotion and prevention aimed at preserving muscle strength to curb functional limitations in the elderly.

Chronic Kidney Disease Interplay with Comorbidities and Carbohydrate Metabolism: A Review

Chronic kidney disease (CKD) poses a global health challenge, engendering various physiological and metabolic shifts that significantly impact health and escalate the susceptibility to severe illnesses. This comprehensive review delves into the intricate complexities of CKD, scrutinizing its influence on cellular growth homeostasis, hormonal equilibrium, wasting, malnutrition, and its interconnectedness with inflammation, oxidative stress, and cardiovascular diseases. Exploring the genetic, birth-related, and comorbidity factors associated with CKD, alongside considerations of metabolic disturbances, anemia, and malnutrition, the review elucidates how CKD orchestrates cellular growth control. A pivotal focus lies on the nexus between CKD and insulin resistance, where debates persist regarding its chronological relationship with impaired kidney function. The prevalence of insulin abnormalities in CKD is emphasized, contributing to glucose intolerance and raising questions about its role as a precursor or consequence. Moreover, the review sheds light on disruptions in the growth hormone and insulin-like growth factor axis in CKD, underscoring the heightened vulnerability to illness and mortality in cases of severe growth retardation. Wasting, a prevalent concern affecting up to 75% of end-stage renal disease (ESRD) patients, is analyzed, elucidating the manifestations of cachexia and its impact on appetite, energy expenditure, and protein reserves. Taste disturbances in CKD, affecting sour, umami, and salty tastes, are explored for their implications on food palatability and nutritional status. Independent of age and gender, these taste alterations have the potential to sway dietary choices, further complicating the management of CKD. The intricate interplay between CKD, inflammation, oxidative stress, and cardiovascular diseases is unraveled, emphasizing the profound repercussions on overall health. Additionally, the review extends its analysis to CKD's broader impact on cognitive function, emotional well-being, taste perception, and endothelial dysfunction. Concluding with an emphasis on dietary interventions as crucial components in CKD management, this comprehensive review navigates the multifaceted dimensions of CKD, providing a nuanced understanding essential for developing targeted therapeutic strategies.

Neurocirculatory regulation and adaptations to exercise in chronic kidney disease

Chronic kidney disease (CKD) is characterized by pronounced exercise intolerance and exaggerated blood pressure reactivity during exercise. Classic mechanisms of exercise intolerance in CKD have been extensively described previously and include uremic myopathy, chronic inflammation, malnutrition, and anemia. We contend that these classic mechanisms only partially explain the exercise intolerance experienced in CKD and that alterations in cardiovascular and autonomic regulation also play a key contributing role. The purpose of this review is to examine the physiological factors that contribute to neurocirculatory dysregulation during exercise and discuss the adaptations that result from regular exercise training in CKD. Key neurocirculatory mechanisms contributing to exercise intolerance in CKD include augmentation of the exercise pressor reflex, aberrations in neurocirculatory control, and increased neurovascular transduction. In addition, we highlight how some contributing factors may be improved through exercise training, with a specific focus on the sympathetic nervous system. Important areas for future work include understanding how the exercise prescription may best be optimized in CKD and how the beneficial effects of exercise training may extend to the brain.

Muscle plasticity is influenced by renal function and caloric intake through the FGF23-vitamin D axis

Skeletal muscle, the main metabolic engine in the body of vertebrates, is endowed with great plasticity. The association between skeletal muscle plasticity and two highly prevalent health problems: renal dysfunction and obesity, which share etiologic links as well as many comorbidities, is a subject of great relevance. It is important to know how these alterations impact on the structure and function of skeletal muscle because the changes in muscle phenotype have a major influence on the quality of life of the patients. This literature review aims to discuss the influence of a nontraditional axis involving kidney, bone, and muscle on skeletal muscle plasticity. In this axis, the kidneys play a role as the main site for vitamin D activation. Renal disease leads to a direct decrease in 1,25(OH)₂-vitamin D, secondary to reduction in renal functional mass, and has an indirect effect, through phosphate retention, that contributes to stimulate fibroblast growth factor 23 (FGF23) secretion by bone cells. FGF23 downregulates the renal synthesis of 1,25(OH)₂-vitamin D and upregulates its metabolism. Skeletal production of FGF23 is also regulated by caloric intake: it is increased in obesity and decreased by caloric restriction, and these changes impact on 1,25(OH)₂-vitamin D concentrations, which are decreased in obesity and increased after caloric restriction. Thus, both phosphate retention, that develops secondary to renal failure, and caloric intake influence 1,25(OH)₂-vitamin D that in turn plays a key role in muscle anabolism.

Aerobic Exercise Attenuates Kidney Injury, Improves Physical Performance, and Increases Antioxidant Defenses in Lungs of Adenine-Induced Chronic Kidney Disease Mice

The association between chronic kidney disease (CKD) and pulmonary pathophysiological changes is well stablished. Nevertheless, the effects of aerobic exercise (AE) on lungs of CKD need further clarification. Thus, Swiss mice were divided in control, AE, CKD, and CKD + AE groups. CKD was induced by 0.2% adenine intake during 8 weeks (4 weeks of CKD induction and 4 weeks of AE). AE consisted in running on treadmill, at moderate intensity, 30 min/day, 5 days/week, during 4 weeks. Twenty-four hours after the last training day, functional capacity test was performed, and 48 h after the test, mice were euthanized. CKD mice showed a significant increase in urine output, serum urea, and creatinine concentrations, and decreased body weight and urine density, besides oxidative damage (p = 0.044), edema area (p < 0.001), leukocyte infiltration (p = 0.040), and collagen area in lung tissue (p = 0.004). AE resulted in an increase of distance traveled (p = 0.049) and maximum speed (p = 0.046), increased activity of catalase (p = 0.031) and glutathione peroxidase (p = 0.048) in lungs, increased levels of nitric oxide (NOx) in serum (p = 0.001) and bronchoalveolar lavage fluid (p = 0.047), and decreased kidney histological injury (p = 0.018) of CKD mice. However, AE also increased oxidative damage (p = 0.003) and did not change collagen content or perivascular edema in lungs (p > 0.05) of CKD mice. Therefore, AE attenuated kidney injury and improved antioxidants defenses in lungs. Despite no significant changes in pulmonary damage, AE significantly improved physical performance in CKD mice.

Functional Status and Engagement in Physical Activity Among Maintenance Dialysis Patients: A Mixed Methods Study

Rationale & Objective

People receiving maintenance hemodialysis (HD) experience significant activity barriers but desire the ability to do more and remain independent. To learn about how to help people who require dialysis stay active, a mixed methods study was designed to assess functional status and explore participants’ lived activity experiences.

Study Design

A concurrent mixed methods design was chosen to increase understanding of the real-life activity experiences of people who require dialysis through in-depth interviews paired with functional status measures. The qualitative findings were fully integrated with the quantitative results to link characteristics associated with different physical activity levels.

Setting & Participants

A purposive sample of 15 adult patients receiving maintenance HD for at least 3 months was recruited from 7 dialysis centers in Newark, New Jersey.

Analytical Approach

Thematic analysis using principles of interpretive phenomenology. Fully integrated quantitative and qualitative data with joint displays and conversion mixed methods.

Results

Participants had a median age of 58 years and were predominantly African American (83%) and men (67%). Three descriptive categories were generated about the participants. They described physical activity as a routine daily activity rather than structured exercise. All participants experienced substantial hardship in addition to chronic kidney disease and expressed that family, friends, and faith were essential to their ability to be active. An overarching theme was generated for participants’ mindsets about physical activity. Within the mindset theme, we discerned 3 subthemes comprising characteristics of participants’ mindsets by levels of engagement in physical activity.

Limitations

While code saturation and trends in functional status measures were achieved with 15 participants, a larger sample size would allow for deeper meaning saturation and statistical inference.

Conclusions

Patients receiving maintenance HD with an engaged mindset exhibited more adaptive coping skills, moved more, wanted to help others, and had a normal body weight habitus. These participants employed adaptive coping skills to carry out daily life activities of importance, highlighting the value of adaptive coping to help overcome the challenges of being physically active.

Testosterone Treatment As a Function-Promoting Therapy in Sarcopenia Associated with Aging and Chronic Disease

Sarcopenia is characterized by loss of muscle strength and physical ability because of aging and/or chronic disease. Supplemental testosterone and other androgenic-anabolic steroids have been investigated as countermeasures to ameliorate the negative consequences of sarcopenia; these trials show dose-related improvements in lean body mass, maximal voluntary strength, stair climbing power, aerobic capacity, hemoglobin, and self-reported function, but less consistent improvements in walking speed. Randomized clinical trials with large cohorts and patient-important outcome measures are needed to determine long-term efficacy and safety of testosterone treatment in improving physical function and reducing physical disability, falls, and fractures in older adults with sarcopenia.

Seven months of aerobic intradialytic exercise training can prevent muscle loss in haemodialysis patients: an ultrasonography study

PURPOSE

This study aimed to evaluate the effects of 7-month intradialytic exercise training (IDE) on vastus lateralis (VL) muscle architecture, functional capacity and quality of life in stable haemodialysis (HD) patients.

METHODS

44 HD patients were randomly assigned into an Exercise Group (EG = 21), which they received 7 months of IET, at 60% of pre-assessed maximum aerobic power, 3/week) or into a Control Group (CG = 23, no exercise). VL architecture was evaluated with ultrasonography, functional capacity was assessed using a series of functional tests (6 min walking test, 5 repetitions sit-to-stand, sit-to-stand 60 s, handgrip strength), and maximal aerobic power determined with a modified version of the Åstrand test. Quality of life and fatigue levels were evaluated using validated questionnaires.

RESULTS

VL fascicle angle and length did not change significantly in both groups (P > 0.05). Muscle thickness decreased in CG (P = 0.02) while it was fully preserved in the EG. Functional capacity increased only in the EG (6 min walking test 15.79 ± 12.35%, P < 0.001; max aerobic power 26.36 ± 1.24%, P < 0.001; STS-60rep: 10.23 ± 1.60%, P < 0.000; hand grip strength: 5.14 ± 28.30%, P < 0.02).

CONCLUSION

Intradialytic aerobic exercise training, improves functional capacity and prevents thigh muscle mass loss in HD patients. It is evident that muscle ultrasonography could play a pivotal role in assessing muscle quality changes in haemodialysis patients. A higher level of training intensity or combination with resistance exercises may be required to further improve anabolism and influence muscle architecture in this patient population.

CLINICAL TRIAL REGISTRY NUMBER

NCT03905551.

Associations between kidney function and outcomes of comprehensive cardiac rehabilitation in patients with heart failure

AIMS

To investigate the impact of baseline kidney function on outcomes following comprehensive cardiac rehabilitation (CR) in patients with heart failure (HF).

METHODS

We reviewed a total of 3,727 patients who were admitted for HF treatment. Estimated glomerular filtration rate (eGFR), quadriceps strength (QS), and 6-min walk distance (6MWD) were measured at hospital discharge as a baseline and 5 months thereafter in participants of outpatient comprehensive CR. The association between outpatient CR participation and all-cause events was evaluated using propensity score-matched analysis in subgroups across eGFR stages. The changes in QS and 6MWD following 5-month CR were compared between eGFR stages.

RESULTS

Out of the studied patients, 1585 (42.5%) participated in outpatient CR. After propensity matching for clinical confounders, 2680 patients were included for analysis (pairs of n = 1340 outpatient CR participants and nonparticipants). The participation in outpatient CR was significantly associated with low clinical events in subgroups of eGFR ≥ 60 [hazard ratio (HR): 0.65, 95% confidence interval (CI): 0.51-0.84] and eGFR 45-60 (HR: 0.71, 95% CI: 0.55-0.92), but not in eGFR 30-45 (HR: 0.83, 95% CI: 0.64-1.08) and eGFR < 30 (HR: 0.88, 95% CI: 0.69-1.12). QS and 6MWD were significantly higher after 5-month CR than those at baseline (P < 0.001, respectively), but lower baseline eGFR correlated with lower changes in QS and 6MWD (trend P < 0.001, respectively).

CONCLUSIONS

Although low baseline kidney function attenuates the outcomes of CR, outpatient CR seems to be associated with a better prognosis and positive change in physical function in HF patients with low kidney function.

Maintenance of Skeletal Muscle to Counteract Sarcopenia in Patients with Advanced Chronic Kidney Disease and Especially Those Undergoing Hemodialysis

Life extension in modern society has introduced new concepts regarding such disorders as frailty and sarcopenia, which has been recognized in various studies. At the same time, cutting-edge technology methods, e.g., renal replacement therapy for conditions such as hemodialysis (HD), have made it possible to protect patients from advanced lethal chronic kidney disease (CKD). Loss of muscle and fat mass, termed protein energy wasting (PEW), has been recognized as prognostic factor and, along with the increasing rate of HD introduction in elderly individuals in Japan, appropriate countermeasures are necessary. Although their origins differ, frailty, sarcopenia, and PEW share common components, among which skeletal muscle plays a central role in their etiologies. The nearest concept may be sarcopenia, for which diagnosis techniques have recently been reported. The focus of this review is on maintenance of skeletal muscle against aging and CKD/HD, based on muscle physiology and pathology. Clinically relevant and topical factors related to muscle wasting including sarcopenia, such as vitamin D, myostatin, insulin (related to diabetes), insulin-like growth factor I, mitochondria, and physical inactivity, are discussed. Findings presented thus far indicate that in addition to modulation of the aforementioned factors, exercise combined with nutritional supplementation may be a useful approach to overcome muscle wasting and sarcopenia in elderly patients undergoing HD treatments.

Effects of graded exercise training on functional capacity, muscle strength, and fatigue after renal transplantation: a randomized controlled trial

Successful renal transplantation (RT) recipients suffer residual muscle weakness, fatigue, and low functional capacity. A safe, feasible, structured, early graded exercise training to improve functional capacity, muscle strength, and fatigue is the need of the hour. The aim of the study is to assess the effectiveness of graded exercise training on the functional capacity, muscle strength, and fatigue after RT. It is a randomized controlled trial conducted at a tertiary care hospital from January 2012 to December 2016. This trial included 104 consented, stable renal transplant recipients without cardiopulmonary/neuromuscular impairment. They received either routine care (51) or graded exercise training (53) for 12 weeks after randomization. The functional capacity, isometric quadriceps muscle strength, and fatigue score were measured at baseline, six, and 12 weeks later to induction. The outcomes of the study and control groups were analyzed using the /-test, Wilcoxon signed-rank test, ANOVA, and Pearson's correlation. For all analyses, P <0.05 was fixed acceptable. The functional capacity improved by 147 and 255 m, the muscle strength by 6.35 and 9.27 kg, and fatigue score by 0.784 and 1.781 in the control and the study group (SG), respectively, significantly more in the SG. Functional capacity had a positive and negative correlation with muscle strength and fatigue, respectively (P <0.05). The graded exercise training significantly improved the functional capacity, fatigue levels, and muscle strength after RT.

Maximizing Participant and Staff Safety During Assessment of Physical Function in the COVID-19 Era

Physical performance measures, including cardiopulmonary exercise testing (CPXT), are widely used in geriatric practice and aging research. Theoretically, research participants and study personnel could get infected in the closed environment of the exercise laboratory by contact with respiratory droplets from an infected person, by breathing virus-laden aerosols, or by touching fomites. Older adults are at increased risk of developing more severe disease and of dying from SARS-CoV-2 infection. This special article offers guidance-informed by a synthesis of scientific data and recommendations of the CDC and WHO-on procedures that can be implemented in exercise laboratories to minimize risk of SARS-CoV-2 and other respiratory infections. Most tests of physical function (e.g., gait speed, Short Physical Performance Battery) are not aerosol-generating and are associated with only a small increase in minute ventilation; in contrast, CPXT markedly increases minute ventilation and is potentially aerosol-generating. Researchers should evaluate the benefit-to-risk ratio of information gained from the laboratory assessment versus the risk of SARS-CoV2 infection. Risk mitigation strategies described here fall into four categories: personal hygiene and the use of personal protective equipment; standardized screening; reconfiguration of laboratory space; and optimization of laboratory ventilation. The proposed safety measures are not intended to replace institutional policy, state, or federal guidelines; they may not apply to all settings and are expected to evolve as more definitive information becomes available. These practical measures to maximize protection against SARS-CoV2 infection can help maximize participant and staff safety, reduce anxiety, and facilitate protocol adherence, and study integrity.

Role of comorbidities in heart failure prognosis Part 2: Chronic kidney disease, elevated serum uric acid

Despite improvements in pharmacotherapy, morbidity and mortality rates in community-based populations with chronic heart failure still remain high. The increase in medical complexity among patients with heart failure may be reflected by an increase in concomitant non-cardiovascular comorbidities, which are recognized as independent prognostic factors in this population. Heart failure and chronic kidney disease share many risk factors, and often coexist. The presence of kidney failure is associated with incremented risk of cardiovascular and non-cardiovascular mortality in heart failure patients. Chronic kidney disease is also linked with underutilization of evidence-based heart failure therapy that may reduce morbidity and mortality. More targeted therapies would be important to improve the prognosis of patients with these diseases. In recent years, serum uric acid as a determinant of cardiovascular risk has gained interest. Epidemiological, experimental and clinical data show that patients with hyperuricaemia are at increased risk of cardiac, renal and vascular damage and cardiovascular events. Moreover, elevated serum uric acid predicts worse outcome in both acute and chronic heart failure. While studies have raised the possibility of preventing heart failure through the use of uric acid lowering agents, the literature is still inconclusive on whether the reduction in uric acid will result in a measurable clinical benefit. Available evidences suggest that chronic kidney disease and elevated uric acid could worsen heart failure patients' prognosis. The aim of this review is to analyse a possible utilization of these comorbidities in risk stratification and as a therapeutic target to get a prognostic improvement in heart failure patients.

Lower Limb Strength Profile in Elderly with Different Pathologies: Comparisons with Healthy Subjects

Sarcopenia and muscle strength reduction are a frequent disorder in non-communicable chronic diseases. The aims of this study are: a) to verify if the absolute and relative to body weight muscle strength of lower limb is affected by the presence of pathology; b) to verify if the trends are different among knee and ankles joints. One-hundred and forty-five elderly were recruited (16 liver transplant recipients, 48 kidney transplant recipients, 52 elderly with obesity, 30 healthy elderly). Muscular strength of lower limb was evaluated. Evaluation protocol included maximal isometric knee extension, maximal isokinetic knee extension and flexion, maximal isokinetic ankle (both right and left) extension and flexion. A statistically significant interaction between measurement and group membership was found for absolute strength measure (F(4.23, 170.56) = 3.316, p = 0.011, partial η2 (η2p) = 0.076), and relative strength measure(F(4.44, 174.72) = 16.407, p < 0.01, partial η2 (η2p) = 0.294). Elderly patients living with kidney transplants showed the lower level of absolute muscular strength, while relative muscular strength is mainly lacking in the elderly with obesity. The strength profile of elderly subjects is affected by obesity, liver transplantation, and kidney transplantation.

Home-based inspiratory muscle training in pediatric patients after kidney transplantation: a randomized clinical trial

BACKGROUND

Chronic kidney disease (CKD) represents the irreversible stages of renal failure and is a growing worldwide public health issue associated with increases in morbidity, mortality, and decreased quality of life. Kidney transplantation is considered one of the best treatment options in this population. However, even after surgery, respiratory muscle strength is below normal values, and inspiratory muscle training (IMT) improves respiratory muscle function, strength, and endurance. This study aimed to evaluate the effects of IMT regarding respiratory muscle strength, functional capacity, and pulmonary function in pediatric kidney transplant recipients with CKD, and secondarily, to assess the biochemical profile of patients after intervention.

METHODS

This is a randomized, double-blind, placebo-controlled trial. Patients were randomized into two groups, intervention (IG) and control (CG) and performed IMT home-based training for 6 weeks. In the IG, the load was adjusted to 40% of the maximal inspiratory pressure and in the CG was adjusted to a minimum placebo load (9 cm H₂O).

RESULTS

Thirty-one patients were randomly allocated to the intervention (n = 16) or control (n = 15) groups. There were no differences at baseline between groups. Increase of 35% in the maximal inspiratory pressure predicted and 26% in the maximal expiratory pressure predicted in the IG were found, compared with 5 and 4% in the CG. There was an increase in hemoglobin and hematocrit values in the IG.

CONCLUSIONS

Home-based IMT provides a significant increase in respiratory muscle strength, without changes in functional capacity and pulmonary function. Benefits regarding biochemical markers (hemoglobin and hematocrit) were also observed.

Muscle fatigability in patients with type 2 diabetes: relation with long-term complications

AIMS

It is unclear whether long-term complications play a role in muscle fatigue characteristic of patients with type 2 diabetes mellitus (T2DM). The purpose of this study was to investigate the association between muscle fatigability and microvascular and macrovascular complications in patients with T2DM.

METHODS

One-hundred forty-six patients with T2DM (80 males, 66 females, aged 66.9 ± 7.9 years) were recruited. Maximal voluntary contraction (MCV) and endurance time (ET, 50% of the MVC) were assessed at the knee extensor muscles with an isometric dynamometer. Univariate and multivariate correlations of ET values with diabetic complications, a wide range of surrogate measures of these sequelae, and cardiovascular risk factors were examined.

RESULTS

A higher muscle fatigability was detected in patients with diabetic peripheral neuropathy (DPN, ET: -32.4%), cardiovascular disease (CVD, ET: -32.1%), retinopathy (ET: -35.8%), and nephropathy (ET: -30.4%). At univariate analysis, muscle fatigability was associated with age, physical activity level, diabetes duration, HbA_1c , systolic blood pressure, albuminuria, eGFR, and several parameters of nervous and vascular function. Multivariate analysis showed that, after adjusting for covariates, ET was independently associated with sensory nerve conduction velocity, vibration perception threshold at malleolus, and ankle-brachial index. In addition, ET values were independently associated with the presence of DPN, CVD, and retinopathy.

CONCLUSIONS

In T2DM, muscle fatigability is associated with presence of DPN, CVD, and retinopathy. Such defect appears to be mediated predominantly by sensory nerve and peripheral vascular dysfunction.

Is the peripheral muscle weakness a limitation to exercise on chronic kidney disease?

Abstract Introduction: Chronic kidney disease (CKD) is a global public health problem with systemic repercussions, compromising muscle function and making patients less exercise tolerant. Objective: To verify the contribution of peripheral muscle strength in the exercise capacity of patients in hemodialysis (HD), as well as to compare peripheral muscle strength and exercise capacity between renal patients and healthy individuals. Method: 50 patients with chronic kidney disease (CKD) who performed HD and 13 healthy subjects underwent anthropometric evaluation, evaluation of peripheral muscle strength, pulmonary function test and exercise capacity assessment. Results: Simple linear regression indicated that the peripheral muscle strength contributed 41.4% to the distance walked in the six-minute walk test (R2 0.414; p < 0.001), showing that for every 1 Kgf reduced in the right lower limb the patient it stops walking 0.5m while for every 1 Kgf reduced in the lower left limb the patient stops walking 0.8m. In addition, it was observed that patients with CKD had a reduction in right lower limb muscle strength (129.44 ± 48.05 vs. 169.36 ± 44.30, p = 0.002), left (136.12 ± 52, 08 vs 168.40 ± 43.35, p = 0.01) and exercise capacity (421.20 ± 98.07 vs. 611.28 ± 80.91, p < 0.001) when compared to healthy pairs. Conclusion: Peripheral muscle weakness is an important limiting factor for exercise in CKD and patients on HD experience a decline in peripheral muscle strength and exercise capacity when compared to healthy individuals.

Evidence of functional deficits at the single muscle fiber level in experimentally-induced renal insufficiency

Chronic kidney disease patients present with metabolic and functional muscle abnormalities, called uremic myopathy, whose mechanisms have not yet been fully elucidated. We investigated whether chronic renal insufficiency (CRI) affects skeletal muscle contractile properties at the cellular level. CRI was induced surgically in New Zealand rabbits (UREM), with sham-operation for controls (CON), and samples were collected at 3 months post-surgery, following euthanasia. All protocols had University Ethics approval following national and European guidelines. Sample treatments and evaluations were blinded. Maximal isometric force was assessed in 382 permeabilized psoas fibers (CON, n = 142, UREM, n = 240) initially at pH7, 10 °C ('standard' conditions), in subsets of fibers in acidic conditions (pH6.2, 10 °C) but also at near physiological temperature (pH7, 30 °C and pH6.2, 30 °C). CRI resulted in significant smaller average cross sectional areas (CSAs) by ∼11% for UREM muscle fibers (vs CON, P < 0.01). At standard conditions, UREM fibers produced lower absolute and specific forces (i.e. normalized force per fiber CSA) (vs CON, P < 0.01); force increased in 30 °C for both groups (P < 0.01), but the disparity between UREM and CON remained significant. Acidosis significantly reduced force (vs pH7, 10 °C P < 0.01), similarly in both groups (in UREM by -48% and in CON by -43%, P > 0.05). For the first time, we give evidence that CRI can induce significant impairments in single psoas muscle fibers force generation, only partly explained by fiber atrophy, thus affecting muscle mechanics at the cellular level.

Quadriceps muscle strength after training with a cycloergometer in patients on hemodialysis

Abstract Introduction: Functional disability is common in patients with chronic kidney disease, especially in those on hemodialysis. Muscle strength can be evaluated by a dynamometer; however, no study using this technique on the quadriceps of patients undergoing hemodialysis was found in literature. Objective: To assess the effects of cycloergometer training on the quadriceps muscle strength of patients with chronic kidney disease undergoing hemodialysis. Method: This was a clinical trial including 46 patients, both men and women, over 18 years old who had been undergoing hemodialysis for more than six months and signed an informed consent form. Patients were allocated into two groups: intervention group (n = 22) and control group (n = 20). The intervention group underwent intradialytic training in a physical therapy protocol with the cycloergometer for two months, whereas the control group, in turn, was only reevaluated two months after the initial evaluation. All patients were assessed for demographic data at baseline and, two months later for quadriceps muscle strength by standardized dynamometry and with the use of a rigid belt and suction cups. Results: A significant increase was detected in quadriceps muscle strength in the right and left lower limbs in the intervention group when compared with the control group. Conclusion: Quadriceps muscle strength improved after patients with chronic kidney disease on hemodialysis underwent training with the cycloergometer.

Gradual reduction in exercise capacity in chronic kidney disease is associated with systemic oxygen delivery factors

Background

The cause of reduced exercise capacity (ExCap) in chronic kidney disease (CKD) is multifactorial. The aim of this study was to investigate determinants of aerobic ExCap in patients with mild to severe CKD not undergoing dialysis.

Methods

We included 52 individuals with CKD stage 2–3, 47 with stage 4–5, and 54 healthy controls. Peak workload and peak heart rate (HR) were assessed by a maximal cycle exercise test. Cardiac function including stroke volume (SV) and vascular stiffness were evaluated by ultrasound at rest. Handgrip strength, body composition, haemoglobin level and self-reported physical activity were assessed.

Results

Peak workload (221±60, 185±59, 150±54 W for controls, CKD 2–3 and CKD 4–5 respectively), peak HR (177±11, 161±24, 144±31 beats/min) and haemoglobin level (14.2±1.2, 13.5±1.4, 12.2±1.3 g/dL) were all three significantly lower in CKD 2–3 than in controls, (p = 0.001, 0.001 and 0.03 respectively) and were even lower in stages 4–5 CKD than in CKD 2–3 (p = 0.01, 0.001 and <0.001 respectively). Resting SV and lean body mass did not differ between groups and handgrip strength was significantly lower only in CKD 4–5 compared to controls (p = 0.02). Peak workload was strongly associated with the systemic oxygen delivery factors: SV, peak HR and haemoglobin level. These three factors along with age, sex and height² explained 82% of variation in peak workload. Peak HR contributed most to the variation; the peripheral variables handgrip strength and vascular stiffness did not improve the explanatory value in regression analysis.

Conclusions

In this cross-sectional study of CKD patients not on dialysis, aerobic ExCap decreased gradually with disease severity. ExCap was associated mainly with systemic oxygen delivery factors, in particular peak HR. Neither muscle function and mass, nor vascular stiffness were independent determinants of aerobic ExCap in this group of CKD patients.

Whole body vibration to attenuate reduction of explosive force in chronic kidney disease patients: a randomized controlled trial

To investigate whether whole body vibration (WBV) training increases the explosive force of the knee extensors in chronic kidney disease (CKD) patients. Fourteen CKD patients undergoing hemodialysis were randomly allocated in WBV training or Sham group. Explosive force parameters (contractile impulse [CImp] and relative rate of force development [RFDr]) obtained in early (30 and 50 msec) and late phases (100 and 200 msec) of the knee extensors force/time curve. CImp and RFDr obtained at the early phase of force/time curve reduced after the intervention period, with a smaller decline for WBV (CImp at 50 msec [~-15% and -51%, P=0.038], RFDr at 30 msec [~-22% and -52%, P=0.044] and RFDr at 50 msec [~-11% and -54%; P=0.008]). In the late phase there was a lower decline for WBV group compared to Sham group, respectively: CImp: 100 msec (~-8% and -55%, P=0.025), 200 msec (~-3% and -46%, P= 0.025); RFDr 100 msec (~0.01% and -56%, P=0.033), 200 msec (~-5% and -36%, P=0.004). Three months of WBV training may attenuate the explosive force reduction in CKD patients.

Fibroblast growth factor 23 does not directly influence skeletal muscle cell proliferation and differentiation or ex vivo muscle contractility

Skeletal muscle dysfunction accompanies the clinical disorders of chronic kidney disease (CKD) and hereditary hypophosphatemic rickets. In both disorders, fibroblast growth factor 23 (FGF23), a bone-derived hormone regulating phosphate and vitamin D metabolism, becomes chronically elevated. FGF23 has been shown to play a direct role in cardiac muscle dysfunction; however, it is unknown whether FGF23 signaling can also directly induce skeletal muscle dysfunction. We found expression of potential FGF23 receptors ( Fgfr1-4) and α-Klotho in muscles of two animal models (CD-1 and Cy/+ rat, a naturally occurring rat model of chronic kidney disease-mineral bone disorder) as well as C2C12 myoblasts and myotubes. C2C12 proliferation, myogenic gene expression, oxidative stress marker 8-OHdG, intracellular Ca2+ ([Ca2+]i), and ex vivo contractility of extensor digitorum longus (EDL) or soleus muscles were assessed after treatment with various amounts of FGF23. FGF23 (2-100 ng/ml) did not alter C2C12 proliferation, expression of myogenic genes, or oxidative stress after 24- to 72-h treatment. Acute or prolonged FGF23 treatment up to 6 days did not alter C2C12 [Ca2+]i handling, nor did acute treatment with FGF23 (9-100 ng/ml) affect EDL and soleus muscle contractility. In conclusion, although skeletal muscles express the receptors involved in FGF23-mediated signaling, in vitro FGF23 treatments failed to directly alter skeletal muscle development or function under the conditions tested. We hypothesize that other endogenous substances may be required to act in concert with FGF23 or apart from FGF23 to promote muscle dysfunction in hereditary hypophosphatemic rickets and CKD.

Assessment of sarcopenia in virally suppressed HIV-infected Asians receiving treatment

OBJECTIVES

In a clinic-based, treated HIV-infected cohort, we identified individuals with sarcopenia and compared with age, sex and ethnically matched controls; and investigated associated risk factors and health outcomes.

DESIGN

Sarcopenia (age-related muscle loss) causes significant morbidity to the elderly, leading to frequent hospitalizations, disability and death. Few have characterized sarcopenia in the HIV-infected who experience accelerated aging.

METHODS

Sarcopenia was defined as low muscle mass with weak grip strength and/or slow gait speed using lower 20th percentiles of controls. Multivariate logistic and linear regression analyses were used to explore risk factors and health-related outcomes associated with sarcopenia among HIV-infected individuals.

RESULTS

We recruited 315 HIV-infected individuals aged at least 25 years with at least 1-year history of undetectable viral load on treatment (HIV RNA <50 copies/ml). Percentage of sarcopenia in 315 HIV-infected was 8%. Subsequently, 153 of the 315 were paired with age, sex and ethnically matched HIV-uninfected. The percentage of sarcopenia in the HIV-infected (n = 153) compared with uninfected (n = 153) were 10 vs. 6% (P = 0.193) respectively, whereas of those at least 50 years of age among them were 17% vs. 4% (P = 0.049), respectively. Associated risk factors among the HIV-infected include education level, employment status, BMI, baseline CD4 cell count, duration on NRTIs and GGT levels. Identified negative outcomes include mortality risk scores [5.42; 95% CI 1.46-9.37; P = 0.007) and functional disability (3.95; 95% CI 1.57-9.97; P = 0.004).

CONCLUSION

Sarcopenia is more prevalent in HIV-infected at least 50 years old compared with matched controls. Our findings highlight associations between sarcopenia with loss of independence and greater healthcare burden among treated HIV-infected individuals necessitating early recognition and intervention.

Whole body vibration improves maximum voluntary isometric contraction of knee extensors in patients with chronic kidney disease: A randomized controlled trial

BACKGROUND

Whole body vibration (WBV) training improves maximum voluntary isometric contraction (MVIC) of knee extensors, postural balance, functional capacity, and quality of life (QOL) in several diseases. The objective was to assess the efficacy of WBV training in patients with chronic kidney disease (CKD) on hemodialysis (HD) in the interdialytic period.

METHOD

A randomized, controlled trial study with concealed allocation, intention-to-treat analysis, and triple blinding. Sixteen patients with CKD of both genders aged over 40 years were allocated in two groups, the WBV group or the sham group, training 2 times a week for 12 weeks. The primary outcome was knee extensor muscle strength, and the secondary outcomes were quadriceps thickness, distance walked, balance, and QOL.

RESULTS

The WBV group improved MVIC of knee extensors with a difference between groups in improvement of 117.29 N (95% CI, 32.25-202.24) at the end of training. The other outcomes were not different between groups. Practical applications: The WBV program has shown to be effective and may be able to help in prescribing the appropriate training program for CKD.

CONCLUSION

WBV training improves MVIC of knee extensors in patients with CKD on HD in the interdialytic period. WBV training could be considered in the management of patients with CKD.

Aerobic exercise training rescues protein quality control disruption on white skeletal muscle induced by chronic kidney disease in rats

We tested whether aerobic exercise training (AET) would modulate the skeletal muscle protein quality control (PQC) in a model of chronic kidney disease (CKD) in rats. Adult Wistar rats were evaluated in four groups: control (CS) or trained (CE), and 5/6 nephrectomy sedentary (5/6NxS) or trained (5/6NxE). Exercised rats were submitted to treadmill exercise (60 min., five times/wk for 2 months). We evaluated motor performance (tolerance to exercise on the treadmill and rotarod), cross-sectional area (CSA), gene and protein levels related to the unfolded protein response (UPR), protein synthesis/survive and apoptosis signalling, accumulated misfolded proteins, chymotrypsin-like proteasome activity (UPS activity), redox balance and heat-shock protein (HSP) levels in the tibialis anterior. 5/6NxS presented a trend towards to atrophy, with a reduction in motor performance, down-regulation of protein synthesis and up-regulation of apoptosis signalling; increases in UPS activity, misfolded proteins, GRP78, derlin, HSP27 and HSP70 protein levels, ATF4 and GRP78 genes; and increase in oxidative damage compared to CS group. In 5/6NxE, we observed a restoration in exercise tolerance, accumulated misfolded proteins, UPS activity, protein synthesis/apoptosis signalling, derlin, HSPs protein levels as well as increase in ATF4, GRP78 genes and ATF6α protein levels accompanied by a decrease in oxidative damage and increased catalase and glutathione peroxidase activities. The results suggest a disruption of PQC in white muscle fibres of CKD rats previous to the atrophy. AET can rescue this disruption for the UPR, prevent accumulated misfolded proteins and reduce oxidative damage, HSPs protein levels and exercise tolerance.

A study of pulmonary function in end-stage renal disease patients on hemodialysis: a cross-sectional study

BACKGROUND

The aim here was to study acute effects of hemodialysis among end-stage renal disease (ESRD) patients.

DESIGN AND SETTING

Prospective study in tertiary-level care center.

METHODS

Fifty ESRD patients undergoing hemodialysis were studied. Spirometric pulmonary function tests were performed before and after four-hour hemodialysis sessions.

RESULTS

The patients' average age was 45.8 ± 10.0 years; 64% were males and 64% had normal body mass index. Anemia (94%) and hypoalbuminemia (72%) were common. Diabetes mellitus (68%), hypertension (34%) and coronary artery disease (18%) were major comorbidities. Forty-five patients (90%) had been on hemodialysis for six months to three years. The patients' pre-dialysis mean forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) were below normal: 45.8 ± 24.9% and 43.5 ± 25.9% of predicted, respectively. After hemodialysis, these increased significantly, to 51.1 ± 23.4% and 49.3 ± 25.5% of predicted, respectively (P < 0.01). The increase in mean FEV1/FVC, from 97.8 ± 20.8% to 99.3 ± 20.1% of predicted, was not significant (P > 0.05). The pre-dialysis mean forced expiratory flow 25-75% was 50.1 ± 31% and increased significantly, to 56.3 ± 31.6% of predicted (P < 0.05). The mean peak expiratory flow was below normal (43.8 ± 30.7%) and increased significantly, to 49.1 ± 29.9% of predicted (P < 0.05). Males and females showed similar directions of change after hemodialysis.

CONCLUSIONS

Pulmonary function abnormalities are common among ESRD patients. Comparison of pre and post-hemodialysis parameters showed significant improvements, but normal predicted values were still not achieved.

[Common therapeutic approaches of sarcopenia in the elderly and uremic myopathy]

The gradual loss of weight and function of muscle in patients with chronic kidney disease as in the elderly impacts the quality of life. Early management should help slow the functional limitation. Physical activity is the first therapy to propose that ensures stability of muscle mass and improved function. Resistance training programs have proven effective but are not yet widely available in nephrology units. The nutritional management should not be forgotten because there is a resistance to anabolism and protein intake should be involved in physical activity program. Associated treatments should not be neglected: vitamin D, anti-inflammatory, androgens. Some are still under evaluation. Therapeutic option, tomorrow, could be anti-myostatin antibodies and glitazones.

Attenuation of diabetic nephropathy by Sanziguben Granule inhibiting EMT through Nrf2-mediated anti-oxidative effects in streptozotocin (STZ)-induced diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetic nephropathy (DN) is an acute and serious diabetic complication characterized by renal hypertrophy and renal fibrosis with the expansion of extracellular matrices. Diabetic nephropathy has become a major cause of end-stage kidney disease. Sanziguben Granule (SZGB) is a compound prescription which has been widely applied in clinical medicine for the prevention and treatment of diabetic nephropathy as well as for acute and chronic kidney injuries. However, the mechanism of protective effects of SZGB in DN remains unclear.

MATERIALS AND METHODS

In this research, we investigated the effects of SZGB on renal interstitial fibrosis, antioxidant proficiency, and apoptosis in streptozotocin (STZ)-induced diabetic rats. Diabetic rats were prepared by performing a right uninephrectomy along with a single intraperitoneal injection of STZ. Rats were divided into six groups including sham, DN, SZGB-D, SZGB-Z, SZGB-G and fosinopril. SZGB and fosinopril were given to rats by gavage for 12 weeks. Samples from urine, blood and kidneys were collected for biochemical, histological, immunohistochemical and western blot analyses.

RESULTS

We found that rats treated with SZGB showed reduced 24-h urinary protein excretion along with reduced serum total cholesterol (TC) and triglyceride (TG) levels. SZGB was also shown to prevent the disruption of catalase activity and reduce serum urea, creatinine, and renal malondialdehyde while increasing glutathione levels. Moreover, SZGB administration markedly improved the expression levels of E-cadherin, 4-HNE, Nrf2, HO-1, and Bcl-2, while it decreased the expression levels of Vimentin, α-SMA and Cleaved caspase-3 in the kidneys of diabetic rats. The renoprotective effects of SZGB was believed to be mediated by its antioxidant capacity, and SZGB treatment attenuated renal fibrosis through stimulating the nuclear factor erythroid-2-related factor 2 (Nrf2) signaling pathway in the diabetic kidneys.

CONCLUSIONS

Therefore, it is suggested that SZGB can restrain epithelial-mesenchymal transition (EMT) through stimulating the Nrf2 pathway, which improves renal interstitial fibrosis in DN.

Physical Exercise and Patients with Chronic Renal Failure: A Meta-Analysis

Chronic renal failure is a severe clinical problem which has some significant socioeconomic impact worldwide and hemodialysis is an important way to maintain patients' health state, but it seems difficult to get better in short time. Considering these, the aim in our research is to update and evaluate the effects of exercise on the health of patients with chronic renal failure. The databases were used to search for the relevant studies in English or Chinese. And the association between physical exercise and health state of patients with chronic renal failure has been investigated. Random-effect model was used to compare the physical function and capacity in exercise and control groups. Exercise is helpful in ameliorating the situation of blood pressure in patients with renal failure and significantly reduces VO2 in patients with renal failure. The results of subgroup analyses show that, in the age >50, physical activity can significantly reduce blood pressure in patients with renal failure. The activity program containing warm-up, strength, and aerobic exercises has benefits in blood pressure among sick people and improves their maximal oxygen consumption level. These can help patients in physical function and aerobic capacity and may give them further benefits.

Effect of Chronic Kidney Disease and Supplemental Polyunsaturated Fatty Acid Use on Exercise Levels During Cardiac Rehabilitation in Patients With Coronary Artery Disease

PURPOSE

The correlation between chronic kidney disease (CKD) and increased cardiovascular disease-related mortality is well established. Cardiac rehabilitation (CR) improves exercise capacity, quality of life, and risk factors in patients with coronary artery disease (CAD). Data on the benefits of CR in patients with CKD are sparse. The purpose of this study was to compare outcomes after CR in patients with CAD but normal renal function, versus those with CAD and CKD.

METHODS

We studied 804 patients with CAD entering an exercise-based CR program. Demographics, risk factors, exercise capacity in metabolic equivalent levels (METs), and estimated glomerular filtration rate (GFR) were recorded before and after the 3-month CR program. Use of polyunsaturated fatty acid (PUFA) was determined by medical records review. Stage III-V CKD (GFR <60 mL/min/1.73 m) was present in 170 patients at baseline.

RESULTS

After CR, METs improved in all patients, although increases in patients with a GFR 30 to 59 mL/min/1.73 m (Δ1.6) and a GFR <30 (Δ1.2) were smaller than those in patients with a GFR ≥60 (Δ2.6, P < .05 vs GFR 30-59 and GFR <30). In patients with a GFR ≥60 mL/min/1.73 m, PUFA use was associated with a 20% greater increase in MET levels compared with nonusers (Δ3.0 vs Δ2.5, P = .02); and in patients with a GFR 30 to 59, PUFA use was associated with 30% increase in MET level compared with nonusers (Δ2.0 vs Δ1.4, P = .03). These observations persisted after multivariable adjustment for baseline MET level, demographics, and risk factors.

CONCLUSIONS

Potential mitigation by PUFA of the smaller improvement in exercise capacity with decreasing GFR requires confirmation in prospective randomized trials.

Physical exercise modifies the functional capacity of elderly patients on hemodialysis

Abstract Introduction Patients on hemodialysis (HD) improve functional capacity after physical training. However, little is discussed about these effects in elderly patients, since these are usually excluded of studies, due to their physical disabilities and other deficits. Objective To analyze the effects of aerobic and resistance training in the functional capacity of elderly patients submitted to HD. Methods Studied participants were 15 patients, of both genders, and aged over 60 years. Aerobic and resistance training was carried out during the hemodialysis session, three times per week, during four months. Patients were distributed into control (CG) and experimental (EG) groups. Functional capacity was assessed by six-minute walk (6MW), sit-to-stand (STS) and respiratory muscle strength tests. Results After the physical training, EG presented a significant increase in the distance covered in 6MW (Z = 2.521, p < .012), respiratory muscle strength (inspiratory pressure: Z = 2.533, p < .011; expiratory pressure: Z = 2.536, p < .011); and in number of STS repetitions (2.54; p <.001). Conclusion The training modified the functional capacity of the HD patients, contributing to their rehabilitation.

Lower C-reactive protein and better hemodialysis survival are associated with regular exercise activity: Longitudinal outcomes from the ACTIVE-ADIPOSE special study

Introduction Cross-sectional and longitudinal studies in the general population have shown that a physically active lifestyle may have anti-inflammatory properties, but evidence from studies conducted with maintenance hemodialysis (HD) patients is limited. Methods A multicenter prospective cohort of 755 HD participants aged 20-92 was evaluated in a USRDS special study 2009-2013. Kilocalories/week (kcal/week) of leisure time physical activity (LTPA) was estimated from the Minnesota Leisure Time Activity questionnaire. Predialysis serum samples were obtained concurrent with LTPA report date. Generalized estimating equations (GEE) examined association of participants' LTPA and log-normalized CRP across 24 months. Cox proportional hazards models investigated LTPA and survival over a median follow-up of 718 days. Findings Baseline median CRP concentration was lower for participants with 500+ kcal/week LTPA vs. those with <500 kcal/week LTPA (3.4 mg/L vs. 4.6 mg/L; P = 0.03). Participants who reported lower LTPA (<500 kcal/week) at both baseline and 12 months had a borderline significant increase in CRP concentration (within-group change 4.8 [1.9-10.4] to 5.8 [1.6-15.7]; P = 0.08). Lower LTPA was associated with higher log CRP over 24 months in adjusted GEE analyses (β coefficient = 0.16 [95% CI 0.02-0.31]; P = 0.03). 67/364 (18%) and 43/391 (11%) deaths occurred, respectively, among participants reporting <500 vs. 500+ kcal/week LTPA [adjusted mortality hazard ratio 1.63 (CI, 1.07, 2.47)]. Discussion The data suggest that increased estimated levels of LTPA, a physical activity/exercise opportunity widely applicable to HD patients, may be associated with lower CRP concentration as well as better survival outcome.

Predictors of Peak Troponin Level in Acute Coronary Syndromes: Prior Aspirin Use and SYNTAX Score

The peak troponin level has been associated with cardiovascular (CV) mortality and adverse CV events. The association of peak troponin with CV risk factors and severity and complexity of coronary artery disease remains unknown. We assessed the predictors of peak troponin in patients with acute coronary syndrome (ACS). This study aims to determine the predictors of peak troponin in ACS. Cardiac catheterization (CC) reports and electronic medical records from 2010 to 2013 were retrospectively reviewed. A total of 219 patients were eligible for the study. All major CV risk factors, comorbidities, laboratory data, CC indications, and coronary lesion characteristics were included. Univariate and multivariate regression analyses were done. On multivariate linear regression analysis, ST-elevation myocardial infarction (p = 0.001, β = 65.16) and increasing synergy between percutaneous coronary intervention with Taxus and cardiac surgery (SYNTAX) score (p = 0.002, β = 1.15) were associated with higher peak troponin. The Pearson correlation between SYNTAX score and peak troponin was r = 0.257, p = 0.001. History of daily aspirin use was associated with lower peak troponin (p = 0.002, β = -24.32). Prior statin use (p = 0.321, β = -8.98) and the presence of CV risk factors were not associated with peak troponin. Coronary artery disease severity and complexity, urgency of CC, and prior aspirin use are associated with peak troponin levels in ACS. Our findings may help predict patient population with ACS who would be at a greater risk for short- and long-term CV morbidity and mortality due to elevated peak troponin.

An integrated lipidomics and metabolomics reveal nephroprotective effect and biochemical mechanism of Rheum officinale in chronic renal failure

Chronic renal failure (CRF) is a major public health problem worldwide. Earlier studies have revealed salutary effects of rhubarb extracts in CRF. In this study, we employed lipidomic and metabolomic approaches to identify the plasma biomarkers and to determine the effect of treatment with petroleum ether, ethyl acetate and n-butanol extracts of rhubarb in a rat model of CRF with adenine-induced chronic tubulointerstitial nephropathy. In addition, clinical biochemistry, histological evaluation and pro-fibrotic protein expression were analyzed. Significant changes were found between the CRF and control groups representing characteristic phenotypes of rats with CRF. Treatment with the three rhubarb extracts improved renal injury and dysfunction, either fully or partially reversed the plasma metabolites abnormalities and attenuated upregulation of pro-fibrotic proteins including TGF-β1, α-SMA, PAI-1, CTGF, FN and collagen-1. The nephroprotective effect of ethyl acetate extract was better than other extracts. The differential metabolites were closely associated with glycerophospholipid, fatty acid and amino acid metabolisms. The results revealed a strong link between renal tubulointerstitial fibrosis and glycerophospholipid metabolism and L-carnitine metabolism in the development of CRF. Amelioration of CRF with the three rhubarb extracts was associated with the delayed development and/or reversal the disorders in key metabolites associated with adenine-induced CRF.

High-phosphorus diet maximizes and low-dose calcitriol attenuates skeletal muscle changes in long-term uremic rats

Although disorders of mineral metabolism and skeletal muscle are common in chronic kidney disease (CKD), their potential relationship remains unexplored. Elevations in plasma phosphate, parathyroid hormone, and fibroblastic growth factor 23 together with decreased calcitriol levels are common features of CKD. High-phosphate intake is a major contributor to progression of CKD. This study was primarily aimed to determine the influence of high-phosphate intake on muscle and to investigate whether calcitriol supplementation counteracts negative skeletal muscle changes associated with long-term uremia. Proportions and metabolic and morphological features of myosin-based muscle fiber types were assessed in the slow-twitch soleus and the fast-twitch tibialis cranialis muscles of uremic rats (5/6 nephrectomy, Nx) and compared with sham-operated (So) controls. Three groups of Nx rats received either a standard diet (0.6% phosphorus, Nx-Sd), or a high-phosphorus diet (0.9% phosphorus, Nx-Pho), or a high-phosphorus diet plus calcitriol (10 ng/kg 3 day/wk ip, Nx-Pho + Cal) for 12 wk. Two groups of So rats received either a standard diet or a high-phosphorus diet (So-Pho) over the same period. A multivariate analysis encompassing all fiber-type characteristics indicated that Nx-Pho + Cal rats displayed skeletal muscle phenotypes intermediate between Nx-Pho and So-Pho rats and that uremia-induced skeletal muscle changes were of greater magnitude in Nx-Pho than in Nx-Sd rats. In uremic rats, treatment with calcitriol preserved fiber-type composition, cross-sectional size, myonuclear domain size, oxidative capacity, and capillarity of muscle fibers. These data demonstrate that a high-phosphorus diet potentiates and low-dose calcitriol attenuates adverse skeletal muscle changes in long-term uremic rats.

[Sarcopenia or uremic myopathy in CKD patients]

Often underestimated or misunderstood in chronic renal failure (CRF), muscle wasting is nevertheless common and concerns about 50% of dialysis patients. The consequences of this myopathy on quality of life and outcomes of patients are unfavorable, identical to those observed in sarcopenia in elderly subjects with sarcopenia. The similarities between the two situations also concern the symptoms, the underlying muscle damages and the pathogenic mechanisms and may be partly explained by the frequently high age of ESRD patients. Skeletal muscle involvement should be systematically investigated in the IRC patient as in the elderly with sarcopenia to propose as early as possible a treatment of which physical activity and nutritional interventions are the mainstay.

Knowledge among nephrologists about the importance of exercise in the intradialytic period

[Purpose] To assess knowledge among nephrologists at hemodialysis services about routine intradialytic therapeutic exercise, in the city of Recife. [Subjects and Methods] A cross-sectional study, consisting of 49 nephrologists working in public and/or private hemodialysis services, who responded to a semi-structured questionnaire about their academic background, medical residency, and knowledge about exercise during the intradialytic period. [Results] About 56.3% practiced for more than 10 years as nephrologists, 69.4% did not receive information about intradialytic physical exercise while in residency, 81.6% considered intradialytic exercise to be important, and 53.0% did not prescribe exercise during hemodialysis. About 61.2% consider the level of physical activity among their patients to be poor. Nephrologists graduating within 2 years were 10 times more likely to prescribe exercise, compared to those with more than 2 years since graduation. [Conclusion] Our study found that the nephrologists interviewed do not usually prescribe intradialytic therapeutic exercise, despite understanding its importance as part of the treatment process. It is necessary to update doctors about the importance of exercise for patients during the intradialytic period, as well as to incorporate this knowledge at the undergraduate level.

Slow- and fast-twitch hindlimb skeletal muscle phenotypes 12 wk after ⅚ nephrectomy in Wistar rats of both sexes

This study describes fiber-type adaptations in hindlimb muscles, the interaction of sex, and the role of hypoxia on this response in 12-wk ⅚ nephrectomized rats (Nx). Contractile, metabolic, and morphological features of muscle fiber types were assessed in the slow-twitch soleus and the fast-twitch tibialis cranialis muscles of Nx rats, and compared with sham-operated controls. Rats of both sexes were considered in both groups. A slow-to-fast fiber-type transformation occurred in the tibialis cranialis of Nx rats, particularly in males. This adaptation was accomplished by impaired oxidative capacity and capillarity, increased glycolytic capacity, and no changes in size and nuclear density of muscle fiber types. An oxidative-to-glycolytic metabolic transformation was also found in the soleus muscle of Nx rats. However, a modest fast-to-slow fiber-type transformation, fiber hypertrophy, and nuclear proliferation were observed in soleus muscle fibers of male, but not of female, Nx rats. Serum testosterone levels decreased by 50% in male but not in female Nx rats. Hypoxia-inducible factor-1α protein level decreased by 42% in the tibialis cranialis muscle of male Nx rats. These data demonstrate that 12 wk of Nx induces a muscle-specific adaptive response in which myofibers do not change (or enlarge minimally) in size and nuclear density, but acquire markedly different contractile and metabolic characteristics, which are accompanied by capillary rarefaction. Muscle function and sex play relevant roles in these adaptations.

The Effects of Aquatic Exercises on Physical Fitness and Muscle Function in Dialysis Patients

Purpose. The aim of this study was to assess the impact of a 3-month physical training program, conducted in an aquatic environment with end-stage renal disease patients (ESRD), on the physical fitness and functional parameters of the knee joint muscles. Patients and Methods. The study included 20 ESDR patients with mean age 64.2 ± 13.1 y. treated with hemodialysis in Dialysis Center of the University Hospital in Wroclaw. Before and 3 months after the physical training in water, a test was performed to evaluate the physical fitness of each patient; additionally, a measurement was taken of force-velocity parameters. The 3-month training program took place on nonhemodialysis days, in the recreational pool of the University of Physical Education in Wroclaw. Results. After aquatic training cycle, an improvement was observed in all parameters measured using the Fullerton test. The value of peak torque and its relation to body mass increased in the movement of flexors and extensors of left and right lower extremities in all tested velocities. Conclusions. In assessing the physical fitness of studied women, the biggest improvement was achieved in tests assessing the strength of upper and lower extremities as well as lower body flexibility. Higher values of force-velocity parameters are conducive to women achieving better physical fitness test results.

Impact of continuous positive airway pressure (CPAP) on the respiratory capacity of chronic kidney disease patients under hemodialysis treatment

PURPOSE

Chronic kidney disease (CKD) patients on long-term dialysis present changes in pulmonary function and respiratory muscle strength, negatively influencing physical capacity.

OBJECTIVE

To analyze the impact of a continuous positive airway pressure (CPAP) protocol on the respiratory capacity of CKD patients under hemodialysis.

METHODS

A randomized clinical trial was conducted involving 40 CKD patients 19-83 years old divided into two groups: control (n = 20) and CPAP (n = 20). Subjects were assessed on the respiratory muscle function test, maximal respiratory pressures, peak flow and 6-min walk test, at baseline and again at the 2-month follow-up. CPAP group patients were submitted to CPAP protocol (PEEP: 5 cm H2O, flow: 15 L/min, FiO2: 33 %) three times per week during hemodialysis sessions.

RESULTS

The CPAP group showed higher forced vital capacity, forced expiratory volume in one second, peak expiratory flow, maximal inspiratory pressure, peak flow, as well as lower systolic blood pressure, heart rate, respiratory rate and Borg scale, in addition to a longer distance travelled on the 6-min walk test, compared with the control group.

CONCLUSION

The introduction of a CPAP protocol during hemodialysis sessions had a positive impact on pulmonary function and physical capacity in CKD patients.

Impact of physical therapy on functional capacity and life quality of patients with chronic kidney disease

Introduction Studies have demonstrated beneficial effects of exercise in patients with chronic kidney disease, however, based on current scientific literature, more research is needed to increase evidence level of potential effects of physical activity for this population. Objective To evaluate effects of physical therapy based on the supervised exercise practice on functional capacity and life quality of patients with chronic kidney disease. Material and methods This quasi-experimental study, with repeated measures design, was conducted in the ambulatory of physical therapy, in a public hospital, located in a city of the state of Pará (north region of Brazil). Functional capacity and life quality were assessed at baseline and after six weeks of aerobic and resistance training performed three times per week on alternate days with hemodialysis. Results Eight patients (3M / 5F) with a mean age of 60.38 years (SD = 14.75) were evaluated. There was significant increase of 24% in distance walked in six minute walk test (p = 0.007), and of 47% in number of repetitions during sit-to-stand test (p = 0.002); there was also significant improvement in emotional role (p = 0.043) of life quality assessed with SF36 questionnaire. Conclusion There was a positive impact of only six weeks of rehabilitation with physical exercise on functional capacity and emotional role of life quality of patients with chronic kidney disease.

Abnormal neurocirculatory control during exercise in humans with chronic renal failure

Abnormal neurocirculatory control during exercise is one important mechanism leading to exercise intolerance in patients with both end-stage renal disease (ESRD) and earlier stages of chronic kidney disease (CKD). This review will provide an overview of mechanisms underlying abnormal neurocirculatory and hemodynamic responses to exercise in patients with kidney disease. Recent studies have shown that ESRD and CKD patients have an exaggerated increase in blood pressure (BP) during both isometric and rhythmic exercise. Subsequent studies examining the role of the exercise pressor reflex in the augmented pressor response revealed that muscle sympathetic nerve activity (MSNA) was not augmented during exercise in these patients, and metaboreflex-mediated increases in MSNA were blunted, while mechanoreflex-mediated increases were preserved under basal conditions. However, normalizing the augmented BP response during exercise via infusion of nitroprusside (NTP), and thereby equalizing baroreflex-mediated suppression of MSNA, an important modulator of the final hemodynamic response to exercise, revealed that CKD patients had an exaggerated increase in MSNA during isometric and rhythmic exercise. In addition, mechanoreflex-mediated control was augmented, and metaboreceptor blunting was no longer apparent in CKD patients with baroreflex normalization. Factors leading to mechanoreceptor sensitization, and other mechanisms underlying the exaggerated exercise pressor response, such as impaired functional sympatholysis, should be investigated in future studies.

Action potential-evoked calcium release is impaired in single skeletal muscle fibers from heart failure patients

BACKGROUND

Exercise intolerance in chronic heart failure (HF) has been attributed to abnormalities of the skeletal muscles. Muscle function depends on intact excitation-contraction coupling (ECC), but ECC studies in HF models have been inconclusive, due to deficiencies in the animal models and tools used to measure calcium (Ca2+) release, mandating investigations in skeletal muscle from HF patients. The purpose of this study was to test the hypothesis that Ca2+ release is significantly impaired in the skeletal muscle of HF patients in whom exercise capacity is severely diminished compared to age-matched healthy volunteers.

METHODS AND FINDINGS

Using state-of-the-art electrophysiological and optical techniques in single muscle fibers from biopsies of the locomotive vastus lateralis muscle, we measured the action potential (AP)-evoked Ca2+ release in 4 HF patients and 4 age-matched healthy controls. The mean peak Ca2+ release flux in fibers obtained from HF patients (10±1.2 µM/ms) was markedly (2.6-fold) and significantly (p<0.05) smaller than in fibers from healthy volunteers (28±3.3 µM/ms). This impairment in AP-evoked Ca2+ release was ubiquitous and was not explained by differences in the excitability mechanisms since single APs were indistinguishable between HF patients and healthy volunteers.

CONCLUSIONS

These findings prove the feasibility of performing electrophysiological experiments in single fibers from human skeletal muscle, and offer a new approach for investigations of myopathies due to HF and other diseases. Importantly, we have demonstrated that one step in the ECC process, AP-evoked Ca2+ release, is impaired in single muscle fibers in HF patients.

Pulmonary hypertension in end-stage renal disease and post renal transplantation patients

BACKGROUND

Information regarding lung function parameters and functional capacity in renal failure and post renal transplantation patients with pulmonary hypertension (PH) is limited. The purpose of this study was to examine the clinical characteristics of patients with PH who were receiving hemodialysis (HD) or peritoneal dialysis (PD) or who had undergone renal transplantation.

METHODS

A prospective study was performed on 116 patients (HD =55, PD =17, and post renal transplantation =44) who underwent Doppler echocardiography. PH was defined as systolic pulmonary artery pressure (SPAP) ≥40 mmHg. Demographic information, clinical characteristics, pulmonary function tests (PFTs) and the six-minute walk test (6MWT) were collected and compared between the patients with and without PH.

RESULTS

Twelve (21.8%) patients receiving HD, four (23.5%) patients receiving PD, and eight (18.2%) post renal transplantation patients had PH. In the HD group, the physiological indicators (including pulmonary function test parameters, the final Borg score, and walking distance during the 6MWT) were all significantly lower in the patients with PH compared with those without PH (all P<0.0001). However, in the PD and post renal transplantation groups, no significant differences were noted in the demographic characteristics or in the physiological parameters when the PH patients were compared with those without PH (all P>0.05).

CONCLUSIONS

Among HD patients, marked aberrations in PFT results or walking distance may identify a subset of patients suffering from PH.