Skeletal muscle dysfunction in chronic renal failure: effects of exercise

Role of dyslipidemia in impairment of energy metabolism, oxidative stress, inflammation and cardiovascular disease in chronic kidney disease

Advanced chronic kidney disease (CKD) results in a constellation of dysregulation of lipid metabolism, oxidative stress, and inflammation which are causally interconnected and participate in a vicious cycle. The CKD-associated lipid disorders are marked by impaired clearance of very low density lipoprotein and chylomicrons, hypertriglyceridemia, formation of small dense low-density lipoprotein (LDL), oxidative modification of LDL, intermediate density lipoprotein and chylomicron remnants, and high-density lipoprotein deficiency and dysfunction. This review provides a brief overview of the role of CKD-induced lipid disorders in the pathogenesis of oxidative stress, inflammation, cardiovascular disease, impaired exercise capacity, cachexia and wasting syndrome.

Exhaled breath and fecal volatile organic biomarkers of chronic kidney disease

BACKGROUND

While much is known about the effect of chronic kidney disease (CKD) on composition of body fluids little is known regarding its impact on the gases found in exhaled breath or produced by intestinal microbiome. We have recently shown significant changes in the composition of intestinal microbiome in humans and animals with CKD. This study tested the hypothesis that uremia-induced changes in cellular metabolism and intestinal microbiome may modify the volatile organic metabolites found in the exhaled breath or generated by intestinal flora.

METHODS

SD rats were randomized to CKD (5/6 nephrectomy) or control (sham operation) groups. Exhaled breath was collected by enclosing each animal in a glass chamber flushed with clean air, then sealed for 45 min and the trapped air collected. Feces were collected, dissolved in pure water, incubated at 37 degrees C in glass reactors for 24 h and the trapped air collected. Collected gases were analyzed by gas chromatography.

RESULTS

Over 50 gases were detected in the exhaled breath and 36 in cultured feces. Four gases in exhaled breath and 4 generated by cultured feces were significantly different in the two groups. The exhaled breath in CKD rats showed an early rise in isoprene and a late fall in linear aldehydes. The CKD animals' cultured feces released larger amounts of dimethyldisulfide, dimethyltrisulfide, and two thioesters.

CONCLUSIONS

CKD significantly changes the composition of exhaled breath and gaseous products of intestinal flora.

GENERAL SIGNIFICANCE

Analysis of breath and bowel gases may provide useful biomarkers for detection and progression of CKD and its complications.

Inflammatory activation: cardiac, renal, and cardio-renal interactions in patients with the cardiorenal syndrome

Although inflammation is a physiologic response designed to protect us from infection, when unchecked and ongoing it may cause substantial harm. Both chronic heart failure (CHF) and chronic kidney disease (CKD) are known to cause elaboration of several pro-inflammatory mediators that can be detected at high concentrations in the tissues and blood stream. The biologic sources driving this chronic inflammatory state in CHF and CKD are not fully established. Traditional sources of inflammation include the heart and the kidneys which produce a wide range of pro-inflammatory cytokines in response to neurohormones and sympathetic activation. However, growing evidence suggests that non-traditional biomechanical mechanisms such as venous and tissue congestion due to volume overload are also important as they stimulate endotoxin absorption from the bowel and peripheral synthesis and release of pro-inflammatory mediators. Both during the chronic phase and, more rapidly, during acute exacerbations of CHF and CKD, inflammation and congestion appear to amplify each other resulting in a downward spiral of worsening cardiac, vascular, and renal functions that may negatively impact patients' outcome. Anti-inflammatory treatment strategies aimed at attenuating end organ damage and improving clinical prognosis in the cardiorenal syndrome have been disappointing to date. A new therapeutic paradigm may be needed, which involves different anti-inflammatory strategies for individual etiologies and stages of CHF and CKD. It may also include specific (short-term) anti-inflammatory treatments that counteract inflammation during the unsettled phases of clinical decompensation. Finally, it will require greater focus on volume overload as an increasingly significant source of systemic inflammation in the cardiorenal syndrome.

Aplicação de exercício isotônico durante a hemodiálise melhora a eficiência dialítica

INTRODUÇÃO: A doença renal crônica (DRC) é decorrente de uma lesão renal e perda progressiva e irreversível da função dos rins. A hemodiálise substitui parcialmente essa função, com o objetivo de corrigir as alterações metabólicas na DRC. Para acompanhar a adequação da diálise, é determinado o Kt/V - índice de depuração da ureia por sessão de hemodiálise. O exercício físico de moderada intensidade tem se mostrado de fundamental importância para melhorar os efeitos adversos ao tratamento dialítico. OBJETIVOS: Avaliar o Kt/V em indivíduos com DRC submetidos ao exercício físico isotônico de baixa intensidade durante a hemodiálise. MATERIAIS E MÉTODOS: Analisados dados de 15 voluntários de ambos os sexos, submetidos à hemodiálise três vezes por semana. Após duas horas do início da diálise, foi aplicado um protocolo de exercícios isotônicos de baixa intensidade de membros superiores e inferiores com duração de 30 minutos, por um período de três meses. Os valores do Kt/V foram comparados no período de três meses anteriores sem exercício e após três meses de exercício. RESULTADOS: A média dos valores do Kt/V nos três meses sem exercício foi de 1,13 ± 0,11 e após aplicação do programa de exercícios foi de 1,29 ± 0,12 (p < 0,05). CONCLUSÃO: O programa de exercício físico isotônico de baixa intensidade em pacientes com DRC, aplicados durante a sessão de diálise mostrou a melhora da eficiência dialítica.

Exercise rescued chronic kidney disease by attenuating cardiac hypertrophy through the cardiotrophin-1 -> LIFR/gp 130 -> JAK/STAT3 pathway

BACKGROUND

Chronic kidney disease (CKD) is usually associated with cardiac apoptosis and/or cardiac hypertrophy. We hypothesized that exercise can reduce the CKD-induced cardiac damage.

METHODS AND RESULTS

The doxorubicin-induced CKD (DRCKD) model was used in rats to compare two exercise models: 60-min running and 60-min swimming. Results indicated that in healthy normal groups, the signals cardiotrophin-1 (CT-1), interleukin 6 (IL-6), leukaemia inhibitory factor receptor (LIFR), and gp130 were upregulated and janus kinase (JAK) and signal transducer and activation of transcription (STAT) were downregulated by both exercises. In contrast, all signals were highly upregulated in CKD. After exercise training, all signals (CT-1, IL-6, LIFR, gp130, and STAT) were downregulated, with JAK being only slightly upregulated in the running group but not in the swimming group. The myocyte death pathway (CT-1/IL-6 → LIFR/gp130 → PI3K → Akt → Bad) was excluded due to no change found for Bad. Nitric oxide (NO; normal, 15.63 ± 0.86 µmol/l) was significantly suppressed in CKD rats (2.95 ± 0.32 µmol/l), and both running and swimming training highly upregulated the NO level to 30.33 ± 1.03 µmol/l and 27.82 ± 2.47 µmol/l in normal subjects and 24.0 ± 3.2 µmol/l and 22.69 ± 3.79 µmol/l in the DRCKD rats, respectively. The endothelial progenic cells CD34 were significantly suppressed in DRCKD rats, which were not rescued significantly by exercise. In contrast, the CD 34 cells were only slightly suppressed in the healthy subjects by exercise.

CONCLUSION

Both exercise regimens were beneficial by rescuing cardiac function in CKD victims. Its action mechanism was by way of inhibiting myocyte death and rescuing cardiac hypertrophy.

Inhibitory effects of IL-6 on IGF-1 activity in skeletal myoblasts could be mediated by the activation of SOCS-3

In elderly people, low and high levels of insulin-like growth factor 1 (IGF-1) and interleukin-6 (IL-6), respectively, are well documented and may contribute to reduced muscle mass and poor muscle function of ageing and suggesting a biological interactions between IGF-1 and IL-6. However, the dual effect of IGF-1/IL-6 on skeletal muscle differentiation and proliferation has not been fully investigated. We therefore hypothesised that IL-6 impairs the biological activity of IGF-1 in skeletal muscle through inhibiting its signalling pathways, ERK1/2 and Akt. Our aim was to examine the combined effects of these factors on models of muscle wasting, with objectives to examine skeletal muscle differentiation and proliferation using the murine C2 skeletal muscle cell line. Cells were cultured with DM, IGF-1 and IL-6 alone (control treatments), or co-cultured with IGF-1/IL-6. Co-incubation of C2 cells in IGF-1 plus IL-6 resulted in maximal cell death (22 ± 4%; P < 0.005) compared with control treatments (14 ± 2.9%). This was also confirmed by cyclin D1 expression levels in co-incubation treatments (7 ± 3.5%; P < 0.05) compared with control treatments (≈ 23%). The expression levels of myogenic-specific transcriptional factor mRNAs (myoD and myogenin) were also significantly (P < 0.005) reduced by 70% and 90%, respectively, under the co-incubation regimes, compared with control treatments. Signalling investigations showed significant phosphorylation reduction by 20%, (P < 0.05) of ERK1/2 and Akt in co-incubation treatments relative to either treatment alone. Expression studies for SOCS-3 (1.6-fold ± 0.08, P < 0.05) and IRS-1 (0.65-fold ± 0.13 P < 0.005) mRNAs showed significant elevation and reduction for both genes, respectively, in co-treatments relative to control treatments. These data may suggest that IL-6 exerts its inhibitory effects on IGF-1 signalling pathways (ERK1/2 and Akt) through blocking its receptor substrate IRS-1 by SOCS-3.

Swimming exercise prevents fibrogenesis in chronic kidney disease by inhibiting the myofibroblast transdifferentiation

Background

The renal function of chronic kidney disease (CKD) patients may be improved by a number of rehabilitative mechanisms. Swimming exercise training was supposed to be beneficial to its recovery.

Methodology/Principal Findings

Doxorubicin-induced CKD (DRCKD) rat model was performed. Swimming training was programmed three days per week, 30 or 60 min per day for a total period of 11 weeks. Serum biochemical and pathological parameters were examined. In DRCKD, hyperlipidemia was observed. Active mesangial cell activation was evidenced by overexpression of PDGFR, P-PDGFR, MMP-2, MMP-9, α-SMA, and CD34 with a huge amount collagen deposition. Apparent myofibroblast transdifferentiation implicating fibrogenesis in the glomerular mesangium, glomerulonephritis and glomeruloscelorosis was observed with highly elevated proteinuria and urinary BUN excretion. The 60-min swimming exercise but not the 30 min equivalent rescued most of the symptoms. To quantify the effectiveness of exercise training, a physical parameter, i.e. “the strenuosity coefficient” or “the myokine releasing coefficient”, was estimated to be 7.154×10⁻³ pg/mL-J.

Conclusions

The 60-min swimming exercise may ameliorate DRCKD by inhibiting the transdifferentiation of myofibroblasts in the glomerular mesangium. Moreover, rehabilitative exercise training to rescue CKD is a personalized remedy. Benefits depend on the duration and strength of exercise, and more importantly, on the individual physiological condition.

Muscular exercise capacity and body fat predict VO(2peak) in heart transplant recipients

BACKGROUND

Heart transplant (HTx) recipients usually have reduced exercise capacity, with reported VO2peak levels of 50-70% of predicted values. This study aimed to evaluate central and peripheral factors predictive of VO2peak.

METHODS AND RESULTS

Fifty-one clinically stable HTx recipients >18 years old and 1-8 years after HTx, underwent maximal exercise testing on a treadmill. Clinical laboratory, haemodynamic and echocardiographic data, lung function, and isokinetic muscle strength and muscular exercise capacity were recorded. The mean ± SD age was 52 ± 16 years, 71% were male, and time from HTx was 4.1 ± 2.2 years. The patients were assigned to one of two groups: VO2peak ≤or >27.3 ml/kg/min, which was the median value, corresponding to 80% of predicted value. The group with the higher VO2peak had significantly lower body mass index, body fat, and triglycerides, and significantly higher body water, muscular exercise capacity, high-density lipoprotein (HDL) cholesterol, lung function, mitral annular velocity, peak ventilation, O2 pulse, and VE/VCO2 slope. Donor age, recipient age, sex, medication, ischaemic time, cardiac dimensions, systolic function, and chronotropic responses during exercise were similar. Multiple regression analysis showed that muscular exercise capacity and body fat were the strongest VO2peak predictors.

CONCLUSIONS

Chronotropic incompetence is not a limiting factor for exercise capacity in a population of relatively fit HTx patients. The most significant predictors, representing only peripheral factors, are similar to those often determining VO2peak in healthy, non-athletic individuals. Our findings emphasize the importance of a low percentage of body fat and high muscular exercise capacity in order to attain a sufficient VO2peak level after HTx.

Exploring metabolic dysfunction in chronic kidney disease

Impaired kidney function and chronic kidney disease (CKD) leading to kidney failure and end-stage renal disease (ESRD) is a serious medical condition associated with increased morbidity, mortality, and in particular cardiovascular disease (CVD) risk. CKD is associated with multiple physiological and metabolic disturbances, including hypertension, dyslipidemia and the anorexia-cachexia syndrome which are linked to poor outcomes. Specific hormonal, inflammatory, and nutritional-metabolic factors may play key roles in CKD development and pathogenesis. These include raised proinflammatory cytokines, such as interleukin-1 and −6, tumor necrosis factor, altered hepatic acute phase proteins, including reduced albumin, increased C-reactive protein, and perturbations in normal anabolic hormone responses with reduced growth hormone-insulin-like growth factor-1 axis activity. Others include hyperactivation of the renin-angiotensin aldosterone system (RAAS), with angiotensin II and aldosterone implicated in hypertension and the promotion of insulin resistance, and subsequent pharmacological blockade shown to improve blood pressure, metabolic control and offer reno-protective effects. Abnormal adipocytokine levels including leptin and adiponectin may further promote the insulin resistant, and proinflammatory state in CKD. Ghrelin may be also implicated and controversial studies suggest activities may be reduced in human CKD, and may provide a rationale for administration of acyl-ghrelin. Poor vitamin D status has also been associated with patient outcome and CVD risk and may indicate a role for supplementation. Glucocorticoid activities traditionally known for their involvement in the pathogenesis of a number of disease states are increased and may be implicated in CKD-associated hypertension, insulin resistance, diabetes risk and cachexia, both directly and indirectly through effects on other systems including activation of the mineralcorticoid receptor. Insight into the multiple factors altered in CKD may provide useful information on disease pathogenesis, clinical assessment and treatment rationale such as potential pharmacological, nutritional and exercise therapies.

Efetividade do exercício físico na insuficiência renal crônica

INTRODUÇÃO: O exercício físico em nefropatas submetidos à hemodiálise se faz importante, uma vez que esses pacientes apresentam acentuada redução da funcionalidade e do condicionamento, o que interfere negativamente na qualidade de vida. Contudo, os benefícios, o tipo de exercício mais adequado e parâmetros como intensidade, frequência e duração não estão bem esclarecidos para essa população. OBJETIVOS: Realizar uma revisão de literatura sobre a influência do exercício físico em pacientes renais crônicos submetidos à hemodiálise. MATERIAIS E MÉTODOS: Foram realizadas buscas nas bases MEDLINE, LILACS, PEDro, SciELO e PubMed, sendo selecionados artigos (ensaios clínicos controlados randomizados, séries de casos e estudos de caso) nos idiomas inglês e português, publicados entre 2000 e 2010. RESULTADOS: Foram encontrados 105 artigos, sendo 82 da base de dados PubMed, 16 da base PEDro e 7 da base SciELO. Não foram encontrados artigos nas bases MEDLINE e LILACS. Desses, apenas sete preenchiam aos critérios de inclusão. A partir desses sete artigos, realizou-se busca manual ativa na lista de referências dessas publicações, nas quais foi possível verificar a presença de apenas três referências. CONCLUSÃO: Pôde-se concluir, por meio dos artigos revisados, que os exercícios físicos, seja aeróbico e/ou de resistência, possuem efeitos incrementais na capacidade funcional, função muscular e qualidade de vida de nefropatas submetidos à hemodiálise. Portanto, o treinamento físico deve ser considerado como uma modalidade terapêutica importante, sendo fundamental a inserção do fisioterapeuta nos centros dialíticos, fazendo parte de uma equipe multidisciplinar.

Metabolic and morphometric profile of muscle fibers in chronic hemodialysis patients

Muscle weakness and effort intolerance are common in maintenance hemodialysis (MHD) patients. This study characterized morphometric, histochemical, and biochemical properties of limb muscle in MHD patients compared with controls (CTL) with similar age, gender, and ethnicity. Vastus lateralis muscle biopsies were obtained from 60 MHD patients, 1 day after dialysis, and from 21 CTL. Muscle fiber types and capillaries were identified immunohistochemically. Individual muscle fiber cross-sectional areas (CSA) were quantified. Individual fiber oxidative capacities were determined (microdensitometric assay) to measure succinate dehydrogenase (SDH) activity. Mean CSAs of type I, IIA, and IIX fibers were 33, 26, and 28% larger in MHD patients compared with CTL. SDH activities for type I, IIA, and IIX fibers were reduced by 29, 40, and 47%, respectively, in MHD. Capillary to fiber ratio was increased by 11% in MHD. The number of capillaries surrounding individual fiber types were also increased (type I: 9%; IIA: 10%; IIX: 23%) in MHD patients. However, capillary density (capillaries per unit muscle fiber area) was reduced by 34% in MHD patients, compared with CTL. Ultrastuctural analysis revealed swollen mitochondria with dense matrix in MHD patients. These results highlight impaired oxidative capacity and capillarity in MHD patients. This would be expected to impair energy production as well as substrate and oxygen delivery and exchange and contribute to exercise intolerance. The enlarged CSA of muscle fibers may, in part, be accounted for by edema. We speculate that these changes contribute to reduce limb strength in MHD patients by reducing specific force.

Association between inflammatory-related disease burden and frailty: results from the Women's Health and Aging Studies (WHAS) I and II

Frailty is associated with a pro-inflammatory state, which has been characterized by elevated levels of systemic inflammatory biomarkers, but has not been related to the number of co-existing chronic diseases associated with inflammation. We sought to determine the extent to which a higher number of inflammatory-related diseases is associated with frailty and to identify the most common disease patterns associated with being frail in older adults. We performed binomial regression analyses to assess whether a higher count of inflammatory-related diseases increases the probability of frailty using data from the WHAS I and II, companion cohorts composed of 70-79-year-old community-dwelling older women in Baltimore, Maryland (n=620). An increase of one inflammatory-related disease was associated log-linearly with frailty (Prevalence Ratio (PR)=2.28, 95% Confidence Interval (CI)=1.81-2.87). After adjusting for age, race, education, and smoking status, the probability of frailty remained significant (PR=1.97, 95%CI=1.52-2.55). In the frail population, chronic kidney disease (CKD) and depressive symptoms (Prevalence=22.9%, 95%CI=14.2-34.8%); CVD and depressive symptoms (21.7%, 95%CI=13.2-33.5%); CKD and anemia (18.7%, 95%CI=11.1-29.7%); cardiovascular disease (CVD), CKD, and pulmonary disease (10.7%, 95%CI=5.2-21.0%); CKD, anemia, and depressive symptoms (8.7%, 95%CI=3.9-18.2%); and CVD, anemia, pulmonary disease, and depressive symptoms (5.0%, 95%CI=1.6-14.4%) were among the most frequent disease combinations. Their prevalence percentages were significantly higher in the frail versus non-frail women. A higher inflammatory-related disease count, perhaps reflecting a greater pro-inflammatory burden, increases the likelihood of frailty. Shared mechanisms among specific disease combinations may further contribute to this risk.

Exercise training for adults with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is a worldwide public health problem. In the National Kidney Foundation Disease Outcomes Quality Initiative guidelines it is stressed that lifestyle issues such as physical activity should be seen as cornerstones of the therapy. The physical fitness in adults with CKD is so reduced that it impinges on ability and capacity to perform activities in everyday life and occupational tasks. An increasing number of studies have been published regarding health effects of various regular exercise programmes in adults with CKD and in renal transplant patients.

OBJECTIVES

We aimed to: 1) assess the effects of regular exercise in adults with CKD and kidney transplant patients; and 2) determine how the exercise programme should be designed (e.g. type, duration, intensity, frequency of exercise) to be able to affect physical fitness and functioning, level of physical activity, cardiovascular dimensions, nutrition, lipids, glucose metabolism, systemic inflammation, muscle morphology and morphometrics, dropout rates, compliance, adverse events and mortality.

SEARCH STRATEGY

We searched the Cochrane Renal Group's specialised register, CENTRAL, MEDLINE, EMBASE, CINAHL, Web of Science, Biosis, Pedro, Amed, AgeLine, PsycINFO and KoreaMed. We also handsearched reference lists of review articles and included studies, conference proceeding's abstracts. There were no language restrictions.Date of last search: May 2010.

SELECTION CRITERIA

We included any randomised controlled trial (RCT) enrolling adults with CKD or kidney transplant recipients undergoing any type of physical exercise intervention undertaken for eight weeks or more. Studies using less than eight weeks exercise, those only recommending an increase in physical activity, and studies in which co-interventions are not applied or given to both groups were excluded.

DATA COLLECTION AND ANALYSIS

Data extraction and assessment of study and data quality were performed independently by the two authors. Continuous outcome data are presented as standardised mean difference (SMD) or mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

Forty-five studies, randomising 1863 participants were included in this review. Thirty two studies presented data that could be meta-analysed. Types of exercise training included cardiovascular training, mixed cardiovascular and resistance training, resistance-only training and yoga. Some studies used supervised exercise interventions and others used unsupervised interventions. Exercise intensity was classed as 'high' or 'low', duration of individual exercise sessions ranged from 20 minutes/session to 110 minutes/session, and study duration was from two to 18 months. Seventeen per cent of studies were classed as having an overall low risk of bias, 33% as moderate, and 49% as having a high risk of bias.The results shows that regular exercise significantly improved: 1) physical fitness (aerobic capacity, 24 studies, 847 participants: SMD -0.56, 95% CI -0.70 to -0.42; walking capacity, 7 studies, 191 participants: SMD -0.36, 95% CI-0.65 to -0.06); 2) cardiovascular dimensions (resting diastolic blood pressure, 11 studies, 419 participants: MD 2.32 mm Hg, 95% CI 0.59 to 4.05; resting systolic blood pressure, 9 studies, 347 participants: MD 6.08 mm Hg, 95% CI 2.15 to 10.12; heart rate, 11 studies, 229 participants: MD 6 bpm, 95% CI 10 to 2); 3) some nutritional parameters (albumin, 3 studies, 111 participants: MD -2.28 g/L, 95% CI -4.25 to -0.32; pre-albumin, 3 studies, 111 participants: MD - 44.02 mg/L, 95% CI -71.52 to -16.53; energy intake, 4 studies, 97 participants: SMD -0.47, 95% CI -0.88 to -0.05); and 4) health-related quality of life. Results also showed how exercise should be designed in order to optimise the effect. Other outcomes had insufficient evidence.

AUTHORS' CONCLUSIONS

There is evidence for significant beneficial effects of regular exercise on physical fitness, walking capacity, cardiovascular dimensions (e.g. blood pressure and heart rate), health-related quality of life and some nutritional parameters in adults with CKD. Other outcomes had insufficient evidence due to the lack of data from RCTs. The design of the exercise intervention causes difference in effect size and should be considered when prescribing exercise with the aim of affecting a certain outcome. Future RCTs should focus more on the effects of resistance training interventions or mixed cardiovascular- and resistance training as these exercise types have not been studied as much as cardiovascular exercise.

Models of accelerated sarcopenia: critical pieces for solving the puzzle of age-related muscle atrophy

Sarcopenia, the age-related loss of skeletal muscle mass, is a significant public health concern that continues to grow in relevance as the population ages. Certain conditions have the strong potential to coincide with sarcopenia to accelerate the progression of muscle atrophy in older adults. Among these conditions are co-morbid diseases common to older individuals such as cancer, kidney disease, diabetes, and peripheral artery disease. Furthermore, behaviors such as poor nutrition and physical inactivity are well-known to contribute to sarcopenia development. However, we argue that these behaviors are not inherent to the development of sarcopenia but rather accelerate its progression. In the present review, we discuss how these factors affect systemic and cellular mechanisms that contribute to skeletal muscle atrophy. In addition, we describe gaps in the literature concerning the role of these factors in accelerating sarcopenia progression. Elucidating biochemical pathways related to accelerated muscle atrophy may allow for improved discovery of therapeutic treatments related to sarcopenia.

Sustaining a hemodialysis exercise program: a review

This article reviews the literature addressing exercise programs for dialysis patients to identify elements necessary for sustaining exercise programs in this population. Literature searches for publications (January 1980-February 2009) in Medline (OVID), PubMed, CINAHL (EBSCO), EBSCOhost EJS, ProQuest Central, Web of Science, Cochrane Library, Google Scholar, ScienceDirect, SpringerLink (Kluwer), and Wiley Interscience (Blackwell) were performed. Reference lists from relevant articles were hand-searched for further publications. Criteria for inclusion included full-text primary research and review articles focused on exercise for adult hemodialysis patients. One hundred and seventy one publications were found with a primary focus on exercise in hemodialysis. Of these, 28 primary research and 14 review articles addressed one or more aspects of sustainability of hemodialysis exercise programs. Factors contributing to sustainable exercise programs included: dedicated exercise professionals; encouragement to exercise intradialytically; dialysis and medical staff commitment; adequate physical requirements of equipment and space; interesting and stimulating; cost implications need to be addressed; exercise is not for everyone; requires individual prescription; and there is no age barrier to exercise on hemodialysis.

Anabolic interventions in ESRD

ESRD produces a chronic catabolic state that results in significant skeletal muscle atrophy, weakness, and physical dysfunction. Any intervention that can ameliorate this process can significantly improve quality of life. Some studies have shown that endurance exercise training, even at low intensities, may exhibit anabolic effects and improved physical function. However, resistance exercise training is of primary interest as an anabolic intervention because it is the mode of exercise that is most efficacious in stimulating anabolic responses, improved muscle performance, and physical function. A relatively small number of controlled trials of resistance training in ESRD patients have failed to show significant changes in LBM, although some studies have shown significant improvements in other markers of anabolism. Increases in muscle strength with resistance training are typical but improved physical function, either by objective measurement or self-report, are equivocal. Study durations, loads used during training, and relatively small sample sizes may in part explain the inability of previous studies to observe more substantial changes in LBM and physical function. Androgens and growth hormone have been shown to significantly improve LBM and strength, although longer-term studies for safety and efficacy are necessary before their general recommendation for patients with ESRD.

Anabolic and catabolic mechanisms in end-stage renal disease

Muscle wasting is a prominent feature of end-stage renal disease and is associated with muscle weakness and poor physical functioning. Potential reasons for muscle wasting include advancing age, sedentary behavior, inflammation, poor nutritional intake, androgen deficiency, oxidative stress, metabolic acidosis, and insulin resistance. Each of these conditions can be associated with decreased protein synthesis, increased protein degradation, or both. The primary muscle protein synthesis pathway is the insulin insulin-like growth factor-1/phosphatidyl inositol-3 kinase/Akt pathway, which results in the phosphorylation of the mammalian target of rapamycin and subsequent increased protein synthesis. The major protein degradation pathway is the ubiquitin-proteasome system. This review discusses the ways in which end-stage renal disease tips the balance of protein turnover towards catabolism and the mechanisms by which various interventions may work to mitigate wasting or even cause anabolism.

Segurança e eficácia do treinamento físico na insuficiência renal crônica

A doença renal crônica acarreta alterações em todos os sistemas corporais. Os pacientes cursam com marcada redução do condicionamento cardiorrespiratório, alterações musculares, reduzida performance física e pior qualidade de vida. A atividade física tem sido cada vez mais utilizada como forma de tratamento para essa população. Programas de treinamento físico aeróbio e/ou resistidos de moderada ou baixa intensidade no período interdialítico e durante a hemodiálise têm sido utilizados. Entretanto, os benefícios dessas intervenções no doente renal crônico, a escolha mais apropriada do tipo de treinamento e a segurança da aplicabilidade de atividades específicas não estão bem esclarecidos. Esta revisão tem como objetivo abordar os aspectos relacionados com o tipo de treinamento, período em que este é realizado, assim como os possíveis benefícios que o treinamento físico pode induzir nessa população.

Exercise pressor reflex in humans with end-stage renal disease

Previous work has suggested that end-stage renal disease (ESRD) patients may have an exaggerated sympathetic nervous system (SNS) response during exercise. We hypothesized that ESRD patients have an exaggerated blood pressure (BP) response during moderate static handgrip exercise (SHG 30%) and that the exaggerated BP response is mediated by SNS overactivation, characterized by augmented mechanoreceptor activation and blunted metaboreceptor control, as has been described in other chronic diseases. We measured hemodynamics and muscle sympathetic nerve activity (MSNA) in 13 ESRD and 16 controls during: 1) passive hand movement (PHM; mechanoreceptor isolation); 2) low-level rhythmic handgrip exercise (RHG 20%; central command and mechanoreceptor activation); 3) SHG 30%, followed by posthandgrip circulatory arrest (PHGCA; metaboreceptor activation); and 4) cold pressor test (CPT; nonexercise stimulus). ESRD patients had exaggerated increases in systolic BP during SHG 30%; however, the absolute and relative increase in MSNA was not augmented, excluding SNS overactivation as the cause of the exaggerated BP response. Increase in MSNA was not exaggerated during RHG 20% and PHM, demonstrating that mechanoreceptor activation is not heightened in ESRD. During PHGCA, MSNA remained elevated in controls but decreased rapidly to baseline levels in ESRD, indicative of markedly blunted metaboreceptor control of MSNA. MSNA response to CPT was virtually identical in ESRD and controls, excluding a generalized sympathetic hyporeactivity in ESRD. In conclusion, ESRD patients have an exaggerated increase in SBP during SHG 30% that is not mediated by overactivation of the SNS directed to muscle. SBP responses were also exaggerated during mechanoreceptor activation and metaboreceptor activation, but without concomitant augmentation in MSNA responses. Metaboreceptor control of MSNA was blunted in ESRD, but the overall ability to mount a SNS response was not impaired. Other mechanisms besides SNS overactivation, such as impaired vasodilatation, should be explored to explain the exaggerated exercise pressor reflex in ESRD.

Myosin heavy-chain isoform distribution, fibre-type composition and fibre size in skeletal muscle of patients on haemodialysis

OBJECTIVE

Chronic uraemia is associated with abnormalities in skeletal muscles, which can affect their working capacity. It is also well known that the fibre-type composition of skeletal muscles influences endurance, muscle strength and power. In this study we therefore determined the size and distribution of muscle fibres and the myosin heavy-chain (MHC) isoform composition in patients on haemodialysis (HD) in order to establish any differences with values for untrained control subjects.

MATERIAL AND METHODS

Muscle biopsies were obtained from the vastus lateralis muscle of 14 non-diabetic patients on HD. The size and distribution of muscle fibres were evaluated using adenosine triphosphate synthase (ATPase) histochemistry, whilst MHC isoform composition was determined in muscle homogenates using sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Values were compared to those for a group of age-, gender- and BMI-matched untrained control subjects. The aerobic work capacity of the patients was also determined.

RESULTS

The MHC composition for I, IIA and IIX isoforms was found to be 35.3% +/- 18.2%, 35.9% +/- 7.1% and 28.9% +/- 15.6%, respectively, findings supported by the ATPase histochemically determined fibre-type composition of the vastus lateralis muscle. The mean fibre area of type 1 and 2 fibres was 3283 +/- 873 and 3594 +/- 1483 MICROm2, respectively. The MHC composition and the size of the type 1 fibres of the patients on HD were significantly different from those of the control subjects.

CONCLUSIONS

The data demonstrate relatively fewer type 1 and consequently more type 2x fibres, with a corresponding change in MHC isoforms (MHC I and MHC IIX) in the skeletal muscle of patients on HD. Several patients on HD were found to have <15% type 1 (or relative percentage of MHC I) fibres. Such a low percentage of type 1 fibres is very rarely observed in normal untrained subjects. Chronic uraemia more severely affects the composition than the size of fibres.

Decreased maximal aerobic capacity in pediatric chronic kidney disease

Adult and pediatric patients with ESRD have impaired maximum oxygen consumption (VO(2) max), a reflection of the cardiopulmonary system's ability to meet increased metabolic demands. We sought to determine factors associated with decreased VO(2) max in pediatric patients with different stages of CKD. VO(2) max was measured using a standardized exercise testing protocol in patients with stage 2 to 4 chronic kidney disease (CKD) (n = 46), in renal transplant recipients (n = 22), in patients treated with maintenance hemodialysis (n = 12), and in age-matched healthy controls (n = 33). VO(2) max was similar between children with stage 2 CKD and controls, whereas lower VO(2) max was observed among children with stage 3 to 4 CKD, those treated with hemodialysis, and transplant recipients. In univariate analysis, VO(2) max was significantly associated with body mass index, resting heart rate, C-reactive protein, serum triglycerides, serum creatinine, and measures of diastolic function; no significant associations with left ventricular structure or systolic function were identified. In multivariate regression analysis, patient category versus control and the presence of diastolic dysfunction were independent predictors of lower VO(2) max. These results suggest that aerobic capacity is decreased in the early stages of CKD in children and that lower VO(2) max can be predicted by the presence of diastolic dysfunction, even if systolic function is normal.

Assessment of health-related fitness in the patients with end-stage renal disease on hemodialysis: using Eurofit Test Battery

The main objectives of this study were to evaluate the health-related physical fitness for the patients with end-stage renal disease on hemodialysis and determine the suitability of Eurofit Test Battery for adults to decide their health-related physical fitness level. Eighteen patients with end-stage renal disease (ESRD) on hemodialysis (age 49.7+17.9, 10 female / 8 male) was evaluated and compared with 22 age-matched healthy subjects (age 50.5 + 9.4 years, 13 female / 9 male) for this purposes. Eurofit Test Battery for Adults is composed of aerobic fitness, musculoskeletal fitness, motor fitness, and anthropometry components. Aerobic fitness, which was assessed by six minutes walking distance, was lower in the patient group than controls (p < 0.05). Hemodialysis patients had lower motor fitness (0.000) and musculoskeletal fitness including vertical jump and handgrip tests (0.047, 0.002). Percentage of body fat and skinfold thickness values measured from triceps, subscapular, abdominal, and thigh were also lower in patient group (p < 0.05). Additionally no complication was seen during and/or after the tests. In conclusion, the Eurofit for adults may be considered a useful test battery to evaluate the physical fitness and design the health-related physical fitness program based on the Eurofit results in this population.

Rehabilitative training program for end-stage renal disease patients

A 4–5. (vég-)stádiumú és transzplantált vesebetegek izomereje, állóképessége, cardiovascularis kockázati tényezői, életminősége és a dialízishatásfoka is jelentősen javul a heti 3 × 30–60 perces, 45–60%-os intenzitású testmozgás során, amelyet többnyire a dialízis alatt végez a beteg. A korlátozó tényezők és ellenjavallatok figyelembevételével a vesebetegek többsége számára is kínálni kellene a rehabilitációs programokat.

Effect of Renal Failure on Peak Troponin Ic Level in Patients with Acute Myocardial Infarction

OBJECTIVES

Peak troponin Ic (cTnI) level could be influenced by renal function. We evaluated the effect of moderate to severe renal failure on peak cTnI level during acute myocardial infarction (AMI).

METHODS

One hundred and twenty-five consecutive patients admitted to the coronary care unit of a university hospital in France for primary angioplasty during AMI were retrospectively studied.

RESULTS

The correlations between peak cTnI level, peak creatine phosphokinase (CK) level, peak cTnI/peak CK ratio and creatinine clearance (CrCl) were assessed. The peak cTnI/peak CK ratio was considered in order to standardize the peak cTnI level with the extent of myocardial necrosis. There was no significant correlation between CrCl and peak CK (r = 0.01, p = 0.95), peak cTnI (r = -0.08, p = 0.38) or the peak cTnI/peak CK ratio (r = -0.14, p = 0.13). There was a trend towards higher peak cTnI in patients with moderate to severe renal failure. The peak cTnI/peak CK ratio did not significantly differ among patients according to CrCl stratification, whereas the ratio of log-transformed values was significantly higher in patients with moderate to severe renal failure.

CONCLUSION

In patients with AMI, the peak cTnI level seemed to be influenced by renal function.