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The purpose of this study was to evaluate the effect of a 12-week intradialytic progressive resistance training (PRT) regimen on circulating pro- and anti-inflammatory cytokines. Forty-nine patients (62.6 ± 14.2 years) were recruited from the outpatient hemodialysis unit of the St. George Public Hospital, Sydney, Australia. Patients were randomized to: PRT + usual care (n = 24) or usual care control (n = 25). The PRT group performed two sets of 10 exercises at high intensity using free-weights, 3 times per week for 12 weeks during dialysis, while the control group did not exercise. Tumor necrosis factor-alpha, interleukin-1b, interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10, and interleukin-12 were measured in serum before and after the intervention period. Muscle cross-sectional area (CSA), intramuscular lipid, intermuscular adipose tissue, and subcutaneous and total thigh fat, evaluated via computed tomography of the non-dominant mid-thigh, were also collected at both time points. All cytokines were significantly elevated in the total cohort at baseline compared with normative data. There were no cytokine changes over time or between groups (p > 0.05). In secondary analyses pooling the groups, changes in logIL-6 and IL-8 were inversely related to changes subcutaneous thigh fat (p < 0.05) while changes in logIL-6 were also inversely related to changes in thigh muscle CSA, and total thigh fat (p < 0.03). These data suggest that 12 weeks of intradialytic progressive resistance training does not improve circulating pro- and anti-inflammatory markers. Further research is required to elucidate the implications and mechanisms of the relationships between IL-6 and IL-8 and body composition in ESRD.

Aim: A more precise understanding of the aetiology and sequelae of muscle wasting in end-stage renal disease (ESRD) is required for the development of effective interventions to target this pathology. Methods: We investigated 49 patients with ESRD (62.6 ± 14.2 years, 0.3–16.7 years on haemodialysis). Thigh muscle cross-sectional area (CSA), intramuscular lipid and intermuscular adipose tissue (IMAT) were measured via computed tomography as indices of muscle quantity (i.e. CSA) and quality (i.e. intramuscular lipid and IMAT). Additional health and clinical measures were investigated to determine associations with these variables. Results: Age, energy intake, disease burden, pro-inflammatory cytokines, nutritional status, strength and functioning were related to muscle quantity and quality. Potential aetiological factors entered into forward stepwise regression models indicated that hypoalbuminaemia and lower body mass index accounted significantly and independently for 32% of the variance in muscle CSA ( r = 0.56, P < 0.001), while older age and interleukin-8 accounted for 41% of the variance in intramuscular lipid ( r = 0.64, P < 0.001) and body mass index accounted for 45% of the variance in IMAT ( r = 0.67, P < 0.001). Stepwise regression models revealed that intramuscular lipid was independently predictive of habitual gait velocity and 6 min walk distance, while CSA was independently predictive of maximal isometric strength ( P < 0.05). Conclusion: Ageing, poor nutritional status and elevated interleukin-8 are factors potentially contributing to the loss of muscle quality and quantity in ESRD. These deficits can predict functional impairments, with intramuscular lipid accumulation most closely related to decline of submaximal musculoskeletal performance (walking), and low muscle CSA most closely related to decline of maximal performance (peak isometric strength). [ABSTRACT FROM AUTHOR]