Effects of exercise training on skeletal muscle health in elderly dialysis patients

Metabolic abnormalities and increased sedentary time in patients receiving mHD treatment have led to unfavorable adaptations within the skeletal muscle. Muscle health is determined by the proportions of pure MHC muscle fiber types and prevalence of coexpressing hybrid fibers. Purpose: To determine 1) baseline values of MHC phenotypes in the ESRD population, and 2) the effects of 12-weeks concurrent exercise training on skeletal muscle health in older ESRD patients using single muscle fiber SDSPAGE analysis. Methods: ESRD patients aged 55-80 years are divided into exercise training or usual treatment groups. Muscle biopsies of the vastus lateralis are obtained before and after 12-weeks of training or usual treatment. We isolate ~100 fibers per muscle sample and use SDS-PAGE analysis to determine MHC content. Results: As part of a larger ongoing study, we successfully fiber typed two participants (EX and UT; total 327 fibers). After 12-weeks training, fiber type significantly shifted towards more pure MHC types (p 0.0001), while UT's fiber type was not different compared to baseline (p 0.05). Additionally, we found a very rare MHC I/IIx coexpressing fiber which had only been documented in three previous instances. Conclusion: Our initial findings suggest that 1) ESRD populations have elevated hybrid muscle type proportions, and 2) exercise training has the potential to cause a beneficial shift towards pure MHC phenotypes.