THE EFFECTS OF EXERCISE TRAINING ON MUSCLE ATROPHY IN HEMODIALYSIS-PATIENTS

Background. Patients with end-stage renal disease on haemodialysis (HD ) have limited work capacity. Many structural and functional alteratio ns in skeletal muscles contribute to this disability. Methods. To eval uate the effects of exercise training on uraemic myopathy, seven HD pa tients (mean age 44.1 +/- 17.2 years) were studied. Open muscle biopsi es were taken from their vastus lateralis muscle before and after a 6- month exercise rehabilitation programme and examined by routine light- and transmission electron-microscopy. Histochemical stainings of froze n sections were performed and morphometric analysis was also applied t o estimate the proportion of each fibre type and the muscle fibre area . Spiroergometric and neurophysiological testing and peak extension fo rces of the lower limbs were measured before and after exercise traini ng. Results. All patients showed impaired exercise capacity, which was associated with marked muscular atrophy (mean area 2548 +/- 463 mu m( 2)) and reduction in muscle strength and nerve conduction velocity. Al l types of fibres were atrophied, but type II were more affected. The ultrastructural study showed severe degenerative changes in skeletal m uscle fibres, mitochondria, and capillaries. Exercise training had an impressive effect on muscular atrophy; in particular the proportion of type II fibres increased by 51% and mean muscle fibre area by 29%. Fa vourable changes were also seen on the structure and number of capilla ries and mitochondria. These results were confirmed by a 48% increase in VO2 peak and a 29% in exercise time, as well as an improvement in t he peak muscle strength of the lower limbs and in nerve conduction vel ocity. Conclusions. Skeletal muscle atrophy in HD patients contribute to their poor exercise tolerance. The application of an exercise train ing rehabilitation programme improved muscle atrophy markedly, and the refore had beneficial effects in overall work performance.