Fiber type-specific response of skeletal muscle satellite cells to high-intensity resistance training in dialysis patients.

INTRODUCTION: The aim of this study was to assess the effect of high-intensity resistance training on satellite cell (SC) and myonuclear number in the muscle of patients undergoing dialysis.

METHODS: Patients (n = 21) underwent a 16-week control period, followed by 16 weeks of resistance training 3 times weekly. SC and myonuclear number were determined by immunohistochemistry of vastus lateralis muscle biopsy cross-sections. Knee extension torque was tested in a dynamometer.

RESULTS: During training, SCs/type I fibers increased by 15%, whereas SCs/type II fibers remained unchanged. Myonuclear content of type II, but not type I, fibers increased with training. Before the control period, the SC content of type II fibers was lower than that of type I fibers, whereas contents were comparable when normalized to fiber area. Torque increased after training.

CONCLUSIONS: Increased myonuclear content of type II muscle fibers of dialysis patients who perform resistance training suggests that SC dysfunction is not the limiting factor for muscle growth.