Hybrid training system-induced myokine secretion in healthy men.

The hybrid training system (HTS) is a special and compact system for effective skeletal muscle training by a combined application of volitional and electrical muscle contraction. Lower limbs' muscle training using HTS has been reported to increase not only muscle strength but also plasma interleukin-6 levels; however, little is known in other cytokines. In this study, we measured 52 cytokines and creatine phosphokinase-MM in the serum of 16 healthy men before and after lower limbs' muscle training by the knee flexion and extension using HTS. Skeletal muscle volume-corrected serum concentrations of cutaneous T-cell-attracting chemokine, erythropoietin, and tumor necrosis factor-related apoptosis-inducing ligand increased immediately after the training. These increased cytokines have been reported to play important roles in wound healing, neuroprotection, and cardiovascular protection.