Hybrid training of voluntary and electrical muscle contractions decreased fasting blood glucose and serum interleukin-6 levels in elderly people: a pilot study

Abstract

A new muscle-training method, "hybrid training", utilizing combined voluntary and electrical muscle contractions, is effective for increasing muscle mass and force on lower extremities in elderly people. Although skeletal muscle regulates glucose metabolism, partly by releasing interleukin (IL)-6, the effects of hybrid training on glucose metabolism remains unclear. The aim of this study was to investigate the effects of hybrid training on glucose metabolism and serum IL-6 levels in elderly people. Hybrid training was performed on 7 elderly subjects. Both quadriceps and hamstrings were contracted voluntarily or electrically at the same time for 19min twice a week. The effects on glucose metabolism and serum IL-6 levels were evaluated after 12weeks of hybrid training. All of the subjects completed the study, and no severe adverse events developed during the study period. There were no significant differences in body mass index, serum insulin levels, homeostasis model assessment for insulin resistance values, or hemoglobin A1c values after hybrid training. However, fasting blood glucose levels were significantly decreased after hybrid training (114± 13 vs. 103± 9mg·dL(-1); p = 0.0340). In addition, all 7 subjects showed a decrease in serum IL-6 levels after hybrid training, and this decrease was statistically significant (44.0± 35.6 vs. 14.6± 10.5 pg·mL(-1); p = 0.0180). Furthermore, there was a significant correlation between changes in serum IL-6 levels and changes in fasting blood glucose levels (ρ = 0.883; p = 0.0306). In this study, we showed the safety and good adherence of hybrid training for lower extremities in elderly people. Furthermore, hybrid training decreased fasting blood glucose and serum IL-6 levels in elderly people.