Effect of Low-Intensity Exercise under Cold Environment for Myokines, Involved in Muscle Mass

Abstract

It is important to maintain the skeletal muscle mass for extending healthy life expectancy. Recently, myokine which is released from skeletal muscle by muscle contraction has been paid attention for maintain of muscle mass. Many studies suggested that the myokoines are facilitated by high-volume exercise. The purpose of the present study was to verify that myokines, involved in maintain of muscle mass, are enhanced by low-intensity exercise under cold environment. Six healthy males （Age: 22.4 ± 0.4 yrs, height: 171±2.7 cm, weight: 63.8±2.8 kg） conducted exercise with a normal temperature condition （n = 6） and exercise with a cold temperature condition （n = 6）．All subjects performed pedaling at 60% of maximal oxygen uptake （V･O₂max） for 60 min in each condition. Blood samples were collected before exercise, during exercise, immediately after exercise, and 1, 3, and 24 h after exercise.Unanticipatedly, Irisin and FGF21 concentrations in blood did not show significant difference between groups. However, decreased blood insulin concentration was impaired in cold temperature condition, but not normal temperature condition.Therefore, these results suggested that exercise with cold environment did not effective for myokines, involved in maintain muscle mass response to exercise.