Tohoku J. Exp. Med., 2014 June, 233(2)

High-Intensity Exercise Causes Greater Irisin Response Compared with Low-Intensity Exercise under Similar Energy Consumption

YOSHIFUMI TSUCHIYA,¹ DAISUKE ANDO,² KAZUSHIGE GOTO,¹ MASATAKA KIUCHI,³ MITSUYA YAMAKITA⁴ and KATSUHIRO KOYAMA⁵

¹Graduate School of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan
²Department of Physical Education, National Defense Academy, Yokosuka, Kanagawa, Japan
³Graduate School of Medicine and Engineering, University of Yamanashi, Kofu, Yamanashi, Japan
⁴Faculty of Nursing, Yamanashi Prefectural University, Kofu, Yamanashi, Japan
⁵Graduate School of Education, University of Yamanashi, Kofu, Yamanashi, Japan

Irisin is mainly released from skeletal muscle (myocytes) and promotes thermogenesis by browning of the white adipose tissue. Although exercise has been shown to increase irisin concentration in blood and myocytes via up-regulation peroxisome proliferator receptor γ coactivator-1α (PGC-1α) expression, the influence of exercise intensity on irisin secretion remains unclear. Therefore, we determined circulating irisin responses following a single bout of running at different intensities. Six sedentary males underwent treadmill running under two different conditions: a low-intensity (40% of VO_2max) exercise trial (LIE) or a high-intensity (80% of VO_2max) exercise trial (HIE). The exercises in LIE and HIE were lasted for 20 and 40 min, respectively. All subjects underwent the two trials on separate days, and a randomized cross-over design was used. Blood samples were collected before (Pre) and immediately after exercise, at 3, 6, and 19 h after exercise. Energy consumption during exercise did not significantly differ between the two trials. HIE significantly increased blood lactate and serum lactate dehydrogenase levels (P < 0.05). Compared with pre-exercise levels, the irisin concentrations were elevated at 6 h (18% increase) and 19 h (23% increase) after HIE, but significantly decreased after LIE. The relative irisin concentrations (compared with pre-exercise levels) were significantly greater in HIE than in LIE immediately after exercise, and at 6 and 19 h after exercise (P < 0.05). These findings suggest that irisin secretion after acute running exercise is affected by exercise intensity, independent of energy consumption.

keywords —— Keywords: exercise intensity; fibronectin type III domain-containing 5; irisin; myokine; peroxisome proliferator receptor γ coactivator-1α

© 2014 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2014, 233, 135-140

Correspondence: Katsuhiro Koyama, Ph.D., Graduate School of Education, University of Yamanashi, 4-4-37 Takeda, Kofu, Yamanashi 400-8510, Japan.

e-mail: koyama@yamanashi.ac.jp