en Nutrition Nutrition پژوهشي Research <pre> <span style="font-family:Times New Roman;"><strong>Background and Objectives: </strong>The aim of the present study was to investigate effectsof a single sessionof eccentric or concentric resistance exercise on relative expression of BDNF, PAX7 and IGF-1 in healthy participants. <strong>Materials and Methods: </strong>In a field trial, ten healthy young men were randomly assigned into two equal groupsof concentric and eccentric contractions. Isokinetic contraction protocols included eccentric and concentric knee extensions with maximum power. The torques assigned were similar in the two groups. At the beginning and end ofthe exercise, biopsies of the lateral broad muscle tissue were collectedto assess relative expression of BDNF, PAX7 and IGF-1. <strong>Results: </strong>Statistically significant increases were seen in BDNF and PAX7 expression rates of the concentric exercise group (<em>p</em>= 0.021 and <em>p</em>= 0.014, respectively). Results showed that IGF-1 protein significantly increased after concentric and eccentric exercises(<em>p</em>= 0.005 and <em>p</em>= 0.022, respectively). In eccentric exercise group, BDNF and PAX7 expression rates increasedsignificantly (<em>p</em>=0.034 and <em>p</em>= 0.034, respectively). <strong>Conclusions: </strong>Based on the findings, a single session of eccentric and concentric exercise changes factors involved in skeletal muscle strength and hypertrophy. In addition, these changes were totally more in eccentric contraction group, compared to concentric contraction group. It can be recommended to focus further on eccentric exercisesto increase hypertrophy and muscle strength.Furthermore, these findingscan be used to prevent obesity and type 2 diabetes.</span> </pre> Muscular contractions, Metaboliceffects, exercise modes, hypertrophy, Satellite cells 11 19 http://nfsr.sbmu.ac.ir/browse.php?a_code=A-10-903-1&slc_lang=en&sid=1 Mehrnaz Ghanizadeh mehrghanizadeh_nut@yahoo.com 10031947532846004770 10031947532846004770 No PhD Student, Department of Exercise Physiology, Islamic Azad University, Central Tehran Branch, Tehran, Iran Mohammad Ali Azarbayjani m_azarbayjani@iauctb.ac.ir 10031947532846004771 10031947532846004771 Yes Department of Exercise Physiology, Islamic Azad University, Central Tehran Branch, Tehran, Iran Maghsoud Peeri m.peeri@iauctb.ac.ir 10031947532846004772 10031947532846004772 No Department of Sports Physiology, Islamic Azad University, Central Tehran Branch, Tehran, Iran Hassan Matin Homaeee has.matinhomaei@iauctb.ac.ir 10031947532846004773 10031947532846004773 No Department of Exercise Physiology, Islamic Azad University, Central Tehran Branch, Tehran, Iran