Ingestion of soy protein isolate attenuates eccentric contraction-induced force depression and muscle proteolysis via inhibition of calpain-1 activation in rat fast-twitch skeletal muscle

Eccentric contraction (ECC) is a contraction in which skeletal muscles are stretched while contracting, and it tends to result in a larger and longer-lasting force deficit compared to concentric and isometric contractions [1,2]. Following ECC, there is often muscle injury that is characterized by, e.g., proteolysis of muscle proteins, damage to sarcomeres and plasma membranes, inflammation and swelling, and delayed onset muscle soreness and stiffness [1,3,4,5,6]. Although it remains unclear to what extent these changes contribute to ECC-induced force deficit, recent studies suggest that large and long-lasting force deficit associated with ECC is, in large part, due to proteolysis of muscle proteins (e.g., Ca2+-regulatory proteins) critical for muscle contraction [2,5,7 –9] and that the proteolysis primarily involves the Ca2+-regulated cysteine proteases calpains [5,6,8,10].

Source: Nutrition - July 12, 2018 Category: Nutrition Authors: Keita Kanzaki, Daiki Watanabe, Chihiro Aibara, Yuki Kawakami, Takashi Yamada, Yoshitaka Takahashi, Masanobu Wada Source Type: research