Karina Kouzaki1, Masatoshi Kobayashi2, Kei-Ichiro Nakamura3, Keisuke Ohta3, Koichi Nakazato2. 1. Graduate School of Health and Sport Science, Nippon Sport Science University, 7-1-1, Fukasawa, Setagaya, Tokyo, 158-8508, Japan. kouzaki.karina@gmail.com. 2. Graduate School of Health and Sport Science, Nippon Sport Science University, 7-1-1, Fukasawa, Setagaya, Tokyo, 158-8508, Japan. 3. Division of Microscopic and Developmental Anatomy, Department of Anatomy, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan.
Abstract
INTRODUCTION: We evaluated sciatic nerve impairment after eccentric contractions (ECs) in rat triceps surae. METHODS: Wistar rats were randomly assigned to different joint angular velocity: 180°/s (FAST), 30°/s (SLOW), or nontreated control (CNT). FAST and SLOW groups were subjected to multiple (1-4) bouts of 20 (5 reps, 4 sets) ECs. Nerve conduction velocity (NCV) and isometric tetanic ankle torque were measured 24 h after each ECs bout. We also assessed nerve morphology. RESULTS: After 4 ECs bouts, NCVs and isometric torque in the FAST group were significantly lower than those in the CNT (NCV: 42%, torque: 66%; P < 0.05). After 4 bouts, average nerve diameter was significantly smaller in the FAST group [2.39 ± 0.20 μm vs. 2.69 ± 0.20 μm (CNT) and 2.93 ± 0.24 μm (SLOW); P < 0.05] than that in other two groups. CONCLUSIONS: Chronic ECs with high angular velocity induce serious nerve damage. Muscle Nerve 54: 936-942, 2016.
INTRODUCTION: We evaluated sciatic nerve impairment after eccentric contractions (ECs) in rat triceps surae. METHODS:Wistar rats were randomly assigned to different joint angular velocity: 180°/s (FAST), 30°/s (SLOW), or nontreated control (CNT). FAST and SLOW groups were subjected to multiple (1-4) bouts of 20 (5 reps, 4 sets) ECs. Nerve conduction velocity (NCV) and isometric tetanic ankle torque were measured 24 h after each ECs bout. We also assessed nerve morphology. RESULTS: After 4 ECs bouts, NCVs and isometric torque in the FAST group were significantly lower than those in the CNT (NCV: 42%, torque: 66%; P < 0.05). After 4 bouts, average nerve diameter was significantly smaller in the FAST group [2.39 ± 0.20 μm vs. 2.69 ± 0.20 μm (CNT) and 2.93 ± 0.24 μm (SLOW); P < 0.05] than that in other two groups. CONCLUSIONS: Chronic ECs with high angular velocity induce serious nerve damage. Muscle Nerve 54: 936-942, 2016.