Effect of eicosapentaenoic acid supplementation on blood serum markers after eccentric contractions
Authors: Ochi Eisuke , Tsuchiya Yosuke , Yanagimoto Kenichi 
Published: November 2023

PurposeThis study investigated the effect of eicosapentaenoic acid‐rich fish oil (EPA) supplementation on eccentric contraction‐induced muscle damage markers into blood.MethodsTwenty‐four healthy men were randomly assigned to consume the EPA supplement (EPA, n = 12) or placebo (PL, n = 12) by the double‐blind method. Participants were provided with detailed explanations of the study protocol prior to participation. All participants signed an informed consent form in accordance with the Declaration of Helsinki before enrolled in this study. This study was approved by the Ethics Committee for Human Experiments at Juntendo University (ID: 26‐113) and has been registered at the University Hospital Medical Information Network Clinical Trials Registry (UMIN‐CTR, identifier: UMIN000016149). They consumed EPA or placebo supplement for 8 weeks prior to exercise and continued it until 5 days. The EPA group consumed EPA‐rich fish oil containing 600 mg EPA per day. Subjects performed five sets of six maximal eccentric elbow flexion exercises. Changes in the maximal voluntary isometric contraction (MVC) torque, range of motion (ROM), upper arm circumference, muscle soreness as well as serum creatine kinase, myoglobin, interleukin‐6 (IL‐6), and tumor necrosis factor α levels in blood were assessed before, immediately after, and 1, 2, 3, and 5 days after exercise.ResultsMVC torque was significantly higher in the EPA group than in the PL group at 2–5 days after exercise (PL 78.4 ± 10.4% – 82.6 ± 6.8%, EPA 95.5 ± 20.1% – 98.7 ± 15.0%, p < 0.01). ROM was also significantly greater in the EPA group than in the PL group at 1–5 days after exercise (p < 0.01). Muscle soreness of the brachialis was significantly greater in the PL group than in the EPA group at 3 days after exercise (p < 0.05). Although serum IL‐6 levels in the PL group were significantly increased at 3 days after exercise compared with pre‐exercise vales (p < 0.01), no significant difference in serum IL‐6 levels after exercise compare with pre‐exercise values was observed in the EPA group. Serum IL‐6 levels were significantly higher in the PL group than the EPA group at 3 days after exercise (PL, 1.8 ± 1.1 μg/ml vs EPA, 0.8 ± 0.4 μg/ml; p < 0.05). In contrast, no significant difference in serum TNF‐α levels after exercise compared with pre‐exercise values was observed in either group, with no significant difference observed between groups.Serum Mb levels in the PL group were significant increased at 3 days after exercise compared with pre‐exercise values (p < 0.01); however, no significant difference after exercise compared with pre‐exercise values was observed in the EPA group. No significant difference in serum CK levels after exercise compared with pre‐exercise values were observed in either group, with no significant difference observed between groups. These results were re‐analyzed between groups using logarithmic value and Area Under the Curve (AUC) of Mb and CK data because of heterogeneity of variance. The re‐analyze data indicated significant differences in serum Mb between groups at 3 days after ECC and AUC from 2 to 5 days. These results led us to suppose EPA possess some influence on prevent of muscle damage.ConclusionEPA supplementation for 8 weeks reduces muscle damage after eccentric contractions. Eight‐week EPA supplementation inhibits cytokine response into blood.