Japanese researchers link omega-3 intake to reduced muscle stiffness post-exercise
The study, funded by Japanese fishing company Nippon Suisan Kaisha, found that participants who ingested EPA and DHA for eight weeks had lost less muscle strength, had a delayed onset muscle soreness, and experienced less muscle swelling compared to participants who ingested the placebo.
Though detailed mechanisms are still unclear, the present study provides “evidence on the preventive effect of EPA and DHA supplementation on muscle stiffness after eccentric contraction [when an active muscle is lengthening under a load,” they wrote in their report, published last week.
They were building off of previous studies that have linked omega-3 supplementation (EPA and DHA specifically) to different anti-inflammatory responses in sports nutrition.
The same lab has previously studied omega-3s roles in motor nerve function and strength loss, with positive results.
“These results may be significant in identifying the mechanism associated with the preventive effect of EPA and DHA supplementation on muscle damage,” they argued.
More examples of studies on omega-3 in sports nutrition include a 2015 study out of the University of Toronto that linked omega-3s to improved neuromuscular function and aspects of fatigue for athletes, and a 2017 mice study by researchers from the US and South Korea that linked omega-3 to muscle strength when combined with resistance training.
Study details and results
The study was placebo-controlled and double blind, meaning neither participants nor researchers knew which capsule was consumed by which group until after the end of the study.
Sixteen men completed the study, with eight participants for each the omega-3 and placebo group. They consumed either 600 mg of EPA with 260 mg of DHA or a corn oil soft gel with 300 mg per day within 30 minutes of each meal. Both capsules were identical.
Participants performed six sets of eccentric contraction exercises (preacher curls) at 100% maximal voluntary contraction, or as much dumbbell weight as they assigned themselves.
The researchers measured changes in the contraction torque, range of motion, and upper arm circumference. Using questionnaires, participants reported muscle soreness, while muscle stiffness was measured using ultrasound. All measurements were done before exercise, immediately after exercise, and 1, 2, and 5 days after exercise. Researchers also collected blood samples to measure EPA and DHA.
Final analysis of all measurements revealed that contraction torque and range of motion were significantly higher in the supplemented group compared to the placebo group. Additionally, muscle soreness, muscle stiffness, and muscle echo intensity were significantly higher in the placebo group.
They also found that upper arm circumference was higher in the placebo group, which contradicted their previous studies.
“We speculate that one of reasons for this discrepancy is caused by different exercise load, which is much greater in this study compared with previous study,” they reported.
Due to the small sample size and short exercise period, further investigation is needed, the researchers said.
Source: Journal of the International Society of Sports Nutrition
Published online, https://doi.org/10.1186/s12970-019-0283-x
“Supplementation of eicosapentaenoic acid-rich fish oil attenuates muscle stiffness after eccentric contractions of human elbow flexors”
Authors: Yosuke Tsuchiya, Kenichi Yanagimoto, Hisashi Ueda and Eisuke Ochi