Supplementation of eicosapentaenoic acid-rich fish oil attenuates muscle stiffness after eccentric contractions of human elbow flexors

Abstract

Background This study aimed to investigate the effect of supplementation of fish oil rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the damage of the biceps brachii after eccentric contractions (ECCs) of the elbow flexors, particularly focusing on muscle stiffness. Methods Sixteen men were included in this double-blind, placebo-controlled, parallel design study and the participants were randomly assigned to the EPA and DHA supplement group (EPA, n = 8) and placebo group (PL, n = 8). They consumed either EPA 600 mg and DHA 260 mg per day or placebo supplement for 8 weeks prior to exercise. Moreover, they performed six sets of 10 ECCs at 100% maximal voluntary contraction (MVC) using a dumbbell. Changes in MVC torque, range of motion (ROM), upper arm circumference, muscle soreness, muscle echo intensity, and muscle stiffness were assessed before exercise; immediately after exercise; and 1, 2, and 5 days after exercise. Results MVC torque and ROM were significantly higher in the EPA group than in the PL group after ECCs ( p < 0.05). Muscle soreness, upper arm circumference, and muscle echo intensity were significantly higher in the PL group than in the EPA group after ECCs ( p < 0.05). In addition, muscle stiffness at 150° was significantly higher in the PL group than in the EPA group immediately after ECCs ( p < 0.05). Conclusion The present study showed that EPA and DHA supplementation has a positive role in inhibiting muscle stiffness after ECCs. Trial registration This trial (UMIN000028165) was registered on 10th/July/2017.

4-week eicosapentaenoic acid-rich fish oil supplementation partially protects muscular damage following eccentric contractions

“…Herein, loss of muscle strength, muscle swelling, and increased echo intensity after exercise were not prevented by the 4-week ingestion of EPA and DHA. In a previous study, we have reported that the results of 8-week ingestion at similar doses to those used in the present study reduced the loss of muscle strength 7,9,11 . Furthermore, 30-day ingestion of 287-mg/day EPA and 194-mg/day DHA 13 and 6-week ingestion of 1,300-mg EPA and 300-mg DHA 24 have been shown to be ineffective against loss of muscle strength.…”

“…As a result, the reduction of ROM in the elbow joint until 3 days after exercise in EPA and DHA group was signi cantly less compared with that in the placebo group 7 . In a different study, the 8-week consumption of 600 mg/day EPA and 260 mg/day DHA signi cantly reduced elbow ROM until 5 days after 60 ECCs using dumbbells at 100% MVC 11 . As a study investigating the effectiveness of supplementation for a period shorter than 8 weeks, Lenn et al 13 tested the effect of 30-day consumption of 1,800-mg/day omega-3 fatty acids (398-mg EPA and 269-mg DHA) on muscle damage following 50 ECCs by elbow exions in 21 untrained men and women.…”

“…In addition, no consensus has been obtained thus far on the swelling of muscles. Consumption of EPA (600 mg/day) and DHA (260 mg/day) for 8 weeks has been reported to attenuate muscle swelling after ECCs through elbow exions at an intensity of 100% MVC 11 . Ingestion of 324-mg EPA and 216-mg DHA per day for 30 days has been reported to mitigate muscle swelling after ECCs in lower limbs 10 .…”

“…In addition, we showed that EPA and DHA ingestion reduce the levels of IL-6 as in ammatory response 7 . Furthermore, other studies have reported that ingestion of 8-week EPA (600 mg/day) and DHA (260 mg/day) attenuates nerve dysfunction 9 and muscle stiffness 11 following 60 ECCs using a dumbbell at 100% 1RM. However, the study that conducted these experiments in shorter periods (< 8 weeks) is controversial and insu cient 10,12,13 .…”

“…ECC-induced muscle damage is de ned as morphological changes in the sarcomeres and endomysium and in ammatory responses in muscle bers and connective tissues 8 . Previous studies have reported that EPA and DHA supplementation positively affect these symptoms of muscle damage 7,[9][10][11][12] .…”