In addition, individuals who have taken EPA and DHA supplementation experienced a significantly higher range of motion as compared to the placebo group.
The intervention group also had a smaller increase in their serum creatine kinase levels as compared to the placebo after exercising. Creatine kinase (CK) is an enzyme found in the heart, skeletal muscle, and other tissues. Increased amounts of CK are released when there is muscle damage.
The finding builds up on previous research by Tsuchiya et al that an intake of 600mg of EPA and 260mg of DHA per day for eight weeks could inhibit the reduction in muscle strength and range of motions.
Moreover, EPA and DHA are known to have anti-inflammatory effects, and omega-3 fatty acid supplementation was recently proposed as an ergogenic aid for athletes.
Published in the Journal of the International Society of Sports Nutrition, the RCT was conducted by researchers from Meiji Gakuin University, Teikyo Heisei University, Hosei University, and Nippon Suisan Kaisha – a Japanese health foods firm which supported the study and provided the study materials.
Twenty-two men were recruited into the study and randomly assigned to the intervention and placebo groups.
The intervention group took 600mg of EPA and 260mg of DHA per day, while the placebo group took the placebos.
Both groups took the supplements within 30 minutes after their breakfast for four weeks.
After the four weeks, they underwent an exercise experiment and continued to take the EPA/DHA or placebo in the five days following the exercise experiment.
Their exercise consists of 60 eccentric contractions (ECCs) of the elbow flexors at 100 per cent maximal voluntary contraction (MVC) using a dumbbell.
Changes in their MVC torque, range of motion, upper arm circumference, muscle soreness, muscle thickness, serum creatine kinase, and interleukin-6 (IL-6) were measured before and after exercise.
This is based on the understand that ECCs could cause muscle soreness, limit the range of motion, and muscle swelling.
Higher range of motion
A significantly higher range of motion was observed in the intervention as compared to the placebo group.
Range of motion usually decrease after exercise due to muscle swelling and increased passive muscle stiffness caused by inflammatory responses in the myofibrils.
Range of motion decreased in the placebo group right after exercise and remained lower than the baseline on the first three days after the exercise experiment.
In contrast, the intervention group’s range of motion returned to baseline on day two after exercise.
Also, the range of motion in the EPA and DHA group was significantly higher than that of the placebo group immediately after exercise (76.5 ± 16.7 % Vs 53.1 ± 18.7 %).
There was no significant increase in the serum CK level in the intervention group, while the opposite was seen in the placebo group.
In the placebo group, the serum CK levels were significantly higher than the pre-exercise levels during the third and fifth day after exercise.
Serum CK levels could increase after the exercise due to micro-damage to muscle fibers.
Amongst the intervention group, supplementation of EPA and DHA could have reduced CK levels as they could have been incorporated into the cell and protected the cell membrane in the muscle fiber.
This corresponds to the fact that EPA levels did increase and was significantly higher in the intervention than the placebo group.
“We confirmed the inhibition of increased blood CK level, suggesting protection of muscle damage to muscle fibers,” the researchers said, on the effects of EPA/DHA supplementation.
However, there were no effects on other parameters, such as muscle strength loss, delayed onset muscle soreness, muscle swelling, and serum IL-6 levels.
As such, the researchers said that the effects of EPA, DHA were only “effective to a limited extent for attenuating acute exercise-induced muscular damage.”
Source: Journal of the International Society of Sports Nutrition
4-week eicosapentaenoic acid-rich fish oil supplementation partially protects muscular damage following eccentric contractions
Authors: Tsuchiya, Y., Ueda, H., Yanagimoto, K. et al.