A group of Japanese researchers tested the effects of EPA/DHA supplementation after intense exercise intended to cause muscle soreness and impaired function. For 8 weeks healthy men supplemented with either 600 mg EPA and 260 mg DHA per day or a placebo. After this 2-month supplementation period, they performed 5 sets of maximal arm exercise emphasizing the eccentric (negative) movement. Over 5 days of recovery, the EPA/DHA group maintained a high maximal strength and a greater range of motion than placebo. The EPA/DHA group also had less muscle soreness on day three.
Additional evidence that fish oil has beneficial effects on muscle comes from a recent study in older men and women (60-85 years) who supplemented with 1,860 mg EPA and 1,500 mg DHA per day or a placebo. After 6 months, the placebo group decreased their muscle mass and performance as indicated by a 1% loss in thigh muscle volume and a 1-5% decrease in strength and power. In contrast, after 6 months of fish oil supplementation, the fish oil group showed a 3.6% increase in thigh volume and a 2-6% increase in upper and lower body strength and power.
Collectively, these two recent studies provide evidence that supplementation with fish oil softgels may help prevent the normal loss of muscle strength and range of motion that occurs after eccentric exercise. Over a longer period of time, regular use of fish oil may prevent or even reverse some of the normal age-associated decline in muscle mass and physical function.