The aim of this study was to examine the effects of fish oil supplementation on the magnitude and time-course of postresistance exercise muscle soreness. This study was a randomized, placebo-controlled, double-blind trial. Nonresistance trained females were randomized into one of two groups: fish oil supplementation (6 g/day; 5:1 eicosapentaenoic acid to docosahexaenoic acid (EPA:DHA)) or placebo (6 g/day corn/soy oil).

After consuming the supplements for one week, participants underwent a single bout of resistance exercise consisting of 10 sets to failure of elbow flexion and leg extension machines. Muscle soreness was measured daily over the next week via grounded visual analog scale while participants continued to consume their assigned supplement. At 48 hours and one week postexercise, soreness during functional movements and limb circumferences were measured.

The fish oil group perceived less static and functional muscle soreness than placebo, although the differences were not statistically significant. Effect sizes for resistance exercise-induced static and functional soreness responses were 33 to 42% lower in fish oil versus placebo without changes in upper arm and thigh circumferences.

Supplementing the diet with 6 g per day of fish oil may alleviate muscle soreness experienced after resistance training in young untrained females.