EPA and DHA fatty acids improve blood circulation and lower blood pressure. The exact same effect occurs during a physical load. Improved blood circulation accounts for lower muscle damage and quicker muscle regeneration after a physical load.
A beneficial effect can be observed even on untrained people. 27 people who had abstained from any kind of training 60 days before the test, took part in a randomised, double-blind, placebo-controlled study. The Omega-3 user group (1.8 g per day) experienced less muscle pain after the load, compared to the placebo group.
Research publication: Tartibian B et al. The effects of ingestion of omega-3 fatty acids on perceived pain and external symptoms of delayed onset of muscle soreness in untrained men. Clin J Sport Med. 2009 Mar; 19(2):115-9.