Researches have determined that omega-3 fish oil supplementation improves glucose metabolism in people and animals and positively effects protein metabolism.  For the athlete, this translates into more muscle mass, increased strength and endurance, and increased fat burning capabilities.

What you need to understand is that these increases in muscle are due to fish oil improving the body's capability of using the nutrients in the foods eaten, making the nutrients more boiavailable for your body to assimilate and use. 

Without this ability, much of the nutrients in food pass through you as waste.  Older adults and the consumption of processed foods contribute to diminishing capabilities of assimilating nutrients in food.