Omega-3 fatty acids, get a lot of attention regarding their inflammatory function. The relationship between these fatty acids and exercise though is unclear.
Strenuous exercise, performed repeatedly can lead to chronic inflammation. That is an acceptable claim. What omega-3 fatty acids are thought to do, is by being an acting precursor to prostaglandins (the anti-inflammatory compound) it helps reduce inflammation. They do this by changing cell membrane fluidity, receptor function, and production of cytokines (signals to cells to start repairing). All these supposably reducing muscular damage following a training session.
There are studies that suggest omega-3 supplementation has a positive effect on endurance training. Such studies suggest omega-3’s have a vasodilatory effect and increase mitochondrial (powerhouse of cell) function. This leading to an observed lowering of max heart rate for a given workload, reduced resting heart rate variability, and oxygen consumption when training. All of which, are considered good adaptations that may increase athletic performance. However, when reading these studies or articles it is important to consider the design of the study; the participants, their background, the time period of the study. All very important questions to consider before generalizing a finding.
For example, what might be found to be beneficial for a sedentary individual, may not be true for an individual with years of training experience. Therefore, suggesting an improvement in athletic performance based only on omega-3 supplementation is a bit brash.
Ultimately, a well-balanced diet is the best medicine. It then comes down to the individual and meeting with a professional consultant, like a sports nutritionist or dietician. Such a professional is able to assess the clients goals, needs and situation.