A clinical study was undertaken to evaluate the associations between the tissue levels of omega-3 (N3), also known as the Omega-3 Index (N3 Index), on various clinical and quality of life outcomes in healthy young adults after heavy eccentric exercise.. To ensure an adequate number of participants with an elevated N3 index would be available for comparison to those with a lower N3 Index, a subgroup of the study participants received N3 dietary supplementation (2.7 g·d^-1) for 30 days prior to the performance of the heavy eccentric exercise. The remaining participants received a placebo supplement for the same 30-day period. After 30 days of supplementation, participants performed an eccentric exercise routine and were then measured at baseline (time 0), 24-, 48-, 72-, and 96 hours respectively on the following outcomes; C-reactive protein (CRP) and creatine kinase. Blood lactate levels were analyzed immediately after the exercise. Functional measurements of delayed onset of muscle soreness (DOMS), extension and torque were also analyzed. Quality of life (QOL) was measured by the quantitative questionnaire, the Profile of Mood States Questionnaire (POMS). Safety monitoring and analysis of adverse events was continuous throughout the study. Differences as demonstrated by a reduction in pain following eccentric exercise was experienced at both 72 and 96 hour time points in subjects with a higher N3 Index however there were no differences in extension or strength between the two groups. There was a significant difference in blood lactate levels (p = 0.0309) and improved emotional stability, reflected by the POMS questionnaire, in subjects with a higher N3 Index level. There was a statistically significant difference in CRP levels in subjects with a higher N3 Index level at 24 hours and a trend toward significance over 96 hours. There were no significant differences in creatine kinase levels and no reported adverse events. Subjects with a higher Omega-3 (N3) Index reported less pain related to DOMS following heavy exercise at 72 and 96 hours post-exercise. Reduced pain in the higher N3 Index Group may be due to an increased concentration of omega-3 fatty acids in the muscle cell walls, thus triggering a higher elasticity, flexibility and lower risk of physical damage to muscle tissue during exercise. Serum levels of blood lactate were lower in subjects with a high N3 Index, CRP was reduced at 24 hours and POMS scores were improved in high N3 Index subjects demonstrating better QOL. No serious adverse events were reported further supporting that omega-3 dietary supplementation is safe, bio-available and may improve athletic performance and well being in healthy young adults.

• Omega-3 index (N3) is elevated after supplementation versus placebo in healthy young adults

• Subjects with higher N3 index demonstrated reduced DOMS after heavy exercise

• Subjects with higher N3 index reported better quality of life