Microencapsulated docosahexaenoic acid increases the Omega-3 Index and attenuates the physiological impact of eccentric exercise in physically trained adults: a 12-week double-blind placebo-controlled trial

PURPOSE: This study investigated the effects of docosahexaenoic acid (DHA) supplementation on delayed onset muscle soreness (DOMS), physical function, and inflammation following eccentric exercise-induced muscle damage in physically trained male and female adults (training ≥ 5d/wk). METHODS: Thirty-eight participants (12 Control, 26 DHA) completed a 12-week double-blind, placebo-controlled matched-pair trial. The Control group received high-oleic acid tablets. The DHA group received 715 mg/d of microencapsulated DHA tablets. Participants performed eccentric cycling at weeks 0 and 12, with assessments conducted pre-exercise, 0-h, 24-h, and 48-h post-exercise. The primary outcomes were DOMS (visual analogue scale) and the Omega-3 Index (O3I) (estimated by finger-stick dry blood spot). Secondary outcomes included neuromuscular function and inflammatory cytokines. RESULTS: O3I was not different between groups at week 0 but was elevated in the DHA group (∆2.43%, [95% CI; 2.10, 2.77], P < 0.001) and between Control at week 12 (P < 0.001). DOMS was lower at 24-h and 48-h post-exercise in the DHA group and between Control at week 12 (P < 0.01). At week 12, jump height and peak vertical force improved at 48-h post-exercise in the DHA group (P < 0.05), resulting in moderate (d = 0.60) and small (d = 0.32) effect sizes for 48-h post-exercise area under the curve (AUC) between groups, respectively. There were interaction effects for 48-h post-exercise AUC of IL-6 (P = 0.049), TNF-α (P = 0.010), and IL-10 (P = 0.026). CONCLUSION: A dietary achievable dose of DHA elevated the O3I and reduced DOMS in physically trained adults. These outcomes support protracted intake of DHA to attenuate the physiological impact of eccentric exercise and promote recovery.