Arachidonic acid supplementation transiently augments the acute inflammatory response to resistance exercise in trained men.

Strenuous exercise can result in skeletal muscle damage, leading to the systemic mobilization, activation and intramuscular accumulation of blood leukocytes. Eicosanoid metabolites of arachidonic acid (ARA) are potent inflammatory mediators, but whether changes in dietary ARA intake influence exercise-induced inflammation is not known. This study investigated the effect of 4 weeks of dietary supplementation with 1.5 g/day ARA (n=9, 24 {plus minus} 1.5 years) or corn-soy oil placebo (n=10, 26 {plus minus} 1.3 years) on systemic and intramuscular inflammatory responses to an acute bout of resistance exercise (8 sets each of leg press and extension at 80% 1RM) in previously trained men. Whole EDTA blood, serum, peripheral blood mononuclear cells (PMBCs), and skeletal muscle biopsies were collected prior to exercise, immediately post-exercise and at 2, 4 and 48 h of recovery. ARA supplementation resulted in higher exercise-stimulated serum creatine kinase activity (incremental area under the curve (iAUC) p=0.046) and blood leukocyte counts (iAUC for total white cells p<0.001, neutrophils p=0.007, monocytes p=0.015). The exercise-induced fold change in PBMC mRNA expression of interleukin-1 beta (IL1B), CD11b (ITGAM) and neutrophil elastase (ELANE), as well as muscle mRNA expression of the chemokines interleukin-8 (CXCL8) and monocyte chemoattractant protein 1 (CCL2) was also greater in the ARA group than placebo. Despite this, ARA supplementation did not influence the histological presence of leukocytes within muscle, perceived muscle soreness or the extent and duration of muscle force loss. These data show that ARA supplementation transiently increased the inflammatory response to acute resistance exercise, but did not impair recovery.