Aerobic exercise of moderate intensity and duration (30 min at 60–70% maximal heart rate) produced a mild systemic pro-inflammatory environment 30 min after exercise in metabolic syndrome patients, indicated by increased plasma concentration of the pro-inflammatory mediators TNFα and ICAM1, and also by an increased plasma concentration of the prostaglandins PGE1 and PGE2 and the newly detected hydroxyl saturated fatty acid 16-HPAL, probably reflecting an activated operation of enzymes involved in inflammation processes such as COXs and CYP450. This evidence concerns the gene ICAM1 and metabolic syndrome.