Increased plasma concentrations of intercellular adhesion molecule-1 after strenuous exercise associated with muscle damage

Intercellular adhesion molecule-1 (ICAM-1) plays an important role in leukocyte migration from the circulation and intervention at sites of inflammation. We investigated the effects of various types of exercise on circulating levels of soluble ICAM-1 (sICAM-1) in normal healthy male adults. Plasma concentrations of sICAM-1 were measured before and after bicycle ergometer exercise at intensity of 80% maximal oxygen consumption (VO_2max) (16 min), 42 km endurance running and 30-min downhill running at intensity of ventilation threshold (VT). The plasma sICAM-1 level increased 1 day after the endurance running (12%) and downhill running (14%), but not after ergometer exercise. Plasma C-reactive protein (CRP) and creatine kinase (CK) concentrations also increased 1 day after running. Our data suggest that exercise associated with muscle damage and/or inflammation results in increased levels of plasma sICAM-1. The physiological significance of post-exercise high plasma sICAM-1 levels is not clear at this stage, but changes in plasma sICAM-1 may reflect the status of the immune system.