Treadmill exercise in claudicants on aspirin results in improved antioxidant status but only minimal platelet activation

The consequence of exercise on platelets remains controversial and adverse effects may result from repeated ischaemia reperfusion injury. We investigated platelet activation (platelet P-selectin (PS), and activated glycoprotein (Gp) IIb/IIIa), platelet-monocyte aggregates (PMA) and total plasma antioxidant status (TPAS) in claudicants after exercise. Twenty claudicants, taking 75 mg of aspirin daily, were subjected to repeated treadmill testing (3 km/h, 10% inclination). Blood was sampled before and after exercise. Activated GpIIb/IIIa, PS and PMA were quantified with flow cytometry. TPAS was quantified using a decolourisation assay. Percent positive cells for PS (pre-exercise 3.76% vs. 40 min post-exercise 4.10%; P < 0.05) and platelet-monocyte aggregates (pre-exercise: 25.31% vs. 40 min post-exercise 26.99%; P < 0.05) were significantly higher after exercise. Relative median fluorescence (RMF) for activated GpIIb/IIIa was significantly higher 40 min after exercise (pre-exercise: 3.04 vs. 40 min post-exercise: 4.01; P < 0.05). TPAS was significantly higher post-exercise (pre-exercise: 1.31 mmol/l vs. 1 min post-exercise: 1.40 mmol/l and 40 min post-exercise: 1.38 mmol/l; P < 0.01). Following moderate exercise, 'aspirin treated claudicants' show marginal platelet activation, PMA formation and a favourable improvement in antioxidant status. Further studies are required to assess the effect of additional antiplatelet agents and the significance of platelet-monocyte interactions. The possibility that aspirin contributes to the TPAS changes following exercise needs to be investigated.