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Summary: Introduction: Erythropoietin (EPO) is known to exert at high concentration antioxidative and antiapoptotic effects. Which is the effect of EPO administration at the usual doses on exercise-induced oxidative stress? Patients and methods: Thirty-six Wistar rats were divided into four groups : C (controls), CE (exhausted), T (treated), TE (treated and exhausted). Groups T and TE were treated by human recombinant Epo (rhuEpo [EPREX®]) at a dose of 50 UI/kg three times a week during 6 weeks. The rats in groups C and CE were treated by saline. After a period of habituation on treadmill, rats of groups CE and TE performed an exercise-test until exhaustion at 25 m/min with a slope of 15 %. We measured NADPH oxidase activity in muscle, red cell antioxidant enzymes (Glutathion peroxydase [GPx] and superoxyde dismutase [SOD]) and markers of plasma lipid peroxydation (malondialdehyde [MDA] and F2 isoprostanes [F2IsoP]). Synthesis of facts: EPO treatment increases hematocrit by 11.9 % (46.2 vs 55.1) without any increase in time of running until exhaustion. Exercise increases muscle NADPH oxidase activity (p =0.0245), increases plasma isoprostanes and red cell GPx activity (p =0.0049) while plasma MDA and red cell SOD are unchanged. The effect of exercise is not modified by rhuEpo. Conclusion: While there is no evidence for an effect of either Epo, or the rise it elicits in O2 transfer, on blood markers of oxidant stress after exhausting exercice in rats, exercise increases the quantity of circulating antioxidant enzymes. [Copyright &y& Elsevier]

Abstract: Purpose. – The aim of this work was to study the effect of the posture on the preferred pedalling frequency during uphill cycling. Methods and results. – Ten trained cyclists performed two pedalling trials of three minutes at 80% of maximal aerobic power on a treadmill with a slope of 4%. Two postures (seated and standing pedalling) were studied in a randomized order. During the first minute of each trial, the subjects had to choose their preferred pedalling frequency with adjusting their gear and then kept this rate until the end of the trial. The preferred pedalling frequency was significantly (P <0.05) lower in standing (73±7 rpm) than in seated pedalling (80±9 rpm). Conclusion. – We suppose that cyclists choose a lower pedalling frequency during standing pedalling in order to generate greater peak pedal force and to decrease the number of lateral sways of bicycle and vertical elevations of pelvis, which increase energy cost. [Copyright &y& Elsevier]