High-intensity exercise is associated with increased oxidative stress. Rowing is very demanding requiring maintenance of high power mostly produced from aerobic metabolism. The present study aimed at investigating selective blood oxidative stress markers in response to a rowing race simulation test, consisting of 2,000 m maximal effort on a rowing ergometer, in well-trained male rowers during the preseason preparatory training period. Mean time for the 2,000-m trial was 409.4 +/- 4.0 seconds, and heart rate at 2,000 m was 198 +/- 1 b x min (mean +/- SEM). Blood lactate concentration was 11.2 +/- 0.6 mmol x L. Postexercise whole blood lysate oxidized glutathione (GSSG) concentration significantly increased (19%), whereas reduced glutathione (GSH) concentration remained unchanged, resulting in an overall decreased postexercise GSH:GSSG ratio (20%). Postexercise serum thiobarbituric acid-reactive substance concentration and protein carbonyls increased by 45 and 70%, respectively, as compared with the pre-exercise levels. Likewise, postexercise catalase activity (105%) and total antioxidant capacity (9%) significantly increased. In agreement with other studies, our data illustrate that a 2,000-m rowing ergometer race induces significant blood oxidative stress despite the rowers' high training status. In scheduling an evaluation rowing test or a competition, coaches should allow sufficient recovery time elapsed between the test and the last intensive training session. The 2,000-m rowing performance appears to be a suitable test to assess oxidative stress in rowers and could potentially serve as a model to study oxidative damage in sports science.

Exercise-induced arterial hypoxemia (EIAH), characterized by decline in arterial oxyhemoglobin saturation (SaO(2)), is a common phenomenon in endurance athletes. Acute intensive exercise is associated with the generation of reactive species that may result in redox status disturbances and oxidation of cell macromolecules. The purpose of the present study was to investigate whether EIAH augments oxidative stress as determined in blood plasma and erythrocytes in well-trained male rowers after a 2,000-m rowing ergometer race. Initially, athletes were assigned into either the normoxemic (n = 9, SaO(2) >92%, [Formula: see text]: 62.0 ± 1.9 ml kg(-1) min(-1)) or hypoxemic (n = 12, SaO(2) <92%, [Formula: see text]: 60.5 ± 2.2 ml kg(-1 )min(-1), mean ± SEM) group, following an incremental [Formula: see text] test on a wind resistance braked rowing ergometer. On a separate day the rowers performed a 2,000-m all-out effort on the same rowing ergometer. Following an overnight fast, blood samples were drawn from an antecubital vein before and immediately after the termination of the 2,000-m all-out effort and analyzed for selective oxidative stress markers. In both the normoxemic (SaO(2): 94.1 ± 0.9%) and hypoxemic (SaO(2): 88.6 ± 2.4%) rowers similar and significant exercise increase in serum thiobarbituric acid-reactive substances, protein carbonyls, catalase and total antioxidant capacity concentration were observed post-2,000 m all-out effort. Exercise significantly increased the oxidized glutathione concentration and decreased the ratio of reduced (GSH)-to-oxidized (GSSG) glutathione in the normoxemic group only, whereas the reduced form of glutathione remained unaffected in either groups. The increased oxidation of GSH to GSSG in erythrocytes of normoxemic individuals suggest that erythrocyte redox status may be affected by the oxygen saturation degree of hemoglobin. Our findings indicate that exercise-induced hypoxemia did not further affect the increased blood oxidative damage of lipids and proteins observed after a 2,000-m rowing ergometer race in highly-trained male rowers. The present data do not support any potential link between exercise-induced hypoxemia, oxidative stress increase and exercise performance.

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The aim of this study was to examine and to compare alterations in the secretion of atrial natriuretic peptide (ANP) during different exercise-testing protocols in moderately trained men. Fifteen healthy male physical education students were studied (mean age 22·3 ± 2·5 years, training experience 12·3 ± 2·5 years, height 1·80 ± 0·06 m, weight 77·4 ± 8·2 kg). Participants performed an initial graded maximal exercise testing on a treadmill for the determination of VO(2max) (duration 7·45-9·3 min and VO(2max) 55·05 ± 3·13 ml kg(-1) min(-1) ) and were examined with active recovery (AR), passive recovery (PR) and continuous running (CR) in random order. Blood samples for plasma ANP concentration were taken at rest (baseline measurement), immediately after the end of exercise as well as after 30 min in passive recovery time (PRT). The plasma ANP concentration was determined by radioimmunoassay (RIA). The results showed that ANP plasma values increased significantly from the rest period to maximal values. In the short-term graded maximal exercise testing the ANP plasma values increased by 56·2% (44·8 ± 10·4 pg ml(-1) versus 102·3 ± 31·3 pg ml(-1) , P<0.001) and in the CR testing the ANP levels increased by 29·2% (44·8 ± 10·4 pg ml(-1) versus 63·3 ± 19·8 pg ml(-1) , P<0.001) compared to the baseline measurement. Moreover, the values of ANP decreased significantly (range 46·4-51·2%, P<0.001) in PRT after the end of the four different exercise modes. However, no significant difference was evident when ANP values at rest and after AR and PR were compared. It is concluded that the exercise testing protocol may affect the plasma ANP concentrations. Particularly, short-term maximal exercise significantly increases ANP values, while the intermittent exercise form of active and passive recovery decreases ANP concentrations.