RESUMO
Free diving is associated with extreme hypoxia. This study evaluated the combined effect of maximal static breath holding and underwater swimming on plasma biomarkers of tissue hypoxemia: erythropoietin, neuron-specific enolase and S100B, C-reactive protein, pro-atrial natriuretic peptide, and troponin T. Venous blood samples were obtained from 17 competing free divers before and 3 h after sessions of static apnea and underwater swimming. The heart was evaluated by echocardiography. Static apnea for 293 ± 78 s (mean ± SD) and subsequent 88 ± 21 m underwater swimming increased plasma erythropoietin from 10.6 ± 3.4 to 12.4 ± 4.1 mIU/L (P = 0.013) and neuron-specific enolase from 14.5 ± 5.3 to 24.6 ± 6.4 ng/mL (P = 0.017); C-reactive protein decreased from 0.84 ± 1.0 to 0.71 ± 0.67 mmol/L (P = 0.013). In contrast, plasma concentrations of S100B (P = 0.394), pro-atrial natriuretic peptide (P = 0.549), and troponin T (P = 0.125) remained unchanged and, as assessed by echocardiography, the heart was not affected. In competitive free divers, bouts of static and dynamic apnea increase plasma erythropoietin and neuron-specific enolase, suggesting that renal and neural tissue, rather than the heart, is affected by the hypoxia developed during apnea and underwater swimming.
