Exercise-induced transient increases in pro-angiogenic regulators can promote angiogenesis.This pilot study aims to analyze the potential of exercise to positively affect angiogenic regulators in patients with type 2 diabetes mellitus (T2DM), who often exhibit abnormal angiogenesis, under different environmental conditions. 9 overweight/obese men with uncomplicated T2DM (8 took anti-diabetic drugs) performed submaximal cycling for 40 min in normoxia (≈21 vol%O), hypoxia (≈14 vol%O) and during alternating hypoxia/hyperoxia (≈14 vol%O/≈30 vol%O, 5-min intervals) (3×3 crossover design). Serum pro-angiogenic vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP)-2, MMP-9 and anti-angiogenic endostatin were quantified using enzyme-linked immunosorbent assay (ELISA) kits. Non-parametric statistical tests (Wilcoxon, Friedman analysis of variance) were applied. VEGF increased significantly from pre- to post-exercise with hypoxia and hypoxia/hyperoxia. MMP-2 increased significantly in all experimental runs, while MMP-9 only increased significantly with hypoxia and hypoxia/hyperoxia. Endostatin increased significantly with normoxia and hypoxia. However, the magnitude of changes did not differ significantly between conditions. Capillary blood lactate was significantly lower following cycling with hypoxia/hyperoxia than with hypoxia alone. Although differences in subjective ratings of perceived exertion failed significance, 7 subjects were less exerted with hypoxia/hyperoxia than with hypoxia. Submaximal cycling with hypoxia or alternating hypoxia/hyperoxia may induce a more reliable up-regulation of pro-angiogenic regulators compared with normoxia, while hypoxia/hyperoxia may be better tolerated than hypoxia alone.

Cardiac arrhythmias in athletes are frequent events in medical practice and require a profound diagnostic procedure. It is necessary to differentiate between harmless alterations of cardiac rhythm and potentially dangerous arrhythmias. While the former are mostly the result of an increased vagotone as a consequence of endurance training, the latter are raising the question whether intensive physical and mental strains in competitive exercise are compatible with the cardiac arrhythmias diagnosed. Vagotone-induced alterations of cardiac arrhythmias generally disappear under exercise conditions. It is essential to include the type, intensity and duration of the athletic activities into the differential-diagnostic evaluations. However, those medical considerations frequently collide with economic interests. Sinus bradycardia is a typical example of vagotone-induced arrhythmias, which may be observed especially in highly endurance-trained athletes. Sinus bradycardias are mostly asymptomatic and rarely the cause of grave complications; therapeutic interventions are only required if clinical symptoms such as orthostatic disturbances are present. The different variants of cardiac conduction defects are-within certain limits-also frequently induced by an increased vagotone; generally, they require an intensive cardiologic diagnosis. Another frequent form of arrhythmias are ventricular extrasystoles. Their dignity may be assessed by exercise ECG. Disappearance under exercise conditions is, generally, a positive sign. Diagnosis and therapy of cardiac arrhythmias are based on the established guidelines. Additionally, regular cardiologic screenings are required in high-performance athletes of all age groups.