Aim: The purpose of the present study was to compare the acute hormonal response to a short term high intensity training (HIT) versus a high volume endurance training (HVT) and to determine the contribution of the metabolic acidosis as a stimulus for possibly different reactions of circulating VEGF and bFGF levels. Methods: Eleven subjects participated in three experimental trials. Two times subjects performed four 30 s "all-out" exercise bouts on a cycle ergometer adjusted to an isokinetic mode separated by 5 min rest each (whereas subjects either received NaHCO3 (HIT(B)) or a placebo (HIT(P)) before the exercise). The third exercise trail consisted of a constant load exercise for 1 h at 45 % VO2max (HVT). Venous blood samples were taken under resting conditions, 0h, 1h and 4h after each exercise condition to determine VEGF and bFGF serum concentrations. Capillary blood samples were taken during and after the interventions to determine lactate concentrations and blood gas parameters. Results: Power output, mean lactate concentrations and mean pH values were significantly higher during HIT(B) compared to HIT(P). Blood gas parameters showed no major changes during HVT. Serum VEGF concentration was significantly increased 10 min post-exercise in both HIT interventions. HVT showed no effects on VEGF levels. Additionally it could be shown that the diminished acidosis during HIT(B) attenuates the VEGF response. bFGF showed no reactions to HIT or HVT. Conclusion: The present study suggests that HIT/acidosis is a stimulus for exercise-induced VEGF secretion. These findings might be relevant for arrangements of (interval) training, due to the fact that active or passive recovery during rest periods influence the acid base status and may therefore influence the VEGF response.