Introduction: 

The present study aimed to investigate the influence of two exhaustive incremental step tests on different extracellular matrix (ECM)-related and angiogenesis regulating factors, such as endostatin, matrix metalloprotease (MMP)-2, and MMP-9 in two groups of national class runners. MMP-2 and MMP-9 are crucial players in the vascular bed ECM processing and were shown to generate the 22 kDa heavy, C-terminal collagen XVIII cleavage product endostatin, which is thought to be a potent anti-angiogenic agent. However, we recently demonstrated that endostatin also functions as an angiogenic modulator. Additionally, we demonstrated that endostatin induces the release of the angiogenic vasodilator nitric oxide. Thus, a release of endostatin by MMPs during exercise may contribute to increased performance capacity, because of increased vessel diameters. Recently, it was shown that the mentioned parameters are regulated by cycling exercise.

Methods: 

13 male subjects participated in this study. Due to their competition running distances they were assigned either to the long-track group (LTG) (n=7, 24.92.4 years) or the short-track group (STG) (n=6, 21.50.9 years). Two incremental running step tests (start: 2.5 m ^. s^-1, increased by 0.5 m ^. s^-1 every five minutes) until exhaustion were carried out in November and Mai. Blood samples were taken before the test (pre), 0h post, and 1h post exercise.

Results: 

Endostatin did not show significant increases after the exercise stimulus in the STG in both running tests. In contrast, endostatin was significantly increased in the LTG at 0h post exercise at the second test time point. In both groups endostatin levels were significantly decreased in all time points (pre, 0h post, and 1h post) in the second running test. MMP-2 was neither increased in the first test nor in the second test of STG. In the LTG MMP-2 was only increased at 1h post exercise in the second running test. MMP-2 showed a significant increase at 0h post in the second test of the STG. In the STG MMP-9 was significantly decreased at 1h post exercise in the second test. In the LTG MMP-9 was significantly decreased at 0h post exercise in the second test compared to the first test. Discussion: The present study offers new insights into exercise-induced regulation of endostatin, MMP-2, and MMP-9 in runners. Endostatin was not increased after running, which seems to be in contrast to Suhr et al. The decreased endostatin levels in the second test are in line with the results of Brixius et al. Also the results of MMP-2 and MMP-9 are in contrast to the results of Suhr et al., which might be explained by different exercise modes and especially by different exercise durations. Therefore, additional studies have to clarify the exercise-induced regulation of endostatin and MMPs. This might be important for new training strategies as well as for new therapeutic programs.