Submitted on October 13, 2006
Accepted on April 18, 2007
Effects of Short-term Vibration and Hypoxia during High-intensity Cycling Exercise on Circulating Levels of Angiogenic Regulators in Humans
Frank Suhr1*, Klara Brixius2, Markus de Marées1, Birgit Bölck3, Heinz Kleinöder1, Silvia Achtzehn1, Wilhelm Bloch2, and Joachim Mester1
1 Institute of Training Science and Sport Informatics, German Sport University Cologne, Germany; The German Research Center of Elite Sport, German Sport University Cologne, Germany
2 Department of Molecular and Cellular Medicine, German Sport University Cologne, Germany; The German Research Center of Elite Sport, German Sport University Cologne, Germany
3 Laboratory of Muscle Research and Molecular Cardiology, Department of Internal Medicine III, University of Cologne, Germany
* To whom correspondence should be addressed. E-mail: Suhr{at}dshs-koeln.de.
This study aimed to investigate the biological response to hypoxia as a stimulus as well as exercise- and vibration-induced shear stress, which is known to induce angiogenesis. Twelve male cyclists (27.8 ±5.4 years) participated in this study. Each subject completed four cycle training sessions under normal conditions (NC) without vibration, NC with vibration, normobaric hypoxic conditions (HC) without vibration and HC with vibration. Each session lasted 90 minutes and sessions were held at weekly intervals in a randomised order. Five blood samples (pre-training, 0h post, 0.5h post, 1h post, and 4h post) were taken from each subject at each training session. Hypoxia was induced by a normobaric hypoxic-chamber with an altitude of 2500 m. The mechanical forces (cycling with or without vibration) were induced by a cycling ergometer. The parameters VEGF, endostatin and MMPs were analysed using the ELISA method. VEGF showed a significant increase immediately after exercise only with exogenously-induced vibrations, as calculated with separate ANOVA analysis. Endostatin increased after training under all conditions. Western Blot analysis was performed for the determination of endostatin corresponding to the 22 kDa cleavage product of collagen XVIII. This demonstrated elevated protein content for endostatin at 0h post exercise. MMP-2 increased in three of the four training conditions. The exception was NC with vibration. MMP-9 reached its maximum level at 4h post exercise.
In conclusion, the results support the contention that mechanical stimuli differentially influence factors involved in the induction of angiogenesis. These findings may contribute to a broader understanding of angiogenesis.
