Angiogenic Stimuli of Resistance Exercise and Superimposed Whole-Body Vibrations

Abstract / Zusammenfassung (English) OBJECTIVES: Whole-body vibration (WBV) training has become a popular training mode in the past few years and is nowadays applied in various fields like sports, rehabilitation and preventive medicine. WBV training has been shown to improve peripheral perfusion and may elicit muscle deoxygenation. We hypothesized that the superposition of WBV to resistance exercise would add a pro-angiogenic stimulus to the training and we aimed to find a novel training mode that concurrently induces muscle hypertrophy and capillary growth in order to improve muscle performance. METHODS: A six-week training study including 26 healthy males was conducted in a randomized two-group parallel design, in which one group performed resistance exercise (RE) and the other group resistance exercise with superimposed whole-body vibrations (RVE). Subjects trained 2-3 times per week, concluding 16 training sessions. The training consisted of squatting exercise and calf raises performed with heavy loads that were set at 80% of the one-repetition maximum. During the initial and final exercise sessions of the 6-week intervention, measurements were performed at rest, during and acutely after exercise. Blood volume and tissue oxygenation were determined in gastrocnemius via near infrared spectroscopy. Angiogenic markers (matrix metalloproteinase -2 and -9, vascular endothelial growth factor (VEGF) and endostatin) were measured in serum via ELISA and the proliferative effect upon human umbilical vein endothelial cells was determined in vitro. Finally, long-term effects of the trainings on muscle morphology were determined in soleus biopsies. RESULTS: Our data are to our knowledge the first to describe transient increases of circulating angiogenic markers after resistance exercise. VEGF levels were acutely higher in the RE group, which supposedly provoked increased proliferation of endothelial cells in vitro. Furthermore, acute increases in circulating endostatin were higher in the RE group after the six-week training intervention. These effects were elusive in the RVE group. Despite differences in acute VEGF levels, capillary growth in soleus muscle was not different between groups. However, total blood volume and exercise hyperemia was increased after six weeks of RVE training. CONCLUSIONS: Our data indicate the pro-angiogenic stimulus of RE is not increased by superimposing WBV to the training. While structural adaptations in muscle tissue were similar in both groups, regular RVE training seems to influence the functional state of small arterioles and potentially capillaries, enhancing muscle perfusion and post-exercise hyperemia. Abstract / Zusammenfassung (Deutsch) Hintergrund: Ganzkörper-Vibrationstraining (‚Whole-Body Vibration‘, WBV) ist in den letzten Jahren zu einer beliebten Trainingsmethode geworden und findet heutzutage in vielen Bereichen Anwendung, z.B. in Fitnessstudios oder in der Rehabilitations-und Präventionsmedizin. Bisherige Studien zeigen, dass WBV u.a. einen positiven Effekt auf die Durchblutung hat und eine Deoxygenierung der vibrierten Muskeln herbeiführen kann. Die dieser Arbeit zu Grunde liegende Hypothese ist, dass Ganzkörpervibrationen in Kombination mit konventionellem Widerstandstraining einen zusätzlichen angiogenen Stimulus erzeugen. Ziel war es, eine neue Trainingsmethode zu entwickeln und wissenschaftlich zu überprüfen, die gleichzeitig Hypertrophie und Kapillarwachstum im Muskel induziert und dadurch Muskelleistung im Sinne von Maximalkraft und Ermüdungswiderstandsfähigkeit verbessert. Methoden: Eine sechswöchige Trainingsstudie mit 26 gesunden Männern wurde im Parallel-Design durchgeführt. Eine Gruppe trainierte mit konventionellem Widerstandstraining (‚resistive exercise‘: RE), während die andere Gruppe ein Widerstandstraining kombiniert mit Ganzkörpervibrationen (‚resistive vibration exercise‘: RVE) absolvierte. Die Probanden trainierten 2-3 Mal pro Woche. Das Training bestand aus Kniebeugen und Zehenständen, welche mit hohen Zusatzgewichten durchgeführt wurden (80% des One-Repetition Maximums). Funktionelle Messungen wurden während des ersten und letzten Trainings der sechswöchigen Intervention durchgeführt: jeweils vor, während und direkt nach dem Training. Muskeldurchblutung und Oxygenierung im Gastrocnemius Muskel wurden mit Nah-Infrarot Spektroskopie gemessen. Desweiteren wurden die Angiogenesemarker Matrix Metalloproteinase -2 and -9, Vascular Endothelial Growth Factor (VEGF) und Endostatin im Serum via ELISA gemessen und deren Effekt auf Endothelzellen (human umbilical vein endothelial cells) wurde in vitro bestimmt. Außerdem wurden Langzeit-Anpassungseffekte auf die Morphologie des Soleus Muskels bestimmt. Ergebnisse: Nach dem Widerstandstraining konnten wir eine Erhöhung der gemessenen Angiogenesemarker im Serum feststellen. VEGF-Konzentrationen und Endothelzellen-Proliferation waren in der RE Gruppe höher im Vergleich zur der RVE Gruppe. Außerdem wurde nach der 6-wöchigen Trainingsintervention in der RE Gruppe eine erhöhte Endostatin-Konzentration direkt nach dem letzten Training gemessen, während solch ein Effekt in der RVE Gruppe ausblieb. Morphologische Daten zeigen, dass die strukturellen Muskelanpassungen zwischen beiden Gruppen vergleichbar waren, obwohl sich die funktionelle Muskeldurchblutung der RVE Gruppe erhöhte. Schlussfolgerungen: Die Daten zeigen, dass der Zusatz von Ganzkörpervibrationen zu konventionellem Widerstandstraining den pro-angiogenen Stimulus des Trainings nicht erhöht. Es wurde gezeigt, dass zwischen den beiden Gruppen strukturelle Muskelanpassungen vergleichbar sind. Dennoch scheinen Ganzkörpervibration, wenn sie in Kombination mit Widerstandstraining appliziert werden, die Dilatationsfähigkeit von Arteriolen und eventuell auch von Kapillaren zu beeinflussen was sich in der erhöhten funktionellen Muskeldurchblutung widerspiegelt

Anthropometric data of EVE subjects at baseline.

<p>BMI: Body Mass Index, CMJ: Counter movement jump. There was no difference between the two groups. Values are means ± SEM</p

Circulating matrix metalloproteinase (MMP)-2 levels at rest and 2-75 min after exercise.

<p>Data points indicate mean serum concentrations (± SEM) at the initial and final exercise sessions of a 6-week training intervention (n = 13). Significant differences from resting levels (time effect): †<i>P</i><0.05, ††<i>P</i><0.001; significant differences from the initial exercise at the same time point ^#<i>P</i><0.05; significant differences between groups at the final exercise *<i>P</i><0.01. (A) Acute effects of resistance exercise (RE) and resistive vibration exercise (RVE): MMP-2 was elevated from resting levels only in the RE group. (B) Long-term effects: the acute response after the final exercise in the RVE group was elevated over the time course measured at the initial exercise and the RVE group depicted significantly higher MMP-2 levels at all time points compared to the RE group.</p

Circulating endostatin levels at rest and 2–75 min after exercise.

<p>Data points indicate mean serum concentrations (± SEM) at the initial and final exercise sessions of a 6-week training intervention (n = 13). Endostatin levels were increased over resting levels 2-15 min after training (time effect): ^‡‡<i>P</i><0.01. (A) Acute effects of resistance exercise (RE) and resistive vibration exercise (RVE): the acute exercise effects did not differ between groups. (B) Long-term effects: circulating post-exercise endostatin levels in the RE group were higher at the final exercise compared to the initial exercise: ^#<i>P</i><0.05.</p

Circulating matrix metalloproteinase (MMP)-9 levels at rest and 2–75 min after exercise.

<p>Data points indicate mean serum concentrations (± SEM) at the initial and final exercise sessions of a 6-week training intervention (n = 13). (A) Acute effects of resistance exercise (RE) and resistive vibration exercise (RVE); (B) Long-term effects: In both groups, MMP-9 levels were increased over resting levels 2–15 min after exercise. Significant differences from resting levels (time effect): ^‡‡<i>P</i><0.01. There were no differences between initial and final exercises of the 6-week intervention in neither group.</p

Resting levels of angiogenic markers measured at the initial and final exercise sessions of the 6-week training intervention.

<p>There were no differences in resting levels between the RE and RVE group for MMP-9, VEGF and Endostatin (<i>P</i>>0.68). After the 6-week training intervention, the RVE group had significantly higher MMP-2 levels compared to the RE group (^###<i>P</i><0.001). RE: resistance exercise, RVE resistive vibration exercise MMP: Matrix metalloproteinase, VEGF: Vascular Endothelial Growth Factor. Values are means ± SEM.</p