Muscle tissue oxygenation and VEGF in VO-matched vibration and squatting exercise

Exposure to vibration has traditionally been associated with compromised perfusion. This study investigated whether blood supply during whole body vibration (WBV), as an exercise modality, is in proportion to the metabolic demand by the contracting musculature. As a secondary aim, serum levels of vascular endothelial growth factor (VEGF) were assessed. Ten young healthy males performed WBV and dynamic shallow squatting (Squat) exercise at comparable levels of oxygen uptake for 3 min. Changes in oxygenated, deoxygenated and total haemoglobin (O(2)Hb, HHb and tHb, respectively) along with tissue oxygenation index (TOI) were measured continuously before, during and after the exercise by near-infrared spectroscopy (NIRS, Portamon, Artinis Medical Systems, Zetten, The Netherlands). Vascular endothelial growth factor-A blood levels before and after exercise were assessed by ELISA. Oxygen uptake was comparable in Squat and WBV (11.4 and 10.7 ml kg(-1) min(-1)), respectively, P = 0.49), as were all other cardiopulmonary variables. Near-infrared spectroscopy data were found to be non-stationary during and shortly after WBV, but stationary in Squat. There was an increase in O(2)Hb and TOI, and a decrease in HHb during the first 30 s of WBV, but no significant change was observed during Squat. No group difference was found in VEGF serum levels. These results suggest that oxygen supply during WBV is sufficient, and oxygenation is even enhanced during the first approximately 30 s. Most likely, the transient response is because of local vascular regulatory mechanisms and due to muscle contraction mechanics. This might become clinically relevant under pathological conditions, e.g. in vascular disorders.