title: In the unloaded lower leg, vibration extrudes venous blood out of the calf muscles probably by direct acceleration and without arterial vasodilation.
abstract: OBJECTIVE
  During vibration of the whole unloaded lower leg, effects on capillary blood content and blood oxygenation were measured in the calf muscle. The hypotheses predicted extrusion of venous blood by a tonic reflex contraction and that reactive hyperaemia could be observed after vibration.
  
  
  METHODS
  Twelve male subjects sat in front of a vibration platform with their right foot affixed to the platform. In four intervals of 3-min duration vibration was applied with a peak-to-peak displacement of 5 mm at frequencies 15 or 25 Hz, and two foot positions, respectively. Near infrared spectroscopy was used for measuring haemoglobin oxygen saturation (SmO2) and the concentration of total haemoglobin (tHb) in the medial gastrocnemius muscle.
  
  
  RESULTS
  Within 30 s of vibration SmO2 increased from 55 ± 1 to 66 ± 1 % (mean ± SE). Within 1.5 min afterwards SmO2 decreased to a steady state (62 ± 1 %). During the following 3 min of recovery SmO2 slowly decreased back to base line. THb decreased within the first 30 s of vibration, remained almost constant until the end of vibration, and slowly recovered to baseline afterwards. No significant differences were found for the two vibration frequencies and the two foot positions.
  
  
  CONCLUSIONS
  The relaxed and unloaded calf muscles did not respond to vibration with a remarkable reflex contraction. The acceleration by vibration apparently ejected capillary venous blood from the muscle. Subsequent recovery did not match with a reactive hyperaemia indicating that the mere mechanical stress did not cause vasodilation.
authors: Institute of Aerospace Medicine, Deutsches Zentrum für Luft- und Raumfahrt, DLR e.V., Cologne, Germany, jochen.zange@dlr.de.
authors: Jochen
authors: J
authors: Zange
authors: Sven
authors: S
authors: Molitor
authors: Agnes
authors: A
authors: Illbruck
authors: Klaus
authors: K
authors: Müller
authors: Eckhard
authors: E
authors: Schönau
authors: Matthias
authors: M
authors: Kohl-Bareis
authors: Jörn
authors: J
authors: Rittweger
mesh_terms: D000328:Adult; D002196:Capillaries / Q000502:physiology; D016022:Case-Control Studies; D006801:Humans; D007537:Isometric Contraction; D007866:Leg / Q000098:blood supply / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption; D012018:Reflex; D012039:Regional Blood Flow; D014664:Vasodilation; D014680:Veins / Q000502:physiology; D014732:Vibration
chemical_list: D010100:Oxygen