title: What is the most effective posture to conduct vibration from the lower to the upper extremities during whole-body vibration exercise?
abstract: BACKGROUND
  Whole-body vibration (WBV) exercise is widely used for training and rehabilitation. However, the optimal posture for training both the upper and lower extremities simultaneously remains to be established.
  
  
  OBJECTIVE
  The objective of this study was to search for an effective posture to conduct vibration from the lower to the upper extremities while performing WBV exercises without any adverse effects.
  
  
  METHODS
  Twelve healthy volunteers (age: 22-34 years) were enrolled in the study. To measure the magnitude of vibration, four accelerometers were attached to the upper arm, back, thigh, and calf of each subject. Vibrations were produced using a WBV platform (Galileo 900) with an amplitude of 4 mm at two frequencies, 15 and 30 Hz. The following three postures were examined: posture A, standing posture with the knees flexed at 30°; posture B, crouching position with no direct contact between the knees and elbows; and posture C, crouching position with direct contact between the knees and elbows. The ratio of the magnitude of vibration at the thigh, back, and upper arm relative to that at the calf was used as an index of vibration conduction.
  
  
  RESULTS
  Posture B was associated with a greater magnitude of vibration to the calf than posture A at 15 Hz, and postures B and C were associated with greater magnitudes of vibration than posture A at 30 Hz. Posture C was associated with a vibration conduction to the upper arm that was 4.62 times and 8.26 times greater than that for posture A at 15 and 30 Hz, respectively.
  
  
  CONCLUSIONS
  This study revealed that a crouching position on a WBV platform with direct contact between the knees and elbows was effective for conducting vibration from the lower to the upper extremities.
authors.affiliation: Institute for Integrated Sports Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Tsukahara
authors.affiliation: Institute for Integrated Sports Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Iwamoto
authors.affiliation: Institute for Integrated Sports Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Kosui
authors.initials: K
authors.lastname: Iwashita
authors.affiliation: Institute for Integrated Sports Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Takuma
authors.initials: T
authors.lastname: Shinjo
authors.affiliation: Institute for Integrated Sports Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Azuma
authors.affiliation: Institute for Integrated Sports Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Matsumoto
keywords: lower extremities; upper extremities; whole-body vibration exercise