ISO 2631-5:2004 addresses human exposure to mechanical multiple shocks measured at the seat pad when a person is seated. The adverse health effects of prolonged exposure to vibration that includes multiple shocks are related to dose measures. The method described in ISO 2631-5:2004 is generally applicable in cases where adverse health effects in the lumbar spine are concerned. The calculation of the lumbar spine response described ISO 2631-5:2004 assumes that the person subjected to the vibration is seated in an upright position and does not voluntarily rise from the seat during the exposure. Different postures can result in different responses in the spine.