This part of ISO 2631 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 this part of ISO 2631 is generally applicable in cases where adverse health effects in the lumbar spine are concerned. The calculation of the lumbar spine response described in this part of ISO 2631 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. The limitations of the lumbar spine response models used in this part of ISO 2631 are given in 5.2. Caution is necessary when applying the method to extreme shock conditions.