Invited commentary on: 'The effects of whole body vibration (WBV) intervention on body functions, activity limitations and participation restrictions in people with neurological conditions', Uszynski and Coote.Whole-body vibration (WBV) involves the delivery of mechanical vibrations to the body via a vibration platform. It is thought that the mechanical stimulations generated by WBV may stimulate osteogenesis 1,2 and promote muscle activity. 3 Whole-body vibration has attracted increasing attention in both clinical practice and research in the past decade. While the earlier studies have focused on the use of WBV to improve bone health and neuromuscular function in postmenopausal women and older adults, 4-6 there has been tremendous interest recently in the application of WBV therapy among people with neurological disorders, who often sustain similar problems faced by older adults, such as osteoporosis, muscle weakness, sarcopenia, balance, and gait impairments. The systematic review by Uszynski and Coote 7 provides an overall picture of the available scientific evidence related to the efficacy of WBV on modifying various outcome measures among people with neurological conditions. The results revealed that there is insufficient evidence to support the use of WBV in neurological disorders.One important point, which is also well emphasized in the review, is that there is 'no evidence of effect' as opposed to 'evidence of no effect'. The finding is in agreement with a recent systematic review on the effects of WBV in people with stroke. 8 Some of the major drawbacks include the small number of studies for a given neurological condition, and concerns with methodological weaknesses. One particular issue relates to how well the studies are controlled. When receiving WBV therapy, static or dynamic exercises are often used. Therefore, in order to truly demarcate the additional effects of the imposed vibratory stimuli, the exercises involved in the comparison group must be the same as the WBV group. Otherwise, it would be impossible to differentiate whether the reported improvement (if any) is due to the static/dynamic exercises performed, or the added vibrations. Another major knowledge gap in this field is the physiological mechanisms underlying WBV intervention. For example, although consistent evidence shows that muscle activity is increased during exposure to WBV in various patient populations, 9-11 the physiological processes involved in muscle strength gain following WBV intervention remain largely unknown. As pointed out by the authors of this review, muscle weakness experienced by people with neurological conditions can have both peripheral and central origins. Future research should explore the relative contributions of peripheral versus central processes involved in WBV stimulation. While a good number of clinical efficacy studies have emerged in this field in recent years, more fundamental research that aims to establish the physiological basis of WBV intervention is equally, if not more, important. O. Influenc...
