Vibration of the muscle tendon to enhance muscle contractile force has been studied in healthy people and in people after SCI. This modality may have the potential to decrease disuse atrophy in some people after SCI who have partial voluntary control of muscle and is described as being more comfortable than electrical stimulation (Ribot-Ciscar et al. 2003). Alternatively, vibration also has been considered as an intervention to diminish involuntary muscle contraction after SCI (Butler et al. 2006). The literature on the use of vibration to improve inspiratory and expiratory muscle contraction or to control unwanted spasm of these muscles after spinal cord injury is almost non-existent. One early report examining the physiologic response to this modality in people with spinal cord injury is outlined in the following table.
One report has shown that alternating in-phase vibration applied during inspiration (over the parasternal intercostals) or during expiration (applied over the 7th-10th intercostal spaces) significantly increased VT and VE with an even greater effect on these two variables when in-phase vibration was applied during inspiration and expiration. Further study is required to examine the long-term utility and compliance of this modality to enhance ventilation in people with SCI. Further, the specific parameters of vibration that enhance versus diminish muscle excitation and contraction needs to be explored in people with different levels and types of SCI.
There is level 4 evidence (based on 1 pre-post study) (Homma et al. 1981) that the use of chest wall vibration increases tidal volume and minute ventilation in subjects with tetraplegia.