Utilization of Whole-Body Vibration Intervention for Improving Mobility in Spinal Cord Injury Volume 1 - Issue 3
*Thomas J. Birk
Professor, Kettering College, USA
Received: August 18, 2017; Published: August 28, 2017
Corresponding author: Thomas J. Birk, PhD, MPT, FACSM, Professor and Associate Dean Office of Academic and Student Affairs College of Health Sciences 899 Enderis Hall P.O. Box 413, University of Wisconsin-Milwaukee, Milwaukee, WI 53201-0413, USA
Suffering a spinal cord injury (SCI) constitutes numerous
neurologic, vascular and muscular problems below the level of
injury. Neurologic problems can include sensation and motor
impairments which can limit effective and efficient mobility and
jeopardize safety. Vascular problems can include reductions in
thigh blood flow, femoral artery diameter, vascular reactivity
and capillary alterations [1]. Muscular problem alterations have
included atrophy, particularly of type 2 fibers and eventually a
shift from type 1 to type 2B [1]. These skeletal-muscle changes
seemingly paralleling vascular reductions, over time, increase the
risk of secondary clinical conditions such as pressure ulcers and
cardiovascular disease [1]. Bone mineral density reductions and
architecture due to lack of mechanical loading have been observed
within 12 months post SCI [2]. Skeletal-muscle atrophy, bone
density decreases and vascular insufficiencies, coupled with motor
impairments can lead to subsequent mobility and gait problems.
Mobility interventions for SCI have included conventional
physical therapy. The neurally intact muscle mass that remains
for a person with SCI is generally the focus of acute and chronic
rehabilitative techniques. While conventional physical therapy, such
as electro-stimulation, passive and active assistant and resistive
range of motion, have been featured in reducing dependency with
a SCI, these therapies have not offered consistent and significant
results in improving motor impairments or mobility and gait [3].
Whole body vibration (WBV) is an intervention which has a
person seated or standing on a metal platform which vibrates at
various amplitudes and frequencies. Vibration is transmitted to the
feet by a typically 2’ by 2’ flat metal surface. Amplitudes of the WBV
range from 1 to 6 mm displacement and frequencies range from
20-120 Hz [3].
Significant ill effects from WBV have not been reported. But
regardless of central nervous system (CNS) and/or peripheral
nervous system (PNS) deficits, headaches, dizziness and nausea
have been reported especially when standing with weight bearing
heels on the platform at higher amplitudes [3].
WBV has generally demonstrated positive and beneficial
skeletal-muscle and vascular changes in SCI [1,3,4]. Muscle
strength increases for the lower extremities have been reported in
single session application for motor incomplete SCI, likely due to
enhanced neuromuscular circuit activation [5].
Increased skeletal muscle contraction may improve both blood
flow and arterial diameter [1]. The ability to enhance muscle
contraction could result in greater long term muscle mass which
would increase metabolism. Increased metabolism has been
demonstrated with higher oxygen consumption [1,6]. Bone density
increases in the pelvis and lower extremities have also been
documented [3,7].
Safe and effective mobility and gait can be facilitated by
physiological enhancements such as increased muscle strength,
bone density, and oxygen consumption. Decreased neuromuscular
spasticity, which could facilitate greater gait control, has also been
demonstrated through the use of WBV [8,9]. Only one investigation
has shown gait to improve in SCI, with incomplete transection [10].
However, this study did not measure or associate physiological
measures with gait improvements. Thus, mechanisms and
explanations for increased cadence, speed and overall gait function
were unclear.
The physical benefits highlighted have been reported in both
animal and human models. Eliciting positive physical changes
through WBV occurred through manipulation of vibration intensity,
frequency, and duration. It is not clear what combination of
platform amplitude displacement, frequency, duration in minutes
of intensity and duration per intervention session are needed to
capture the physiological benefits of WBV. How many intervention
sessions per week and the length of the inventions in weeks, are
also in question concerning the amount of WBV needed to deliver
an optimal physiological benefit. These WBV intervention variables
need to be considered for efficacy and safety whether the SCI is
acute, subcute or chronic. Other physical considerations needing
review before determining effective and safe WBV workloads include age, health and fitness status, and cardiopulmonary risk
factors.
Most animal and human investigations on WBV in SCI thus far,
have shown that higher frequencies over 30 Hz and amplitudedisplacement
of 2 mm or more have exhibited the best results
regardless of variable measured [11-15]. Human studies have
shown WBV to be economical and convenient compared to more
costly and/or more cumbersome techniques of eliciting positive
physical changes in SCI [3,16].
WBV mechanisms and explanations at the spinal cord level
could be made clearer by imaging techniques [17]. Reliability issues
have plagued investigations with high resolution such as with the
5 Tesla. The 5 Tesla in prior experiences, has not demonstrated
consistent images over time at the lesion regardless of posture
and positioning. DWI may offer the most accurate way to learn
what occurs at the lesion site when an intervention such as WBV is
applied, both acutely and chronically [17]. Whether neurogenesis
occurs in the injured spinal cord could also be gleaned.
There appears to be sufficient evidence to suggest that WBV
has potential to augment mobility and gait in persons with SCI.
Determining the mechanisms that improve mobility and gait could
increase the efficiency and effectiveness of WBV for different SCI
populations. These findings could predict outcomes and whether
WBV would be applicable for SCI in some cases.
ISSN: 2574 -1241
