Spinal Cord (2011) 49, 554–559& 2011 International Spinal Cord Society All rights reserved 1362-4393/11 $32.00
www.nature.com/sc

ORIGINAL ARTICLE
Effects of whole-body vibration on blood flow and neuromuscular
activity in spinal cord injury
AJ Herrero1,2, H Menéndez1, L Gil1, J Martı́n1, T Martı́n1, D Garcı́a-López2, Á Gil-Agudo3 and PJ Marı́n1,2
1Research Center on Physical Disability, ASPAYM Castilla y León, Valladolid, Spain; 2Laboratory of Physiology, Faculty of Health
Sciences, Miguel de Cervantes European University, Valladolid, Spain and 3Biomechanics and Technical Aids Unit, Physical Medicine
and Rehabilitation Department, National Hospital for Spinal Cord Injury, SESCAM, Toledo, Spain

Study design: Crossover trial.
Objectives: To investigate the effects of whole-body vibration (WBV) on muscular activity and bloodflow velocity after different vibration treatments in patients with spinal cord injury (SCI).
Setting: Research Center on Physical Disability (Spain).
Methods: Eight individuals with SCI received six 3-min WBV treatments depending on a combinationof frequency (10, 20 or 30 Hz) and protocol (constant, that is, three consecutive minutes of WBV, orfragmented, that is, three sets of 1 min of WBV with 1 min of rest between the sets). Femoral arteryblood flow velocity was registered at minutes 1, 2 and 3 of WBV, and at minutes 1 and 2 after the end of
the stimulus. Electromyography activity (EMG) of vastus lateralis (VL) and vastus medialis (VM) was
registered at baseline and during WBV.
Results: Peak blood velocity (PBV) increased after 1, 2 and 3 min of WBV. The 10 Hz frequency did notalter blood flow, whereas the 20 Hz frequency increased PBV after 2 and 3 min of WBV, and the 30 Hz
frequency increased PBV after 1, 2 and 3 min of WBV and during the first minute after the end of thestimulus. No protocol effect was observed for blood parameters. EMG activity of VL and VM increased
independently of the applied frequency or protocol.
Conclusion: WBV is an effective method to increase leg blood flow and to activate muscle mass in SCI
patients, and could be considered to be incorporated in their rehabilitation programs.
Spinal Cord (2011) 49, 554–559; doi:10.1038/sc.2010.151; published online 2 November 2010
Keywords: vibration

frequency;
rehabilitation

oscillating

platform;

Dopplerultrasound;electromyography;

Introduction
Spinal cord injury (SCI) has muscular and vascular consequences below the level of the injury.1 Regarding muscularchanges, these patients suffer a dramatic loss of muscle
mass.2 Immediately after the injury and in the following
months, there is a preferential atrophy of type 2 fibers, but
past 7–10 months post injury, a significant shift of type 1
fibers to type 2B has been observed.3 Regarding vascularchanges, there is a reduction in the thigh blood flow,4femoral artery diameter,1 vascular reactivity,1 and capillaryalterations.3 It has been proposed that changes in the muscle
vascular function are parallel to the skeletal muscle atrophy
in SCI subjects,1 and both changes increase the risk ofcardiovascular disease5 and the development of pressure
ulcers.6 Therefore, part of the rehabilitation of SCI patients
Correspondence: Dr AJ Herrero, Laboratory of Physiology, Faculty of Health
Sciences, Miguel de Cervantes European University, c/Padre Julio Chevalier,
Valladolid 47012, Spain.
E-mail: jaherrero@oficinas.aspaymcyl.org
Received 14 July 2010; revised 22 September 2010; accepted 28 September
2010; published online 2 November 2010

should focus on the activation of muscular and vascularsystems.4
The application of whole-body vibration (WBV) withplatforms has been shown to improve muscular7,8 andvascular9–11 functions. These effects are strongly dependent
on the type of platform, protocols and vibration parameters(that is, frequency).7 Specifically, greater vibration frequencies induce higher-muscle activity8 and greater blood flow11
than lower frequencies. Moreover, the most common
protocol used to apply WBV consists of short bouts (30–90 s) with B60 s rest between the sets. The effects induced by
the application of longer bouts (3 min) on peripheral
circulation have been poorly investigated.
The previously mentioned benefits of WBV have been
observed in healthy subjects; however, no study has focusedon the effects of WBV on the muscle and vascular responses
of SCI patients. Thus, the purpose of this study was toinvestigate the effects of WBV on muscular activity andblood flow velocity after different vibration treatments in
SCI patients.

Whole body vibration in spinal cord injury
AJ Herrero et al555

Materials and methods
Subjects
Eight patients (six males and two females) volunteered toparticipate in the study. All the patients had SCI and usedwheelchair for their locomotion. All the subjects wereclasiffied by the American Spinal Injury Association (ASIA)
as A. Table 1 summarizes the characteristics of the sample.
All the subjects received rehabilitation ten 2-h sessions permonth, which consisted of standing position (or tilt
position), passive movements, low intensity resistancetraining or electrotherapy, and physiotherapy treatment.
Experimental treatments were applied to the subjects before
their rehabilitation routines. Subjects did not allow their
sleeping, eating and drinking habits to change throughout
study participation. We certify that all applicable institutional and governmental regulations concerning the ethicaluse of human volunteers were followed during the course ofthis research.
Experimental design
Each subject was assessed in eight different sessions. In thefirst two sessions, subjects were familiarized with the testingtreatments and vibration stimulus. Both sessions werecarried out within the same week separated with at least
48 h. The other six sessions were carried out on Monday,
Wednesday and Friday during the following two weeks. In
each session, a random WBV treatment was applied. The six
WBV treatments arise from the combination of the independent variables frequency (10, 20 or 30 Hz) and protocol(constant or fragmented). WBV was applied for threeconsecutive minutes during the constant protocol, whereas
three cycles of 1 min of WBV and 1 min of resting period
were applied during the fragmented protocol (Figure 1).

Table 1

1
2
3
4
5
6
7
8

Treatment protocol
Once a subject came to the laboratory, he or she was laid down
and fixed to a tilt table with straps (Figure 2). In the distal partof the tilt table, just beneath the feet, a vibration platform wasplaced (Galileo Home, Galileo, Novotec, Germany). Knee
angle was of 601 flexion (considering 01 the full knee
extension). Subsequently, the tilt table was placed at 451 andthe subject was kept in that position for a period of 10 min
before the application of WBV. All the subjects were familiarized with the tilt table and the chosen angle as they usually
maintain this position in their rehabilitation routines. In that
position, the subject was prepared to register electromyography activity (EMG) and ultrasound variables. The frequency ofvibration was set at 10, 20 or 30 Hz. The amplitude of thevibration was set by the position of the feet on the WBV plate
at 5 mm (peak–peak). Feet were placed parallel to each other
38 cm apart (measured from the midlines of the feet). The
patients were exposed to the vibration each day for a total of
3 min continuous (constant) or fragmented (three bouts 60 s
exposures, separated by 60 s rests).
Ultrasound measurements
Blood parameters were registered through an ultrasoundsystem (MyLab 25, Esaote, Genoa, Italy) using a pulsed color
Doppler with a linear array transducer (LA 523, 7.5–12 MHz;
length, 50 mm; Esaote, Genua, Italy) in the femoral artery as
previously described.11 Blood parameters were analyzed atbaseline, at the end of minutes 1, 2 and 3 of WBV, and at theend of minutes 1 and 2 of recovery after the stop of WBV(Figure 1). Each image recorded by the ultrasound systemcorresponded to a period of 4 s. In that period, there were
between 3 and 5 beats, and the mean of these beats wasanalyzed to obtain: mean and peak systolic blood velocities(MBV and PBV, respectively), as well as heart rate.

Descriptive characteristics of the study sample

GenderAge (years)

Height (m)Mass (Kg)

Years after injury

Level of lesion

ASIA score

PBV (cm s1)a

MBV (cm s1)a

M
M
M
M
M
M
F
F
Mean
s.d.

41
32
32
39
33
32
35
45
36.1
5.0

1.74
1.85
1.98
1.87
1.74
1.73
1.63
1.71
1.78
0.11

83
80
94
82
78
76
78
70
80.1
6.9

24
4
5
3
3
2
6
22
8.6
9.0

T5
T8
C6
T3
C6
C6
L1
C5

A
A
A
A
A
A
A
A

80.4±8.4
66.6±3.547.5±6.8
59.4±6.1
82.2±7.783.2±6.949.2±4.1
66.5±5.0

36.5±3.733.0±3.925.1±5.1
30.1±3.535.7±4.442.8±6.0
26.2±3.534.8±3.2

Abbreviations: MBV, mean blood velocity; PBV, peak blood velocity.
a
Mean±s.d. of the control period values of the six sessions.

Figure 1 Sketch of the experimental phase in 10 s intervals showing the fragmented (top) and constant (bottom) protocols.
Electromyography (diamonds) and blood parameters (circles) were registered.
Spinal Cord

Whole body vibration in spinal cord injury
AJ Herrero et al556
Surface electromyographic activity
Muscle activity of the vastus medialis (VM) and vastus lateralis(VL) was measured using EMG. One set (two measuring
electrodes) of surface electrodes (Ag/AgCl, Skintact, Innsbruck,
Austria) was placed longitudinally to the direction of themuscle fibers and approximately halfway from the motor
point area to the distal part of the muscle. An inter-electrodedistance of 2 cm was maintained. Before electrode placement,
the area was shaved, abraded and cleaned with isopropyl
alcohol in order to reduce skin impedance until it was lower
than 5 kO. The location of the electrodes on the skin wasmarked with permanent ink in order to ensure the sameplacement throughout the different sessions.
Myoelectric raw signals were detected with a twochannel EMG device (MyoTrac Infiniti, Thought Technology, Montréal, Canada). EMG data analysis was performed
with a specific software (BioGraph Infiniti, ThoughtTechnology, Montréal, Canada). The last 10 s corresponding to the control period and corresponding to the third
minute of WBV application were chosen for data analysis
by the aforementioned software (Figure 1). EMG raw data
was averaged by root mean square (EMGRMS) in order toobtain the average amplitude of the EMG signal. On thebasis of the frequency analysis, a bandwidth of ±0.8 Hz

Figure 2 Placement of the subject on the tilt table during theapplication of the whole-body vibration.

around each harmonic was excluded from the root meansquare calculation.
Statistical analysis
The normality of the dependent variables was checked andsubsequently confirmed using the Kolmogorov–Smirnov
test. A three-way repeated-measures analysis of variance infrequency, protocol, and time was applied to analyze EMG
and blood parameters. When a significant F-value wasachieved, pair-wise comparisons were performed using the
Bonferroni post hoc procedure. The reliability and variabilityof blood parameters were assessed with intraclass correlation
coefficient and coefficients of variation (that is,
CV ¼ s.d.*100/mean). A paired t-test was used to analyze
differences between both basal values. Statistical significancewas set at Pp0.05. Effect size statistic, Z,2 was analyzed todetermine the magnitude of the effect independent ofsample size. Values are expressed as mean±s.d.

Results
Blood parameters
Table 2 shows the statistical significance and effect sizesof the analysis of variances. PBV increased after 1, 2 and3 min of WBV (11.3±10.3%, Po0.05, 19.0±13.5% and23.0±14.4%, Po0.01, respectively). At 1 and 2 min after
the stop of the stimulus, PBV decreased at minute 3 of WBV(14.4±9.3% and 14.0±8.5%, Po0.05, respectively) andwas similar to baseline values. Regarding baseline values, the
10 Hz frequency did not modify PBV, whereas the 20 Hz
frequency increased PBV after 2 and 3 min of WBV, and the
30 Hz frequency increased PBV after 1, 2 and 3 min of WBV as
well as during the first minute after the end of the stimulus(Figure 3).
MBV increased after 1, 2 and 3 min of WBV (22.0±10.1%,
31.1±11.0% and 36.0±12.7%, Po0.001, respectively). Likewise, MBV remained increased in respect to baseline 1 minafter the stop of the WBV (14.0±8.1%, Po0.05). The 30 Hz
frequency increased MBV more than the 10 Hz frequency(26.8±8.1% in respect to 13.0±8.7%, Po0.001). However,no differences were observed between the increment with
20 Hz (17.0±11.3%) and the other two frequencies. All thefrequencies increased the MBV in respect to baseline atminutes 1, 2 and 3 of WBV (Figure 4). Furthermore, 30 Hz

Table 2 Summary of the main effects analyzed with the ANOVAs for the dependent variables: PBV, MBV, HR, VM EMGRMS and VL EMGRMSTime
PBV ICC ¼ 0.962; CV ¼ 5.6
MBV ICC ¼ 0.888; CV ¼ 8.4
HR ICC ¼ 0.973; CV ¼ 2.8
VM EMGRMS
VL EMGRMS

Frequency
2

Po0.001; Z ¼ 0.567
Po0.001; Z2 ¼ 0.756
NSPo0.05; Z2 ¼ 0.237
Po0.05; Z2 ¼ 0.268

NSPo0.01; Z2 ¼ 0.403
NS
NS
NS

Time*frequency
2

Po0.001; Z ¼ 0.342
Po0.01; Z2 ¼ 0.254
NS
Po0.05; Z2 ¼ 0.321
Po0.01; Z2 ¼ 0.275

Time*protocol
NS
NS
NS
Po0.05; Z2 ¼ 0.268
Po0.05; Z2 ¼ 0.293

Abbreviations: ANOVA, analysis of variance; CV, coefficient of variation; HR, heart rate; ICC, intraclass correlation coefficient; MBV, mean blood velocity; NS, nonsignificant; PBV, peak blood velocity; VL EMGRMS, vastus lateralis EMG activity; VM EMGRMS, vastus medialis EMG activity.
For each effect, the statistical significance and effect sizes are shown. For the blood parameters, the ICC and CV are shown.
At the beginning and at the end of the control period, blood parameters were registered to analyze their reliability and to establish baseline level as the mean ofboth values.

Spinal Cord

Whole body vibration in spinal cord injury
AJ Herrero et al

Changes on Peak Blood Velocity (%)

557
**
aaa

50
45
40
35
30
25
20
15
10
5
0
-5

10 Hz
20 Hz
30 Hz

**
a
**
**

**

**

Whole body vibration

B

60

120

180

240

300

greater after the constant protocol (28.5±5.7 in respect to23.5±3.3 mV, Po0.05).
Regarding the VL, EMGRMS was higher after 3 min of WBVin respect to baseline values (26.2±5.8 in respect to15.2±1.1 mV, Po0.05). For each frequency, EMGRMS was
higher after 3 min of WBV in respect to baseline values, but
no differences in baseline values nor after WBV wereobserved among frequencies. Finally, for both protocols,
EMGRMS was higher after 3 min of WBV in respect to baseline
values, no differences in baseline values were observed
between protocols, but after WBV, EMGRMS was greater after
the constant protocol (29.7±7.5 in respect to 22.8±4.3 mV,
Po0.05).

Time (s)Changes on Mean Blood Velocity (%)

Figure 3 Time course changes on PBV depending on the frequency
during and after the application of 3 min of whole-body vibrationand three cycles of 1 min of vibration and 1 min of resting period.
** different from baseline at Po0.01. a, aaa different from 10 Hz at
Po0.05 and Po0.001, respectively.

65
60
55
50
45
40
35
30
25
20
15
10
5
0
-5

***
aaa

***
a

10 Hz
20 Hz
30 Hz
***

***
a

**
b

***

**
***

***

**

Whole body vibration
B

60

120

180

240

300

Time (s)Figure 4 Time course changes on mean blood velocity dependingon the frequency during and after the application of 3 min of wholebody vibration and three cycles of 1 min of vibration and 1 min
resting period. **, *** different from baseline at Po0.01 and 0.001,
respectively. a, aaa, b different from 10 Hz at Po0.05, Po0.001 andP ¼ 0.08, respectively.

increased MBV to a higher extent than 10 Hz and maintained
the MBV increased in respect to baseline values 1 min after
the end of the WBV. No protocol effect was observed for PBVor MBV.

EMG
Regarding VM, EMGRMS was higher after 3 min of WBV in
respect to baseline values (26.0±9.9 in respect to18.9±2.8 mV, Po0.05). Likewise, for each frequency,
EMGRMS was higher after 3 min of WBV in respect tobaseline values, but no differences in baseline values nor
after WBV were observed among frequencies. For bothprotocols, EMGRMS was higher after 3 min of WBV in respect
to baseline values, no differences in baseline values wereobserved between protocols, but after WBV, EMGRMS was

Discussion
The main findings of the present study were that WBV alone
can significantly increase leg blood flow velocity and EMG
activity in SCI patients. Moreover, higher frequencies (thatis, 20 and 30 Hz) produced greater increase in leg blood flow
velocity, although a tendency to evoke higher increase inblood flow velocity was observed with 30 Hz, which also
maintained this variable above basal values after the stop of
the stimulus. No difference was observed regarding theapplication of the WBV in a constant or fragmented
protocol.
Leg blood flow velocity was increased during the application of WBV in SCI patients. However, the magnitude ofblood flow response observed in our study is lower than inothers carried out with healthy subjects.9,11 Using anoscillating platform, Kerschan-Schindl9 found a two-foldincrease in mean blood flow in the popliteal arteryand Lythgo et al.11 found a four-fold increase in mean
blood velocity in the femoral artery. These greater responses
in comparison to our results could be due to the fact that:(1) the tilt table provides weight unloading, and as bloodflow highly correlates with work output,12 a reduction inwork output owing to unloaded weight may result in asmaller increase in blood flow;10 (2) greater the active tissue,
higher the metabolic demand; as muscle weakness is afeature of SCI,2 the O2 demand should be reduced andsubsequently would elicit a reduced response; and (3) the
reduced femoral artery diameter and blood flow observed in
SCI patients1 would limit the hemodynamic response
to exercise.
WBV leads to an increased metabolic demand measured byoxygen uptake in a linear relationship with vibration
frequency,13 which is in agreement with our results. As
higher the frequency used, the greater increase in blood flow
velocity was observed. Although there was no difference inthis variable between 20 and 30 Hz, a trend to produce
higher increase with 30 Hz was detected. Furthermore, 30 Hz
maintained the PBV above basal values 1 min after the stopof the vibration. This would recommend using 30 Hz in orderto analyze the long-term effects of the application of WBV in
SCI patients.
To the best of our knowledge, this is the first study to apply
WBV on a tilt table on SCI patients. Other ways of applying
Spinal Cord

Whole body vibration in spinal cord injury
AJ Herrero et al

558
WBV on SCI patients have been through partial standing or
standing on the platform with the help of a specific device.14
In the present study, the tilt table was fixed at an angle of 451
for the following reasons: (1) this angle unloads part of theweight of the subject but less than a sitting position; (2) SCI
patients can experience episodes of orthostatic hypotension
and can faint if angles near to the vertical are reached15 and(3) all the participants were familiarized with this angle as
they used to maintain this position during 30 min in theirrehabilitation routines.
The improvement of lower-extremity circulation is a goalof the rehabilitation of SCI patients.4 Some of the traditional
exercises performed to achieve this goal have been passive
leg movements and passive cycling; however, there isevidence supporting that these methods do not increase
leg blood flow in SCI patients.16 As well as increasing
blood flow, the application of WBV during supine bed restfor 52 days avoided a decrease of the diameter of thecommon femoral artery in respect to a control group.17 Thisobservation has not been reported in SCI patients but futurestudies that combine WBV and Doppler ultrasound measures
should contrast if this preservation is possible in thiscollective.
EMGRMS of VL and VM increased after the application of
WBV independently of frequency or protocol. In healthy
subjects, the same increases have been reported using
frequencies between 15 and 30 Hz.18 In SCI patients,
we have not found any research that combines WBV and
EMG recordings, nevertheless the application of punctual
vibration on thigh muscles during locomotion increased themuscle activity of SCI patients.19 This increase in the
EMGRMS could be due to the fact that mechanical vibrations
applied to the muscle or tendon stimulate sensory
receptors and that activation of muscle spindles facilitates
the activation of a-motoneurons, leading to tonic vibrationreflex.20 In our study, no significant difference wasnoted depending on the frequency. It could be expectedthat 30 Hz would increase EMG amplitude more than
10 Hz, as the acceleration of the platform is higher as thefrequency increases. Furthermore, in healthy subjects, greater EMG activity with high-frequency WBV training (40 and
45 Hz) has been reported when compared with lower
frequencies (25 and 30 Hz).8 In our study, the lack ofdifferences in the EMG activity between frequencies could
be due to the reduced EMG response of SCI patients in
respect to healthy subjects,21 as well as to the marked
difference in the EMG patterns among SCI subjects;21
therefore, this lack of statistical significance could be due
to a type II error.
In conclusion, WBV represents an option to induce a reflex
muscle contraction in subjects with difficulties or inability to
evoke voluntary contractions such as SCI patients. Our
results show that WBV is an effective method to increase leg
blood flow and to activate muscle mass in these patients, andcould, therefore, be considered to be incorporated inrehabilitation programs of this collective. Moreover, themethodology proposed to apply SCI through the use of a tilt
table has been safe, easy to perform and welcomed by the
subjects and therapists.
Spinal Cord

Conflict of interest
The authors declare no conflict of interest.

Acknowledgements
This work was supported in part by a grant from the
IMSERSO (37/2008).

References
1 Olive JL, Dudley GA, McCully KK. Vascular remodeling after
spinal cord injury. Med Sci Sports Exerc 2003; 35: 901–907.
2 Giangregorio L, McCartney N. Bone loss and muscle atrophy inspinal cord injury: epidemiology, fracture prediction, andrehabilitation strategies. J Spinal Cord Med 2006; 29: 489–500.
3 Scelsi R. Skeletal muscle pathology after spinal cord injury: our 20
year experience and results on skeletal muscle changes inparaplegics, related to functional rehabilitation. Basic Appl Myol
2001; 11: 75–85.
4 Nash MS, Montalvo BM, Applegate B. Lower extremity blood flow
and responses to occlusion ischemia differ in exercise-trained andsedentary tetraplegic persons. Arch Phys Med Rehabil 1996; 77:
1260–1265.
5 Kocina P. Body composition of spinal cord injured adults. Sports
Med 1997; 23: 48–60.
6 Cruse JM, Lewis RE, Dilioglou S, Roe DL, Wallace WF, Chen RS.
Review of immune function, healing of pressure ulcers, andnutritional status in patients with spinal cord injury. J Spinal Cord
Med 2000; 23: 129–135.
7 Marin PJ, Rhea MR. Effects of vibration training on
muscle strength: a meta-analysis. J Strength Cond Res 2010; 24:
548–556.
8 Hazell TJ, Jakobi JM, Kenno KA. The effects of whole-bodyvibration on upper- and lower-body EMG during staticand dynamic contractions. Appl Physiol Nutr Metab 2007; 32:
1156–1163.
9 Kerschan-Schindl K, Grampp S, Henk C, Resch H, Preisinger E,
Fialka-Moser V et al. Whole-body vibration exercise leads
to alterations in muscle blood volume. Clin Physiol 2001; 21:
377–382.
10 Hazell TJ, Thomas GW, Deguire JR, Lemon PW. Verticalwhole-body vibration does not increase cardiovascular stress
to static semi-squat exercise. Eur J Appl Physiol 2008; 104:
903–908.
11 Lythgo N, Eser P, de Groot P, Galea M. Whole-body vibration
dosage alters leg blood flow. Clin Physiol Funct Imaging 2009; 29:
53–59.
12 Saltin B, Radegran G, Koskolou MD, Roach RC. Skeletal muscle
blood flow in humans and its regulation during exercise. Acta
Physiol Scand 1998; 162: 421–436.
13 Rittweger J, Ehrig J, Just K, Mutschelknauss M, Kirsch KA,
Felsenberg D. Oxygen uptake in whole-body vibration exercise:influence of vibration frequency, amplitude, and external load.
Int J Sports Med 2002; 23: 428–432.
14 Davis R, Sanborn C, Nichols D, Bazett-Jones DM, Dugan EL. The
effects of whole body vibration on bone mineral density for a
person with a spinal cord injury: a case study. Adapt Phys Activ Q
2010; 27: 60–72.
15 Krassioukov A, Claydon VE. The clinical problems in cardiovascular control following spinal cord injury: an overview. Prog Brain
Res 2006; 152: 223–229.
16 Ter Woerds W, De Groot PC, van Kuppevelt DH, Hopman MT.
Passive leg movements and passive cycling do not alter arterial
leg blood flow in subjects with spinal cord injury. Phys Ther 2006;
86: 636–645.
17 Bleeker MW, De Groot PC, Rongen GA, Rittweger J, Felsenberg D,
Smits P et al. Vascular adaptation to deconditioning and the effectof an exercise countermeasure: results of the Berlin Bed Rest
study. J Appl Physiol 2005; 99: 1293–1300.

Whole body vibration in spinal cord injury
AJ Herrero et al559
18 Torvinen
S,
Kannu
P,
Sievanen
H,
JarvinenTA,
Pasanen M, Kontulainen S et al. Effect of a vibration
exposure on muscular performance and body balance. Randomized cross-over study. Clin Physiol Funct Imaging 2002; 22:
145–152.
19 Cotey D, Hornby TG, Gordon KE, Schmit BD. Increases in muscle
activity produced by vibration of the thigh muscles duringlocomotion in chronic human spinal cord injury. Exp Brain Res
2009; 196: 361–374.
20 De Cuyper H. The tonic vibration reflex]. Acta Belg Med Phys 1985;
8: 41–46.
21 Sherwood AM, McKay WB, Dimitrijevic MR. Motor control after
spinal cord injury: assessment using surface EMG. Muscle Nerve
1996; 19: 966–979.

Spinal Cord

Copyright of Spinal Cord is the property of Nature Publishing Group and its content may not be copied oremailed to multiple sites or posted to a listserv without the copyright holder's express written permission.
However, users may print, download, or email articles for individual use.