ARTICLE

The Use of Vibration as an Exercise Intervention

Marco Cardinale1 and Carmelo Bosco2,3
1
Department of Biomedical Sciences, University of Aberdeen, Scotland; 2Department of Sport Science,
Semmelweis University, Budapest, Hungary; and 3Università di Roma Tor Vergata, Facoltà di Medicina e
Chirurgia, Roma, Italy

CARDINALE, M., and C. BOSCO. The use of vibration as an exercise intervention. Exerc. Sport Sci. Rev., Vol. 31, No. 1,
pp. 3–7, 2003. The use of vibration as a means for enhancing athletic performance is a recent issue in exercise physiology. Current
evidence suggests that vibration is effective in enhancing strength and the power capacity of humans, although the mechanisms
mediating this effect are unknown. Keywords: neuromuscular adaptations, oscillation, muscle strength, muscle power, muscle
spindle

INTRODUCTION The purpose of this review is to summarize the current

knowledge on the effects of vibration on human performance
Vibration is a mechanical stimulus characterized by an os- and to identify the potential mechanisms that underlie the
cillatory motion. The biomechanical parameters determining enhancement of strength and power production.
its intensity are the amplitude, frequency, and magnitude of
the oscillations. The extent of the oscillatory motion deter-
mines the amplitude (peak to peak displacement, in mm) of THE EFFECT OF VIBRATION ON HUMAN
the vibration, the repetition rate of the cycles of oscillation PERFORMANCE
denotes the frequency of the vibration (measured in Hz), and
the acceleration indicates the magnitude of the vibration. The possibility of using vibrations as an exercise interven-
It has been hypothesized that low-amplitude, low-fre- tion is a relatively recent idea. The first application of vi-
quency mechanical stimulation of the human body is a safe bration as an exercise intervention was conducted by Russian
and effective way to improve muscle strength. Increases in scientists, who found that vibration was effective in enhanc-
muscular strength and power in humans exercising with ing strength in well-trained subjects (as cited in (9,10)).
specially designed exercise equipment have been reported Subsequently, the effects of vibration exercise have been
recently (1,2,3,4,15). The effects of whole-body vibration examined after acute and chronic exposure using different
have been studied with subjects exercising on vibrating plates treatment protocols.
(1,2,4,15) that produce sinusoidal vibrations (Fig. 1). Low- Acute enhancement of mechanical power has been
frequency vibration has been also applied locally by means of shown after vibration treatment applied with vibrating
vibrating cables (9,10) and vibrating dumbbells (3). The cables during bilateral biceps curl (elbow flexion and ex-
frequencies used for exercise range from 15 to 44 Hz and tension) on a pulley machine (10). The experimental
displacements range from 3 to 10 mm. The acceleration protocol consisted of vibration delivered to the subjects by
values range from 3.5 to 15 g (where g is the Earth’s gravi- means of vibrating cables producing oscillations at 44 Hz
tational field or 9.81 m·s⫺2). Thus, vibration provides a and 3-mm amplitude (10). In this experiment, both elite
perturbation of the gravitational field during the time-course and amateur athletes showed improvement, respectively,
of the intervention. of 10.4% and 7.9% in maximal power measured during the
bilateral biceps curl exercise. Whole-body vibration ad-
ministered through vibrating plates has been shown to
Address for correspondence: Marco Cardinale, University of Aberdeen, Dept. of enhance vertical jumping ability by 3.8%. In the same
Biomedical Sciences, Human Physiology Building–Foresterhill, AB25 2ZD Aberdeen,
Scotland, UK (E-mail: m.cardinale@abdn.ac.uk).
experiment, mechanical power output by the legs during
Accepted for publication: July 12, 2002. horizontal leg press increased by 7% (4). Five applications
of whole-body vibration at a frequency of 26 Hz lasting
0091-6631/3101/3–7
Exercise and Sport Sciences Reviews
60 s with 60-s rest in female professional volleyball players
Copyright © 2003 by the American College of Sports Medicine resulted in a shift to the right of the force-velocity and

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power-velocity curves as measured by an isoinertial dyna-
mometer during the horizontal leg press exercise (2). Vi-
bration applied for a total time of 5 min with vibrating
dumbbells (30 Hz, 6-mm amplitude) produced an increase
of 13% in average power in the elbow flexor muscles of
elite boxers (3). The increase in mechanical power during
arm flexion was associated with a reduction in the EMG
root mean square (rms) activity in biceps brachii.
Chronic treatments have been also shown to produce
improvement in neuromuscular properties of human skel-
etal muscle. Issurin et al. (9) superimposed vibration, with
cables vibrating at 44 Hz, during weight-lifting exercises
performed on pulley machines and found a significant
improvement in the maximal force (⫹ 49.8%) and flexi-
bility (⫹ 43.6%) after 3 wk of treatment. Whole-body
vibration at a low frequency (26 Hz, 10-mm displacement)
administered for 10 d to active subjects was capable of
enhancing vertical jump height by 12% (1). These find-
ings suggest that vibrations can effectively enhance neu-
romuscular performance.

THE POTENTIAL MECHANISMS MEDIATING THE

EFFECT OF VIBRATION ON NEUROMUSCULAR
PERFORMANCE

It has been suggested that muscle activation by means of

vibration may induce improvements in strength and power
performance similar to those observed with strength training
(1,2,3). The similarity of the effect is probably related to the
characteristics of the load imposed by vibration, which, as
with strengthening and plyometric exercises, increase the
gravitational load imposed on the neuromuscular system.
Vibration exercise has been reported to increase the gravi-
tational load up to 14 g (1,2,3,4,15). Figure 1. Whole-body vibration exercise machine.
Skeletal muscle is a specialized tissue that modifies its
overall functional capacity in response to different stimuli.
The influence of gravitational load on muscular performance through reflex muscular activity and attempt to dampen the
is of paramount importance. In normal conditions, muscles vibratory waves (Fig. 2). To understand the mechanisms
experiencing the daily action of gravity are capable of main- responsible for vibration-induced enhancement of perfor-
taining their performance capabilities. When the gravita- mance, it is necessary to distinguish between the effects of
tional load is reduced (microgravity), a marked decrease in vibration on an active muscle from those occurring after an
muscle mass and force-generating capability is observed (for application of vibration.
a review, see (7)). In contrast, an increase in the gravita- Mechanical vibrations applied to the muscle itself or the
tional load (hypergravity) will increase in the cross-sectional tendon can elicit a reflex muscle contraction named “Tonic
area and force-generating capacity of muscle. Exercise pro- Vibration Reflex” (8). The deformation of the soft tissues
grams designed to increase strength and power are charac- caused by vibration is capable of activating muscle spindles
terized by performing exercises with an increase in gravita- and leading to an enhancement of the stretch-reflex loop.
tional load. These forms of exercise have been shown to Thus, the excitatory inflow during vibration stimulation is
produce specific adaptive responses in skeletal muscles in- mainly related to the reflex activation of the ␣-motor neu-
volving both morphological and neural factors (6). The early ron. An increase in EMG activity is usually observed during
gains in force-generating capacity have been attributed to vibration treatment with values higher than the ones ob-
changes within the nervous system, attributable to the ab- served during voluntary muscular activity. Accordingly, we
sence of an increase in cross-sectional area of muscle fibers in found the root mean square EMG of biceps brachii muscle to
the first several wk of training program (6). be 200% higher in boxers exercising with a vibrating dumb-
Vibration exercise imposes hypergravity activity due to the bell compared with performing a voluntary arm flexion with
high accelerations (1,2,3,4,9,10,15). The mechanical action a load equal to 5% of the subjects’ body mass (3). This effect
of vibration is to produce fast and short changes in the length could be related to an increased synchronization of motor
of the muscle-tendon complex. This perturbation is detected units due to the application of vibration. Reflex muscle
by the sensory receptors that modulate muscle stiffness activity represents the response of the neuromuscular system

4 Exercise and Sport Sciences Reviews www.acsm-essr.org

Figure 2. Schematic diagram illustrating stiffness regulation during vibration stimulation. The quick change in muscle length and the joint rotation
caused by vibration trigger both ␣ and ␥ motor neurons to fire to modulate muscle stiffness. Higher centers are also involved via a long loop.

to a strong perturbation caused by mechanical vibration. This tion stimulus then influences the excitatory state of the
reaction can be mediated not only by monosynaptic but also peripheral and central structures, which could facilitate sub-
by polysynaptic pathways. The primary endings of the muscle sequent voluntary movements. The postvibration enhance-
spindle are more sensitive to vibration than are the secondary ment of performance includes an increase an vertical jump
endings and Golgi tendon organs. Vibration is perceived not height by 2.5% in the first min after 4 min of the treatment
only by neuromuscular spindles, but also by the skin, the (15), an increase in vertical jump by 3.8% after a total of 10
joints, and secondary endings (13). Consequently, whether min of whole-body vibration (5), and an increase of 13% in
using whole-body or locally applied vibration, these sensory the average power recorded during arm flexion in well-
structures likely facilitate the ␥-system during the application trained subjects (4) after 5 min of locally applied vibration.
of vibration and enhance the sensitivity of the primary These improvements in performance have disappeared 60
endings. min after the treatment (15). It is likely that the greater
The acute enhancement of neuromuscular performance levels of force after vibration are due to both an enhance-
after vibration is probably related to an increase in the ment of the stretch reflex and the excitatory state of the
sensitivity of the stretch reflex. Furthermore, vibration somatosensory area. Current evidence, however, does not
appears to inhibit activation of antagonist muscles allow an explanation of the specific neural adaptations that
through Ia-inhibitory neurons, thus altering the intramus- accompany a vibration treatment.
cular coordination patterns leading to a decreased braking Recent evidence suggests that the acute neural potentia-
force around the joints stimulated by vibration. For exam- tion observed after vibration exercise is relatively short last-
ple, pilot data from a recent investigation have shown ing. For example, an acute administration of vibration in-
after the application of vibration there was both an in- creased vertical jump height for 2 min after the treatment but
creased in vertical jump height and an increase in the this effect had disappeared after 1 h (15). It appears that the
range of motion about the hip joint due to improved duration of the vibration exercise is important. Relatively
flexibility of the hamstrings. Therefore, vibration might short exposure (4 –5 min divided in bouts lasting 1 min each
stimulate the proprioceptive discharge occurring during with 1-min rest in between bouts), for example, is capable of
muscle stretch and fast joint rotation although the actual enhancing subsequent voluntary strength exertion. Long-
change in the above parameter is minimal. duration vibration, however, reduces the force-generating
It is also important to consider the influence of vibratory capacity of muscle (14). The long-duration effect could be
stimulation on central motor command. It has been shown due to either activation of inhibitory feedback (e.g., Golgi
that the primary and secondary somatosensory cortex, to- tendon organs) or reduced sensitivity of muscle spindles, such
gether with the supplementary motor area, constitutes the as that caused by depletion of neurotransmitter or presynap-
central processing unit of afferent signals (12). Vibration tic inhibition. A summary of the potential mechanisms de-
applied at different frequencies that is capable of producing termining an increase in neuromuscular performance is sche-
kinesthetic illusion has been shown to activate the supple- matically represented in Figure 3. The vibratory stimulus,
mentary motor area, the caudal cingulate motor area, and being perceived by different sensory structures, stimulates the
area 4a of the brain (12). Moreover, the supplementary motor neuromuscular system to produce reflex muscle activation. If
area of the brain that is activated by vibration (12) is acti- the vibratory stimulus is relatively short, it creates the po-
vated early during self-initiated movements (5). The vibra- tential for a more powerful and effective voluntary activation

Volume 31 䡠 Number 1 䡠 January 2003 Vibration Exercise 5

Figure 3. Schematic diagram illustrating the potential mechanisms that mediate the enhancement of force-generating capacity after acute and chronic
exposure to vibration. Vibrations determine an increased excitatory state of the neuromuscular system due to an increase in the sensitivity of stretch reflexes
and the stimulation of the specific areas of the brain. The central influence also influence the hypothalamus-hypophysis axis, which triggers the secretion
of specific hormones. All these factors contribute to the increase in force-generating capacity of skeletal muscle.

of skeletal muscle. The relative significance of these different adequate stimulus for specific hormonal secretion. In ad-
mechanisms could be assessed by examining the effect of dition to the effects on sensory feedback, for example,
vibration on various evoked responses, such as with trans- vibration also increases testosterone and growth hormone
cranial magnetic stimulation and the H-reflex. levels in humans (4). Furthermore, recent investigations
Hormonal factors could also be involved in the neuro- underscore the interaction between proprioceptors and
muscular adaptations. The responses of mammals to ex- hormonal responses. For example, the modulation of a
ternal environmental changes inevitably involve neural muscle afferent-pituitary axis on bioassayable growth hor-
and hormonal responses, including changes in gravita- mone secretion has been identified after vibration-induced
tional acceleration (7,11). Prolonged exposure to micro- activation of specific muscles (11). It seems reasonable to
gravity has been shown to result in a decrease in muscle suggest that the increased levels of testosterone observed
mass and force-generating capacity (7). Moreover, studies after vibration treatments are related to the increased
conducted on astronauts have shown that microgravity force output. In particular, the possible influence of this
produces a decline in androgen levels and growth hormone androgen hormone on calcium-handling mechanisms in
(in 11) in salivary, urinary, and plasma samples. This is skeletal muscle could facilitate a more powerful muscular
due to the fact that microgravity represents a strong per- activation.
turbation to the homeostasis of the body because of the
lack of physical tension on the musculoskeletal system, CONCLUSION AND APPLICATION
loss of hydrostatic pressure, and alteration of the sensory- Vibration represents a strong stimulus for musculoskeletal
motor system. In contrast, an increase in gravitational load structures due to the need to quickly modulate muscle stiff-
by means of strengthening exercises has been shown to ness to accommodate the vibratory waves. This response is
increase the previously mentioned hormones. This partic- mediated by monosynaptic and polysynaptic afferent path-
ular form of exercise provides high stress on the musculo- ways, which are capable of triggering specific hormonal re-
skeletal structures and requires high levels of neural ac- sponses. It appears that a subsequent voluntary activation can
tivity. It represents an increased demand as compared with be performed with central and peripheral structures in an
the homeostatic conditions and then stimulates rapid elevated excitatory state.
physiological responses. During strength training exercise, These findings suggest that vibration could represent an
rapid endocrine activation is triggered by collaterals of the effective exercise intervention for enhancing neuromuscular
central motor command and transmitted to the hypotha- performance in athletes. However, it seems appropriate to
lamic neurosecretory and autonomic centres. The re- consider other applications to the general population. We are
sponses are further supported by feedback influences from convinced that vibration could be an effective exercise in-
proprioceptors and metaboreceptors in the muscle. The tervention for reducing the effects of aging on musculoskel-
mechanical characteristics of vibration could provide an etal structures. The potential influence of vibration on hor-

6 Exercise and Sport Sciences Reviews www.acsm-essr.org

monal activity also opens interesting perspectives for its 5. Cunnington, R., C. Windischberger, L. Deecke, and E. Moser. The prep-
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