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PubMed2002

Effect of chest wall vibration on the canine diaphragm during breathing.

High-frequency mechanical vibration of the ribcage reduces dyspnoea in patients with chronic obstructive pulmonary disease, and the suggestion has been made that this effect might be related to a decrease in central respiratory drive resulting from an increase in afferent inputs from intercostal muscles. In the present studies, the effects of ribcage vibration on central respiratory drive have been assessed without the confounding influence of conscious reactions. The electromyographic (EMG) activity of the diaphragm and the changes in pleural (Ppl) and abdominal (Pab) pressure were measured in six anaesthetized, spontaneously-breathing dogs while the rostral, the middle, or the caudal portion of the ribcage was vibrated at intervals during inspiration. The EMG activity of the external and parasternal intercostals was also measured. Ribcage vibration consistently elicited a marked increase in the inspiratory EMG activity recorded from the external intercostals, thus indicating that the procedure did activate intercostal muscle spindles. However, no alteration in diaphragmatic or parasternal intercostal EMG activity was seen in any animal. Transdiaphragmatic pressure and the relationship between deltaPab and deltaPpl during inspiration were also unaltered. The authors conclude that ribcage vibration and, with it, stimulation of external intercostal muscle spindles has no significant influence on phrenic motoneurones or on medullary inspiratory neurones. It is unlikely, therefore, that the beneficial effect of the procedure on dyspnoea results from a specific reduction in central respiratory drive.

Animals↗
PubMed2005

Effects of whole-body vibration in patients with multiple sclerosis: a pilot study.

OBJECTIVE: To examine whether a whole-body vibration (mechanical oscillations) in comparison to a placebo administration leads to better postural control, mobility and balance in patients with multiple sclerosis. DESIGN: Double-blind, randomized controlled trial. SETTING: Outpatient clinic of a university department of physical medicine and rehabilitation. SUBJECTS: Twelve multiple sclerosis patients with moderate disability (Kurtzke's Expanded Disability Status Scale 2.5-5) were allocated either to the intervention group or to the placebo group. INTERVENTIONS: In the intervention group a whole-body vibration at low frequency (2.0-4.4 Hz oscillations at 3-mm amplitude) in five series of 1 min each with a 1-min break between the series was applied. In the placebo group a Burst-transcutaneous electrical nerve stimulation (TENS) application on the nondominant forearm in five series of 1 min each with a 1-min break between the series was applied as well. MAIN OUTCOME MEASURES: Posturographic assessment using the Sensory Organization Test, the Timed Get Up and Go Test and the Functional Reach Test immediately preceding the application, 15 min, one week and two weeks after the application. The statistical analysis was applied to the change score from preapplication values to values 15 min, one week and two weeks post intervention. RESULTS: Compared with the placebo group the intervention group showed advantages in terms of the Sensory Organization Test and the Timed Get Up and Go Test at each time point of measurement after the application. The effects were strongest one week after the intervention, where significant differences for the change score (p = 0.041) were found for the Timed Get Up and Go Test with the mean score reducing from 9.2 s (preapplication) to 8.2 s one week after whole-body vibration and increasing from 9.5 s (preapplication) to 10.2 s one week after placebo application. The mean values of the posturographic assessment increased from 70.5 points (preapplication) to 77.5 points one week after whole body vibration and increased only from 67.2 points (preapplication) to 67.5 points one week after the placebo application. No differences were found for the Functional Reach Test. CONCLUSION: The results of this pilot study indicated that whole-body vibration may positively influence the postural control and mobility in multiple sclerosis patients.

Adult↗
PubMed1999

Diminished regional cerebral blood flow response to vibration in patients with blepharospasm.

OBJECTIVE: To determine whether patients with blepharospasm have abnormal sensorimotor processing similar to patients with writer's cramp. BACKGROUND: Blepharospasm is a focal dystonia manifest by involuntary, excessive blinking and squeezing of the eyes. Altered sensorimotor processing may contribute to the development of dystonic movements. Previously the authors demonstrated decreased vibration-induced cortical blood flow responses in hand primary sensorimotor area (PSA) in patients with hand dystonia. METHODS: In this prospective, case-control study, seven patients with blepharospasm were compared with seven normal subjects. PET measurements of regional blood flow were obtained using bolus administration of H(2)15O at rest or during sequential vibration of either the left or the right hand or side of the mouth. RESULTS: PSA activation decreased significantly in the patients with blepharospasm both ipsilateral (-68%; p = 0.0004) and contralateral to the side of facial stimulation (-56%; p = 0.0009). Patients had a 31% lower mean contralateral PSA response to hand vibration and a 51% smaller right supplementary motor area response to left-hand vibration than normal subjects, but these differences did not reach statistical significance. CONCLUSIONS: Patients with blepharospasm have abnormal sensorimotor processing in response to lower face vibration. They may also have abnormal brain responses to stimulation of clinically uninvolved parts of the body, but this requires confirmation.

Aged↗
PubMed1987

Modulated vibration-sensitivity of lamprey Mauthner neurones.

The vibration-sensitivity of larval lamprey Mauthner (Mth) neurones is dependent on behavioural state. Animals are maximally vibration-sensitive when at rest and less so when active or aroused. To demonstrate this effect in freely behaving larvae, we provided repeated vibratory or electrical stimuli to the vestibular labyrinths while animals made transitions between rest and activity. Stimuli which were adequate to elicit Mth spikes 100% of the time in a resting animal (recorded extracellularly from the spinal cord) were consistently subthreshold while the animal was swimming. The same effect was seen in semi-intact preparations, both moving and curarized, while recording intracellularly from Mth cell bodies. Mth vibration-sensitivity decreased abruptly with the onset of 'arousal', defined here by the presence of tonic, descending spinal cord discharge. During arousal, the Mth soma exhibited a slight depolarization (2-8 mV), an increased membrane conductance, and a strong depression of vibration-evoked excitatory postsynaptic potential (EPSP) amplitude. This Mth PSP depression (MPD) appears to underlie altered vibration-sensitivity.

Animals↗
PubMed1987

Physiological features of the opercularis muscle and their effects on vibration sensitivity in the bullfrog Rana catesbeiana.

The amphibian opercularis muscle connects a movable otic element (the operculum) to the pectoral girdle and can act in reception of ground vibrations. Various physiological parameters of the opercularis muscle of the bullfrog Rana catesbeiana were measured and compared with similar measurements on the iliofibularis muscle of the hindlimb. The opercularis muscle is a very slowly contracting muscle, with a Vmax of 1.81 muscle lengths s-1 compared to a Vmax of 6.24 muscle lengths s-1 for the iliofibularis muscle. The opercularis muscle develops tension slowly, taking about 10 s to attain maximum isometric tension when stimulated at 100 Hz. The muscle can retain high levels of tension for several minutes, and following stimulation has a time to half-relaxation of about 4-6 s. The slow velocity of contraction, slow rate of tension development, fatigue-resistance and slow rate of relaxation of the opercularis muscle support morphological evidence that it consists mostly of tonic muscle fibres. Experiments were also made to examine the effects of muscle tension on reception of ground vibrations as measured by inner ear microphonics. Severing the nerve supplying the opercularis muscle produced slight decreases of no more than 2 dB in responses to vibrations from 25 to 200 Hz. Artificial stimulation of the opercularis muscle after severing the nerve supplying the muscle increased responses to vibration across the entire frequency range. Higher tension levels produced greater increases in responses; at the highest tensions used (about 120 kN m-2) responses were increased by as much as 4.5 dB. The opercularis muscle is therefore specialized for slow but prolonged contractions, and tension is important in its sensory function. A tensed opercularis muscle appears to transmit faithfully motion of the forelimb, produced by vibrations, to the operculum such that the latter moves relative to the inner ear fluids.

Animals↗
PubMed1991

Intervertebral motion during vibration.

Vibration exposure is widely recognized as a risk factor for low back pain. An experimental protocol was designed to quantify the intervertebral motion response in human subjects to sinusoidal vertical vibration at 5 and 8 Hz, and at a variety of acceleration levels. Intervertebral motion in the mid-sagittal plane was measured using a transducer linkage system attached to pins placed directly into the spinous processes of adjacent vertebrae. The postures of the subjects were carefully controlled. The effects of forward flexion, arm support, gravitational load, and sitting on a cushion were evaluated. The rigid body motion of the superior vertebra with respect to the inferior vertebra was expressed in terms of relative sagittal plane rotation, axial translation, and anterior-posterior shear translation. It was found that the lumbar motion segments exhibited coupled periodic behaviour in response to sinusoidal vertical vibration, with up to 1 mm peak-to-peak displacement in the axial direction. The greatest intervertebral motion occurred when the subject was exposed to 5 Hz vibration as compared to 8 Hz. For a constant frequency of 5 Hz excitation, the peak-to-peak amplitudes of the computed motions tended to increase as the acceleration level increased. In the flexed posture, with no arm support, the active trunk musculature helped reduce the intervertebral motion. Additional gravitational load on the shoulders caused increased relative axial displacement. A polyethylene foam cushion placed on the seat reduced vibration transmission at 5 Hz excitation and consequently decreased the intervertebral motion.

Adult↗
PubMed1987

A new forced swimming test for the evaluation of antidepressants in rats by recording vibration of a water tank.

In order to more objectively evaluate drug effects in the forced swimming test proposed by Porsolt et al. as a screening method for antidepressants, vibrations of the wall of a tank caused by rats trying to escape from water were recorded. Locomotor activity was also measured in an activity cage. Male Wistar rats were forced to swim once daily for 15 min in a tank of 25 degrees C water filled to a depth of 20 cm. After 4 d sessions of swimming, drugs were administered i.p. 3 times (24, 5 and 1 h prior to the test session). On day 5, 45 min after the last injection of a test drug, locomotor activity was measured for 15 min and then the rat was subjected to the forced swimming test. All antidepressants tested, dose-dependently increased tank vibration. Nomifensine, atropine, methamphetamine, chlorpheniramine and diazepam increased locomotor activity. The remaining drugs had no effect or reduced locomotion. In addition, the pattern of the tank vibrations, caused by rats treated with most drugs, like atropine, showed a burst during the first 5 min followed by sporadic vibrations. Nomifensine and methamphetamine, on the other hand, caused vibrations throughout the 15 min test session. A specific effect of antidepressants was revealed by this forced swimming test in combination with the measurement of locomotor activity.

Animals↗
PubMed2003

Strength increase after whole-body vibration compared with resistance training.

PURPOSE: The aim of this study was to investigate and to compare the effect of a 12-wk period of whole-body vibration training and resistance training on human knee-extensor strength. METHODS: Sixty-seven untrained females (21.4 +/- 1.8 yr) participated in the study. The whole-body vibration group (WBV, N = 18) and the placebo group (PL, N = 19) performed static and dynamic knee-extensor exercises on a vibration platform. The acceleration of the vibration platform was between 2.28 g and 5.09 g, whereas only 0.4 g for the PL condition. Vibration (35-40 Hz) resulted in increased EMG activity, but the EMG signal remained unchanged in the PL condition. The resistance-training group (RES, N = 18) trained knee extensors by dynamic leg-press and leg-extension exercises (10-20 RM). All training groups exercised 3x wk-1. The control group (CO, N = 12) did not participate in any training. Pre- and postisometric, dynamic, and ballistic knee-extensor strength were measured by means of a motor-driven dynamometer. Explosive strength was determined by means of a counter-movement jump. RESULTS: Isometric and dynamic knee-extensor strength increased significantly (P < 0.001) in both the WBV group (16.6 +/- 10.8%; 9.0 +/- 3.2%) and the RES group (14.4 +/- 5.3%; 7.0 +/- 6.2%), respectively, whereas the PL and CO group showed no significant (P > 0.05) increase. Counter-movement jump height enhanced significantly (P < 0.001) in the WBV group (7.6 +/- 4.3%) only. There was no effect of any of the interventions on maximal speed of movement, as measured by means of ballistic tests. CONCLUSIONS: WBV, and the reflexive muscle contraction it provokes, has the potential to induce strength gain in knee extensors of previously untrained females to the same extent as resistance training at moderate intensity. It was clearly shown that strength increases after WBV training are not attributable to a placebo effect.

Adolescent↗
PubMed1994

Mathematical model of the effects of mechanical vibration on crossbridge kinetics in cardiac muscle.

We previously reported that the application of an external mechanical vibration to the epicardial surface caused a vibration-induced-depression (VID) of left ventricular (LV) function. The magnitude of the VID of peak LV pressure increased as either the amplitude or the frequency of the vibration increased. When LV contractility was altered by the administration of propranolol or by continuous infusion of dobutamine, the magnitude of the VID of peak LV pressure was inversely correlated with LV contractility. These characteristics were observed in open-chest and isolated canine preparations. In the present study, we constructed a muscle model to obtain a theoretical explanation for these effects. This model was first proposed by Gray, Gonda and Cheung, and has been extended in this report to explain twitch tension. This new, improved model is able to explain twitch tension and the effects of external vibration on twitch contraction semi-quantitatively. The successful predictions of the this model support the idea that external vibration directly affects contractile protein and modulates crossbridge kinetics.

Adenosine Triphosphatases↗
PubMed1992

[Effects of whole-body vibration exposure on DOPAC and VIP-like immunoreactivity in the rat brain].

In order to clarify the involvement of cerebral 3,4-dihydroxyphenylacetic acid (DOPAC) and vasoactive intestinal polypeptide (VIP) in whole-body vibration stress, DOPAC and VIP-like immunoreactivity (VIP-LI) in various discrete brain regions of rats exposed to whole-body vibration (4G, 20 Hz, 90 min) were assayed. The results showed that the whole-body vibration increased the DOPAC level in the frontal cortex and nucleus accumbens, but did not induce a concurrent change of VIP-LI in these regions. VIP-LI was significantly increased in the amygdala, and decreased in the hippocampus, accompanied by no significant change of DOPAC. These results show that whole-body vibration affects cerebral VIP neuron systems in addition to its nonspecific action, i.e. the activation of mesofrontal and mesoaccumbens dopamine neuron systems. It is assumed that the amygdalofugal VIP neuronal system is involved in the regulation of hypothalamic and pituitary hormone secretions, and that VIP in the hippocampus plays a part in modulating the blood circulation in the cortex in whole-body vibration stress.

3,4-Dihydroxyphenylacetic Acid↗
PubMedDate not supplied

Vibration disease: plasma electrolytes and trace elements.

102 patients with vibration disease (mean age 46 +/- 7, length of service in different jobs using vibration tools 17 +/- 7 years) were studied. Plasma electrolytes and trace elements (sodium, potassium, calcium, magnesium, phosphorus, chloride, iron, copper, zinc, cobalt and manganese) and plasma osmolality were investigated, as well as some specific tests indicative of vibration exposure--cold provocation test, vibration sense, thermoasymmetry (left/right hand), skin electric resistance and hand and finger blood flow (Doppler-ultrasound sonometry). In a large number of patients increased values for the following variables were found--magnesium in 43%, zinc in 45%, cobalt in 57%, manganese in 70% and plasma osmolality in 66%. It is suggested that vibration affects mineral metabolism. However, these disturbances in mineral metabolism are secondary to other pathological changes in the body.

Adult↗
PubMed2004

Effect of vibration during fatiguing resistance exercise on subsequent muscle activity during maximal voluntary isometric contractions.

This investigation was designed to determine if vibration during fatiguing resistance exercise would alter associated patterns of muscle activity. A cross-over design was employed with 8 subjects completing a resistance exercise bout once with a vibrating dumbbell (V) (44 Hz, 3 mm displacement) and once without vibration (NV). For both exercise bouts, 10 sets were performed with a load that induced concentric muscle failure during the 10th repetition. The appropriate load for each set was determined during a pretest. Each testing session was separated by 1 week. Electromyography (EMG) was obtained from the biceps brachii muscle at 12 different time points during a maximum voluntary contraction (MVC) at a 170 degrees elbow angle after each set of the dumbbell exercise. The time points were as follows: pre (5 minutes before the resistance exercise bout), T1-T10 (immediately following each set of resistance exercise), and post (15 minutes after the resistance exercise bout). EMG was analyzed for median power frequency (MPF) and maximum (mEMG). NV resulted in a significant decrease in MPF at T1-T4 (p < or 0.05) and a significant increase in mEMG at T2 during the MVC. V had an overall trend of lower mEMG in comparison to NV. The mEMG and MPF values associated with NV were similar to previously reported investigations. The lower mEMG values and the higher MPF of V in comparison to NV are undocumented. The EMG patterns observed with vibration may indicate a more efficient and effective recruitment of high threshold motor units during fatiguing contractions. This may indicate the usage of vibration with resistance exercise as an effective tool for strength training athletes.

Adult↗
PubMed2004

Whisker vibration information carried by rat barrel cortex neurons.

Rats can make extremely fine texture discriminations by "whisking" their vibrissa across the surface of an object. We have investigated one hypothesis for the neuronal basis of texture representation by measuring how clusters of neurons in the barrel cortex of anesthetized rats encode the kinetic features of sinusoidal whisker vibrations. Mutual information analyses of spike counts led to a number of findings. Information about vibration kinetics became available as early as 6 msec after stimulus onset and reached a peak at approximately 20-30 msec. Vibration speed, proportional to the product of vibration amplitude (A) and frequency (f), was the kinetic property most reliably reported by cortical neurons. Indeed, by measuring information when the complete stimulus set was collapsed into feature-defined groups, we found that neurons reduced the dimensionality of the stimulus from two features (A, f) to a single feature, the product Af. Moreover, because different neurons encode stimuli in the same manner, information loss was negligible even when the activity of separate neuronal clusters was pooled. This suggests a decoding scheme whereby target neurons could capture all available information simply by summating the signals from separate barrel cortex neurons. These results indicate that neuronal population activity provides sufficient information to allow nearly perfect discrimination of two vibrations, based on their deflection speeds, within a time scale comparable with that of a single whisking motion across a surface.

Animals↗
PubMed2005

Hand arm vibration syndrome among quarry workers in Vietnam.

Few studies have focused on the health effects of vibrating tools on workers in the tropical area. Work conditions and health effects related to rock drill operation were studied in 102 quarry workers, including 73 rock drill operators in Vietnam. We aimed to clarify (1) risk of vibration exposure, (2) occurrence of vibration-induced white finger (VWF), and (3) characteristics of hand-arm vibration syndrome (HAVS). Total weighted r.m.s. acceleration of the Chinese -or Russian-made rock drills, was 45-55 m/s(2). According to work observation studies, daily exposure time to vibration was 160-210 min. ISO5349 predicted that this exposure level would be associated with a high risk of HAVS in workers. We found no clear evidence of VWF. There may be several reasons why no worker exhibited VWF: (1) warmer work conditions, (2) younger and less experienced workers, (3) seasonal changes in work operations, and (4) healthy worker effect. On the other hand, 5-10% of rock drill operators might be suffering from moderate HAVS which was sensori-neural type dominant. There may be some characteristic features of HAVS among quarry workers in the tropical area.

Adult↗
PubMed1987

[Peripheral somatic and autonomic nerve functions in patients with occupational vibration disease].

In order to evaluate the functions of the peripheral somatic nerve and autonomic nerve in patients with occupational vibration disease objectively and quantitatively, four examinations were performed on twenty 44-63 yr old patients with occupational vibration disease and their total operating time ranged from 5,000 to 43,750 h. 1) Motor nerve conduction velocities (MCV) and sensory nerve conduction velocities (SCV) of the ulnar and median nerves were measured using conventional methods. 2) Electrogustatory thresholds under the controlled area of the chorda tympani nerve were measured by Tomita's method using an electrogustometer (610-M, M.E.C.). 3) Dopamine-beta-hydroxylase (DBH) activity in blood was assayed by the photometric assay of Nagatsu and Udenfriend. 4) Coefficient of variation of R-R interval in ECG (CVR-R) was measured after 15-min-resting in supine position by using a R-R interval analyzer (Autonomic R 100, M.E.C.). The results of these examinations were compared with those of special examinations for the diagnosis of vibration disease. In patients with occupational vibration disease, MCV and SCV of the ulnar and median nerve were lower in value than those in age-matched healthy controls. In particular, MCV of the ulnar nerve, MCV and SCV of the median nerve were significantly lower in the patients than in the controls. Nerve conduction velocities were significantly correlated with skin temperature and nailpress test, though diminished nerve conduction velocities observed in vibration disease patients were considered to be attributable to peripheral circulatory disturbance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2005

[Evaluation of forklift trucks operated in dockyards for reducing exposure to whole-body vibration].

Our preceding study revealed that many fork-lift truck drivers in Japanese dockyards suffer from fatigue symptoms such as low back pain (LBP). It has been suggested that exposure to whole-body vibration (WBV) is a cause of their LBP. Using forklift models manufactured from 1982 to 2000, we measured and evaluated the vibration of forklift trucks operated in dockyards, adopting experimental procedures based on the European Standard. We investigated various factors related to WBV, with the main focus on attenuating seat vibration. This study showed that (1) the seats did not attenuate vibration in the vertical direction, (2) forklift trucks and their seats had not improved in terms of WBV attenuation for a decade, (3) some forklift trucks in which the seat suspension could no longer be adjusted to the driver's weight continued to be used without being repaired, and impractical seat adjustment methods were adopted, and (4) the seats did not attenuate vertical vibration well in the most undesirable frequency range. We conclude that forklift trucks and especially their seats should urgently be improved with regard to WBV attenuation in order to prevent LBP in forklift truck drivers.

Back Pain↗
PubMed2004

Influence of heat and vibration on the movement of the northern fowl mite (Acari: Macronyssidae).

Heat and vibration are common host-generated cues that ectoparasites use to orient to hosts. Three experiments evaluated effects of heat and vibration on the movement of northern fowl mite, Ornithonyssus sylviarum (Canestrini & Fanzago). Individual arrested mites in an isolation chamber always initiated movement (walking) after substrate vibration (7.8-min walking duration), but only initiated movement 50% of the time (2.8-min walking duration) upon exposure to a 3 degrees C heat fluctuation. Heat fluctuation in combination with vibration extended the period of activity by approximately 50% (11.6-min walking duration) compared with activity initiated by vibration alone. Mites with longer time off-host moved for shorter durations. In a choice test, individual mites consistently moved closer to a 35 degrees C heat source 1 or 6 mm away, but not to a heat source 11 mm away. In a circular arena, mites were able to orient accurately to a 35 degrees C heat source and reached the arena edge almost 4 times faster (11.2 s) than mites without a heat source (41.2 s). These results suggest that northern fowl mite is capable of directed thermo-orientation, as well as modulation of activity depending on the type of sensory information perceived. The adaptive significance of this orientation for a "permanent" ectoparasite is discussed.

Acaridae↗
PubMed1989

The response of normal and failing heart to externally applied vibration in the canine open chest preparation.

We examined the left ventricular functional response to externally applied vibration using four canine open chest preparations. A sinusoidal 30 Hz vibration (2.7 mm in amplitude) was applied to the ventricular epicardium at each level of propranolol-induced myocardial depression. External vibration in control conditions induced no significant change either in peak left ventricular pressure (LVP) or in stroke volume (SV). With propranolol, 0.1 and 0.3 mg/kg, peak LVP and SV were depressed by the application of external vibration, even though there was no significant change of these values in the nonvibrating condition compared to control. We conclude that the ventricular response to vibration depends on the underlying myocardial viability.

Animals↗