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PubMed1994

Hand-arm vibration syndrome among travertine workers: a follow up study.

In a six year follow up study of the handarm vibration syndrome, 62 stoneworkers operating hand held vibrating tools in 10 travertine quarries and mills were first investigated in 1985 and then in 1991. The frequency weighted acceleration of vibration from the rock drills and stone hammers used by the travertine workers exceeded 20 m/s2, indicating a hazardous work activity according to the proposal of the EC directive for physical agents. A clinical examination and a cold provocation test were repeated with the same procedures as those adopted at the time of the first survey. The stoneworkers were divided into groups according to current work state: active stoneworkers who continued to use powered tools during the follow up (n = 21, median exposure time 22 years), and ex-stoneworkers with retirement vibration free intervals of three years (n = 22, median exposure time 27.5 years) and of six years (n = 19, median exposure time 20 years). In the group of active stoneworkers, a 38% onset a new cases of vibration-induced white finger (VWF) was found during the follow up (p < 0.01). Among the retired stoneworkers affected with VWF (n = 24), one recovered from VWF, one showed improvement, 20 remained stationary, and two deteriorated. The ex-stoneworkers experienced no significant change in sensorineural disturbances and a decrease in musculoskeletal symptoms of the upper limbs. At the cold provocation test, the currently active stoneworkers with VWF showed, on a group basis, a delayed finger rewarming time between the two examinations (p = 0.002). An abnormal response to cold provocation persisted in the fingers of the ex-stoneworkers with VWF, even in those reporting subjective improvement. These findings indicate a tendency towards the irreversibility of sensorineural and VWF symptoms in a group of ex-stoneworkers with prolonged exposure to high vibration levels in the past. The increased occurrence of VWF in the active stone workers after a few extra years of vibrating tool usage argues for an urgent implementation of preventive measures in the stone industry.

Arm↗
PubMed1995

Acute effects of vibration from a chipping hammer and a grinder on the hand-arm system.

OBJECTIVES: The purpose of this study was to compare various effects on the hand-arm system of vibration exposure from a chipping hammer and a grinder with the same frequency weighted acceleration. Grip and push forces were measured and monitored during the exposure. The various effects were: muscle activity (measured with surface electrodes), discomfort ratings for different parts of the hand-arm system (made during and after exposure), and vibration perception threshold (for 10 minutes before and 10 minutes after the exposure). RESULTS: No increase in muscle activity due to exposure to vibration was found in the hand muscle studied. In the forearm, conversely, there was an increase in both muscle studied. For the upper arm the muscle activity only increased when exposed to impact vibration. Subjective ratings in the hand and shift in vibration perception threshold were effected more by the grinder than the hammer exposure. CONCLUSION: These results show that the reaction of the hand-arm system to vibration varies with frequency quantitatively as well as qualitatively. They do not support the notion that one single frequency weighted curve would be valid for the different health effects of hand-arm vibration (vascular, musculoskeletal, neurological, and psychophysiological).

Adult↗
PubMed2000

Cross sectional study of a workforce exposed to hand-arm vibration: with objective tests and the Stockholm workshop scales.

OBJECTIVES: Medical surveillance of workforces exposed to vibration has been recommended with the Stockholm workshop scales. The aims of this study were (a) to evaluate how the results of the objective tests individually and jointly associated with the final Stockholm workshop staging, (b) how this staging related to the history of exposure to vibration, and (c) how different trades were affected by the hazards from vibrating tools. METHODS: All workers exposed to vibration in a heavy engineering company were examined with a questionnaire and a battery of tests. An assessment of staging by the Stockholm workshop scales was made. Estimates of the daily exposure and lifetime dosage of vibration of the various trades were reached. RESULTS: The average years of tool use was 23.3 years (range 3-47 years) and the mean lifetime exposure was 11,022 (range 1012-46,125) hours. The individual neurological tests were all strongly associated with the Stockholm neurological staging but the cold provocation test was not associated with the Stockholm vascular staging. Neurological staging was significantly associated with age, years of tool use, and total hours of exposure to vibration, but not with trade or smoking. Vascular staging was significantly associated with age, years of tool use, total hours of exposure to vibration, and trade, but not with smoking. The mean neurological latent period was 19.7 (range 2-40) years and for the vascular component 19.1 (range 2-40) years. These means varied significantly by trade. The overall prevalence of neurological findings of 62% was greater than the overall prevalence of vascular findings, which was 33%. CONCLUSIONS: (1) The neurological objective tests were found to be of use in neurological staging. The cold provocation test was not associated with the vascular staging and therefore was of little value. (2) Years of tool use was the exposure variable most significantly associated with evidence of damage to neurological component while years of tool use and trade were the variables most associated with vascular damage. (3) The prevalence of neurological symptoms (62%) was greater than the prevalence of vascular symptoms (33%). (4) Dressers and welders have shorter latent periods than platers and fitters.

Adult↗
PubMed2004

Plantar vibration improves leg fluid flow in perimenopausal women.

Recent studies have indicated that plantar-based vibration may be an effective approach for the prevention and treatment of osteoporosis. We addressed the hypothesis of whether the plantar vibration operated by way of the skeletal muscle pump, resulting in enhanced blood and fluid flow to the lower body. We combined plantar stimulation with upright tilt table testing in 18 women aged 46-63 yr. We used strain-gauge plethysmography to measure calf blood flow, venous capacitance, and the microvascular filtration relation, as well as impedance plethysmography to examine changes in leg, splanchnic, and thoracic blood flow while supine at a 35 degrees upright tilt. A vibrating platform was placed on the footboard of a tilt table, and measurements were made at 0, 15, and 45 Hz with an amplitude of 0.2 g point to point, presented in random order. Impedance-measured supine blood flows were significantly (P = 0.05) increased in the calf (30%), pelvic (26%), and thoracic regions (20%) by plantar vibration at 45 Hz. Moreover, the 25-35% decreases in calf and pelvic blood flows associated with upright tilt were reversed by plantar vibration, and the decrease in thoracic blood flow was significantly attenuated. Strain-gauge measurements showed an attenuation of upright calf blood flow. In addition, the microvascular filtration relation was shifted with vibration, producing a pronounced increase in the threshold for edema, P(i), due to enhanced lymphatic flow. Supine values for P(i) increased from 24 +/- 2 mmHg at 0 Hz to 27 +/- 3 mmHg at 15 Hz, and finally to 31 +/- 2 mmHg at 45 Hz (P < 0.01). Upright values for P(i) increased from 25 +/- 3 mmHg at 0 Hz, to 28 +/- 4 mmHg at 15 Hz, and finally to 35 +/- 4 mmHg at 45 Hz. The results suggest that plantar vibration serves to significantly enhance peripheral and systemic blood flow, peripheral lymphatic flow, and venous drainage, which may account for the apparent ability of such stimuli to influence bone mass.

Blood Pressure↗
PubMed1977

Parameters for assessing vibration-induced cardiovascular responses in awake dogs.

The vibration parameters for assessing the response of the cardiovascular system to whole-body vibration were studied. Six awake, chronically instrumented canines were restrained with their spines vertical, and exposed to GZ sinusoidal vibration of 2-12 HZ for a constant peak acceleration amplitude of +-1.0 G. Vibration exposures of 30 s with intervening recovery periods of 2 min were employed. The following variables were measured: mean heart rate (MHR), stroke volume (SV), mean aortic flow (MAF), mean aortic pressure (MAP), the peak net force transmitted to the canine/body weight (PNF/BW), and the vibration platform frequency (ft), displacement, and acceleration. The percentage change from control (no vibration) of MAF varied linearly with PNF/BW for all cases. MAF also varied linearly with the log MHR/ft for the number of dogs which primarily changed MHR during the vibration exposures. The response of MAP was minimal in all cases, indicating a decrease in total peripheral resistance with increasing PHF.

Animals↗
PubMed2001

Modification of soft tissue vibrations in the leg by muscular activity.

Vibration characteristics were recorded for the soft tissues of the triceps surae, tibialis anterior, and quadriceps muscles. The frequency and damping of free vibrations in these tissues were measured while isometric and isotonic contractions of the leg were performed. Soft tissue vibration frequency and damping increased with both the force produced by and the shortening velocity of the underlying muscle. Both frequency and damping were greater in a direction normal to the skin surface than in a direction parallel to the major axis of each leg segment. Vibration characteristics further changed with the muscle length and between the individuals tested. The range of the measured vibration frequencies coincided with typical frequencies of impact forces during running. However, observations suggest that soft tissue vibrations are minimal during running. These results support the strategy that increases in muscular activity may be used by some individuals to move the frequency and damping characteristics of the soft tissues away from those of the impact force and thus minimize vibrations during walking and running.

Adult↗
PubMed2004

Difference in aftereffects following prolonged Achilles tendon vibration on muscle activity during maximal voluntary contraction among plantar flexor synergists.

It has been suggested that a suppression of maximal voluntary contraction (MVC) induced by prolonged vibration is due to an attenuation of Ia afferent activity. The purpose of the present study was to test the hypothesis that aftereffects following prolonged vibration on muscle activity during MVC differ among plantar flexor synergists owing to a supposed difference in muscle fiber composition. The plantar flexion MVC torque and surface electromyogram (EMG) of the medial head of gastrocnemius (MG), the lateral head of gastrocnemius (LG), and the soleus (Sol) were recorded in 13 subjects before and after prolonged vibration applied to the Achilles tendon at 100 Hz for 30 min. The maximal H reflexes and M waves were also determined from the three muscles, and the ratio between H reflexes and M waves (H/Mmax) was calculated before and after the vibration. The MVC torque was decreased by 16.6 +/- 3.7% after the vibration (P < 0.05; ANOVA). The H/Mmax also decreased for all three muscles, indicating that Ia afferent activity was successfully attenuated by the vibration in all plantar flexors. However, a reduction of EMG during MVC was observed only in MG (12.7 +/- 4.0%) and LG (11.4 +/- 3.9%) (P < 0.05; ANOVA), not in Sol (3.4 +/- 3.0%). These results demonstrated that prolonged vibration-induced MVC suppression was attributable mainly to the reduction of muscle activity in MG and LG, both of which have a larger proportion of fast-twitch muscle fibers than Sol. This finding suggests that Ia-afferent activity that reinforces the recruitment of high-threshold motor units is necessary to enhance force exertion during MVC.

Adaptation, Physiological↗
PubMed2004

Vibration-induced activation of muscle afferents modulates bioassayable growth hormone release.

The effects of tendon vibration on bioassayable growth hormone (BGH) secretion from the pituitary gland were investigated in anesthetized adult male rats. The tendons from predominantly fast-twitch ankle extensor muscles (gastrocnemius and plantaris) or a predominantly slow-twitch ankle extensor (soleus) were vibrated by using a paradigm that selectively activates group Ia afferent fibers from muscle spindles. The lower hindlimb was secured with the muscles near physiological length, and the tendons were vibrated for 15 min at 150 Hz and a displacement of 1 mm. Control rats were prepared similarly, but the tendons were not vibrated. Compared with control, vibration of the tendons of the fast ankle extensors markedly increased (160%), whereas vibration of the slow soleus decreased (68%), BGH secretion. Complete denervation of the hindlimb had no independent effects on the normal resting levels of BGH, but it prevented the effects of tendon vibration on BGH secretion. The results are consistent with previous findings showing modulation of BGH release in response to in vivo activation or in situ electrical stimulation of muscle afferents (Bigbee AJ, Gosselink KL, Grindeland RE, Roy RR, Zhong H, and Edgerton VR. J Appl Physiol 89: 2174-2178, 2000; Gosselink KL, Grindeland RE, Roy RR, Zhong H, Bigbee AJ, and Edgerton VR. J Appl Physiol 88: 142-148, 2000; Gosselink KL, Grindeland RE, Roy RR, Zhong H, Bigbee AJ, Grossman EJ, and Edgerton VR. J Appl Physiol 84: 1425-1430, 1998). These data provide evidence that this previously described muscle afferent-pituitary axis is neurally mediated via group Ia afferents from peripheral skeletal muscle. Furthermore, these data show that activation of this group Ia afferent pathway from fast muscles enhances, whereas the same sensory afferent input from a slow muscle depresses, BGH release.

Afferent Pathways↗
PubMed1997

Modification of human left ventricular relaxation by small-amplitude, phase-controlled mechanical vibration on the chest wall.

BACKGROUND: Direct clinical manipulation to improve an impairment of left ventricular (LV) relaxation has not been reported. We investigated whether the LV relaxation rate in humans could be modulated by phase-controlled mechanical vibration applied to the patient's anterior chest wall and whether there are some quantitative differences in the responses of normal (N), hypertrophied (H), and failing (F) ventricle. METHODS AND RESULTS: In 46 patients (N, 10; H, 18 [hypertrophic cardiomyopathy]; F, 18 [heart failure]), the vibrator was attached to the precordium and a 50-Hz, 2-mm sinusoidal mechanical vibration was applied, with the timing restricted from the onset of isovolumic relaxation to end-diastole during cardiac catheterization. Heart rate and peak LV pressure showed no difference with vibration. However, in all patients, precordial vibration caused an acceleration of the LV pressure fall. The magnitude of the induced reduction of the time constant of LV pressure decay (delta T) was larger (P < .01) in H and F than in N (4.6 +/- 2.3, 4.0 +/- 1.6, and 0.6 +/- 1.5 ms for H, F, and N, respectively). Delta T correlated strongly with the magnitude of impaired relaxation and the magnitude of transmitted vibration to the ventricle. CONCLUSIONS: Phase-controlled, small-amplitude vibration on the chest wall can directly modulate LV relaxation rate, especially in those with hypertrophy or failing ventricle.

Adult↗
PubMed2001

Response of the canine internal intercostal muscles to chest wall vibration.

Although high-frequency mechanical vibration of the rib cage reduces dyspnea, its effects on the respiratory muscles are largely unknown. We have previously shown that in anesthetized dogs, vibrating the rib cage during inspiration elicits a marked increase in the inspiratory electromyographic (EMG) activity recorded from the external intercostal muscles but does not affect tidal volume (VT). In the present studies, we have tested the hypothesis that the maintenance of VT results from the concomitant contraction of the internal interosseous (expiratory) intercostals. When the rib cage was vibrated (40 Hz) during hyperventilation-induced apnea, a prominent activity was recorded from the external intercostals but no activity was recorded from the internal intercostals, including when the muscles were lengthened by passive inflation. The internal intercostals remained also silent when vibration was applied during spontaneous inspiration, and the phasic expiratory EMG activity recorded from them was unaltered when vibration was applied during expiration. Thus, the internal interosseous intercostals in dogs are much less sensitive to vibration than the external intercostals, and they do not interfere with the action of these latter during rib cage vibration. This lack of sensitivity might be the result of a reflex inhibition of the muscle spindle afferents by afferents from external intercostal muscle spindles.

Animals↗
PubMed2006

Physiological effects of vibration in subjects with cystic fibrosis.

The physiological mechanisms by which vibration and other physiotherapy interventions may clear secretions in subjects with cystic fibrosis are unknown. The main aim of this study was to compare the expiratory flow rates and frequencies of airflow oscillation of vibration to those of Acapella(R), Flutter(R), positive expiratory pressure and percussion. Respiratory flow rates were measured during interventions, the order of which was randomised. The oscillation of the airflow of the interventions was determined by frequency spectral analysis. In 18 young adult subjects with cystic fibrosis, the mean peak expiratory flow rate of vibration was greater than Flutter(R), percussion, Acapella(R) and positive expiratory pressure. The mean+/-sd of the oscillation of the airflow of vibration (8.4+/-0.4 Hz) was lower than Acapella(R) (13.5+/-1.7 Hz) and Flutter(R) (11.3+/-1.5 Hz) but similar to percussion (7.3+/-0.3 Hz). Theoretically, the higher peak expiratory flow rate of vibration compared to the other physiotherapy interventions may promote secretion clearance. In addition, the frequency of oscillation of vibration was within the range demonstrated to increase mucus transport. This study has provided some evidence for the physiological rationale for the use of vibration to aid secretion clearance.

Adult↗
PubMed1977

Reflex effects of vibration in patients with spinal cord lesions.

The vibration reflex was studied in 49 patients with traumatic spinal cord lesions. It was elicited in all patients, even after presumably complete division of the cord. The vibration relfex consisted of a short-latency, brief outburst of phasic activity of motor units, followed by rapidly decreasing phasic component and a later slowly declining tonic component. When periods of vibration were repeated at short intervals of 2 to 10 seconds, the responses showed an approximately exponential decline, although the beginning of each subsequent response was always larger than the end of the preceding response. A large part of this decline can be characterized as a habituation of the vibration reflex. In comparison with the vibration reflex in normal subjects, the phasic component was increased and the tonic one reduced. The tonic component was especially susceptible to potentiation and dishabituation by voluntary effort to contract the vibrated muscle, even in some patients with no other evidence that the lesion was incomplete. We suggest that the tonic component of the human vibration reflex depends, at least in part, on segmental interneurons and their descending spinal pathways, while the phasic component depends mainly on the excitability level of spinal motoneurons.

Evoked Potentials↗
PubMed2000

Behaviour-locked signal analysis reveals weak 200-300 Hz comb vibrations during the honeybee waggle dance.

Waggle-dancing honeybees produce vibratory movements that may facilitate communication by indicating the location of the waggle dancer. However, an important component of these vibrations has never been previously detected in the comb. We developed a method of fine-scale behavioural analysis that allowed us to analyze separately comb vibrations near a honeybee waggle dancer during the waggle and return phases of her dance. We simultaneously recorded honeybee waggle dances using digital video and laser-Doppler vibrometry, and performed a behaviour-locked Fast Fourier Transform analysis on the substratum vibrations. This analysis revealed significantly higher-amplitude 200-300 Hz vibrations during the waggle phase than during the return phase (P=0.012). We found no significant differences in the flanking frequency regions between 100-200 Hz (P=0.227) and 300-400 Hz (P=0.065). We recorded peak waggle phase vibrations from 206 to 292 Hz (244+/-28 Hz; mean +/- s. d., N=11). The maximum measured signal - noise level was +12.4 dB during the waggle phase (mean +5.8+/-2.7 dB). The maximum vibrational velocity, calculated from a filtered signal, was 128 microm s(-)(1) peak-to-peak, corresponding to a displacement of 0.09 microm peak-to-peak at 223 Hz. On average, we measured a vibrational velocity of 79+/-28 microm s(-)(1) peak-to-peak from filtered signals. These signal amplitudes overlap with the detection threshold of the honeybee subgenual organ.

Animal Communication↗
PubMed1992

Acute vibration--its effect on digital blood flow by central and local mechanisms.

In order to establish underlying mechanisms responsible for the vasospastic disorder vibration white finger (VWF), the acute effect of vibration on digital blood flow was assessed. Thirteen patients with primary Raynaud's phenomenon (RP), 15 patients with WVF and 13 controls were exposed to acute vibration in the middle digit of one hand for 1 and 3 minutes. Blood flow was measured in that digit and in the middle finger of the contralateral hand using strain gauge plethysmography before and after vibration. The measurements were then repeated following digital nerve blockade using 2% Lignocaine in the vibrated digit. The results demonstrate that vibration affects digital blood flow through two independent mechanisms. Vibration appears to cause both an axonal vasoconstrictor reflex and an active local vasodilation phenomenon. In patients with established vasospastic disorders this vasoconstrictor reflex is exaggerated.

Adult↗
PubMed2004

Physiological effect of vibrations on tractor drivers under variable ploughing conditions.

The vibration conditions to which tractor operators are subjected are complex and varied with multi axis translation and rotational vibration inputs to different parts of the body. Working under such conditions may lead to human fatigue and other driving related hazards. The present research was carried out to study the operators under varying conditions of vibration while driving a tractor with and without farm equipment on different fields. Test runs were conducted in wet and dry fields to determine the levels of vibration generated at different engine speeds. On the basis of this study three levels of vibration namely 2.5, 3.5 and 5.0 m/s(2) were selected. Five subjects, all males, with no experience in the field of tractor driving participated in the study. The data were analyzed on the basis of three factor repeated measure kind of experimental design. The results showed that the main effects of farm equipment and the vibration level were statistically significant but the effect of field type was found to be statistically non-significant. The results of the study call upon the ergonomists to design and develop a tractor where the driver may be relieved of vibration induced stresses. Front loading of farm equipment is recommended for improved visibility and better working posture.

Adult↗
PubMed1988

[Functions of the sympathetic-adrenomedullar system and adrenocortex in patients with vibration syndrome. Investigations of plasma and urine catecholamine and plasma cortisol during cold exposure].

Much discussion has been made as to whether vibration syndrome is a peripheral or systemic disorder. We studied plasma and urine norepinephrine and epinephrine, and plasma cortisol under resting and cold exposure conditions (7 degrees C cold room for 30 min). The subjects were 20 patients with vibration syndrome and with a history of Raynaud's phenomenon, 20 patients with vibration syndrome without a history of Raynaud's phenomenon, and 20 healthy controls. They were all males and the three groups were matched by age. The following results were obtained. 1. Mean temperatures of finger skin in the patient groups under resting and cold exposure conditions were lower than in the control group. Mean systolic and diastolic blood pressures in the patient groups under both conditions were higher than in the control group. Mean values of blood pressure change produced by cold exposure in the patient groups were lower than in the control group. Some of these differences were statistically significant (p less than 0.05 or p less than 0.01). 2. Mean levels of plasma norepinephrine in the patient groups under resting and cold exposure conditions were significantly higher (p less than 0.01 or p less than 0.05) than in the control group. This finding indicates that the patients with vibration syndrome had hyperfunction of the sympathetic nervous system. Mean levels of urine norepinephrine in the patient groups were not significantly different from the control group. 3. Mean levels of plasma epinephrine in the patient groups under resting and cold exposure conditions were lower than in the control group. The differences between the patient groups and the control group were significant (p less than 0.05 or p less than 0.01) in the cold exposure condition. This finding suggests that the patients with vibration syndrome had hypofunction of the adrenomedullar system. Urine epinephrine in the patient groups was not significantly different from the control group. 4. Mean levels of cortisol in the patient groups were higher than in the control group. The difference in cortisol level between the group of patients without Raynaud's phenomenon and the control group was significant (p less than 0.01) in the resting condition. This finding may suggest that the patients with vibration syndrome had hyperfunction of the adrenocortex. The foregoing data support the hypothesis that vibration syndrome is a systemic dysfunction, which includes disorders of the sympathetic-adrenomedullar system and adrenocortex.

Adrenal Cortex↗
PubMed1990

[Raynaud's phenomenon and cutaneous changes due to hand-arm vibration].

Vibration of hand-held tools is considered to induce disorders in the peripheral circulation, peripheral nerve and organs, muscles, bones and joints (vibration syndrome). Above all, Raynaud's phenomenon is known as a prominent sign of vibration syndrome. This paper describes the findings obtained from the observation of the skin of the hands exposed to vibration and evaluates the relation between Raynaud's phenomenon and cutaneous changes. A total of 124 chain-saw workers in a forestry company in Gifu Prefecture were investigated in connection with compulsory health examination. In medical occupational interview, every worker was asked whether he had any experience of Raynaud's phenomenon or not. Moreover, the following symptoms of the skin and nails of the hand(s) were examined: 1. sclerodactylia, 2. pitting scar, 3. edema, 4. erythema around the nail, and 5. elongation and bleeding of proximal nailfolds and cuticles. To determine whether vibration induces the above mentioned cutaneous changes, the relation between the prevalence of the changes and the duration of exposure to vibration was assessed. The workers were classified into four groups by duration of exposure to vibration (in intervals of 10 years). The evaluation was made by comparing the prevalence of cutaneous changes between the workers with Raynaud's phenomenon and those without it. Subjects were restricted in age from 40 to 59 years. There was a significant relationship between age and duration of exposure (p less than 0.001). The prevalence of Raynaud's phenomenon was significantly high among the workers in the fifties (15.8%). The prevalence of Raynaud's phenomenon was significantly increased in workers with longer exposure. The prevalence of Raynaud's phenomenon was 6.9% in workers in the forties. Though the prevalence of sclerodactylia and elongation and bleeding of proximal nailfolds and cuticles was higher in workers in the fifties than those in the forties, (1. 34.7% in the 50 s, 24.1% in the 40 s 5. 27.4% in the 50 s, 17.2% in the 40 s), no relation could be demonstrated between the duration of exposure and the prevalence of cutaneous changes. There were no significant differences in the prevalence of cutaneous changes between the workers with Raynaud's phenomenon and those without Raynaud's phenomenon.

Adult↗
PubMed2000

Infant massage compared with crib vibrator in the treatment of colicky infants.

OBJECTIVE: To evaluate the effectiveness of infant massage compared with that of a crib vibrator in the treatment of infantile colic. METHODS: Infants <7 weeks of age and perceived as colicky by their parents were randomly assigned to an infant massage group (n = 28) or a crib vibrator group (n = 30). Three daily intervention periods were recommended in both groups. Parents recorded infant crying and given interventions in a structured cry diary that was kept for 1 week before (baseline) and for 3 weeks during the intervention. Parents were interviewed after the first and third weeks of intervention to obtain their evaluation of the effectiveness of the given massage or crib vibration. RESULTS: At baseline, the mean amount of total crying was 3.6 (standard deviation: 1.4) hours/day in the massage group infants and 4.2 (2.0) hours/day in the vibrator group infants. The mean amount of colicky crying was 2.1 (standard deviation: 1.1) hours/day and 2.9 (1.5) hours/day, respectively. The mean number of daily intervention periods was 2.2 in both groups. Over the 4-week study, the amount of total and colicky crying decreased significantly in both intervention groups. The reduction in crying was similar in the study groups: total crying decreased by a mean 48% in the massage group and by 47% in the vibrator group, and colicky crying decreased by 64% and 52%, respectively. The amount of other crying (total crying minus colicky crying) remained stable in both groups over the intervention. Ninety-three percent of the parents in both groups reported that colic symptoms decreased over the 3-week intervention, and 61% of the parents in the massage group and 63% of the parents in the crib vibrator group perceived the 3-week intervention as colic reducing. CONCLUSIONS: Infant massage was comparable to the use of a crib vibrator in reducing crying in colicky infants. We suggest that the decrease of total and colicky crying in the present study reflects more the natural course of early infant crying and colic than a specific effect of the interventions.

Analysis of Variance↗