Work-related musculoskeletal pain among physical therapists: a cross-sectional study in Kyoto and Shiga prefectures, Japan.

OBJECTIVES: This study aimed to determine the actual working conditions and prevalence of musculoskeletal pain among physical therapists in Japan, and the risk factors associated with low back pain (LBP) and upper limb pain (ULP). METHODS: A cross-sectional study of physical therapists in the Kyoto and Shiga prefectures was conducted using a self-administered questionnaire. The survey contents included questions regarding personal, work-related, and musculoskeletal pain factors. Logistic regression models were used to analyze factors associated with LBP and ULP. RESULTS: Responses from 1479 participants were included in the analyses. The prevalence of LBP at the time of the survey and in the past year was 40.1% and 74.3% in females, and 37.8% and 69.9% in males, respectively. The prevalence of ULP was 34.8% and 64.2% in females, and 27.2% and 53.3% in males. The numbers of patients who performed manual therapy per day, worked using a fixed-height bed, performed manual therapy, had job dissatisfaction and stress, were over 40 years old, and slept less than 6 hours were associated with LBP and ULP. Assistance task was a risk factor only for LBP, and female sex a risk factor only for ULP. CONCLUSIONS: The prevalence of LBP and ULP among physical therapists in Japan was as high as that in nurses and care workers. Work-related factors associated with LBP and ULP were identified among physical therapists. Thus, to prevent work-related musculoskeletal disorders, measures to reduce the physical burden from the perspective of occupational health are required.

Effects of different bed heights on the physical burden of physiotherapists during manual therapy: an experimental study.

This study aimed to determine the effect of physiotherapists' physical burden caused by different bed heights during manual therapy. Thirty-three male physiotherapists performed tasks simulating lumbar massage and passive hip abduction range-of-motion exercise (ROM) on the beds with low height (LH) and adjusted height (AH), with each task performed three times. The anterior inclination angle of the physiotherapist's trunk was measured, the surface electromyograms of the erector spinae and trapezius muscles were recorded, and perceived stress was assessed. The indexes obtained were statistically compared for different bed heights. Additionally, the lumbar disc compression force and flexion torque were estimated. The lumbar burden caused by the excessive bending and the biomechanical burden and perceived stress were stronger at LH than AH. In ROM tasks using the right hand, the muscle activity was lower at the left lumbar region at LH than at AH. At LH, the anterior inclination angle increased and the lumbar muscle activity declined as the number of tasks increased. The burden on the shoulders was not significantly different by bed heights. Our results showed that, when physiotherapists perform manual therapy, it is necessary to adjust the bed height to reduce physical burden and ensure higher quality of service.

Extraction of apex beat waveform from acoustic pulse wave by sound sensing system using stochastic resonance.

With a sound sensing system using stochastic resonance (4SR), it became possible to obtain an acoustic pulse wave (APW)-a waveform created via a mixture of apex beat and heart sound. We examined 50 subjects who were healthy, with no underlying cardiovascular diseases. We could determine boundary frequency (BF) using APW and phonocardiogram signals. APW data was divided into two bands, one from 0.5 Hz to BF, and a second one from BF to 50 Hz. This permitted the extraction of cardiac apex beat (CAB) and cardiac acoustic sound (CAS), respectively. BF could be expressed by a quadratic function of heart rate, and made it possible to collect CAB and CAS in real time. According to heart rate variability analysis, the fluctuation was 1/f, which indicated an efficient cardiac movement when heart rate was 70 to 80/min. In the frequency band between 0.5 Hz and BF, CAB readings collected from the precordial region resembled apex cardiogram data. The waveforms were classified into five types. Therefore, the new 4SR sensing system can be used as a physical diagnostic tool to obtain biological pulse wave data non-invasively and repeatedly over a long period, and it shows promise for broader applications, including AI analysis.

[Supporting a balance between work schedules and treatment regimens among cancer patients: A questionnaire survey focusing on company size in Wakayama Prefecture, Japan].

OBJECTIVES: The support from businesses to create a balance between work schedules and treatment regimens among employees suffering from cancer seems to be insufficient. The aims of this study were to investigate efforts to find a balance between work schedules and treatment regimens among cancer patients focusing on company size and to identify potential workplace improvements for these employees. METHODS: Seven hundred and seventy businesses in Wakayama Prefecture, Japan, were randomly selected from a workplace list consisting of businesses that had received support from either the Wakayama Occupational Health Support Center or the Regional Occupational Health Center. An anonymous questionnaire was distributed by mail. It consisted of question items on the workplace, support systems, current employees who had suffered or were suffering from cancer (cancer patient employees), their reinstatement, promoting reinstatement and employment of cancer patient employees, and job description of respondents. RESULTS: A completed questionnaire was collected from 188 businesses (response rate: 24.4%). Among small-sized businesses (less than 50 employees), 55% carried out or recommended consultation for cancer screening. This ratio was higher than that of medium-sized businesses (50-99 employees) or large-sized businesses (100 or more employees). Approximately 20% of the businesses had a support system for employees who were working while undergoing cancer treatment, and more small-sized businesses had a system of annual paid leave by the hour than the medium-sized or large-sized businesses. Among the small-sized businesses, 51% had a system of sick leave for regular employees, but this ratio was significantly lower than that among the large-sized businesses. Approximately 20% of businesses had established a system of paid sick leave for regular employees. Reinstatement of employment was possible in over 80% of the businesses. The condition for reinstatement that was most frequently stipulated was that the employee's doctor had provided a medical certificate stating that the employee was able to return to work. However, among small-sized businesses, the condition that colleagues at the workplace were willing to accept him/her was more frequently stipulated. CONCLUSIONS: Cancer screening, annual paid leave by the hour, and institutionalization of sick leave are recommended as workplace improvements for cancer patient employees.

A field study of exposure to whole-body vibration due to agricultural machines in a full-time rice farmer over one year.

OBJECTIVES: The aims of this study were to clarify in detail the levels of whole-body vibration (WBV) exposure from a variety of agricultural machines in a rice farmer over one year, and to evaluate the daily level of exposure compared with European and Japanese threshold limits. METHODS: The subject was a full-time, male rice farmer. We measured vibration accelerations on the seat pan and at the seat base of four tractors with various implements attached, one rice-planting machine, two combine harvesters, produced by the same manufacturer, and one truck used for transportation of agricultural machines. The position and velocity of the machines were recorded in parallel with WBV measurements. In addition, during the year starting in April 2010, the subject completed a questionnaire regarding his work (date, place, content, hours worked, machines used). We calculated the daily exposure to WBV, A(8), on all the days on which the subject used the agricultural machines. RESULTS: The WBV magnitude in farm fields was relatively high during tasks with high velocity and heavy mechanical load on the machine, and had no dominant axis. The subject worked for 159 days using the agricultural machines during the year, and the proportion of days on which A(8) values exceeded the thresholds was 90% for the Japan occupational exposure limit and 24% for the EU exposure action value. CONCLUSIONS: Our findings emphasize the need for rice farmers to have health management strategies suited to the farming seasons and measures to reduce WBV exposure during each farm task.

A field study on the physiological workload of garbage collectors in the Japanese summer.

A field study designed to reveal the physiological workload on garbage collectors (GC) was conducted in Japan. Three drivers who only operated a garbage truck, three loaders who actually collected as a team, three solo collectors, and one clerical worker, totaling 10 male workers participated in this study. The ambient temperature and the relative humidity, activity intensity, and heart rate were measured on the three days in July. The mean heart rate of the workers, excluding the clerical worker, was 97.5 bpm. There were cases in which the heart rate limit, as defined by ACGIH, was exceeded, including a case in which the loader sustainably exceeded this limit for over an hour. There were 10 worker-days in which the 58%HRmax level (corresponding to the permissible limit specified in the Netherlands) was exceeded based on the findings of the 18 worker-days for the loaders and solo collectors. There were many cases in which the energetic load of GC in the humid summertime in Japan exceeded the permissible limits as established in the U.S.A. and the Netherlands. The careful inspection of the actual work conditions and improvements in the work environment should be implemented for the occupational safety and health of GC.

A case of cervico-brachial disorder due to tactile interpretation for deaf-blind persons.

OBJECTIVES: We herein report a case of cervico-brachial disorder (CBD) due to long-term tactile interpreting. METHODS: The patient was interviewed to investigate her past history, occupational history, work conditions and clinical course in detail. The case was diagnosed in accordance with the "Diagnostic Criteria for CBD 2007" established by the Research Association for CBD of the Japanese Society for Occupational Health. RESULTS: The patient was a 49-year-old female who has worked as a regular occupational instructor at a welfare work activity center for deaf people since April 22, 2010. Her primary job is to instruct and aid others in learning confectionery manufacturing and coffee shop tasks. She also performs tactile interpreting for two deaf-blind workers during a morning health check and during any meetings. On September 3, 2010, she interpreted by tactile signing for about three hours alone during a meeting, due to the absence of other interpreters. She developed severe pain in her back immediately after carrying out this interpretation, and the pain thereafter continued and developed in the upper extremities. She was diagnosed with a severe and prolonged case of the non-specific type of CBD. DISCUSSION: Interpretation by tactile signing may impose a heavier burden on the upper extremities, shoulders and neck than that imposed by common sign language. A shorter time of interpretation, ensuring the availability of rest time and supporting tools or methods for the upper extremities, are therefore considered to be necessary to prevent the incidence of CBD among interpreters using tactile signing.

Effectual points of view in occupational health management for persons with cerebral palsy --interventional case approach in VDT work--.

In our previous study, we elicited effectual points of view (POV) in occupational health management for visual display terminals (VDT) operators with disabilities. In order to validate the POV, two VDT operators with cerebral palsy newly-participated in our case study. Problems were ascertained, and in order to attempt to reduce the workload and improve operability, we performed intervention using ergonomic measures. Evaluations were conducted through observations of the equipment used and posture, as well as measurements of sitting pressure distribution and surface electromyogram. For Case 1 (a 33 yr-old male), a trunk support was introduced inside the armrest of his chair to maintain the trunk in a comfortable position. For Case 2 (a 21 yr-old female), in order to improve her unstable sitting position, we changed her chair and adjusted it to an appropriate desk height. For both cases, we confirmed improvements in posture, sitting pressure distribution, myoelectric potential or operability. We were able to confirm that "maintaining of a comfortable trunk" and "alleviation of excessive bending, extension, and curvature of the spinal column and joints" obtained from the previous study as POV in health management are also effective in the present interventional cases.

Sleeping and working hours of residents at a national university hospital in Japan.

This study aimed to examine the status of time spent working and sleeping by resident doctors before the introduction of the New Training System for Residents in Japan. A time-budget survey was conducted over a 4-wk period on 102 residents at the Shiga University of Medical Science Hospital, and the response rate among residents was 76% of a total of 2,722 person-days. The average number of hours spent sleeping was the lowest and spent in the hospital including commuting time was the highest in residents of the surgery department, at 4.4 h and 18.9 h, respectively. Forty percent of residents reported dozing off at work, with the incidence rate being highest in residents of the surgery department (0.7 times/person-day). Dozing appeared to occur in response to the lack of sleep and fatigue, since the same residents slept longer on nights before days they reported not dozing off than on nights before days when they did doze off. Strong correlations were observed between the number of sleeping and working hours and between working hours and the number of patients in a resident's care. In order to maintain high standards of training and to get sufficient sleep it is therefore necessary for residents to manage their work and the number of patients in their care.

Effect of nursing assistance tools on preventing musculoskeletal pain among staff in schools for disabled children.

Objective is to clarify whether nursing assistance tools (a mat with attached handles, a pair of trousers with knee pads and a waist holding belt) prevent musculoskeletal pain, such as low back pain and upper arm pain, and depression, and improve the burden on the lower back and upper arm among staff in schools for disabled children. This study design was a non-randomized intervention trial. The subjects were 41 staff in two schools for disabled children in Japan. Nursing assistance tools were used with the intervention group to help with their nursing activities. We investigated the one-month prevalence of low back pain and the degree of burden on the lower back using a questionnaire at the baseline and at the end point 4 to 6 months later. The prevalence of low back pain did not change significantly in either group. In the intervention group, the prevalence of upper arm pain decreased from 47.6% at the baseline to 23.8% at the end point (p=0.063). The percentage of participants with a high level of burden on the lower back from excretory nursing activity decreased from 57.1% at the baseline to 33.3% at the end point (p=0.063) in the intervention group. These results suggest that nursing assistance tools may prevent upper arm pain and improve the burden on the lower back among staff in schools for disabled children; however, these tools did not significantly prevent low back pain and depression.

Work schedule differences in sleep problems of nursing home caregivers.

Nursing home caregivers (n=775; 604 women; mean age 33.6 years) were studied to examine how work schedules affect their sleep. The shift group (n=536) worked under a rotating two-shift system (n=365), a rotating three-shift system (n=66), or other types of shifts (n=78). The non-shift group included 222 caregivers. Participants completed a questionnaire about working conditions, sleep problems, health, lifestyle, and demographic factors. The two-shift caregivers reported the highest levels of difficulty initiating sleep (DIS, 37.6%), insomnia symptoms (43.0%), and poor quality of sleep (24.9%) among the groups. Adjusted odds ratios for these problems were significantly greater for the two-shift caregivers than for non-shift counterparts: DIS (odds ratio 2.86, 95% confidence interval 1.57-5.20), insomnia symptoms (2.33, 1.36-4.02), and poor sleep quality (2.15, 1.09-4.22). Our data suggest that working under a rotating two-shift system, which has a longer night shift, is associated with an elevated risk of sleep problems for nursing home caregivers.

Effect of mental stress on hemoglobin dynamics in trapezius muscles.

We examined the effect of mental stress on hemoglobin concentrations in the trapezius muscles of 20 healthy, non-smoking women. The participants held their arms out horizontally (physical stimulus) while standing upright for 1 min with 5 min intervals of seated rest, or performed Stroop's Color Word Test (mental stimulus), or both simultaneously. We measured heart rate, muscle tissue hemoglobin (oxy-hemoglobin, OxyHb; deoxy-hemoglobin, DeoHb; total hemoglobin, TotHb) concentrations in, and obtained surface electromyograms from the right upper trapezius muscle. Changes in the hemoglobin concentration (DeltaOxyHb, DeltaDeoHb, DeltaTotHb) induced by physical and/or mental stimuli were calculated. Changes with physical stimulus alone were compared with those induced by physical plus mental stimuli using repeated measures ANOVA. The DeltaDeoHb with physical and mental stimuli was significantly lower (p=0.013) than that with the physical stimulus alone, whereas the DeltaOxyHb and the DeltaTotHb values did not significantly differ (p=0.281, p=0.230). This finding indicates that mental load affects DeltaDeoHb in the trapezius muscle. We think that mental stimulus might provoke a reduction in oxygen consumption by the trapezius muscle. Further investigations using a longer duration of physical and mental stimuli are required.

Job stressors and job stress among teachers engaged in nursing activity.

Teachers and staff members engaged in nursing activity experience more stress than other workers. However, it is unknown whether teachers engaged in nursing activity in schools for handicapped children experience even greater stress. This study evaluated job stressors and job stress among such teachers using a cross-sectional study design. The subjects were all 1,461 teachers from all 19 prefectural schools for handicapped children in Shizuoka Prefecture, Japan. We used a brief job stress questionnaire for the survey and 831 teachers completed the questionnaire. Job stressors among teachers engaged in nursing activity were compared with those among teachers not engaged in nursing activity. Job stress among such teachers was estimated by the score for total health risk, and was compared with the score in the Japanese general population. Male and female teachers engaged in nursing activity had a significantly higher level of job stressors for physical work load and job control compared with those not engaged in nursing activity. The scores for total health risk among male and female teachers engaged in nursing activity were 102 points and 98 points, respectively. These scores were not markedly above 100 points which is the mean score in the Japanese general population.

[Exposure to whole-body vibration of forklift truck operators in dockyards--actual exposure in Japan and evaluation by EN 13059].

Low-back disorders are well documented as occupational hazards among forklift truck operators. The potential risk factors that may lead to low-back pain include exposure to whole-body vibration (WBV). In Europe, test methods were developed to evaluate WBV in industrial trucks, and the European Standard which defines the methods has been published. We measured the vibrations of forklift trucks operated in the Hanshin harbour area adopting procedures based on the CEN test and report the evaluation results. If the WBV magnitudes of the ride on forklift trucks in the workplace were less than or comparable to those in the CEN test, the CEN test could be considered useful for the risk assessment of forklift truck operators exposed to WBV. In order to verify the applicability of the CEN test to the evaluation of WBV exposure in the field, we conducted measurements of the WBV of four forklift trucks for 19 d. The trucks had already been examined by the CEN test. The truck velocity, driver position (sitting or not), and gear lever position were also measured, and video footage was obtained for the study. The results indicate that the vertical WBV magnitudes of the four forklift trucks were below the CEN test values. No dominant WBV direction was observed on any of the measurement days. The Health value (obtained by combining the values determined from the vibration in orthogonal coordinates) was comparable to that from the CEN test for one truck. The values for the other three trucks were lower. The data obtained for three forklift trucks were analyzed in each operating condition. The vertical WBV magnitudes and Health values for the three trucks were below the CEN test values when the trucks were travelling forwards with a load. The WBV in the anterior-posterior direction had the largest adverse effect on the human body of the three orthogonal directions when the trucks were used for loading and unloading. The results suggest the CEN test can be applied to the evaluation of exposure to WBV from forklift trucks operating in the vicinity of the Hanshin harbour. It was observed that the anterior-posterior WBV is considerable, mostly through exposure occurring in the lifting mode. However, the CEN test is based on the travelling mode, and further WBV measurements under real working conditions with exact descriptions of detailed work situations and operating conditions are required.

Prevalence of and risk factors for low back pain among staffs in schools for physically and mentally handicapped children.

The objective of this study is to clarify the prevalence of and risk factors for low back pain (LBP) in schools for physically and mentally handicapped children. This study design is a cross-sectional study. The subjects included were 1,869 staff members from 19 prefectural schools for children in Shizuoka Prefecture, Japan, which included schools for the blind, deaf-mutes, physically handicapped, and mentally retarded children. A total of 975 subjects completed two postal questionnaires which included morbidity, demographic factors, nursing activity, and psychosocial factors. The answer rate was 52%. The one-month prevalence of LBP was 45%. According to the classification of nursing activity, assistance in movement 1.67 (95% CI 1.27-2.14), excretory function 1.45 (1.11-1.88), and feeding 1.44 (1.10-1.90) showed significant increases in the odds ratio. The adjusted odds ratio significantly increased by 2.35 (1.78-3.11) in the group with depression symptoms as well as in the group with job stressors such as quantitative, qualitative, and physical work loads, job control, utilization of technique, interpersonal conflicts, and degree of satisfaction with their work/home life.

Dependency of temporary threshold shift of vibratory sensation in fingertip on 1/3 octave-band hand-arm vibration exposure period.

OBJECTIVES: To investigate the dependency of temporary threshold shift of vibratoty sensation (TTS(v)) in fingertip on hand-arm vibration exposure period. METHODS: Six healthy students were instructed to grip a vibrating or nonvibrating handle in the experimental room. The gripping force was 40 N. The vibratory sensation threshold at 125 Hz was measured before and after the exposure in the exposed middle fingertip. The exposure vibration was vertical and the 1/3 octave-band vibration with had a central frequency of 200 Hz and an intensity of 39.2 m/s(2). The exposure periods were 8, 15, 30, 60, 120, 240 and 600 s. TTS(v,t) was evaluated as the difference in vibratory sensation threshold between immediately before and t seconds after the exposure. RESULTS: TTS(v) recovered exponentially as in several previous studies and its use enabled us to estimate the time constant and TTS(v,0). TTS(v,0) with vibration exposure was significantly larger than that without it. The regression analysis of the relationship between vibration exposure period (T) and TTS(v,0) (T) for each subject confirmed the good fit of the equation TTS(v,0)(T)=B(0)+B(1) (*)Log(10)(T), where B(0) and B(1) are the calculated constants (adjusted R(2)=0.56-0.87). The time constants did not show such a clear dose effect relationship of exposure period as TTS(v,0). CONCLUSION: The dependency of TTS(v,0) on vibration exposure period was asymptotically proportional to the logarithm of gripping period. To more quantitatively confirm the relationship of the time constants for recovering time course of TTS(v), it may be necessary to improve the measurement method for TTS(v).

Neuro-physiological study in persons with cervico-brachial disorders.

OBJECTIVES: In order to clarify the involvement in the nervous system by cervico-brachial disorders (CBD), we performed neurophysiological tests on the peripheral nervous system (PNS) and the central nervous system (CNS) in patients with CBD, subclinicals and healthy controls. SUBJECTS AND METHODS: We employed antidromic sensory nerve conduction velocities (SCV) in the hands and fingers for PNS function and event-related potentials (P300) for CNS higher function. Subjects for SCV were 27 patients, 14 workers with sign and symptoms of CBD (subclinicals) and 22 controls. Subjects for P300 were 23 patients, 12 subclinicals and 10 healthy controls. CONCLUSIONS: In the PNS, since significant reduction SCV in the index finger among patients was observed, we could not find clear evidence of decrease of conduction function. In the CNS, since the latencies and amplitudes of auditory P300 among patients were significantly delayed and decreased, respectively, and the latencies significantly correlated with symptom score, it was suggested that the dysfunction of the cognition and memory function. However, further investigation is necessary to clarify the mechanism.

[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.