Biomedical subjects

Gert-Ake Hansson

Publications and source records attributed to Gert-Ake Hansson.

6 recordsLinked to original sources

PubMed2005

Validity of self-assessed reports of occurrence and duration of occupational tasks.

To obtain quantitative estimates of the physical workload in epidemiological and intervention studies of musculoskeletal disorders, there is a need to extend task based exposure data to job exposure profiles. For this purpose a work task diary was developed and evaluated. This was validated against direct observations of a day's work for twenty-two female office workers and twenty female hospital cleaners. There was a good agreement regarding the occurrence of the main tasks. However, the less time-consuming tasks were under-reported. Moreover, about two thirds of the changes between tasks were not reported. The difficulties of defining tasks that function as occupational entities seems to be a major reason for the lack of agreement. The underestimation of the duration of breaks/pauses was most pronounced for the cleaners. Still, the diary would be useful for the calculation of job exposure, by time-weighting task exposure data, when the tasks and/or their duration vary between days.

Adult↗

PubMed2003

Increases in local pressure pain thresholds after muscle exertion in women with chronic shoulder pain.

OBJECTIVE: To examine the relation between muscular tenderness and local muscular fatigue. DESIGN: Before-after trial, measuring pressure pain thresholds and signs of local muscular fatigue by using surface electromyography before, after, 10 minutes after, and 20 minutes after intervention. SETTING: University rehabilitation department in Sweden. PARTICIPANTS: Nineteen female hospital cleaners with unilateral chronic shoulder pain for 1 year. No previous trauma, surgery, or signs of systemic or neurologic disease. INTERVENTION: Static abduction endurance test with submaximal unilateral activation of the trapezius and deltoid muscles. MAIN OUTCOME MEASURES: Pressure pain thresholds and electromyographic fatigue parameters (root mean square [RMS]; mean power frequency [MPF]). RESULTS: Mean normalized pressure pain threshold values increased significantly (95% confidence interval [CI]) and lasted for 20 minutes: in the trapezius, threshold values increased to 115% to 120% (95% CI, 100%-140%; P=.04-.05); and in the deltoid, the threshold increased to 112% to 115% (95% CI, 100%-130%; P=.02-.05). Development of significant electromyographically defined fatigue was seen: in the trapezius, the RMS increased to 130% (95% CI, 119%-141%), and in the deltoid, the MPF decreased to 78% (95% CI, 74%-82%), but normalized within 15 seconds to 10 minutes. CONCLUSION: Lasting bilateral increases in pressure pain thresholds but transient local muscular fatigue were seen after a unilateral static endurance test. The sensitivity of the sensory nervous system may change during a static muscle contraction and sometimes contributes to a localized sensation of numbness.

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PubMed2003

Highly repetitive work operations in a modern milking system. A case study of wrist positions and movements in a rotary system.

With the use of electrogoniometers wrist positions and movements were measured in 13 milkers while working in a modern rotary milking system. The rotary system put considerable demands on the wrists and hands regarding both velocities and repetitiveness. Values were found close to those described in other repetitive industrial work with high risk of wrist and hand disorders. For the right hand the repetitiveness was 0.57 Hz and 0.46 Hz for the left hand. In addition, the median value (50th percentile) of the angular velocity distribution was also high, being 36 degrees /s for the right hand and 26 degrees /s for the left, and with respect to the peak value (90th percentile) the corresponding values were 155 degrees /s and 135 degrees /s, respectively. Furthermore, when milking in the rotary system, there was less possibility to hold the hands still than in the other milking systems. The right hand rested only 1.4% of the milking time and the left only 1.0%. The hands were therefore moving throughout almost the entire milking procedure. High velocity, repetitiveness and fewer opportunities for rest are risk factors that might lead to disorders in the wrists and hands. Regarding wrist positions, the left wrist was held in a more dorsiflexed position than the right, 37 degrees and 29 degrees, respectively. Compared with tethering and loose-housing parlour milking, the wrist positions were, however, improved in the rotary system. When introducing new milking systems these negative effects on wrist and hand movements must be borne in mind in order to minimize the prevalence of wrist and hand disorders.

Adult↗

PubMed2002

Carpal tunnel syndrome in repetitive work: a follow-up study.

BACKGROUND: The Project on Research and Intervention in Monotonous work (PRIM) studied Danish workers for 3-4 years to determine the effects of monotonous work. The present study is a subset of that cohort and compares prevalence and incidence differences of carpal tunnel syndrome (CTS) between workers with highly repetitive work tasks and workers with varied work tasks. METHODS: The baseline study included 731 participants. Follow-up examinations were performed after 6 and 18 months. The CTS diagnosis was based on symptom interviews and nerve conduction tests. The repetitiveness levels were determined with electrogoniometers and observation of cycle times. RESULTS: The overall prevalence of CTS was 1.6% on the working hand and 0.7% on the other hand. There was a significantly increased risk of CTS for every 10-hr increase of repetitive non-forceful work (OR = 1.84; 95% CI = 1.06-3.19) on the working hand. This result, however, was based on few cases and a low prevalence in the control group. The overall annual CTS incidence was 0.62% on the working hand and 0.44% on the other hand. For the repetitive work tasks, the mean power frequencies ranged from 0.53 to 0.79 Hz. CONCLUSIONS: In the baseline study, highly repetitive work was associated with CTS. The CTS incidence was too low to perform any analyses of exposure differences.

Adult↗

PubMed2002

Physical workload on neck and upper limb using two CAD applications.

The aim was to evaluate (1) the physical workload on neck and upper limb in computer-aided design (CAD) work; (2) the impact of two applications (PROFESSIONAL-CADAM and PRO/Engineering) and (3) two input devices (computer mouse and keyboard), as well as (4) sitting and standing work positions. Fifteen CAD operators were interviewed and examined physically. For nine subjects, the physical workload was measured: electromyography (EMG) of trapezius and forearm extensor muscles, inclinometry of the head, the upper back and upper arms, as well as wrist goniometry. The muscular load was low in CAD work, but the inter-individual variation was considerable. Neither the positions were extreme, nor the movements. The applications, per se, did not have a large impact on the workload, but because of the need for different input devices the effect was strong. Using a keyboard meant higher angular velocities than using a mouse. Hence, when choosing a new software, which requires mainly a mouse as input device, this has to be balanced against the risk of disorders.

Adult↗

PubMedDate not supplied

Efficient one-day sampling of mechanical job exposure data--a study based on upper trapezius activity in cleaners and office workers.

This ergonomics exposure assessment study compared the efficiency of eight 1-day-only strategies, that is, the relationship between the number of data collected per subject and the precision of the resulting mean exposure estimate. Whole-day electromyographic recordings from the right upper trapezius muscle in 24 cleaners and 23 office workers were processed to give minute-by-minute values of gap time and jerk time-parameters representing the level and frequency dimensions of muscle activation, respectively. On-site observations provided data on time spent in each of eight exhaustive task categories in the job, seven of which were associated with activities during work, and the last comprising breaks. On average, sampling at fixed intervals without regard to tasks doubled efficiency as compared with random sampling, which in turn was several times as efficient as consecutive sampling. Stratified sampling according to the two broad categories, work and breaks, increased efficiency for random and fixed-interval sampling, but the gain was distinct only among cleaners (about 20%). The commonly used strategy in ergonomic studies of sampling consecutively for short periods within tasks was highly inefficient. Further classification of work into the seven subcategories resulted in marginal additional increases in efficiency; on average less than 2%. A decision algorithm is given for determining appropriate sampling strategies in different types of jobs.

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