The effect of appraisers in estimating metabolic rate with the Edholm scale

A study was made of the appraisers' effect on the estimation of metabolic rate with the Edholm scale and a table of the ISO 7243 heat stress standard. The appraisers, five experienced and five inexperienced persons, estimated the metabolic rate of three different work tasks from videotapes. Analysis of variance indicated significant ( [Formula: see text] ) differences in the appraisers' recordings of the activities. The appraisers were grouped according to the similarity of the estimated values they gave. The groups thus contained both experienced and inexperienced appraisers, and it was not possible to classify the appraisers into experienced and inexperienced groups according to their earlier experience. The metabolic rates according to the Edholm scale were higher than according to the ISO 7243 table. The differences in metabolic rates given by the individual observers varied from 38 to 118 W/m(2). The variations in the estimation of metabolic rates were greater when the Edholm scale was used. This variation caused considerable variation also in the predicted mean vote, PMV index. It is recommended that the appraisers be selected carefully, because it is not possible to know whether a randomly selected appraiser is an 'average' or an 'extreme' appraiser without a test. Before conducting extensive field surveys where several appraisers estimate the metabolic rates, it would be useful to arrange training in order to calibrate the levels of the Edholm scale as well as ISO method among the appraisers because training clearly unified the estimation.     

When is light work heavy? Components of the physical workload of sewing machine operators working at piecework rates

Epidemiologists have associated the job of sewing machine operators with a high incidence of musculoskeletal and other health problems, despite its classifications as light work according to energy expenditure criteria. An ergonomic analysis was undertaken in a trouser factory in order to describe components of the physical load of this work: force exerted, repetitions, time allocation and postures. Work activity of ten operators was observed and timed in situ, and forces were measured with a dynamometer. The time required to sew one seam is very short, 10-15 s per trouser leg. This short cycle is repeated more than 1500 times during the work day, involving quasi-continuous movements of the same parts of the body. The fact that movements are repeated so many times means that small details of the task assume a great importance. During the work day, a substantial force is exerted, only part of which can be measured with current technology. By these measurements, operators lift an average 406.1 kg of trousers per day and exert an average total force of 2858.4 kg with the upper limbs and 24 267.9 kg with the lower limbs. The work posture is static: seated with upper back curved and head bent over the sewing machine. Movements of the upper limbs involve abduction and adduction of the shoulders while exerting a force. For the same task, there is considerable variation in the dimensions of workstations. Interviews were conducted to determine the types of musculoskeletal complaints. The components of work activity could be treated to these complaints and to existing epidemiological data on musculoskeletal problems among sewing machine operators. This type of detailed examination can be applied by health and safety personnel to identify task components which could be changed to minimize the probability of musculoskeletal problems.     

Variation in light scattering and water-holding capacity along the porcine Longissimus dorsi muscle

The meat quality of M. longissimus muscle was evaluated in 851 pigs by using the Fibre Optic Probe (FOP) at three sites in the muscle and in both halves of the carcass. A systematic difference between sites was found, with the lowest light scattering (indicating the best meat quality) in the mid-part of the muscle and higher light scattering in the anterior and posterior parts. A non-systematic variation was also observed, with the opposite pattern in some animals, even though it was not frequent. A negative influence of the shackling was found, yielding higher FOP values in the shackled half.

Drip loss measurements in the Longissimus muscle, taken from another 100 pig carcasses, were evaluated using three methods. Drip loss, too, showed a considerable variation along the Longissimus muscle, with minimum losses around the last rib. Repeatability estimates, calculated from two non-consecutive pieces of the Longissimus dorsi muscle from each carcass, varied from 0·4 when keeping samples vacuum packed for 2 days, to 0·5 when the samples were either kept in plain plastic bags for 2 days or in a meat container with a squared inset for 1 or 2 days.