The aim of this study is to obtain an understanding of the subjective discomfort of working postures and the degree of physical effort these postures give rise to. 31 students have rated their perceived exertion on Borg's scale (1982) based on a collection of photographs of different work postures of varying complexity, including a kinaesthetic description. Each one of the 78 postures was held for 45 seconds, with rated perceived exertion (RPE) given after 15, 30 and 45 seconds. The whole test series was repeated twice. The results show that it is possible to evaluate different body postures by RPE achieving a total reliability alpha-value over 0.96. Despite the fact that the rating pattern between the different postures was the same for all subjects, it is shown that each person assessed according to a certain individually-influenced pattern. A certain person can for example, deviate consistently towards higher values on Borg's scale, a so-called "high rater". Finally, the different postures were grouped according to how the ratings changed in time (regression slope between the RPE's after 15, 30 and 45 seconds). The third-cluster, which showed a high basic rating-level and the greatest regression slope, included only extreme outer limits of movement. This indicates that the outer limit postures have a tendency to static load and need to be studied by more additional methods when remaining unchanged even for short periods.

Adult↗

PubMed1986

With what degree of precision can voluntary static muscle force be repeated?

The aim of this investigation was to get an apprehension of the capacity of repeating voluntarily exerted static forces in a row without visual feed-back in three situations viz. two-hand-lift, foot pedal press and thigh-raise. Seven subjects participated. It seems that the degree of precision is approximately a little below 10%.

Biomechanical Phenomena↗

PubMed1985

[Leonardo da Vinci as anatomist].

Explore the source record for details and available documents.

Anatomy↗

PubMed1982

The effect of vibration on the skeleton, joints and muscles. A review of the literature.

Owing to the elasticity and plasticity of the skeleton, joints and muscles, the musculoskeletal system is capable of absorbing and damping mechanical vibration without damage as long as the vibration level is within tolerable limits. However, technical developments have led to the exposure of many people to intolerable variation levels with destructive changes as a result. These injuries to the musculoskeletal system continue to be the subject of research interest. Initially, the joints and joint complaints attracted the greatest attention. Vibration damping takes place mainly in the joints. The incidence of destructive joint changes has been examined in comprehensive clinical, epidemiological and radiographic studies, mainly concentrating on the joints of the hand and arm. The response of muscles to vibration is often expressed in the form of a tonic vibration reflex (TVR) which arises as a result of stimulation of the muscle spindles and therefore resembles the classic tonic stretch reflex. There is increased muscular activation for stabilisation of the joint positions, especially during whole-body vibration. Studies have also disclosed how vibration affects body equilibrium and equilibrium control and how vibration can elicit muscle pain, cramps and reduced muscular strength.

Journal Article↗

PubMed1980

A back and lift test.

In addition to the standard medical examination, a back and lift test has been introduced in the hiring of new employees. 100 men have been tested to date. Only people with no history of back trouble were tested. Body height and weight were measured and the isometric capacity of the back extensors and the strength of abdominal musculature were measured with a Darcus dynamometer. A series of lifts with gradually increasing weight were performed in order to find the subject's 'acceptable weight'. The correlation coefficients for these different test variables was consistently poor, and thus it is not possible to predict a person's true lifting capacity from knowledge of muscle strength, height and body weight. The subjects stood upon a force plate during the lifts, which recorded the vertical and horizontal forces, and the force of inertia exerted by the subject during the lift could be calculated. The activity in the back extensors, rectus abdominis and external oblique muscle was recorded. The flexibility of the lumbar spine was calculated.

Journal Article↗

PubMed1978