World at work: bricklayers and bricklayers' assistants.
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Construction Materials↗
Biomedical subjects
H F van der Molen
Publications and source records attributed to H F van der Molen.
Evaluation of methods to assess push/pull forces in a construction task.
The objective of the present study was to determine the validity of methods to assess push/pull forces exerted in a construction task. Forces assessed using a hand-held digital force gauge were compared to those obtained using a highly accurate measuring frame. No significant differences were found between the methods, except for peak push forces, for which the forces assessed with the force gauge were significantly lower than those assessed with the measuring frame. When the construction task was reproduced close to the actual workplace by simulation against a fixed object using the force gauge, all exerted forces on the force gauge were significantly lower than those on the measuring frame, except for mean pull forces. When self-reports were compared to the exerted forces on the measuring frame, the construction workers overestimated the exerted push/pull forces by 50%. In conclusion, when applied for direct measurements, the force gauge can be used to validly assess push/pull forces at the workplace.
Adult↗
History and future of ergonomics in building and construction.
In this paper an overview is given of what has been done in the field of ergonomics on behalf of the building and construction industry. Characteristics of the building and construction are given in relation to working conditions. The developments within this branch of industry are described in view of perspectives for a better future.
Construction Materials↗
Functional characteristics of rat gastrocnemius and tibialis anterior muscles during growth.
Several morphological and functional characteristics of the rat gastrocnemius medialis and tibialis anterior muscle were studied in young, adult, and old rats to assess the influence of growth. Antagonist muscles were studied to determine how changes of muscle architecture and functional characteristics are influenced by the demands of increased body weight and by the specific roles of these muscles in locomotion. Both muscles change drastically, for instance, in muscle length, volume, physiological cross-sectional area aponeurosis length, and their muscular geometry changes allometrically for both muscles. The relationships between muscle length, distance between origin and insertion, tendon length, and tibial length also change with growth. Both muscles are rather pennate, so that the increase of physiological cross-sectional area is a major factor in the determination of muscle length. No significant difference could be shown for fundamental physiological characteristics (i.e., functional characteristics normalized for muscular dimensions such as maximal work per unit volume). The changes of morphological and functional variables of both muscles parallel each other as is apparent from the index of antagonist characteristics, which is constant for all variables studied with the exception of muscle volume and tendon length. Consequently, the considerable and similar changes of TA and GM morphology and functional characteristics that take place during growth from approximately four weeks postnatally is not caused by changes of muscular material but by changes of the amount and architectural arrangement of the material involved.
Animals↗