| Titre : | The stress of lifting when seated | | Type de document : | texte imprimé | | Auteurs : | H. Boudrifa, Auteur ; B. T. Davies, Directeur de thèse | | Editeur : | Birmingham [Royaume-Uni] : University of Birmingham | | Année de publication : | 1984 | | Importance : | 289 f. | | Présentation : | ill. | | Format : | 30 cm. | | Note générale : | Thèse de Doctorat : Génie Mécanique : Birmingham, University of Birmingham : 1984
Bibliogr. f. 290 - 307 . Annexe f. 309 - 319 | | Langues : | Anglais (eng) | | Mots-clés : | Lifting
Backrest inclination
Safe weight limits | | Index. décimale : | D003684 | | Résumé : | This thesis is concerned with studying the stress of lifting when seated. The investigation looks at some workplace aspects, starting with the effects of the backrest inclination, the lumbar and thoracic supports on the intra-abdominal pressure and back muscle activity. The investigation is then extended to the effect of the seat surface inclination as well as the table height, to find possible ways to minmise the stress of lifting when seated. Qther postures concerned in daily life activities such as bending or rotation of the trunk, moving a weight away or towards the body in the middle or at either side, and moving a load from the middle to the side and side to middle, or from left to right and vice versa. The main part of this project is concerned with setting safe weight limits for lifting when seated, not only with the back straight but also in other industrial or daily life circumstances such as lifting a single load with two hands when bending forward or when lateral flexion and rotation are involved, lifting with the right or left hand when either the back is straight or bent forward, and lifting with either left or right hand or both hands when a backrest is used. It was found that the IAP and iEMG were reduced when either the backrest inclination, or the lumbar support, or the thoracic support, or the seat surface inclination, is increased, and when the table height is decreased to elbow level. Lifting from the middle was found to induce less IAP or iEMG than lifting from either the left or right side. Both parameters increased as bending of the trunk increased. The IAP is also less when a weight is moved from the middle to either left or right as comparing to moving the same weight from either sides to middle. The IAP was also less when a weight is moved away from the body either in the middle or left or side compared to moving the weight towards the body. Safe weight limits are set for lifting with the right or left hand, or both hands, either with the back straight or bent forward or when a backrest is used. The results are in general agreement with those obtained by Davis and Stubbs (1977a, b, and 1980). The size of the weight was found to have no effect on the IAP and iEMG, either when lifting with back straight or bent forward, whilst sitting or standing, but when a psychophysical approach was used, it was evident that subjects found it easier to lift loads that varied in length (across the bodu) than width (in front of the body), and thought that the smallest box was the heaviest and the largest box being lightest. Bending of the trunk forward also increased truncal stress as did standing. |
The stress of lifting when seated [texte imprimé] / H. Boudrifa, Auteur ; B. T. Davies, Directeur de thèse . - Birmingham (Royaume-Uni) : University of Birmingham, 1984 . - 289 f. : ill. ; 30 cm. Thèse de Doctorat : Génie Mécanique : Birmingham, University of Birmingham : 1984
Bibliogr. f. 290 - 307 . Annexe f. 309 - 319 Langues : Anglais ( eng) | Mots-clés : | Lifting
Backrest inclination
Safe weight limits | | Index. décimale : | D003684 | | Résumé : | This thesis is concerned with studying the stress of lifting when seated. The investigation looks at some workplace aspects, starting with the effects of the backrest inclination, the lumbar and thoracic supports on the intra-abdominal pressure and back muscle activity. The investigation is then extended to the effect of the seat surface inclination as well as the table height, to find possible ways to minmise the stress of lifting when seated. Qther postures concerned in daily life activities such as bending or rotation of the trunk, moving a weight away or towards the body in the middle or at either side, and moving a load from the middle to the side and side to middle, or from left to right and vice versa. The main part of this project is concerned with setting safe weight limits for lifting when seated, not only with the back straight but also in other industrial or daily life circumstances such as lifting a single load with two hands when bending forward or when lateral flexion and rotation are involved, lifting with the right or left hand when either the back is straight or bent forward, and lifting with either left or right hand or both hands when a backrest is used. It was found that the IAP and iEMG were reduced when either the backrest inclination, or the lumbar support, or the thoracic support, or the seat surface inclination, is increased, and when the table height is decreased to elbow level. Lifting from the middle was found to induce less IAP or iEMG than lifting from either the left or right side. Both parameters increased as bending of the trunk increased. The IAP is also less when a weight is moved from the middle to either left or right as comparing to moving the same weight from either sides to middle. The IAP was also less when a weight is moved away from the body either in the middle or left or side compared to moving the weight towards the body. Safe weight limits are set for lifting with the right or left hand, or both hands, either with the back straight or bent forward or when a backrest is used. The results are in general agreement with those obtained by Davis and Stubbs (1977a, b, and 1980). The size of the weight was found to have no effect on the IAP and iEMG, either when lifting with back straight or bent forward, whilst sitting or standing, but when a psychophysical approach was used, it was evident that subjects found it easier to lift loads that varied in length (across the bodu) than width (in front of the body), and thought that the smallest box was the heaviest and the largest box being lightest. Bending of the trunk forward also increased truncal stress as did standing. |
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