This study is a subset of a larger body of research that examined shoulder time to fatigue during overhead work in an attempt to reduce the prevalence and impact of work-related musculoskeletal problems in the shoulder associated with overhead work, particularly during automobile assembly. Existing evidence suggests that shoulder injuries are diverse in terms of tissues affected and symptoms presented. Furthermore, the cause of these injuries is multifactorial. The work presented here assumes that musculoskeletal injuries of the shoulder mechanism are at least related to, if not caused by, fatigue localized to the shoulder musculature. While the exact relationship between fatigue and injury has not been clearly established, there is consensus among researchers that fatigue plays and important role. Muscular fatigue, therefore, is viewed as a surrogate measure of risk, and task design to avoid fatigue is seen as a rational method to minimize this risk. An experiment to determine the effects of tool weight on shoulder fatigue and performance during overhead work with work/rest cycles was performed. Times to fatigue were derived based on dependent measures including total task duration, controlled maximum muscle contractions, subjective ratings based on Borg's CR-10 RPE scale, electromyogram behavior (MdPF), and hand force performance measures. Experimental findings indicated that duty cycle (percentage of total task cycle time spent working) significantly affected task duration (p<0.0001), changes in maximum voluntary contraction values for the infraspinatus (p<0.05), and the minimum time for any shoulder muscle to fatigue as determined by changes in the EMG power spectrum (p<0.05). Time to fatigue for the mid deltoid as determined by changes in the median frequency of the EMG power spectrum was shown to change significantly (p<0.05) with change in tool weight. Large intersubject variation was observed for the dependent measures, which showed subjects experiencing different levels of fatigue while performing the same task. Limitations of the study and recommendations for future direction are also discussed. / Master of Science

L’objectif de cette recherche est double. Etudier les causes et conséquences du Burnout des soignants, dans un premier temps, et comprendre l’effet de la présence d’un jardin dans un secteur gériatrique hospitalier dans un second temps. Les infirmiers et aides-soignants de neuf services de gériatrie ont répondu à un questionnaire construit à partir des théories et échelles de Karasek et Theorell (1990), Siegrist (1996), Shirom (2004) et Kurorinka (1987). Ainsi, le Burnout est confronté aux facteurs psychosociaux, à la Vigueur (bien être) et aux douleurs physiques pour extraire les causes et conséquences de ce trouble psychologique. Ces mêmes équipes ont également participé à des entretiens de type « focus groups » et à des entretiens individuels semi-dirigés afin de s’exprimer sur leurs conditions de travail, ainsi que sur leur vécu et leur ressenti de la présence ou l’absence d’un jardin aménagé ou non aménagé dans leur environnement de travail. Ces équipes de soins appartenaient à trois types de services gériatriques : unité cognitivo-comportementale, soins palliatifs, soins de réadaptation. Les résultats principaux du questionnaire mettent en cause le manque de soutien de la hiérarchie comme aspect augmentant les risques de Burnout. Ce résultat est par la suite confirmé par les entretiens. De plus, le Burnout semble moins présent dans les services avec jardin que sans jardin, et il existe également une amplification de ce bénéfice dans les jardins thérapeutiques. On observe une sensation de Vigueur, tant physique que psychologique, plus importante dans les services avec jardin, et une tendance à l’augmentation des T.M.S. dans les services avec jardin thérapeutique. Cette constatation amène à s’interroger sur l'ergonomie du travail dans ce type d'environnement. En conclusion, le jardin apparaît comme un dispositif systémique favorable aux interactions de travail dans un lieu spécifiquement aménagé, permettant par là-même de combattre les sources de Burnout et de défendre la Vigueur. Il favorise l’épanouissement des soignants et la réduction du Burnout mettant tout de même en lumière un principe de précaution sur la charge physique et l’ergonomie de ce lieu à explorer / The aim of this research was twofold. Study the causes and consequences of Burnout caregivers, initially, and understand the effect of the presence of a garden in a hospital geriatric sector in a second time. Nurses and caregivers of nine geriatric services answered a questionnaire constructed from the theories and scales of Karasek and Theorell (1990), Siegrist (1996), Shirom (2004) and Kuorinka (1987). So, the Burnout is faced with psychosocial factors, the vigor (wellness) and physical pain to extract the causes and consequences of this psychological disorder. These same teams also participated in such conversations "focus groups" and semi-structured individual interviews to speak about their working conditions, as well as their experience and felt the presence or absence a arranged garden or undeveloped in their work environment. These care teams belonged to three types of geriatric services: cognitive behavioral unit, palliative care, rehabilitation care. The main results of the questionnaire involve lack of support from the hierarchy appearance as increasing the risk of Burnout. This result is confirmed by interviews. In addition, Burnout was a lesser incidence of Burnout in care services with a garden that those without a garden, and and there is also with an amplification of the benefit with specially-designed gardens. The feeling of strength, both physical and psychological, was less present when the care services did not have a therapeutic garden. A trend toward an increase in musculoskeletal disorders in services with a therapeutic garden versus no garden was observed. Upon analyzing the results, the authors recommend particular attention in the designing of hospital gardens in order to facilitate the ergonomics of nursing work. In conclusion, the overall results advocate the use of the garden as a systemic structure conducive to work interactions in a specially designed area by allowing the same to combat the sources of Burnout and defend Vigor. It encourages the development of nursing and reducing Burnout highlighting a precautionary principle on the physical load and ergonomics of this place to explore.