Manual material handling performance and fatigue

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The long term objective of the applicant’s research program is to understand fatigue-related influences on neuromuscular control patterns of work tasks in men and women in order to guide best work practices (i.e., work:rest guidelines), work productivity (i.e., task organization) and worker safety. Manual material handling (MMH) such as lifting are complex human movements requiring the organization of multiple degrees of freedom in the neuromuscular system of the upper and lower extremities. Movement patterns are the result of individual muscles and neuropathways working collectively to achieve a functional outcome to meet system constraints. It has been suggested that the inability to synergistically orchestrate the many degrees of freedom present in the neuromuscular system is a hallmark of pathological movement patterns. In much the same vein, neuromuscular coordination may be compromised due to neuromuscular fatigue resulting in modification of movement patterns required to complete the task. Previously NSERC funded research began to develop an understanding of the kinematic, kinetic and neuromuscular adaptations made when challenged by fatigue either associated with prolonged lifting, back fatigue or arm fatigue. Using a principle component analysis approach to assess lifting waveforms and relative joint phase analyses, accommodations to the coordination of joint movements were realized. The understanding of the movement accommodations were further strengthened through neuromuscular analysis between tired and ‘fresh’ muscles during the prolonged lifting activities. To date, research has investigated the impact of different lifting activities in isolation where lifting only is considered the major work task. In many work environments require workers to sit for a long period of time and then lift heavy loads upon arriving at the intended destination (EMS, fire, police, transportation/truck drivers). The five-year granting cycle intends to build off the work of the current research projects and has three major research objectives. The first is to use the PCA modeling approach to discriminate the kinematic (segment motions); kinetic (shoulder, thoracic and lumbar spine joint loading); and coordination (electromyographic monitoring of shoulder and back musculature patterns) motion profiles over the entire lifting cycle of absolute loads between men and women. This will better inform the challenges associated in the workplace related to gender differences during fatigued states. The second objective is to determine the lifting accommodations related fatigue and tissue stiffness related to prolonged sitting prior to lifting. The third objective is to explore the use of a dermoskeleton as a means to mitigate the effects of fatigue during prolonged lifting activities.