Musculoskeletal disorders (MSDs) are twice as high among females compared to males and as the work force ages and sedentary low-force work (e.g. computer work) becomes more prevalent, the concern for MSDs for older workers is growing. The reason why females in general, and specifically older females, are more susceptible to MSDs is currently unknown. It is reasonable to assume inherent gender and aging differences in biological and/or physiological expressions to be factors.
Muscle fatigue is a frequently discussed physiological change connected with the development of MSDs. Therefore, monitoring fatigue would be a relevant biomarker for exposure to low-level repetitive work. However, detecting such fatigue is difficult by conventional means. Electrical stimulation (ES) of the muscle proves to be an effective and sensitive method for detecting muscle fatigue resulting from low-force activity.
Disturbed microcirculation and oxidative metabolism are suggested to be associated to MSDs, which encourages monitoring hemodynamic and/or oxygenation patterns before symptoms occur. Near infrared spectroscopy (NIRS) is a non-invasive technique for monitoring local muscle oxygenation and blood volume, and therefore a useful tool for studying metabolic and hemodynamic function.
In this study we will combine ES and NIRS to determine the onset and recovery of muscle fatigue and hemodynamics for young males and females, as well as for older females for low-force work. Such data can serve as important fundaments for understanding why gender and aging play a role in the incidence of MSDs, and in a wider perspective can give insight for designing primary prevention methods to reduce the occurrence of such injuries.
Understanding muscle hemodynamics, oxygenation and fatigue in response to computer work may provide insight into mechanisms behind work-related disorders. Detecting changes in the underlying physiology of the muscle before the onset and development of an injury, could lead to primary prevention methods to reduce the occurrence of such injuries.
A peek in the lab (link to pictures)
Pete Johnson, Environmental and Occupational Health Science, University of Washington, Seattle, Washington, USA
Bente Jensen, Institut för Idrottsmedicin, Köpenhamn universitet
Svend Erik Mathiassen