Musc-ed - Use small muscles for precision Use large muscles...

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IE 327 1 IE 327 Introduction to Work Design Dr. Andris Freivalds Class #4
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IE 327 3 Ch. 4 – MUSCULOSKELETAL SYSTEM (and Work Design)
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IE 327 4 MUSCLE STRUCTURE Muscle and tendon Bundle of fibers Blood vessels Muscle fiber Myofibril Thick filament = myosin Thin filament = actin Sliding filament theory
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IE 327 5 FORCE-LENGTH RELATIONSHIP (Max strength at midrange)
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IE 327 6 Achieve max muscle strength at midrange of motion Where is midrange? Relaxed posture No muscle force Weightless astronaut in space Avoid extremes!!
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IE 327 7 FORCE-VELOCITY RELATIONSHIP Max muscle force with slow motion Use momentum to assist work Minimize fighting gravity
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IE 327 8 OPTIMIZE HUMAN STRENGTH Use optimum postures Use large muscles for power Avoid using back Design tasks so that most can do!
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IE 327 9 MUSCLE ENDURANCE Static hold Occlusion of blood flow Rapid fatigue Stay < 15% max Short, frequent work-rest cycles Dynamic work
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IE 327 10 MOTOR UNIT RECRUITMENT
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Unformatted text preview: Use small muscles for precision Use large muscles for power Power vs. pinch grip!! IE 327 11 CONTROL OF MOVEMENTS #1 Use lowest classification of movement Decrease difficulty of task distance target width IE 327 12 CONTROL OF MOVEMENTS #2 Pivot on elbow Curved motions Use both hands Begin and end motion simultaneously Move simultaneously to and from body Use natural rhythms Whole body = 17/min Whole arm = 35/min Forearm = 60/min IE 327 13 MINIMIZE EYE MOTION (Within normal line of sight) IE 327 14 KEY POINTS: Design work according to human capabilities and limitations For manipulative tasks: Dynamic motion rather than static holds Strength requirements < 15% max Avoid extreme ranges of motion Small muscles for speed and precision Large muscles for strength...
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This note was uploaded on 05/04/2010 for the course I E 327 taught by Professor Staff during the Spring '08 term at Pennsylvania State University, University Park.

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Musc-ed - Use small muscles for precision Use large muscles...

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