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• Work Physiology

   Muscle contraction

   metabolism & meeting the demands

   workload & energy requirements

   efficiency

  Work-rest Schedule
• Sources of energy during the first few minutes of moderately heavy work. High-energy phosphate stores (ATP and CP) provide most of the energy during the first seconds of work
• Anaerobic glycolysis supplies less and less of the energy required as the duration of work increases and aerobic metabolism takes over.
• Basal metabolic rate - the amount of energy needed to keep the body functioning

  Big people > small people

  men > women

  younger > older

  Any activity requires additional energy
• Occupational EMG • Electrodes placed over muscle belly • Raw EMG signal amplified and recorded • EMG processing: – Full-wave rectify & lowpass filter – Indirect quantification of muscle force
• - Phosphagen phase does not care about food, energy is already stored in the ATP and you use it and then it is gone. Energy for immediate application
• - Aerobic Phase: Always need food and oxygen

  - Anaerobic Phase: If you don’t have the above then you go to this phase
• Everything is directly or indirectly affected by the food and oxygen
• If you can measure oxygen consumption then they can determine how much work the person has done in Kcal
• Energy expenditure is 5x the oxygen consumption
• If my max capacity is 100% then NIOSH says I should never pass 33% in 8 hours
• Demand of static job is always high but time it takes for muscles to go back to normal is reduced
• Borg scale is used everywhere in research studies. Compare different work processes
• Borg Scales

  Limitations is people lying on these scales or just being over dramatic. If it is done honestly then it is very valid for identifying the impact jobs have on certain parts of the body
• Fatigue Endurance graph is based on physical not mental. As the time increases the strength of the person is reduced
• In dynamic jobs people can take breaks which is why we want the job to be dynamic and not static to keep them moving and promote blood circulation in the body
• Spitzer’s and Murrel’s model is the easiest and most used model for determining how much rest is required for someone to be able to complete a job. ONLY FOR DYNAMIC
• Murrel is for heavier job and Spitzer is for medium
• -        Murrel usually not used in most workplaces in Canada
• o   Myo = muscles

  o   Graphy = graphical
• -        EMG – Electromyography
• -        EMG amplifies the message from the muscles. These messages can tell you if the muscles is tired or not. Measures fatigue
• EMG -        Not used in workplaces only used in studies
• -        Issues with EMG if used in occupational studies and could also be research studies

  o   Sweat

  o   They come off very easily
• -        . If the muscles are not acting to keep you straight then the pressure is on the discs
• -        As the EMG activity increases the force that you can lift is increased and the relationship is almost linear. Scientists used it to show how much force is applied to the muscle