Work Capacity
Work Capacity
  • Depends on Max. Heart Rate
  • Type of Work
  • Duration of Work
Type of Work
  • Dynamic - using both pumps (Primary and Secondary)
  • Static - not using both (not using secondary)
    - only 2/3 of the work done using dynamic
Max Average Heart Rate
  • 220 -age = max heart rate average (ex 30 year old will have max heart rate of 190)
  • Older the person, lower the max heart rate
Example
190 heart rate for a 30 year old person or 16 kilocalaries per minute (energy unit is calories) 
Duration of Work
  • Maximum Physical Work Capacity 
  • Short Term = 3x Long Term
  • BINK Curve - decide between short term and long term. 
    - Time working on job
    - MPWC x Percent of Aerobic Activity
Note
Description
Measuring Job Metabolism Energy Requirements
Air volume 
Measure of O2 Consumption Rate
  • Use Conversion O2 -> energy 
  • Most reliable
Cons:
  • Cumbersome
  • Expensive
  • Not convenient
Heart Rate
Pros:
  • Easy to use
Cons: 
  • Not very reliable 
  • Heart rate is affected by a lot of things. 
Macro Studies
Using table values to compute energy expenditure for whole job
Micro Studies
  • Use of prediction equations based on elementary tasks
  • More precise and accurate
  • Time consuming
Conversions
  • 21% of air intake is oxygen
  • For every liter of oxygen, we convert about 5 kilocalories of energy
Heart Rate Calibration
  • Standard procedure to measure heart rate: 
    - Relax, measure.
    - Treadmill/Bike
       Use 20 % energy
     -measure
    - Break
    - Treadmill use 40%
    - Break
    - Treadmill use 80%
  • Collect data points, measured O2 estimate of aerobic energy expenditure vs Heart rate
Note
Description
Equation to Use
Ejob = (Sum(Eposi * ti) + Sum(Etaskj) ) /T

Where
  • Ejob = avg energy expenditure rate of the job (Kcal/min)
  • Eposi = Metabolic energy expenditure rate necessary to maintain the posture (Kcal/min)
  • ti = time duration of the ith posture
  • Etaskj = net metabolic energy expenditure of the ith task in steady stat (Kcal)
  • T = time duration of the job
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