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.
Use 20 % energy
-measure
- Break
- Break
• 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