INSY 3020

Work Physiology

Dr. Robert E. ThomasIndustrial & Systems Engineering Department

Auburn UniversitySpring 2005

ANTERIOR POSTERIOR

Systems Most Relevant To Work Physiology

• Muscular

• Cardiovascular

• Respiratory

• Nervous

Types of Muscle Tissue

- Skeletal

- Cardiac

- Smooth

Muscle System Functions

• Movement / Posture

• Circulation

• Blood Pressure

• Food Movement

• Heat Production

• Breathing

• Expelling of Waste Products

Skeletal Muscle Motor Units

“The functional unit of neuro-muscular control of movement. It consists of an anterior motor neuron in the spinal cord, the nerve fibers that innervate muscle cells, and junctions between the nerve and muscle cells.”

Physiology vs. Work Physiology

Physiology

The study of the functions of the body parts. ie. How the body parts work.

Physiology Vs.. Work Physiology(cont’d)

Exercise / Work Physiology

The study, description, evaluation, and explanation of the physiological changes in the human body resulting from either a single or repeated series of exposure to work stresses.

Exercise Physiology vs. Work Physiology(cont’d)

Primary differences are in the target populations and in some assumptions about where and how they are working.

Exercise Physiology

• Goal: Maximize the physiological efficiency of the target population.

• Target Population: Fit, healthy, young, and motivated.

• Environment: Usually optimum or controlled.

Work Physiology

• Goal: To ensure worker can perform task efficiently and safely within the environment.

• Target Population: All kinds of people.

• Environment: Usually not optimal or controlled (noise, heat, etc.)

How Do We USE Work Physiology?

• To enhance EFFICIENCY – To monitor energy expenditure and avoid excess fatigue

• To ensure SAFETY - do not push people beyond their physical limitations.

Example Uses of Work Physiology• Can the job be safely accomplished by people----

for the required duration using prescribed tools and methods.

• Which methods are easier?

• Can a specific individual perform a job safely?

• How should jobs be ranked (for compensation & work-rest cycle purposes)?

EFFICIENCY

Heart Rate Measurements

• Palpation

• Electronics

• Light

• Sound

Reference Konz, pg. 123

Effects of Aging

• Decline starts at about 30 years

• Progressive loss of muscle mass

• Lost muscle tissue replaced by fat

• Decrease in maximal strength

• Diminishing of muscle reflexes

Fatigue

Two general types:

• Central . . . Nerve related

• Peripheral . . . Muscle related

Efficiency Lesson

• Use heart rate to evaluate energy usage

• Design work for light to moderate energy expenditure

SAFETY

Heart Rate

• Max HR (Beats/Min)= 220-Age (In Years)

• Criteria: Rest: 65-85 BPM Not Consistently Above (Moderately

Heavy Work): 120-150BPM

Work –Rest Cycles

Work-Rest Cycles

AIHA CRITERIA

For Work Rest Cycles

Summary

• Ergonomics uses physiological responses to address both efficiency and safety issues

• Responses of the respiratory and cardiovascular systems are are most accessible

• Oxygen uptake and Heart Rate are the most frequently used measures…..but particularly heart rate

• Work -Rest Cycles are used to practically achieve efficiency and safety goals when work varied and includes is moderate to heavy components