Toggle navigation
MYNDBOOK
Popular
My Library
Signup for free!
Login
Ergonomics
6.2 Applied Work Physiology: Localized Muscle Fatigue
Create your own note maps today! Sign up for a
free
account.
Graph Analysis
When muscles get tired, intensity (magnitude) (biceps brachii EMG power) goes up
Frequency goes down
Peak of curves on original graph will move up and left basically
Local Muscle Fatigue
Local Muscle Physiology
Technology/Tesign: Suits that amplify muscle strength
Motor Unit
One Nerve Fiber
and all muscle fibers innervated by that particular fiber
One nerve fiber can control multiple muscle fibers
Spinal nerve, spinal cord, cell body of neuron, nerve fiber, muscle fibers, myofibrils, sacromeres
Rohmert Curve
How long can muscle work without getting tired? What is going on?
Rohmert Curve
Description
Analysis:
Asymptote: If less than 15% then you can basically do the activity forever.
WHY does this drop so quickly?
Contracting muscles squeeze blood vessels and don't allow blood to flow
The mechanical action of static muscle contraction restricts
blood flow
through the muscle and forces anaerobic metabolism.
There is an increase, then a decrease in blood flow as grip contraction increases.
EMG - Electromyography
Measure electrical activity
EMG Electromyogram - "Electricity" "muscle" "graph"
Measuring LMF
Two ways: quantitative and qualitative
Both forms are indirect
Ask the workers!
Figure out where the workers are having issues
Subjective "discomfort" survey
Psychophysical
Reducing Local Muscle Fatigue
Couple ways.
Adequate Rest
Interjecting adequate rest between exertions
most common
Reduce Loads
Reduce sustained/static loads
Evaluate static work postures to reduce the load moments on the various joints
Use of Floor Mats
Soft and thick floor mats seem to reduce leg swelling and discomfort
Symptoms of Muscle Fatigue
Local hot/jabbing pain
Reduced motion control
Increased tremor
EMG decreases frequency increases amplitude
Increased strain injuries
Login
to remove ads
X
Feedback
|
How-To