Fatigue Assessment and Scientific
organisation of work-rest Regimes to
control fatigue.
By:- Prashant Patel
Objectives
• What is fatigue
• Causes of fatigue
• Types of fatigue
• Mechanism of fatigue
• Fatigue assessment
• Management of fatigue
Fatigue:
• It is state during which person is unable to carry out a particular
activity any longer after performing it repeatedly for some time.
• It is generalized sensation of tiredness and accompanying decrements
in performance.
Common Causes of
Fatigue:
Common Condition
Causing Fatigue:
• Stress work
• Over work
• Life style and environmental
disturbances
• Sleep disturbances
• Nutrition deficiency
• Muscle weakness
• Psychological reasons
• Nervous system reasons
• COPD
• Heart Failure
• Multiple Sclerosis
• Myasthenia Gravis
Signs and symptoms of fatigue:
• Inability to solve work
• Long eyes blink
• Forgetting instructions
• Yawning
• Irritability
• Lack of motivation
• Depression
• Giddiness
• Headache
• Sleepiness
Effects of fatigue:
• Reduced decision making and planning
• Reduced communication skills
• Reduced performance
• Reduced attention
• Inability to stay awake
• Increase medical risks
• Increase error in judgment
• There are mainly 2 types of fatigue:
1. Local fatigue : in which fatigue is
noticed in isolated muscle.
Example: if specific muscle is made
to contract voluntarily or artificially
by stimulation.
• Initial repetition act as warm up.
• Repeated contraction cause an
increased contractility.
• If the contractions continued than
muscle begins to fatigue.
• Later on stage – If continued
contraction Muscle fails to produce
Flicker of contraction.
2. General fatigue : in which fatigue
is not in one or two muscles but to
most of the muscle in the body.
Example: Marathon running,
Swimming, Playing football.
• Here, seat of fatigue lies in the
central synapses located in anterior
horn cells.
• Dexedrine is anabolic steroid can
delay the general fatigue by acting
on synapses in sportsman but is an
illegal drug.
Mechanism of fatigue:
Energy systems and fatigue
1. PCr depletion
2. Glycogen depletion
metabolic by products and fatigue
1. Heat, Muscle temperature and fatigue
2. Lactic acid, Hydrogen ion and fatigue
Neuromuscular fatigue
Central nervous system
Energy systems and fatigue
Energy in true physiological sense of providing ATP from substrates
Lactic acid work as source of Energy during exercise.
1. PCr depletion:- (Percentage-phospho creatine)
ATP depletion > PCr depletion
After ATP concentration decrease both ATP & PCr depleted.
It’s potential cause of fatigue.
2. Glycogen depletion:- ATP synthesis is also maintained by
breakdown of muscle glycogen. Unfortunately glycogen depleted
quickly.
 Glycogen depletion in different fibers
 Glycogen depletion in different Muscle group
 Glycogen depletion in Blood glucose
Metabolic by products and fatigue
 Heat, Muscle Temperature & fatigue:Energy expenditure in body as result large heat production.
Increased body temperature through carbohydrate utilization &
glycogen depletion increased.
 Lactic Acid, Hydrogen ions & fatigue:Lactic acid is by-product of anaerobic glycolysis.
Lactic acid dissociates & converting to lactate & accumulation of
hydrogen ions.
This hydrogen ions cause muscle acidification, known as acidosis.
Neuromuscular fatigue
Fatigue may result from inability to activate muscle fibers.
(function of Nervous system)
 Neural transmission :Fatigue may occur at the neuromuscular Junction, preventing nerve
impulse transmission to muscle.
Most of the causes for neuromuscular blocks associate with
neuromuscular diseases like Myasthenia Gravis.
Central nervous system
There is some CNS involvement in most types of fatigue.
When subjects Muscle near to exhausted – Verbal encouragement,
shouting, playing music or direct stimulation is increase the strength
of muscle.
CNS role in fatigue are not fully understood.
Fatigue assessment:
History:• Demographic data
• Chief complain
• Onset of fatigue
• Impacts on daily life
• Medical, family, drug history
• Social, allergy history
Laboratory Studies:• Complete blood count
• Erythrocyte sedimentation rate
• Serum calcium and phosphate
levels
• Liver transaminase levels
• Fasting blood sugar level
• Creatine kinase level
• Urinalysis for protein, blood
and glucose
Physical Examination: General appearance: level of alertness, psychomotor agitation or
retardation, grooming (psychiatric disorder)
 Presence of lymphadenopathy: a possible sign of chronic infection or
malignancy
 Evidence of thyroid disease: goiter, thyroid nodule, ophthalmologic
changes
 Cardiopulmonary examination: signs of congestive heart failure and
chronic lung disease
 Neurological examination: muscle bulk, tone and strength, deep tendon
reflexes, sensory and cranial nerve evaluation.
• There are three type of assessment:
1. Systematic Assessment
 Anaerobic Fatigue assessment
 Measurement of Blood lactate levels
 Measurement of Aerobic capacity
 Measurement of energy expenditure
2. Local Assessment
 Electro physiological studies
3. Scales for fatigue assessment
Systematic Assessment:
A) Anaerobic fatigue assessment
During anaerobic power when vigorous exercises continued more than few second.
• Katch Test:- Patient perform static cycle with resistance on flywheel.
[6kg for men , 5kg for women] - duration is 40 second.
Thus, anaerobic fatigue can be found out as the percentage decline in the power
output during the test.
• Wingate cycle ergometer test:- determine anaerobic power, fatigue and capacity.
3 min warm up & than pedal the cycle as fast as he can without resistance.
Within 3 second fixed resistance applied, pedal for 30 second.
Electrical device continuously records flywheel revaluation in 5 sec interval.
• Test scores:Peak Power output- highest power output observed during first 5 second.
PP output = Force*Distance divided by time.
5.5 kg*(12*6) divided by time
396 divided by 0.083
Anaerobic fatigue- it is the percentage decline in power output during test.
AF= high power output –low power output divided by high power * 100
Ex:- if man weight 73.3 kg
AF= 776.8-323.7 divided by 776.8*100
= 58.3%
B) Measurement of blood lactate levels
• Presence of lactate in muscle & blood indicates the contribution from the
anaerobic metabolism to give energy to the work performed.
c) Measurement of aerobic capacity
• it’s give information regarding fatigue that occurs due to lack of O2.
• Aerobic capacity of an individual measured by calculating VO2 max.
• VO2 max= cardiac output * arteriovenous O2 difference.
Cardiac output=heart rate * stroke volume
Arteriovenous O2 diff= arterial O2- venous O2
D) Measurement of energy expenditure
• can determined easily by “open circuit spirometry & telemetry”
• In spirometry energy expenditure computed from amount of O2 consumed.
• In telemetry the heartrate transmitted to a graphic printout system.
Local Assessment:
A) Electrophysiological studies:
• Decremental studies:Muscular fatigue produced in certain disorders. Fatigue is tested electro
physiologically its decremental study.
In which – repetitive stimulation of all muscle fibers, motor potential will
show consistently lesser amplitude indicating generation of fatigue.
• EMG:EMG recording when patient contract the muscle voluntary also will show –
decrease in amplitude of the motor unit potential due to onset of fatigue.
Fatigue- decrease the force of contraction . So
Decrease in the amplitude of potential.
• MMT:- In this procedure “Power generated by the muscle is assessed
manually without any gadgets”
Normal muscle grade is 5.
Fatigue occurs so grade comes down. Procedure of 10rm testing can
also be used to find out specific muscle ha fatigue or not.
• Endurance testing:- it’s the ability of muscle to continuously perform a
specific task without rest.
Asked to repeat contraction without any resistance till fatigue occurs,
Lesser repetition shows the more tendency of muscle to develop
fatigue.
Scales for fatigue assessment:
• Brief fatigue inventory
• Piper fatigue scale
• Fatigue severity scale
• Fatigue impact scale
• Visual analogue fatigue scale
• Borg rating of perceived exertion
Management of fatigue:
• Aerobic training
• Yoga
• Energy effectiveness strategies
• Energy conservation strategies
• Activity pacing
• Exercise pacing
• Cognitive and behaviour therapy
• Ergonomic modification
Thank You…