1. Muscle Fatigue
Causes and Reduction

2. Fatigue
Fatigue is physical and/or mental exhaustion that can be triggered by stress, medication, overwork, or mental and physical illness or disease
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3. Fatigue Fatigue is caused by : The type of activity
Muscle Fibre type (White fast twitch/Red slow twitch)
The type of muscle contraction
The intensity of exercise
The duration of exercise
The level of fitness
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4. Types of Fatigue Local : pain or heaviness at the muscle
General : can be both physical and mental fatigue, e.g. : exhausted from training
Long term : over training and will lead to injury
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5. Causes of Fatigue
Depletion of Fuels, e.g. , ‘hitting the wall’ is a term used when glycogen is depleted resulting in the athlete burning fats instead of CHO.
Depletion of phosphate compounds (high intensity activity).
Reduced rate of energy liberation (you can’t produce the same amount of energy).
Increases in ADP and inorganic phosphate.
Elevated body temperature.
Dehydration.
Reduced Blood flow.
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6. Depletion of Fuels
CP and Glycogen is the dominate fuel used for high intensity activities.
Once these fuels run out your body can no longer work at high intensity and must resort to fats. This is not as efficient and causes the athlete to slow down or stop.
CP stores will last continually for 10 seconds.
Your body has enough Glycogen stores for 90 – 180 minutes of continual exercise.
Anaerobic glycolysis will last continually at high intensity for seconds or for as long as the individual can with stand the increasing by products
High intensity activities require fast twitch muscle fibre (white) that fatigue faster than slow twitch (Red).
Refer to page 134 of Nelson. Write your explanation for all the graphs.
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7. By-Products Inorganic phosphate (Pi) Pyruvic Acid Lactic Acid (LA)
Hydrogen ions (H+)

8. By-Product Inorganic Phosphate (Pi) :
By-Products
By-Product Inorganic Phosphate (Pi) :
Produced from the breakdown of CP
Pi is leading cause of fatigue in muscles

9. By-Product Pyruvic Acid :
Formed when the body creates ATP through Anaerobic glycolysis.
Pyruvic Acid will not cause fatigue and can actually be used to create ATP when there is plenty of oxygen present.

10. By-Product Lactic Acid :
Lactic Acid does not cause muscle fatigue but will increase pH.
Increased pH will not cause muscle fatigue but will increase recovery time.
LA will inhibit key enzymes from working producing slower reaction times.
LA will inhibit calcium which is needed for muscle contractions.

11. By-Product Hydrogen ions (H+) : Inhibits muscular contractions.
Increases pH.
Inhibits enzymes that assist glycolysis

12. Dehydration Effected by : Loss of fluid from :
- Sweat, the bodies natural response to thermoregulation
Vasodilatation, the increase in size of capillaries to reduce heat
Effected by :
Duration of exercise
Environment, e.g. hot day, humid
Athletes acclimatisation to conditions

13. Dehydration Dehydration will result in :
Continual loss of water will increase body temperate
An increase in body temperature will require the body to increase sweat production and vasodilatation
This will result in more loss of water and higher temperatures
Results in fatigue
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14. Dehydration Effects of Dehydration : Cramps Heat stress Heat stroke
Fatigue

15. Dehydration Guidelines to avoid Dehydration :
Be well hydrated before exercise up to several hours prior to exercise
Do not wait until you are thirsty as an indicator to dehydration
Cold water is absorbed faster
Drink at least 500ml 30 minutes before exercise
Drink at least 200ml every 15 minutes while exercising
Drink at least 500ml to 1 litre of water after exercise
1 kilo of weight loss during exercise = 1 litre of water loss
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16. Recovery The aim of recovery is to minimise the effects of fatigue
It aims to :
Replenish CP and ATP stores
Breakdown and remove LA
Restore muscle and liver glycogen
Rehydration replace lost water and electrolytes
Repair damaged muscle tissue
Reduce oxygen debt
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17. Passive Recovery Athlete remains still or lies on the ground
Best for :
Replenishing muscle PC
Is the faster form of recovery
70% of PC restored in 30 seconds
95 % of PC restored in 120 seconds

18. Active Recovery Involves athlete moving walking after exercise
This pumps oxygen to the working muscle
Oxygen is essential in :
Breaking down and removing LA
Removing H+
Removing Pi and removing
50% removal of LA takes 30 minutes with Passive recovery
50% removal of LA takes 15 minutes with Active Recovery

19. Thank You Done By : Khalid Al3bsi Ali Sa7ari Fahad Al3taibi
Esam H i