A2 PE - Chapter 4



A reduced capacity to complete work, Exhaustion (physical or mental) resulting from prolonged exertion

What Causes Fatigue?

-          Lack of/reduction in available energy

-          Lack of oxygen

-          Dehydration

-          Not a long enough period of rest/recovery

-          Depletion of calcium ions – no muscle contraction

-          Not adjusted to climate

-          Central Governor Theory

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Central Governor Theory

“Fatigue is an emotional response that begins in your brain, not a physiological one originating in the muscle”

Intrigued about 3 issues:

-          Role of lactic acid in the fatiguing process

-          Amount of muscle fibre recruitment during progressively maximal intensity

-          Muscle glycogen depletion

They believe your brain paces your muscle to keep them back from the brink of exhaustion when the brain (central governor) decides it’s time to quit, it creates the distressing sensations you interpret as muscle fatigue.

       Argue that the governor monitors signals to set levels of fatigue. Therefore physiological factors are not the direct cause of fatigue. Rather they are signals the governor takes into account.

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Glycogen Facts

Carbohydrate is stored as glycogen in the liver and muscles

Glycogen depletion is dependant on the bodies ability to resynthesize its stores from other sources, which in turn is affected by intensity and duration of exercise

We have approximately 350g of glycogen in our body which is approximately 90 minutes worth of glycogen fuelled activity

Used as primary energy source following PC depletion at a high intensity

Used in both lactic acid and aerobic energy systems depending on intensity

Glycogen stores made up in metabolic process after the breakdown of carbs, fats and proteins

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Glycogen Facts

Blood sugar evels go up during exercise as a result of muscle and liver glycogen being broken down in to glucose molecules, this produces the feeling of fatigue

After an 800 metre race, glycogen levels can be restored in about 2 hours. After a marathon, it can take up to 48 hours depending on the athletes body type

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