Unit 3 - AOS 2 - Fatigue Flashcards
Onset and rate of development of fatigue is dependent on:
- Type of activity (intermittent or continuous)
- Muscle fibers(fast or slow twitch)
- Muscle contractions (isometric, isotonic, isokinetic)
- Intensity & duration
- Fitness of performer
Fatigue Definition
Exercise induced redution in maximal fore and/or power generating capacity of a muscle and an inability to continue the activity
What are the mechanisms of fatigue?
- Depletion of fuel stores
= Adenosine Triphosphate
= Creatine Phosphate
= Glycogen - Accumulation of Metabolic By-products
= Inorganic Phosphate
= Lactic Acid (H+)
= Adenosine Diphosphate - Thermoregulation
= Dehydration
= Increased core body temp
= blood flow and redistribution
Depletion definition (energy production)
Reduced rate of energy and ATP production
What happens in the process of Creatine phosphate depletion?
- Depletes in 10secs (high intensity activity)
- Glycogen is called upon (stored in muscles)
- Intensity cannot be sustained = SLOWER RATE OF ATP PRODUCTION from the Anaerobic Glycolysis or aerobic energy system
What happens in the process of glycogen depletion?
- Depletes in 90-120 minutes when there is not muscle or liver glycogen available
- If fats then become the major fuel source = intensity will reduce (greater O2 cost of using fats) = SLOWEST RATE OF ATP PRODUCTION
How and where is glycogen broken down anaerobically?
Glycogen -> Glucose -> Pyruvate
–> Lactic Acid
- In the cytoplasm
What does the anaerobic breakdown of glycogen lead to?
Leads to intracellular accumulation of H+ ions
- Lactic acid is formed due to the insufficient O2 that is available (anaerobic) = Pyruvate cannot be broken down
how do the H+ ions in lactic acid effect the body?
Accumulation of H+ ions leads to reduction in pH levels, increasing acidity and leading to acidosis inside the muscle.
The 2 ways lactic acid can go aerobically?
At a resting intensity
= It is converted back to glycogen, contributes to glycogen stores
At submaximal intensity
- Is broken down by the muscle cells and tissues to provide energy for immediate use through the aerobic energy system (if oxygen is present)
what is LIP
Lactate inflection Point
= The final exercise intensity or oxygen uptake value where lactate production and removal from the blood are balanced
What happens to the body past the LIP?
Due to the increased contribution from the anaerobic pathway to meet the ATP demand - there is a more rapid onset of fatigue
= due to the accumulation of metabolic by products if the anaerobic system.
There is a imbalance in the production and removal of lactic acid.
The process of muscle contraction
- The ‘action potential’ passes down the motor neuron to the motor end plate
- At the motor end plate the action potential releases acetylcholine
- Acetylcholine crosses the gap and activates the release of calcium ions the sarcoplasmic reticulum.
- Calcium activate the cross bridges on the myosin filaments preparing it for the power stroke, and the movement of the actin filament along the myosin filament
ATP Hydrolysis
Catabolic reaction process by which chemical energy stored in the bonds of ATP is released after splitting those bonds.
What happens if there is an accumulation of Inorganic posphate (Pi)
- Increased Pi levels reduce crossbridge force production as it inhibits (restrains) the release and transfer of calcium via a range of mechanisms in the muscle cell
- Therefore, fewer cross-bridges would be in high-force states and the force production would decrease as Pi increases during fatigue development
