Chapter Eight: Energy System Fatigue and Recovery Mechanisms Flashcards
What does levels of fatigue depend on?
Intermittent and continuous Fast or slow twitch fibres Concentric, eccentric or isometric contractions Intensity and duration Level of fitness
Fatigue
Causes a reduction in muscle strength and power
Power equation
Power = Force X Velocity
Central fatigue
In the central nervous system, where muscular function is decreased due to central nervous impairment
Peripheral fatigue
At the muscle, when muscle function is disrupted by internal muscle functions
Levels of fatigue
Local
General
Chronic
Local level of fatigue
Experienced in one or local group of muscles, feels heavy and cramps
When called repeatedly on during training
2-4/10
After completing a weight session
General level of fatigue
Occurs after intense training or game of sport, all muscles feel weakened
6-8/10
Full on game of netball
Chronic level of fatigue
Unhealthy breakdown of the immune system caused by overtraining has persistent muscle soreness and low immune system function
10/10
Diagnosed as chronic fatigue
Key factors contributing to fatigue
Fuel depletion
Build up of metabolic byproducts
Elevated body temp
Neuromuscular events
Fuel depletion factors
Intramuscular ATP
Phosphocreatine (PC)
Blood glucose
Muscle glycogen
Build up of metabolic byproduct factors
H+ ions in plasma/muscle
Inorganic phosphate
ADP
Calcium ions
Elevated body temp factors
High core temp Increased dehydration rate Blood redistribution Elevated blood pressure Decreased plasma levels Electrolyte loss
Neuromuscular events
Decreased firing of CNS
Intramuscular ATP
When muscles contract they use ATP but there is a very limited store of ATP within the muscles and the rates of ATP breakdown can exceed rates of resynthesis the body must then use PC stores
Phosphocreatine (PC)
When ATP is used up the muscles use PC to resynthesise ADP, however there is also limited stores of PC in the muscles, the body must then use the anaerobic system which has fatiguing byproducts
Blood glucose
When blood glucose is depleted it causes decreased carbohydrate oxidation and increased fat oxidation, causing fatigue
Muscle glycogen
When blood glucose drops, blood glycogen is used to create more ATP but when it drops it causes high fatigue and fat oxidation becomes prominent causing the body to slow its work rate
H+ ions in plasma/muscle
When the muscles break down glucose anaerobically they produce H+ ions which build up and cause decreased pH level in the muscle (acidosis), this prevents the body from converting lactate back to glucose
Inorganic phosphate
They decrease the ability of the muscle to contract as strongly, reduce calcium ion release from sarcoplasmic reticulum, no. of cross bridges in weakly bound states increases
ADP
Can reduce force and slow relaxation in muscles by adversely affecting their contractile microfilaments and calcium ion uptake into sarcoplasmic reticulum
It reduces the strength the muscle can produce
Calcium ions
No bonds with troponin, preventing the actin and myosin to form cross bridges, preventing muscle from using ATP in the muscle
High core temp
If core temp rises above 37 degrees the body will lose consciousness increases the amount of fluid the body loses
Increased dehydration rate
Decreases muscular strength and aerobic ability and person may lose consciousness
Blood redistribution
Redistribution to skin means less blood and o2 to working muscles therefore slowing rate of ATP resynthesis
Decreased plasma levels
Means that less water is within the blood meaning that the blood cannot flow to the muscles and a buildup of byproducts occurs
The heart has to increase the heart rate to maintain cardiac output which can push the body above LIP and cause fatigue
Electrolyte loss
Electrolytes carry the electrical charges needed for muscle contractions
They help the body maintain fluid
When they are lost it causes fatigue in the muscles and higher risk of dehydration
Decreased firing of CNS
When the brain detects fatigue it sends weaker signals to the working muscles to slow down the working rate and decrease intensity. The nerves fatigue and cannot send the message as efficiently preventing the muscles from working to max potential
Delayed onset muscle soreness (DOMS)
The result of microscopic tears incurred during eccentric contractions
Occurs after heavy eccentric work or unaccustomed work
24-48 hours after
Body adapts and heals creating muscle growth
Muscular condition, not a fatigue factor
Alleviating DOMS
Warming up and cooling down
Staying hydrated
Foam roller
Active recovery
Fatigue in the ATP-PC system
Accumulation of ADP and Pi
Depletion of ATP and PC
Fatigue in the AG system
Accumulation of H+ ions, working above LIP
Fatigue in the aerobic system
Depletion of blood glucose>muscle/liver glycogen> fats
Decreased neural firing/motor unit recruitment
CNS/brain self-limiting mechanisms
Elevated core body temp causing dehydration, loss of electrolytes and redistribution of blood
Aim of recovery
To return the body to its pre-exercise conditions and reverse effects of fatigue
Active recovery - is it appropriate?
In all events other than restoring PC
Passive recovery definition
A recovery that typically involves complete rest or exercise at a slow walking pace
Refuelling - Blood glucose and muscle glycogen
Different training levels need different levels of carbs
Glycogen replenishment depends on how long high GI foods are ingested after the event
Effects of glycogen depletion can be minimised by ensuring that there is adequate stores in the body (carb loading)
Hypertonic sports drinks prevent some glycogen getting drained from liver
Glycogen replenishment (high GI food ingestion)
1 hour - 55% restored within 5 hours, 100% in 24
1-2 hours - 100% within 24-48 hours
5+ hours - up to 5 days
Rehydration
Reverse any fluid loss incurred during exercise
Hydration, glycogen/electrolyte replenishment
Enhance performance, maintain consistent core temps and assist recovery
Replace 1.5L of water for every kg lost during exercise
Venus Pooling definition
Accumulation of blood in one part of the body
Time it takes to remove H+ ions for active/passive recovery
Double the amount for passive
Removing inorganic phosphates and ADP
If ADP accumulates in the muscle an enzyme is activated in the muscle to break down PC
Extra creatine is converted to creatinine and excreted through urine
Refuelling protein
Assists with muscle repair after high-intensity
Recommended that 30-40g of protein after exercise
Recommended that protein and carbs are consumed together
Passive Recovery
Restores PC stores
Good aerobic systems will restore it faster
Ten mins
Helps remove buildup of ADP and Pi
Helps recover from reduced firing of CNS
Produces PC from liver from amino acids or from dietary creatine such as red meat
Active Recovery
Maintains higher O2 levels to speed up the removal of H+ ions
Creates a muscle pump to help speed up circulation for O2 supply and removal of wastes
Prevents venous pooling
Massage (although passive) acts as a muscle pump`
Hypotonic drinks
Low carbs
Contains electrolytes
Isotonic
Contains sugar and salt concentrations that are similar to the body
Hypertonic
High CHO containing drinks
