fatigue and recovery. key knowledge the multi-factorial mechanisms (including fuel depletion,...

FATIGUE AND RECOVERY

Key Knowledge • the multi-factorial mechanisms (including fuel depletion,

metabolic by-products and thermoregulation) associated with muscular fatigue as a result of varied exercise

intensities and durations • passive and active recovery methods to assist in returning the

body to pre-exercise levels.

Key Skil ls explain the role the energy systems play in enabling activities to

occur as well as their contribution to active and passive recovery explain the multi-factorial mechanisms associated with fatigue

during physical activity and sporting events resulting from the use of the three energy systems under varying conditions

compare and contrast suitable recovery strategies used to counteract fatigue and promote optimal performance levels.

KEY KNOWLEDGE AND SKILLS

UNDERSTANDING FATIGUE

Fatigue - Physical and or mental lethargy or exhaustion triggered by stress, exercise, overwork, illness or disease.

Fatigue is caused by many factors = multifactorial

Robert Malpeli - Balwyn High School 2010

Fatigue can be

Local – in muscles General – Whole body Chronic – Long term

Peripheral – at muscles Central – Central nervous system

FATIGUE

The causal mechanisms which aff ect muscular fatigue are

Type, duration and intensity of the exercise being performed,

Fibre-type composition of the involved muscle or muscles

The fi tness and training status of the athlete

The nutritional state of the athlete

The mental state of the athlete.

FACTORS AFFECTING FATIGUE

Myth Busters : Lactic Acid = “Good Guy”

•Lactic acid is continuously being produced and removed – even at rest

•When glycogen is broken down pyruvate is formed, and broken down when plenty of oxygen is available

•With low oxygen levels / supply, pyruvate becomes lactate and hydrogen ions (H+)

•Lactate and hydrogen ions (H+) enter muscle tissue and are then transported to the blood stream and “shuttled” to other muscles and cells where this exists in lower concentrations where the lactate is broken down to produce more energy / ATP or converted into glycogen to again be used as a fuel source.


CAUSAL MECHANISMS

Fuel Depletion - ATP & PC

•ATP is an immediate energy source but very limited (2 seconds supply)

•PC occurs in limited supply at the muscles (10-12 seconds supply)

These are quick to supply ATP but just as quickly depleted - then muscle glycogen and liver glycogen is used in larger amounts.


Fuel Depletion – Glycogen & Fats

•Muscle glycogen is used first during aerobic activities and then liver glycogen

•Once liver glycogen runs low, muscles increasingly use FFA and then stored fats

•The rate of ATP resynthesis decreases quickly (50 – 100% slower) once the body switches to fats as the main fuel source – this causes slowed performances

•Proteins are called upon when fat stores run low and this leads to an ever greater slowing down


CARBS AND FATS

Ms Ahearn finish an half ironman in 6 hours and 5 minutesa) Describe Ms Ahearns relationship of carbohydrates and fats as

an energy source over 6 hours of continuous exercise. b) What effect would this have on performance and why?

https://www.youtube.com/watch?v=LKf1eTzmK14

HITTING THE WALL

M.socrative.comRoomnumber = mrsaunders

SPACE RACE

Metabolic by-products

•H+ ions – increased muscle acidity which slows the actions of glycolytic enzymes and the rate of glycogen breakdown (usually associated with _________________ system dominance)

•Inorganic phosphate - reduces the contraction force of muscles and slows the release of calcium ions (usually associated with _________________ system dominance)

•ADP – accumulates during explosive activities and reduces the power muscles can exert (usually associated with _________________ system dominance)


Elevated Body Temperature•Normal core temperature = 36.5 – 37.5 degrees celcius (optimal)

•80-90% of body heat comes from muscles contracting

•Heat loss from the body occurs mainly by evaporation/sweating. This becomes less effective in hot (temps above 36 deg celcius) and humid environments

•Evaporative cooling caused by sweat is assisted by blood being shunted towards the skin’s surface – this takes with it important fuels & oxygen and reduces waste removal rate

•Decreased plasma volumes resulting from increased sweating cause increased heart rate to maintain adequate blood supply to working muscles


11 degrees is the perfect temperature to exercise at. Anything above and below this causes to body to fatigue quicker.

THERMOREGULATION

List for yourselfFactors aff ecting peripheral fatigue

The causal mechanisms

Do test your understanding page 122 Questions 1-11

SUMMARY

Fatigue at the neuromuscular junction The nerve impulses sent from the brain can sometimes be

prevented from reaching the the muscle fibre. This is mainly caused by a reduction in acetycholine which

relays the nerve impulse across the synaptic cleft between the motor neuron and the muscle membrane.

Central nervous system fatigue The CNS can be a cause of fatigue. What are some forms of motivation we often use to overcome

this? The stress of exercise often leads to a conscious decision to

terminate the activity rather than tolerate further pain. Indeed, research has generally found that the perceived discomfort of fatigue precedes the onset of physiological fatigue in all but the most highly motivated athletes. E.g gut running in AFL

CENTRAL FATIGUE MECHANISMS

When we are fatigue it becomes harder to convert our electrical impulses from the brain to muscular contraction. Have you ever thought you want to run faster but you just can’t do it?

The accumulation of hydrogen ions, inorganic phosphate and ADP are involved in this as well as pottasium

Pottasium can also aff ect the functioning of our muscles.

IMPAIRED MUSCLE EXCITABILITY

When our body sweats we lose a mixture of water and electrolytes.

Sweating can create a lower level of blood plasma volume which aff ects blood fl ow to working muscles.

Also can cause a lack of blood fl ow to the skin for dissipating heat which can cause an even bigger rise in body temp.

Factors Duration of session Environmental conditions Athletes acclimatization

2% decrease in body weight through fl uid loss = 20% reduction in performance

3-5% decrease can result in severe performance decrement along with impaired reaction time, concentration, decision making and mental abil it ies

15% decrease = dead

DEHYDRATION

Predominant cause of fatigue100-metre sprint (9.78 seconds) 800-mere run (1 minute, 48.45 seconds) Marathon (2 hours, 5 minutes, 46.32 seconds)

•Oxygen Deficit – occurs when oxygen supply lags behind oxygen demands – typically at the start of exercise and when exercise intensities rapidly increase - mainly anaerobic energy systems

•Steady State – occurs when oxygen supply meets oxygen demand – largely aerobic energy system

•Oxygen Debt = EPOC (Excess Post – exercise Oxygen Consumption) – occurs during recovery whilst oxygen levels remain above resting levels – largely aerobic energy system


EPOC – It’s sometimes good to extend this via an active recovery


RECOVERY

WHAT SHOULD A RECOVERY INCLUDE?

A cool down or active recovery immediately post exercise.

Passive restReplenishment of energy stores. PC, glycogen in the

muscle.Replenishment of fluids

COOL-DOWN OR ACTIVE RECOVERY

Research has shown that a cool-down or active recovery is an effi cient fi rst step in enabling the body to recover from exercise.

Allows for Increased oxygen consumption Increased blood flow Muscle Pump helps move blood from veins

PreventsVenous poolingAllows for quicker removal of waste productsPrevents muscle sorenessWhat should an active recovery include? When should we use it?

Good when increased blood flow is not necessary Good for restoring PC stores

PASSIVE RECOVERY

WHERE DO WE USE EACH

Passive recovery Energy systems - Events -

Active recovery – Energy systems - Events and example of active recovery -

Restoring Fuels - PC•PC is restored as soon as a passive recovery starts

•PC comes from amino acids (liver) or dietary creatine (red meats, fish or supplements)

•PC is rapidly restored during first couple of minutes of EPOC/oxygen debt


Restoring Fuels – Glycogen

•Glycogen can be “restored” during exercise and athletes often consume hypertonic sports drinks to lessen glycogen being drained from the liver (during moderate exercise 1 gram glucose is drained per minute)

•High GI foods should be consumed within first 30 – 60 mins of recovery to ensure rapid and complete restoration within 24 hrs. Delayed intake will delay restoration.

NB – Carbohydrates not stored at the muscles/liver will be converted to fatRobert Malpeli - Balwyn High School 2010

Removal of Metabolic By-productsH+ ions – removed quickest during an active recovery (same activity @reduced intensity)

Why?

•Oxygen levels remain above resting levels for longer and this assists breakdown

•A “muscle pump” is created when muscles squeeze blood vessels and more oxygen is supplied to working muscles and wastes removed at a quicker rate. Promotes shunting to areas of lower concentration

•Promotes venous flow and prevents venous pooling

•Massage and contrast bathing also promote blood flow and speed up H+ removal fro muscles

•Inorganic Phosphate (Pi) is also removed quickest when high levels of oxygen are present and benefits from an active recovery Robert Malpeli - Balwyn High School 2010

Sodium, Potassium & other Electrolytes

•The movement on sodium and potassium is crucial to the transmission of messages to and from muscles.

•Sodium, potassium, calcium and chloride are electrolytes critical to ATP resynthesis

•Electrolyte or sports drinks and excellent for quick electrolyte replacement and counteracting fatigue


PROTEIN INTAKE

Protein and carbohydrates make for perfect partners in post exercise nutrition.

They promote glucose delivery to depleted muscle cells

Counteracting Dehydration and Elevated Body Temperature•Ice baths / cool pools when off the field/court or at end of activity – (body temperature can cool down 25 times faster when immersed in cold water)•Cool/cold showers (when off the field/court or at end of activity)

•Ice vests (during breaks in play, interchange situations)

•Refrigerated cool rooms (during long breaks in play when players taken from the field)

•Ventilation / fans (on side of playing venue)

•Protective shade (either natural – trees, surrounding buildings, etc.. or via shade sails or umbrellas)

•Reduced / modified clothing (to avoid overheating it’s recommended that loose fitting, light weight and light colored clothing is worn)


YOUR TURN!

Find 2 sports that you play/have played and list some nutritional strategies for recovery.

http://www.ausport.gov.au/ais/nutrition/factsheets/sports/

fatigue and recovery. key knowledge the multi-factorial mechanisms (including fuel depletion,...

Documents

recovery slide

skills slide

muscular fatigue

liver glycogen

energy atp

fuel depletion atp pc

muscles general

limited supply