1. Fatigue and Recovery Mechanism
Understanding of the multifactorial mechanisms (including fuel depletion, metabolic by products and thermoregulation) association 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
Oxygen uptake at rest, during exercise and recovery, including oxygen deficit, steady state and excess post-exercise oxygen consumption

2. Fatigue-Fuel Depletion
The multifactorial mechanism of fatigue…
… record some of the key words and messages in this clip.

3. Fatigue…
… is an exercise-induced reduction in the power-generating capacity of a muscle and an inability to continue the activity. …the onset and development of fatigue depends on the type, intensity and duration of activity, the muscle fibres being used the type of muscular contractions and the performers fitness levels.

4. The onset is dependant on…
Type: E.g. intermittent of continuous
Intensity: E.g.
Duration of activity:E.g.
Muscle fibres being used:E.g.
Type of muscular contractions:E.g
Performers fitness levels: E.g

5. Classifying fatigue Fatigue can be classified as fuel depletion
accumulation of metabolic by-products
neuromuscular interruptions
elevated body temperature.
But remember it is often multifactorial

6. Fatigue is multifactorial (caused by a combination of many factors)
Fuel Depletion
Neuromuscular Event
Metabolic By-Products
Elevated Body Temperature
List as many that you know in the boxes they belong in.
How many can you think of?

7. Fatigue is multifactorial (caused by a combination of many factors)
Fuel Depletion
Neuromuscular Event
Intramuscular ATP
Decrease in CNS firing (rate and intensity)
Phosphocreatine
Impaired sodium (Na+) and potassium (K+) gradients
Muscle Glycogen
Blood Glucose
Metabolic By-Products
Elevated Body Temperature
H+ ions in plasma and muscles
Very high core temperature
Inorganic phosphate
Increased rates of dehydration
Adensine diphosphate (ADP)
Redistribution of blood away from muscles to assist cooling=less blood/ 0
Ca+

8. Methods of generating ATP during muscle activity
Table 6.3 (p.149)

9. Lactic Acid- Good or Bad
Read page 148
Define the term DOMS, Lactate Inflection Point, Glycolysis, NAD +, acidosis
What is one benefit of lactic acid?
Explain the process of glycolysis with and without oxygen
How is it that triathletes have near resting levels of fatigue despite performing for hours?
How is training beneficial in accelerating lactate clearance?
How does lactate and acidosis effect muscle performance?
Passive vs active recovery. What is better?

10. Thinking things through…
List the metabolic consequence of supplying ATP via the lactic acid system?
How is it possible for triathletes to have near-resting levels of lactic acid despite performing for over a couple of hours?
Explain how the accumulation of H+ is implicated in muscle fatigue
Why are lactate levels tested regularly during training sessions by physiologists, fitness advisors and coaches?
Explain how aerobic training reduces lactate accumulation at any given workload and yet results in a greater level of lactate accumulation during maximal efforts.
What is lactic acid buffering?

11. Something else to consider…
Study Figure 6.2. Explain the uptake of oxygen and oxygen deficit for an athlete 800m runner during an event lasting 2 minutes
Study figure 6.4. Explain the oxygen debt and its two parts, fast and slow.
List the fast and slow process of EPOC

12. Oxygen uptake during STEADY STATE EXERCISE
Can you identify the location of oxygen deficit, steady state, oxygen debt (EPOC)?

13. Define the following key terms
Oxygen Deficit
Steady State and Plateaus
Oxygen debt or EPOC
VO2
VO2 Max
Buffering
Myoglobin
Worksheet

14. LIP in terms of Steady State…
The Beep Test CD comes with the ability to have students run 5 minutes at Level 6, 8, 10 etc......
Rather than continuing with more rapidly occurring beeps. Most people can handled level 6, this is due to LIP not having been exceeded, there is energy system interplay, abundance of fuels.
What would happen if you allow a 5 min break and then complete next 5 minute set. What does this mean in terms of LIP?
Few students could sustain 5 minutes at level 10 – Once again, what is happening to lactate and therefore hydrogen accumulation? If students can keep up with this pace it’s clear they haven’t triggered LIP.

15. Oxygen uptake with increasing workload
What predictions can you make regarding this individual’s performance?

16. Returning to a pre-exercise state
High intensities = high EPOC
EPOC has two stages; EPOC fast replenishment and EPOC slow replenishment
EPOC fast is primarily restoration of PC (taking 2-3 minutes)
EPOC slow is primarily concerned with removal of lactic acid though buffering
See table 6.5 (p.154) for a summary

17. Likely Causes of fatigue
Predominant ES
Likely causes of Fatigue
Types of recovery
ATP-PC
Fuel depletion of ATP and PC
Passive recovery
Lactic Acid
Accumulation of by product
H+ ions
Inorganic Phosphates
Non dietary
Active recovery
Massage
Hydo/water based therapies
Aerobic
Fuel depletion
Glycogen stores, then fats
Elevated body temperature
Causing dehydration and blood flow away from muscles
Dietary
High GI
Rehydration via sports drinks
Non-dietary
Hydro/water based therapy

18. Depletion of Fuel
Only a factor when using the ATP-PC (PC depletion) and predominantly aerobic events lasting over 1 hour
CHO is the only source of energy during maximal intensity exercise but fats are used increasingly during prolonged endurance events
Muscle glycogen is the first fuel, as this is depleted, the muscles use glycogen stored in the liver, once this is depleted it looks towards blood-born fats and stored fats.
The rate of energy production using glycogen is 50 to 100% faster that the production using fats. This is due to a more complex chemical reaction and great amounts of oxygen required. Small amounts of glycogen is needed to actually breakdown fats.
Protein can be used but only in extreme circumstances lasting over 5 hours

19. Carbohydrate and Fat utilisation during endurance events
What would happen to the athletes performance once fat is the predominant energy source? Why?

20. Metabolic By-products
H+ ions
Inorganic Phosphate
The negative effects on performance associated with lactate accumulation is due to the increase in hydrogen ions
The breakdown of glucose or glycogen produces lactate and H+ (1 for 1)
The hydrogen ions makes the muscle acidic
As the concentration increases the blood and muscles become more acidic
This acidic environment will slow down enzyme activity and the breakdown of glucose itself
During muscle contraction ATP is broken down to ADT and P1 (inorganic phosphate)
Both are released during the cross bridge cycle of the sliding filament theory explaining muscle contractions
P1 is linked to the power stroke of the cross bridge cycle
P1 accumulation occurs rapidly during high intensity exercise resulting in decreased contractile force production
P1 reduces the amount of Ca that can be released via the sodium-potassium pump and hence slows contraction
ADP is released near the end of the cross bridge cycle after the ATP split to release energy
Accumulation of ADP causes a decrease in the maximal velocity of shortening in the cross bridge and an associated reduction in power output

21. Neuromuscular Factors
Decreased CNS ‘firing’
The brain detects fatigue and acidosis so sends weaker signals to working muscles in an effort to reduce intensity and slow down the work rate of the muscles
Less electrical stimulation created by sending fewer signmald eill result in less force and less frequent muscle contractions
This is a self protection mechanism

22. Elevated Temperature
Is only an issue while performing in environmental conditions of high heat an humidity
Normal core temperature ranges from to 37.5 degree Celsius
Hyperthermia is unusually high body temperature and elevated core temperature and severely affects performance
Muscles produce heat as they work
Our bodies must loose this heat via radiation, conduction, convection and evaporation
Once the body looses 2-3% of it’s body weight through sweating, thermoregulation is impaired (the bodies ability to keep the core temp. within certain boundaries

23. Physiological result of sweat loss- see fig 6.9 (p.160)

24. Recovery Strategies
Recovery aims to return the body to pre-exercise conditions and reverse the effects of fatigue.
Efficient recovery strategies will enhance adaptation to exercise loads as well as preparing the athlete for future training.
Read pages Summarise the following recovery strategies
Refuelling: Phosphocreatine, muscle glycogen and blood glucose
Metabolic by-product: Removal of H+ ions in plasma and muscles and replenishing inorganic phosphate (Pi) and Adenosine diphosphate (ADP)
Addressing neuromuscular factors.
Lowering body temperature.

25. Active vs Passive Passive PC Active Dietary refueling and hydration
Removal of H+ ions
Rebounding P1 to ADP
Addressing nueronmuscular factors
Strategies for cooling
Passive PC

26. Refueling

27. Application Tasks
1. Work the Web: Review of Sports Drinks on the Market (p.166) Record Key Findings of the study. 2. Follow the following link to investigate the number of ways the AIS promotes performance recovery. Record Key findings 3.Investigate Strategies for cooling . Record Key findings 4. Student directed presentation on chosen fatigue management strategy E.g. Compression garments, hydration, ice baths, etc! Explain the scientific theory that underpins your chosen method