1. Energy Systems

2. ATP ATP (Adenosine triphosphate)
Provides the energy for ALL body functions.
Eg muscular efforts, nerve transmissions, brain activity
Energy is released when ATP breaks down to form ADP + P + energy (+ a free phosphate)
The body cannot use energy directly derived from foods, so it is used to form ATP which is a usable form of energy
It is stored in limited amounts in muscles.

3. Sources of ATP
Carbohydrates (CHO eg breads, cereals)- broken down to form glucose and transported in blood. Stored as glycogen in muscles and liver
Fats (eg fast foods, dairy)- broken down to fatty acids and triglycerides. Stored in body as adipose tissue
Protein (eg meat and fish)- used as emergency source. Stored as amino acids in muscles.

4. FOOD ENERGY ATP(ADP + P) ENERGY MUSCULAR ACTIVITY

5. Forms of food and storage sites

6. Production of ATP There are 3 ways ATP is produced in muscles:
From energy released by the breakdown of creatine phosphate (CP) ie ATP-CP system.
When glucose is converted without O2 to lactic acid ie the Lactic Acid System
When CHO and fats are are broken down using O2 ie the Aerobic System

7. ENERGY SYSTEMS
ATP-CP (also phosphate, phosphagen, phospho-creatin, CP, PC, alactacid)
Fuelled by Creatin Phosphate, occurs in cytoplasm of cell
Lactic Acid (also Anaerobic glycolysis, lactacid system)
Fuelled by glucose (glycogen), occurs in cytoplasm of cell
Aerobic (also Aerobic glycolysis and Oxygen and Oxidative System)
Fuelled by glucose (glycogen), occurs in mitochondria of cell

8. ATP Production at REST
When resting, demand for ATP is minimal and any demand can be met under aerobic conditions as there is abundant O2 and low HR.
Fats 2/3 and CHO (after they have been broken down to glucose and stored as glycogen) 1/3 contribute to energy production.
O2 + CHO CO2 + H2O + energy

9. ATP Production DURING ACTIVITY
During activity the system used to provide ATP depends on:
how long the activity goes for
how vigorous the activity is
the level of the individual’s aerobic fitness
the level of recovery between each effort

10. ATP Production DURING ACTIVITY
The body tries to produce all energy aerobically (ie the Aerobic System) because it is the most efficient system, but this is not always possible, as it takes time for O2 to get in and around the body.
If the body cannot keep up with the increased demands for O2 in an activity, it will use one of the anaerobic (without O2) systems ie the Creatine Phosphate
or Lactic Acid Systems.

11. The three energy systems

12. Creatine Phosphate System
ATP stored in the muscles supplies the initial energy for muscle contraction. When it is used up, the ADP + P is reconverted to form ATP. CP is used for this process.
No O2 is required for this process.
Used for explosive efforts, and at the beginning of sub-max efforts, 0-8secs
Stores of CP are limited and will be exhausted after 6-8 secs of high intensity activity (eg throwing for distance, sprints)
Need 2-6 mins of rest to recover, then can be used again
Produces less than one molecule of ATP

13. Lactic Acid System
As CP stores become exhausted, this system supplies the majority of energy.
No O2 is required for this process, but a build up of lactic acid is toxic and limits this process
Glycogen converted to glucose, broken down to form lactic acid releases the energy required.
Used for activities of high intensity lasting 10 secs to 2 mins (eg 400m run, gym floor routine)
Can also be used for phosphate efforts when there hasn’t been sufficient recovery time.
Produces 2 molecules of ATP
Recovery times vary with type of recovery and time above OBLA (between 5mins and 30mins)
Active recovery is best
Produces large amounts of lactic acid
Occurs in cytoplasm of cells

14. Aerobic System
Once activity has begun, the body tries to increase O2 delivery to working muscles. After a short ‘lag’, if the activity is sub-max, the O2 supply will be sufficient (ie equal to demand) to produce ATP ie Steady State
CHO (glucose), fats (and protein in emergencies) provide energy required. CHO for longer, more intense activity and fats for VERY sub-max efforts (as they need more O2 to break down).
Main provider of energy for activities of low intensity lasting longer than 2 mins.
CHO produces 38 molecules of ATP, fats >100
Recovery of glycogen stores can be up to 48 hours depending on the time and intensity of effort
This process occurs in mitochondria of cells

15. Contributions of fat and carbohydrates during exercise

16. Examples of activities and the major energy system relied upon.

17. Summary of Energy Systems

18. An example of the interplay of energy systems- a 5km run
NOTE- ALL SYSTEMS ARE OPERATING TO SOME EXTENT AT ALL TIMES IN ALL ACTIVITIES
Interplay is important to provide maximum potential for performance.
For the first 6 secs, the main energy system is the CP system
As the run continues at a steady pace, the CP system drops off and the lactic acid system takes over. By 30 secs into the run, it is supplying most of the energy
By the 2 min mark, O2 supply has increased so the aerobic system can contribute to production of ATP
By the 5 min mark, the aerobic system is providing most of the energy and will continue to do so, provided the athlete does not speed up. For hills and sprints, the anaerobic systems come back into play depending on time, intensity. Aerobic system vital for recovery.

19. An example of the interplay of energy systems- a team game
NOTE- ALL SYSTEMS ARE OPERATING TO SOME EXTENT AT ALL TIMES IN ALL ACTIVITIES
Predominant energy systems are the anaerobic systems- required for sprints, leads, chasing an opponent, kicking, throwing etc. ATP-CP for explosive bursts, lactic acid system for longer (10 sec –1 min) bursts of activity.
Aerobic system vital for recovery periods in between these bursts, for light jogs back to position, during resting phases and to last the duration of the game.

20. Lactate Threshold
Also known as OBLA (onset of blood lactate accumulation)
This is reached when the body cannot supply enough O2 to continue the breakdown of lactic acid formed in the blood.
The point above which lactic acid begins to accumulate rapidly in the blood. Below this point, levels of lactic acid do not inhibit activity ie person may be working at a steady state
Once this level is reached, the athlete must stop or slow down- Lactate levels and HR are too high to continue
Lactic acid is toxic in large amounts. It causes fatigue and discomfort eg ‘heavy legs’
Everyone has a different OBLA. It depends on genetics and training
OBLA occurs when working between 60-90% of maximum HR, 50-80% of VO2 max, depending on fitness.

21. Steady State
When a person is taking in enough O2 to meet the demand of working muscles, it is called a ‘steady state’.
HR is steady
Low lactate levels are maintained as the body is providing enough O2 to reconvert it to a usable energy source.
Steady state occurs between 70-80% of MHR, and 40-70% VO2 max.

22. Analysis of Shuttle run test Look at the following graph and see if you can identify steady state, OBLA and max HR

23. Oxygen deficit and debt
When we begin exercise, mostly at a high intensity, there is not enough O2 in the body to produce energy aerobically, thus energy is produced anaerobically. For the duration of the activity or until the body can work aerobically, an O2 deficit is produced.
After exercise, the body must ‘pay back’ the O2 used to produce energy was created without O2.
An athlete does that by panting after the race. The length of time required depends on the length of time working anaerobically.

24. Lactic Acid Removal
Lactic acid levels change throughout activities depending on the intensity. Some lactic acid can be converted/removed during sub-max efforts.
Existing exertion levels determine the rate of lactic acid removal
An active recovery is best- as HR is lower than at the OBLA, but still high enough to disperse lactic acid and continue blood flow with O2 to muscles. Recommended is a walk or slow jog ie no more than 40-50% of VO2max
Most lactic acid is converted back to pyruvic acid (by presence of O2), then to ATP. The liver can also reconvert lactic acid to glycogen
Some lactic acid is removed via respiration, excretion and perspiration.

25. Maximum Oxygen Uptake
Also VO2 max, is measured as millilitres per minute per kilogram
A measure of the amount of oxygen the body can take in, pump around the body and use in the muscles for energy production.
A measure of a person’s aerobic fitness
Eg active people 40-50mL/kg/min, trained sportspeople mL/kg/min
Training has a positive affect on VO2max
A test of VO2 max is the Shuttle run test
Eg level 5- 30mL/kg/min, level 8-40mL/kg/min,
level 11-50mL/kg/min, level mL/kg/min
Read case study LIU2 pg 143.

26. Training at altitudes “Live high, train low”
Living at high altitudes will stimulate red blood cell production. An increase in haemoglobin will increase O2 carrying capacity of the blood to the working muscles and increase O2 supply for energy production, therefore increasing endurance.
Training at sea level then allows the athlete to utilise (with the chronic changes made to the body) the available O2 in the air. Training at altitude does not induce chronic changes in the CV system.