Energy systems

kreb cycle• Series of chemical reactions in the

mitochondria• Oxidizes acetyl CoA to produce ATP

(Adenosine Triphosphate = energy molecule found in all cells)

• CO2 is formed in this process

anaerobic energy• Muscles Fibers need energy to

sustain contraction• 2 main sources of stored energy– ATP (Adenosine Triphosphate)– PCr (Creatine Phosphate)

anerobic energy• When stored energy runs low, the

body must produce more ATP– Carbohydrate (glycogen) stored in

muscle and liver• Anaerobic glycolosis • By-product is lactic acid

anerobic energy• Non – oxidative (without oxygen) • Brief; but intense• Byproduct is Lactic Acid• Important at the onset of exercise• Important for events of short

duration • Low efficiency 1 glucose = 3ATP

anaerobic power• Maximal all out effort for several seconds• ATP-PCr energy system– Nervous system sends a message to muscle cell– ATP is split to ADP to release energy– PCr restores ADP to ATP, thus repeating the

cycle.

• Anaerobic glycolysis– Break-down of glycogen without oxygen.– 3 ATP / 1 glucose– Produces lactic aid

lactic acid• By product of anaerobic

metabolism• Change the acid-base

balance in the muscle cell• Causing burning sensation

in muscles, nausea physical and mental fatigue

• Training reduces production of Lactic acid and improves the body’s ability to remove it from the system.

aerobic energy• Uses oxygen to produce energy• With exercise heart rate and breathing

rate increases so more oxygen is getting to the muscles.

• Within a few minutes the muscles are supplied with enough oxygen for aerobic respiration.

• Abundant energy stores• Carbohydrates 4 Kcal / gram• Fat is abundant and rich energy source 9 Kcal /

gram

aerobic energy• More efficient than anaerobic– 1 glucose = 36 ATP

• Occurs in Mitochondria of the cell. • Glucose + O2 = CO2 + H2O + energy

* Protein is essential to build, maintain and repair issue, but is not a preferred energy source.

aerobic capacity• The ability of the aerobic system to

take in, transport and utilize oxygen.• a product of the respiratory,

cardiovascular and muscular systems.

• Measured in L/min• Higher measures indicate excellence

in non-weight bearing sports.

aerobic energy• Aerobic energy is used for low to

moderate intensity and long duration.

• It offers a high energy yield, allowing activity to be maintained for long periods.

aerobic energy• Elite athletes

may use their aerobic pathways to perform what would be high intensity to lesser athletes.

aerobic energy• Aerobic system uses oxygen to break

down food fuels• CARBOHYDRATES & FATS• High energy yield

energy supplied against time

A = ATP-PC - Lactic Acid threshold. The point at which ATP-PC system is exhausted and the lactic acid system takes over.

B = Lactic Acid - Aerobic threshold. The point at which the lactic acid system is exhausted and the aerobic system takes over.

energy continuum

energy continuum• Considers the importance of each

energy system in a particular activity.

• Intensity and duration will decide which energy system is used.

• Often there will be a combination of all three.

energy continuum• e.g: Marathon• ATP-PC System –

Start of race.• Aerobic System –

Majority of race.• Lactate

Anaerobic System – Sprint finish.

energy continuum• e.g: Midfield in football• ATP-PC System – Sprinting

for the ball.• Lactate Anaerobic System –

High intensity work, chasing ball, moving into space, dribbling with ball.

• Aerobic System – Less intense periods when play does not involve the player. Time to recover using aerobic system.

to do• Complete theory of knowledge on

page 66.• The triathlon is an athletic event that involves

performers undertaking a long distance swim, immediately followed by a cycle race and then finally a run of several kilometres.– What would be the major energy

sources used by a triathlete?– Briefly explain how these energy sources

are used for regeneration of ATP.

Briefly explain how these energy sources

are used for regeneration of ATP.

What would be the major energy sources used by a triathlete?

O2 deficit & EPOC • Oxygen deficit: temporary oxygen

shortage resulting from immediate, strenuous exercise

O2 deficit & EPOC • EPOC = excess post-exercise oxygen

consumption• during recovery from exercise, O2 utilization

continues at a rate greater than need at rest• Offsets anaerobic metabolism during early

phase of exercise

O2 deficit & EPOC • Oxygen needed in recovery for:– Rebuild ATP % PCr stores–Myoglobin (protein) oxygenation– Cost of elevated respiration to clear out

excess CO2– O2 needed to cool the body ( breathing)* See page 70, fig 3.18

to do• Draw your own fig 3.19, p.71 to help

understand the relationship between exercise intensity & rate of ATP demand.

• Test yourself page 72– Question 1 and 2. – Then: explain each sport and the energy

systems they use: why and when are they used/dominant.

• Self-study questions p.73-74