Energy Systemsfor Exercise

BIOENERGETICS

Cells don’t get Energy directly from food, it must be broken down into:

ATP-Adensosine TRIphosphate

ATP = a form of energy one can immediately use, it is needed for cells

to function & muscles to contract

Location?

Nutrients that give us energy:

CarbohydratesFatsProteins

GlucoseFatty acidsAmino Acids

Digestion

Absorbed into the blood & transported to cells

(muscle, liver & nerve)

They are used to produce ATP or stored

Carbohydrates

Eaten – Absorbed initially in the mouth

Stomach – broken down in stomach

Fully absorbed in small intestine by CHO receptors and transported to Liver

Glucose or Glycogen• Glycogen is stored glucose.

• Initially by the liver then sent in blood to muscles, so stored in blood

• Liver releases glucose when needed [Glucogenosis via Cori Cycle]

http://upload.wikimedia.org/wikipedia/commons/9/95/Glucose_metabolism.svg

Conversion of excess glucose to fat

• Sustained high glucose intake in the diet leads to increased fat synthesis. If glucose intake continues after muscle and liver glycogen stores are saturated, the glucose is not excreted or wasted. It is converted to a fuel storage form which has an unlimited capacity i.e. triglycerides stored in adipose tissue. Glucose is converted to pyruvate by glycolysis.

Blood Sugar

• The blood sugar level is the amount of glucose (sugar) in the blood. It is also known as plasma glucose level. It is expressed as millimoles per litre (mmol/l).

• Normally blood glucose levels stay within narrow limits throughout the day: 4 to 8mmol/l. But they are higher after meals and usually lowest in the morning.

ATP is stored in small amounts, therefore the rest is stored as:

• Glucose = Glycogen (muscle & liver)

• Fatty Acids = Body fat

• Amino Acids = Growth, repair or excreted as waste

Cells in the body need energy to function

FOOD=ENERGY (E)

The ATP Molecule

Adenosine

Adenosine

Energy

a. Adenosine Triphosphate (ATP)

b. The breakdown of ATP:

PP

P

PP P

ATP = ADP + energy for biological work + P

(ADP = Adenosine Diphosphate)

ATPase = Enzyme

Energy for cellular function

The human body is made to move in many ways:

• Quick and powerful• Graceful & coordinated

• Sustained for many hours

And is dependent upon the capacity to produce energy

We have a great amount of diversity

• Quick movements-lasts a few seconds• Reduced speed-lasts for several minutes

• Reduced intensity(50%)-lasts for several hours

The body uses different energy systems for each activity

Enyzmes

Enzymes are proteins that catalyze (i.e., increase the rates of) chemical reactions.

Affected by HEAT

PH

Predominant Energy Pathways

• ATP (2-3 seconds)

• ATP-CP Energy System (8-10 seconds)

• Anaerobic Energy System (2-3 minutes)

• Aerobic Energy System (3 minutes +)

0 sec 4 sec 10 sec 1.5 min 3 min +

Strength – Power:power lift, shot put, golf swing

Sustained Power:sprints, fast breaks, football

Anaerobic Power – Endurance:200-400 m dash, 100 m swim

Aerobic Endurance:Beyond 800 m run

Immediate/short-term Aerobic-oxidativenon-oxidative systems system

Anaerobic Energy System

• Without oxygen = Activities that require a large burst of energy over a short period of time

• ATP/System• Anaerobic Glycolysis = Production of ATP from

Carbohydrates without oxygen (breakdown of glucose)

ATP-CP Energy System

ATP-CP Energy System

ATP is stored in the muscle & liver for “Quick Energy”

• Nerve impulses trigger breakdown of ATP into ADP• ADP = Adenosine Diphosphate & 1 Phosphate

• The splitting of the Phosphate bond = Energy for work

Ex. Muscle Contraction, Moving hand from a hot stove, Jumping & Throwing

The Immediate Resynthesis of ATP by CP

CreatineP

Creatine P

Energy

High energy bond

a. Creatine Phosphate (CP)

b. CP = Creatine + energy for resynthesis of ATP + P

Adenosine PP

P

c. ADP + energy from CP + P = ATP (reversal of ATP = ADP + P + energy for work)

ATP-CP Energy System

• Creatine Kinase [CK] catalyzes the transfer of the phosphate from the the high energy compound creatine phosphate to re-synthesise ADP to ATP

For contractions to continue… ATP must be REBUILT

This comes from the splitting of CP (Creatine Phosphate a Hi energy source, automatic)

When ATP is used – it is rebuilt – as long as there is CP

Energy released from CP breaking down, resynthesizes the ADP & P

REMEMBER – only small amounts of ATP are stored = only 2-3 sec. of Energy

ATP-CP = 8-10 sec. of Energy

The usefulness isn’t the AMOUNT of Energy but the QUICK & POWERFUL movements

For longer periods of work = The Aerobic & Anaerobic Energy System must be utilized

Anaerbic Glycolysis

Anaeorbic Glycolysis

• Add its most basic

• CHO – 18chemical steps- ATP resynthesis• Pyruvate – Lactic Acid- Lactate+H1

• Needs 2 ATPs – produces 4ATP’s

Since glycogen is stored in the muscle & liver, it is available quickly

This system provides ATP when ATP-CP runs out

PFK = Enyzme Phosphofructokinase the most important regulatory enzyme

of glycolysis

1.The process to produce ATP is not as fast as ATP-CP, which makes muscle contraction slower

2.When oxygen is not present the end product of glycolysis is lactic acid, which causes the

muscles to fatigue

3.Anaerobic Glycolisis is less efficient in producing ATP than Aerobic Glycolisis, BUT is

needed for a large burst of energy lasting a few minutes

Without Oxygen

Glucose = 2ATP + 2LA

(digested component of carbohydrates)

Glycogen = 3ATP + 2LA

(the storage form of glucose)

ATP/PC and Anaerobic Glycolysis takes place in the

Cytoplasm.

Cytoplasm is basically the substance that fills the cell

So Anaerobic Glycolysis

• costs 2ATPS and produces 4ATPS• creates 2 pyruvate sugars (pyruvic acid)• 2 Hydrogen Atom• + lactate [lactic acid ] if NO oxygen is present

• Also it produces one 2NAD moleculeswhich become 2NADH1 with 02

NAD and FAD

Nicotinamide adenine dinucleotide (NAD) and flavin adenine dinucleotide (FAD) are

coenymes which carry H1 to 02 into the ECT

NAD = Niacin [B3]FAD = Riboflavin [B2]

LACTIC ACID

The graph above illustrates the two thresholds and also indicates the effects of training on the lactate curve. The blue line illustrates pre-training with the red post-training. The post-training curve has moved to the right indicating that the athlete can now exercise at a higher work rate at the different thresholds. By regularly monitoring the lactate curve (i.e. every 3-4 months), training intensities can be altered to reflect these improvements in performance.

LACTIC ACID

LACTIC

During prolonged intensive exercise (e.g. 800m race) the heart may get half its energy from lactic acid. It is converted back to pyruvic acid and used as energy by the heart and other muscles.

It is thought that 70% of lactic acid produced is oxidised (buffered by bicarbonate and turned into CO2, 20% is converted to glucose (energy) in the liver.

10% is converted to protein.

How long does it take to remove lactic acid?

About 1 hour if cooling down with gentle exercise. It can take 2 hours or more if you don’t warm down with gentle exercise.

EPOC

Excess post-exercise oxygen consumption (EPOC) is a measurably increased oxygen intake

following strenuous activity rate of intended to erase the body's "oxygen

debt."

Aerobic Energy System

Mitochondria“Power house of the cell”

Mitochondria can vary greatly in both size (0.5 micrometers - 10 micrometers) and number (1 - over 1000) per cell

Aerobic Energy System

• With Oxygen = Using large muscle groups continuously over a period of time

• Aerobic Glycolisis & Fatty Acid Oxidation = The production of ATP from Carbohydrates & Fat

Oxidative PhosphorylationBack to the end of anaerobic glycolysis

If 02 is present NAD grabs the H1 and takes them to link to 02Therefore pyruvate doesn’t turn to lactate….

Instead if goes somewhere else…..

Pyruvate nows gets broken down and turned into

ActylCoA [transition reaction]

This creates 2more NAD’s

ActylCoA enter the Krebs Cycle (TCA) another two ATPs are produced along with 6 more NAD’s

And 2 FAD’s

Enzyme = Citrate synthase

http://upload.wikimedia.org/wikipedia/commons/0/0b/Citric_acid_cycle_with_aconitate_2.svg

So far then. We have…

4 ATP’s [2 in glycolysis, 2 Krebs]

10 NADs [2 in glycolysis. 2 in transition and 6 in the Krebs]

2 FADs [Krebs cycle]

So wheres are the other 34ATPs coming from?

An electron transport chain couples a chemical reaction between an electron donor (such as NADH) and an electron acceptor (such as O2) to the transfer of H+ ions across a membrane, through a set of mediating biochemical reactions. These H+ ions are used to produce adenosine triphosphate (ATP), the main energy intermediate in living organisms

electron transport chain

With Oxygen

Glucose + O2 = 38ATP + H2O + CO2

Fatty Acids + O2 = 129ATP

Body Fat is a great source of ENERGY

1.O2 enters the system, stopping the breakdown of glycogen to lactic acid

2.With oxygen, glycogen breaks down into: ATP + CO2 + H20

3.These byproducts are easier to get rid of

CO2 is expelled by the lungs

H20 is used in the muscle

FAT METABOLISM

Lipolysis breakdown of trigyserides into free fatty acids

[by enzyme – lipase]

Once freed from glycerol, free fatty acids can enter blood and muscle fibre by diffusion.

Beta oxidation splits long carbon chains of the fatty into acetyl CoA, which can eventually enter the TCA

cycle then ETC.

1molecule of fat produces 5times more than glucose – 129ATPS

• Each system plays an important role in energy production

• This gives us a variety of movements

• The systems interact to supply Energy for the activity

Glucose and ExerciseIncreasing muscle activity requires adequate fuel supply for ATP synthesis by muscle. When muscle activity is anticipated, the adrenal glands secrete adrenaline. Adrenaline increases muscle glycogen degradation (by activating the breakdown enzymes and de-activating the synthesis enzymes).

When muscle activity ceases, adrenaline secretion is switched off. When glucose becomes available again after a meal glycogen stores in muscle are replenished. Glucose can only be supplied to muscle cells either by utilising stored muscle glycogen or supply from the liver via the bloodstream. Muscle does not carry out gluconeogenesis

REVISION PAPER