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]
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
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