Energy Systems In Human Body

Presented by,

Dr. Priti Rajak

M.P.Th.

Cardio-Respiratory

Physiotherapy

“ENERGY”

• Is defined as the ABILITY or

CAPACITY to do WORK.

• It is expressed in JOULES, as

Energy = work/time

Cells don’t get Energy directly from food, it

must be broken down into:

ATP -Adenosine Triphosphate

ATP = a form of energy one can immediately

use, it is needed for cells to function &

muscles to contract

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

ATP (2-3 seconds)

ATP-CP Energy System (8-10second)

Anaerobic Energy System (2-3 minutes)

Aerobic Energy System (3 minutes +)

Predominant Energy Pathways

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 PhosphateThe splitting of the Phosphate bond = Energy for

work Ex. Muscle Contraction, Moving hand from a

hot stove, Jumping & Throwing

The ATP Moleculea. Adenosine Triphosphate (ATP)

Adenosine PPPP

PP P

b. The breakdown of ATP:

Adenosine PPPP PPP

Energy

Energy for cellular function

ATP = ADP + energy for biological work + P

(ADP = Adenosine Diphosphate)

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

The Immediate Resynthesis of ATP by CP

a. Creatine Phosphate (CP)

Creatine

PHigh energy bond

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

Creatine P

Energy

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

Adenosine P

PP

P

Anaerobic Energy System

Without oxygen = Activities that require a

large burst of energy over a short period of

time

Anaerobic Glycolysis = Production of ATP

from Carbohydrates without oxygen

(breakdown of glucose)

Since glycogen is stored in the muscle &

liver, it is available quickly

This system provides ATP when ATP-CP

runs out.

Again, ATP-CP lasts for a few seconds, the

Anaerobic Energy System allows for 2-3

minutes of work

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 Glycolysis is less efficient in

producing ATP than Aerobic Glycolysis,

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)

Aerobic System uses oxygen to break down food fuels. This gives off a high energy yield.

Carbohydrates and fats are used.

Three stages of the aerobic pathwayare…….

CO2 is expelled by the lungs

• ATP must be re-formed from ADP+Pi. This required energy!

• The energy comes from breaking down Glycogen.

• Breaking down glycogen is called Glycolysis.

• The LA system does this without 02 and is therefore refereed to as anaerobic glycolysis.

• Because there is no 02 present the glycogen is not totally broken down and the by-product lactic acid is formed.

Soooooo….

• Lactic acid present in the muscle

decreases muscle pH, which in turn

decreases the amount on glycolytic

enzymes and the rate of ATP resynthesis,

causing FATIGUE!

• Glycolytic enzymes are responsible for

breaking down glycogen.

• As we exercise pyruvate is formed • When insufficient oxygen is available to breakdown the

pyruvate then lactate is produced • Lactate enters the surrounding muscle cells, tissue and blood • The muscle cells and tissues receiving the lactate either

breakdown the lactate to fuel (ATP) for immediate use or use it in the creation of glycogen

• The glycogen then remains in the cells until energy is required

• 65% of lactic acid is converted to carbon dioxide and water, 20% into glycogen, 10% into protein and 5% into glucose.

• The process of lactic acid removal takes approx. one hour, but this can be accelerated by undertaking an appropriate warm down that ensures a rapid and continuous supply of oxygen to the muscles.

• The normal amount of lactic acid circulating in the blood is about 1 to 2 millimoles/litre of blood. The onset of blood lactate accumulation (OBLA) occurs between 2 and 4 millimoles/litre of blood. In non athletes this point is about 50% to 60% VO2 max and in trained athletes around 70% to 80% VO2 max.

• Lactic acid (lactate) is not:• responsible for the burn in the leg muscles when

exercising very fast • responsible for the soreness you experience in the 48

hours following a hard session • a waste product • Lactate, which is produced by the body all day long,

is resynthesized by the liver (Cori Cycle) to form glucose that provides you with more energy. Sounds like a friend to me.

• The breakdown of glucose or glycogen produces lactate and hydrogen ions - for each lactate molecule, one hydrogen ion is formed. The presence of hydrogen ions, not lactate, makes the muscle acidic that will eventually halt muscle function. As hydrogen ion concentrations, increase the blood and muscle become acidic. This acidic environment will slow down enzyme activity and ultimately the breakdown of glucose itself. Acidic muscles will aggravate associated nerve endings causing pain and increase irritation of the central nervous system. The athlete may become disorientated and feel nauseous.

Hydrogen ions

Improving your Lactate Threshold

• The aim is to saturate the muscles in lactic acid that will educate the body's buffering mechanism (alkaline) to deal with it more effectively. The accumulation of lactate in working skeletal muscles is associated with fatigue of this system after 50 to 60 seconds of maximal effort. Sessions should comprise of one to five reps (depends on the athlete's ability) with near to full recovery.

• Training continuously at about 85 to 90% of your maximum heart rate for 20 to 25 minutes will improve your LT.

• A session should be conducted once a week and commence eight weeks before a major competition. This will help the muscle cells retain their alkaline buffering ability. Improving your LT will also improve your duration of VO2max.