Physiology of Fitness

Energy systems and their role in sport and exercise

Learning Outcomes• List the 3 main energy systems and their cellular fuel

• Describe the 3 energy systems giving sports related examples

• Explain why some sports require more of one energy system than another

• Measure and record the body’s responses to different types of exercise

• Explain the recorded measurements

• Produce a short magazine article describing the three main energy systems using examples.

 

Actin & Myosin• What are the

contractile proteins in muscle?

• Actin & Myosin

http://www.youtube.com/watch?v=gJ309LfHQ3M

http://www.physics3110.org/images/240_actin.gif

• The key terms to remember from that clip are:

• ATP• ADP + Creatine Phosphate

• Myosin • Actin

• When ATP is released onto myosin the chemical bond breaks releasing a lot of energy causing actin and myosin filaments to contract ie muscle contraction

Contractile proteins

What is ATP?• ATP is a protein

(Adenosine) with 3 phosphates attached to it

• When chemical bonds are broken, energy is released and ATP becomes ADP (Adenosine diphosphate Di=2)

• The energy from this breaking is used to make muscles contract

The release of energy from ATP

Energy Systems• What are the 3 main

energy systems that convert chemical fuel from food into energy?

1. Creatine Phosphate System

2. Lactic Acid System

3. Aerobic Energy System

What is this?

The mitochondrion, shown here, is a tiny cellular structure that turns chemical fuel into cellular energy ie ATP.

Creatine Phosphate System

Creatine Phosphate SystemCP System

(immediate energy)• Here ATP is made without

the presence of oxygen.

• When exercise intensity is high, or energy needs are instantaneous, creatine phosphate stored in your muscle is broken down to provide energy to make ATP.

• Explosive work can be achieved, but only for short periods of time at maximum intensity, as the supply of creatine phosphate is very limited, up to 10 seconds.

ActivityList as many sports activities as possible that use mainly the CP system.

Creatine Phosphate System

Primary energy source:

Duration of activity:

Sporting events:

Advantages:

Limiting factors:

Stored ATP, CP

7-12 s

Weight lifting, high jump, long jump, 100m run, 25m swim

Produce very large amount of energy in a short amount of time

Initial concentration of high energy phosphates (ATP, PC)

Creatine Phosphate System

Training The CP Systema) Interval training: eg 1min low intensity 1min high

intensity & repeat

- 20% increase in CP (creatine phosphate) stores

- no change in ATP stores- increase in ATPase function (ATP -> ADP+P)- increase in CPK (creatine phosphokinase)

function (CPK breaks down CP molecule and allows ATP resynthesis)

b) Sprint training:

- increase in CP stores up to 40%

- 100% increase in resting ATP stores

Lactic Acid Energy System

Lactic Acid Energy System• high intensity exercise • up to 2 minutes.• ATP is made by the

partial breakdown of glucose and glycogen. This is caused by anaerobic glycolysis

• It’s an anaerobic process (no O2)

• Where does the body store glycogen?

– Muscles – Liver

• What is the by-product of anaerobic glycolysis?

– Lactic acid

• http://www.youtube.com/watch?v=JLaVIPlPm6g&feature=related

Lactic Acid Energy System

Primary energy source:

Duration of activity:

Sporting events:

Advantages:

Limiting factors:

Stored glycogen, blood glucose

12 s – 3 min

Lactic acid build up, H+ ions build up (decrease of pH)

800m run, 200m swim, downhill ski racing, 1500 speed skating

Ability to produce energy under conditions of inadequate oxygen

Lactic Acid Energy System

Lactic Acid Energy SystemAnaerobic Threshold

• The exercise intensity at which lactic acid begins to accumulate within the blood

• The point during exercise where the person begins to feel discomfort and burning sensations in their muscles

• Lactic acid is used to store pyruvate and hydrogen ions until they can be processed by the aerobic system

Lactic Acid Energy System• The primary source of substrates is carbohydrate

Carbohydrates: – primary dietary source of glucose– primary energy fuels for brain, muscles, heart,

liver

Aerobic Energy System

Primary energy source:

Duration of activity:

Sporting events:

Advantages:

Limiting factors:

Glycogen, glucose, fats, proteins

> 3 min

Lung function, max.blood flow, oxygen availability, excess. energy demands

Walking, jogging, swimming,

walking up stairs

Large output of energy over a long period of time, removal of lactic acid

Aerobic Energy System

Aerobic Energy System

Aerobic Energy System•The most important energy system in the human body•Blood lactate levels remain relatively low (3-6mmol/L bl)Primary source of energy (70-95%) for exercise lasting longer than 10 minutes provided that:

a) working muscles have sufficient mitochondria to meet energy requirements b) sufficient oxygen is supplied to the mitochondria c) enzymes or intermediate products do not limit the Kreb’s

cycle •Primary source of energy for the exercise that is performed at an intensity lower than that of the anaerobic oxidative system

Aerobic Energy System• Long term energy,

system for light exercise and every day movements.

• Uses O2

• The production of energy in the aerobic system does not start instantly.... Why?

• In groups discuss this and write down your agreed answer

Answer:

It takes a few minutes for the heart to deliver oxygenated blood to the working muscles.

Long, continuous moderate exercise produces energy using this system.

Types of Sport that use each system• Remember, energy at any given time

is derived from all 3 energy systems.

• However the emphasis changes depending on:– the intensity of the activity– the efficiency of your aerobic fitness

Energy Systems Summary

1. Creatine Phosphate energy system ... for very short high intensity exercise

• ADP + Phosphocreatine ATP + creatine • requires no O2 but only enough stored for

about 10secs e.g. power lifting...

2. Lactic Acid Energy System: short-term energy system

• Glucose 2 ATP + 2 lactic acid + heat• Glycogen 3 ATP + 2 lactic acid + heat

requires no O2 but produces energy for high intensity exercise for up to 60 – 90 secs e.g. 400m race..

Energy Systems Summary

3. Aerobic Energy System: long-term energy system

– Glucose +O2 38 ATP + CO2 + water + heat

– Fatty acids + O2 129 ATP + CO2 + water

+ heat