Exercise physiology Intro The very basis of exercise

Exercise physiology

Intro �The very basis of exercise is dependent on the body’s ability to take up and utilise oxygen in order to produce energy. �This unit examines the production of energy (ATP) and those factors that influence the uptake and delivery of oxygen to working muscles

ATP, ADP and AMP �Energy for muscular contraction comes from the breakdown of ATP (adenosine Tri Phosphate) �The three (tri) phosphate molecules are the key to the release of energy �As a phosphate is split off, energy is released

ATP, ADP and AMP �Why is it preferable to break down ATP in the muscle cells? �Because the muscles are the site of action. �It makes sense to break ATP down where it will be used �The body however only has limited stores of ATP. The body needs a mechanism for the creation of a regular supply of ATP for muscular work? �What might this be? �Food break down to provide the fundamental components of ATP

Sources of ATP �The nutrients we extract from food are used to produce ATP. These are: Carbohydrate b. Fat c. protein a.

1. Carbohydrates Carbohydrate is broken downglucose into glycogen ____ and stored as _____ in the muscle or liver Carbohydrates are the preferred source of ATP and can be used to produce energy either with or without oxygen present

2. Fats �Fats are broken down triglyceride into s free fatty acids or _____________ �Fats are stored in the body as adipose ______ Fats tend to be used in the chemical production of ATP during very submaximal exercise and increasingly during aerobic exercise

Proteins �Proteins are broken downamino into acids ______ andtissues are used to create ______ �Proteins are used as a source of ATP in extreme cases only �Why? Because it requires breaking down tissue

Chemical production of ATP �Production of ATP at rest �At rest ATP is produced in the presence of oxygen (aerobically) �This process is called: �Cellular respiration �This process occurs in muscle fibres in the �Mitochondria �The production of ATP at rest uses a mix of carbohydrates (glucose) and fats (free fatty acids)

�Why is it preferable to burn mostly fats at rest? �So the carbohydrates are made available in exercise when they are the preferred energy source

Chemical pathway is: 1/3 glucose Free fatty acids ADP + P CO 2 Energy TCA or Krebs Cycle Heat ATP Water Muscular contractions

Equation Oxygen Glucose + free fatty acids Energy CO 2 + H 2 O + Heat +

�What happens to the CO 2 produced? �It is breathed out �What happens to the water produced? �Breathed out as vapour but also lost via sweat �This is a very efficient system for producing ATP. For every molecule of glucose or fat used 38 molecules of ATP are produced �What would this ATP be used for at rest? �Heart beating, breathing, skeletal muscle pumps, gut contracts

Production of ATP during exercise �During exercise, production of ATP depends upon the energy system being used. This in turn will be governed by the intensity and duration of the exercise. a. ATP-CP system this system uses the ATP already stored within the muscles. The breakdown of ATP to ADP releases ATP energy for muscular contraction Stored Creatine Phosphate Energy ADP + P

What is the role of creatine phosphate within the muscles? �Used to reform ATP from the broken down components of ATP. A theory is that the more stores of CP the more the ATP-CP, the more ATP -CP system can be used What might the advantages be of taking the dietary supplement creatine? �To increase the stores of CP in the body, so this process can occur more frequently �This system occurs without the presence of oxygen (anaerobically) and provides energy for intense exercise over 0 -10 sec

b. Anaerobic glycolysis (Lactic acid system) �Anaerobic means �In the absence of oxygen �Glycolysis means �Breakdown of glycogen �Anaerobic glycolysis is defined as the breakdown of glycogen in the absence of oxygen for energy production

The pathway of energy production Glycogen Glucose ADP + P ATP Pyruvic acid Insufficient O 2 Lactic acid Muscular contractions

What are the consequences of the product produced at ‘D’ �Causes fatigue and the ‘burn’ associated with high intensity, repetitive exercise �This system provides energy over 30 -120 seconds for high to moderate intensity exercise

c. Aerobic glycolysis (aerobic system) �Aerobic means �In the presence of oxygen �Glycolysis means �the breakdown of glycogen in the presence of oxygen �Aerobic glycolysis is defined as the breakdown of glycogen in the presence of oxygen for energy production

Aerobic Glycolysis pathway Glycog en Glucos e Muscular contractions Pyruvic acid CO 2 Sufficient O 2 TCA or Krebs Cycle ACETYL COA Sufficient O 2 Fats triglycerid es Free fatty acids Energy Heat Water

Continued �Initially this process uses blood glucose, followed by stored glycogen. This process produces 36 molecules of ATP for every molecule of glycogen used. �This is the preferred system during aerobic exercise of moderate intensity, e. g. Running and swimming

�For sub-maximal exercise such as walking, fats (as free fatty acids) are the main source of fuel for the aerobic system. Explain why. �Because there is plenty of oxygen to break it down. Also it saves the carbohydrates for more intense work �For prolonged exercise such as marathons, the main fuel source once again turns to fats. Why? �Because stores of glycogen are used up �Fats however require more oxygen than carbohydrates to produce the same amounts of ATP. What are the consequences of this for the athlete? �They have to slow down to increase oxygen uptake

What happens when an athlete hits the wall? �When an athlete ‘hits the wall’ there is a sudden decrease in the amount of glycogen used and matching rise in fatty acid usage. As a result, there is an increased requirement for oxygen to use fatty acids as a fuel for exercise. If they do not slow down, they will start to produce ATP anaerobically. Lactic acid levels will rise, causing a sudden decrease in performance