ENERGY ANALYSIS ENERGY BALANCE DESCRIPTION Neutral -------- If the amount of energy in food intake exactly equals the amount of energy expended by the muscles in performing external work and internal functioning, then bodyweight remains constant. Positive + If the amount of energy in food intake is greater than the amount of energy expended by means of external work and internal functioning, the bodyweight increases. Negative - Conversely, if the energy derived from food intake is less than the body s immediate energy requirements, the body must use stored energy to supply energy needs, and accordingly, bodyweight decreases.
ADENOSINE TRIPHOSPHATE WHAT IS ADENOSINE TRIPHOSPHATE? Adenosine Triphosphate (ATP) is a high-energy molecule that is the immediate and essential source of energy for muscle contraction. WHY DO MUSCLES NEED ATP? Without ATP, muscles cannot contract. However, muscle contains only a small amount of ATP, about enough to expend energy at maximal rate for only one second. If muscle contraction is to continue, additional ATP must be supplied. The faster you want your muscles to contract, the more rapidly you must replenish ATP. The purpose of the 3 Energy Systems is to supply this additional ATP, but the rate at which they can supply it varies. WHAT IS ADENOSINE DIPHOSPHATE? ADP is the resulting molecule after ATP has released its energy. The broken down ADP molecules can be re-synthesised (reformed) through the arrival of Creatine Phosphate (CP). WHAT IS CREATINE PHOSPHATE? Creatine Phosphate is produced naturally by the body, and is also available in small quantities in the muscles. Its primary function is to re-synthesise ADP back into ATP, which it is able to do so - for up to around 4.5 seconds of intense physical activity.
ENERGY SYSTEMS ATP-CP SYSTEM (0-4.5 SECS) The ATP-CP Energy System consists of mobilising ATP and CP within the first few seconds of exercise to supply energy. This system is completely anaerobic. Both ATP and CP are in very short supply within the muscles, and there is only enough available CP to re-synthesise ADP back into ATP for an additional 4-5 seconds of exercise (maximal exertion) at one time. LACTIC ACID SYSTEM (4.5-90 SECS) The Lactic Acid Energy System is where the body uses carbohydrates for fuel in the absence of oxygen (anaerobic). A process called Anaerobic Glycolysis facilitates the breakdown of Glucose into ATP within the Mitochondria. As you move from the ATP-CP System into the Lactic Acid System, the rate of Anaerobic Glycolysis increases to help meet your need for additional ATP. Through a series of chemical reactions in the muscle cell, the formation of Lactic Acid is associated with fatigue processes within the muscle cell, so there is a limit to this energy system during exercise. OXYGEN SYSTEM (90 SECS +) The Oxygen Energy System is where the body uses oxygen to breakdown carbs and / or fats during exercise into ATP within the Mitochondria. Although the Oxygen system cannot produce ATP as rapidly as the two Anaerobic systems, it is capable of producing greater quantities of ATP. If a steady exercising pace is maintained, the body can then learn how to mobilise fat as a primary fuel, burning in the fire of oxygen and carbohydrate.
ENERGY SYSTEMS TERMINOLOGY TERM Aerobic Glycolysis Anaerobic Glycolysis DEFINITION The breakdown of Glucose into ATP within the Mitochondria - using the Oxygen Energy System. The breakdown of Glucose into ATP within the Mitochondria - using the Lactic Acid Energy System. Fast-Glycolytic Type II b Fast-Oxidative Type II a White Fast-Twitch Anaerobic Muscle Fibre Type. Pink Intermediate Muscle Fibre Type that can adapt aerobically or anaerobically. Haemoglobin Respiratory protein molecules, designed to transport oxygen via Red Blood Cells (Erythrocytes). Mitochondria An organelle that produces ATP. Pyruvic Acid The chemical precursor of lactic acid - derived from the initial stage of Anaerobic Glycolysis. Slow-Oxidative Type 1 Red Slow-Twitch Aerobic Muscle Fibre Type.
RATE OF ENERGY EXPENDITURE The chart below is based upon a 70 Kg individual - with average physical activity and lean tissue %. FORM OF ACTIVITY ENERGY EXPENDITURE (KCAL / HOUR) Sleeping 65 Awake - lying still 77 Sitting at rest 100 Standing relaxed 105 Walking slowly on level (2.6 mph) 200 Carpentry - painting a house 240 Cycling on level (5.5 mph) 304 Shovelling snow / sawing wood 480 Swimming 500 Jogging (5.3 mph) 570 Rowing (20 SPM) 828 Walking upstairs 1100
THE MEASUREMENT OF ENERGY HOW IS ENERGY MEASURED? Energy can be measured in either joules or calories. A joule (J) can be defined as the energy used when 1 kilogram (kg) is moved 1 metre (m) by the force of 1 Newton (N). A calorie (cal) can be defined as the energy needed to raise the temperature of 1 gram of water from 14.5 to 15.5ºC. In practice, both units are used, just as different units are used to measure liquids, e.g. pints and litres. One calorie is equivalent to 4.184 joules. People use large amounts of energy so nutritionists use larger units. 1 kilojoule (kj) = 1,000 joules 1 megajoule (MJ) = 1,000,000 joules 1 kilocalorie (kcal) = 1,000 calories or 1 Calorie (Cal) To convert from one unit to another: 1 kcal = 4.184 kj 1 MJ = 239 kcal Therefore, a 1000 kcal diet provides 4.184 MJ or 4184 kj. Copyright WABBA Qualifications 2009. All Rights Reserved.