Chapter 5: How does training affect performance?
* alactacid system (ATP/PC)
* lactic acid system
* aerobic system
* The human body requires energy for its organs to function, internal processes to take place and to power muscular contractions for movement * Energy in the human body is stored in the chemical bonds that join atoms and is released when needed * The transformation of food, chemical energy, into energy that the muscles can use, mechanical energy, is the role of energy systems * Chemical energy is energy stored in bonds between atoms * Mechanical energy is motion or movement energy
* Energy provided by food is measured in kilojoules (kJ)
* Adenosine triphosphate (ATP) is a high energy compound that stores and transfers energy to body cells * The ATP compound consists of a large molecule call adenosine and three smaller molecules called phosphate, each phosphate is held together by high energy bonds * When the last or terminal phosphate is detached, the energy stored in this bond becomes available and is transferred to the cells * Energy from ATP allows the fibres in muscles to contract, enabling movement * Once the phosphate molecule has detached it is referred to as Adenosine diphosphate * Resynthesis is the process of restoring ATP to its former state The three systems that make ATP available are:
* The alactacid system (ATP/PC)
* The lactic acid system (glycolytic system)
* The aerobic system (oxygen system)
* The alactacid and lactic acid systems are anaerobic pathways as they do not use oxygen for the resynthensis of ATP * The aerobic system uses oxygen for the resynthesis of ATP and is oxygen dependent * Although the energy systems are examined in isolation, they function together, the predominant energy system is the one being most utilised at that point in time
Alactacid system (ATP/PC)
* ATP supplies within the body are only large enough to enable one explosive muscular contraction and lasts 1-2 seconds * Further muscular contraction relies on creatine phosphate breaking down, which provides energy for the phosphate to combine with the adenosine diphosphate to once again form adenosine triphosphate * Creatine phosphate (CP) is an energy rich compound that serves as an alternative energy source for muscular contraction * CP supplies are exhausted in 10-12 seconds and takes only 2 minutes to be fully restored in the presence of oxygen * We have about 90 grams of ATP stored and about 120 grams of CP stored * There are no fatiguing by-products of this system, however heat is produced Lactic acid system
* Glycogen is the storage form of glucose and is used for fuel when blood glucose levels decline * Glycolysis is the process of using glycogen or glucose as fuel * Anaerobic glycolysis is a process where glucose is broken down in the absence of oxygen to produce energy * Lactic acid is produced because insufficient oxygen results in the partial breakdown of glucose, providing quick but limited ATP production, as well as the by-product lactic acid * As sufficient oxygen is not available during intense exercise, lactic acid levels rise and continue to rise as intensity increases * The fuel of the lactic acid system is carbohydrate in the form of glucose in the blood and stored glycogen * It is the dominant system used for intense activity performed between 30 seconds and 2/3 minutes * Excessively high levels of lactic acid prevent the muscle fibres from contracting and result in a rapid deterioration in performance * Lactate is processed in the mitochondria in the muscle cells, most is converted to carbon dioxide and water and some is converted to fuel * The lactate threshold is the point at which lactic acid accumulates rapidly in the blood * Lactic acid diffuses from the muscle and into the...