Chapter 5-6 Flashcards
Adenosine Triphosphate
ATP is the major source of energy that keeps every cell in the body going, including muscles. ATP is a chemical fuel source, and consists of an adenosine molecule with three phosphates joined together in a row. Energy is released when one of the phosphates spills off, changing ATP into adenosine diphosphate (ADP) and an inorganic phosphate (Pi). The chemical reactions that turn the energy contained in ATP into energy for use in muscular contractions can be summarised as follows.
Food Fuels
Carbohydrates Fats Protein
Glycogen (Carbohydrates)
- Energy for muscular contraction stems first from muscle glycogen and then liver glycogen. - bodies preferred fuel source in high-intensity exercises and in comparison to fat, as less they require less oxygen to break down to produce the same amount of energy. - It can be broken down with and without oxygen, this is known as aerobic Glycolysis (with oxygen) and one glucose molecule yields 36 to 38 ATP molecules whilst only 2 to 3 ATP molecules are produced without oxygen (anaerobic Glycolysis). High-intensity aerobic exercise predominantly uses carbohydrates as its preferred fuel source.
Fats (Triglyceride)
- Fats in the form of triglycerides are stored through the body in adipose tissue, under the skin and in the muscles. - Triglycerides are broken down into free fatty acids, which in turn are broken down aerobically to provide energy for movement. - Fats can only be broken down in the presence of oxygen (aerobically) however they are not the preferred fuel source as it puts added stress of the oxygen and transport and delivery system. - During sub-maximal prolonged exercise, fat becomes predominant as glycogen depletes. 1 triglyceride produces 450 ATP molecules, whilst 1 FFA (free fatty acid) produces 147 ATP molecules.
Fats as a fuel source
A problem occurs when liver glycogen is depleted and an athlete is unable to sustain blood glucose levels. Hypoglycaemia sets in and the athlete depends heavily on fat to supply energy. This is quickly resolved by ingesting sugary drinks. Endurance athletes tend to increase their ability to use fatty acids for ATP resynthesises by increase the number of mitochondria they develops, and by glycogen sparing.
Glycogen Sparing
A long term adaptation (resulting from aerobic training) that allows fats to be used more readily and earlier during performances; this results in less use of lactic acid system and allow glycogen to be used much later in performances.
The Energy Systems
Which of the three systems operates during exercise depends on: • The duration of the exercise • The intensity of the exercise • Whether or not oxygen is present • The depletion of chemical and food fuels during exercise. . Rate: How quickly the systems can resynthesis ATP Yield: How much ATP the system typically resynthesises ATP-PC: High Rate, Low Yield Anaerobic Glycolysis: High Rate, Low Yield Aerobic System: Low Rate, High Yield
Rate and Yield of all three energy Systems
ATP-PC Very Fast 1 ATP Anaerobic Glycolysis Fast 2 ATP *Aerobic Glycolysis Moderate 38 ATP *Aerobic Lipolysis Slow 100+ ATP
ATP-PC energy system
• does not require oxygen • provides the fastest rate of ATP release for energy because it depends on simple and short chemical reactions and ready availability of PC in muscles. • A limited amount of PC is stored in the muscles (about 10 seconds worth at maximal intensity), with larger muscles capable of storing slightly more PC than this (12-14 seconds at maximal intensity) • ATP and PC are stored in the muscles and available for immediate energy release. This system is limited by the amount of PC stored in the muscles – the more intense the activity, the quicker this is utilised to produce ATP. After 5 seconds of maximal activity the anaerobic Glycolysis system becomes the major producer of ATP • Once PC has been depleted in the muscle, ATP must be resynthesised from another substance – typically glycogen, which is stored in the muscles and liver – via anaerobic Glycolysis using the anaerobic Glycolysis system. • The individual must rest for 3 minutes, for this system to replenish • This system supports maximal intensity activity (95%) + maximum heart rate). Max heart rate = 220 – age.
Anaerobic Glycolysis system
- all of the pyruvic acid produced during anaerobic Glycolysis is converted into lactic acid. -A by-product of this process is the production of hydrogen ions (H+), which cause muscles to become more acidity therefore restraining Glycolysis. . • This system produces lactic acid, which can be broken down (without oxygen) to glycogen to provide energy (ATP) • Peak power is usually reached between 5 and 15 seconds and the system continues to contribute to ATP production until it fatigues, after 2 to 3 minutes. • An active recovery is the best way to recover this system. It keeps oxygen levels elevated, meaning there is more oxygen in the system to break down lactic acid faster.
The Aerobic Glycolysis System
• It requires oxygen which can be provided (90% VO2 max) within 60 seconds • It prefers the break down of carbohydrates rather than fats to release energy as less oxygen is needed to break down carbohydrates • The aerobic system does not release toxic or fatiguing by-products and can be used indefinitely • Fats can produce more ATP than carbohydrates, but they require more oxygen to produce an equivalent amount of ATP
Training the ATP-PC system
- Short-interval, sprint training or plyometrics are favoured - It is recommended that high or maximal- intensity efforts lasting up to 10 seconds are followed by adequate time to allow full replenishment of PC, usually 3 minutes of passive recovery is enough to restore PC levels. -Alternatively, resistance or weight training can be used, where maximal effort occurs up to 5 seconds. This would involve several repetitions of heavy weights, performed explosively, and mindful of using muscle groups specific to actions observed during games analysis.
Training the Anaerobic Glycolysis system
- Training sessions occurring about the anaerobic threshold (85% max HR) for 45-60 seconds will improve the anaerobic Glycolysis system. -This system has also been proved to have the greatest capacity to improve with training. - Any work performed at or above the anaerobic threshold will promote increase lactic acid tolerance and delayed lactate inflexion point. - WOrk to rest ratio of 1:1
Training the Aerobic System
An aerobic performer who can significantly increase their anaerobic threshold can perform at a higher intensity more efficiently. Training the aerobic system can be divided into high or low intensity bouts and can use continuous or long-interval training sessions
Interplay
A situation in which all three energy systems contribute to ATP production, with one system being the major ATP producer at any time.
Glycolysis
The breakdown of glycogen either aerobically (with oxygen) or anaerobically (without oxygen)
Aerobic Glycolysis
The breaking down of glycogen with sufficient oxygen, resulting in the release of ATP and carbon dioxide, water and heat.
Anaerobic Glycolysis
The breaking down of glycogen with insufficient oxygen, resulting in the production of lactic acid, lactate and hydrogen ions and contributing to fatigue.
Hypoglycaemia
A condition created when blood glucose levels are significantly reduced, often during extended endurance activities calling upon glycogen reserves in the liver
Glycogen sparing
A long-term adaptation (resulting from aerobic training) that allows fats to be used more readily and earlier during performances; this results in less use of the anaerobic Glycolysis system and allows glycogen to be used much later in performances
Lactate inflection point (LIP
The exercise intensity beyond which lactate production exceeds removal
VO2 maximum (VO2 max):
The maximum amount of oxygen that can be taken up, transported and utilised per minute
Plyometrics
Explosive movements completed at maximal intensity, usually lasting a couple of seconds.
Fatigue
Fatigue is generally accepted as the inability to sustain required exercise intensity, it can also be thought of as being the point when exercise begins to deteriorate or falter.
The onset and rate of development of fatigue is dependent on
• The type of activity being undertaken: intermittent or continuous • The muscle fibre type used: fast or slow twitch fibres (slow-twitch fibres are more fatigue resistant) • The types of muscular contractions occur. Isotonic, isometric or isokinetic (isometric cause fatigue quickest) • The intensity and duration of the activity undertaken (fatigue is more rapid with high-intensity or anaerobic work) • The level of fitness or training adaptations of the performer possesses.
Levels of Fatigue
Local General Chronic
Local Fatigue
• Experienced in a muscle or localised group of muscles • Occurs if the same muscle group is called upon repeatedly during training, without sufficient recovery • Muscles experience heaviness, tingling pain
General FAtigue
• Occurs after completing a full training session or game• Insufficient recovery • All muscles experience ‘weakness’ • Often accompanied by psychological fatigue
Chronic Fatigue
• Breakdown of immune system • Often caused by overtraining, poor training program design, inappropriate recovery strategies • Increases susceptibility to illness • Persistent muscle soreness • Reduced motivation levels
Central Fatigue
Involves the Central Nervous System (brain, spinal chord and neurons) weakening singles sent to muscles
Peripheral Fatigue
Involves a reduction of muscular contractions due to impairment/fatigue at the actual muscle. It is possible for central and peripheral fatigue to occur at the same time.
Key factors that contribute to muscular fatigue
Fuel depletion • Intramuscular ATP • Phosphocreatine (PC) • Muscle glycogen • Blood glucose Metabolic by-products • Hydrogen ions in plasma and muscle • Inorganic phosphate • ADP Neuromuscular events • Decreased firing of the CNS • Impaired sodium and potassium gradients Elevated body temperature • Very high core temperature • Increased rates of dehydration • Redistribution of blood to assist in cooling
Fuel Depletion
The aerobic Glycolysis system depletes glycogen quicker as it uses more oxygen whilst the anaerobic Glycolysis system does not as it has a low duration (30 second- 1 minute)
Metabolic By-Products
Acidity increases in the muscle, which slows down glycotic enzymes that in turn slows down the break down of glycogen By-Product Energy System
Elevated Body Temperature
Neuromuscular Fatigue
Oxygen Debt or EPOC
Oxygen debt referred to the elevated amount of oxygen athletes consume after exercise has finished during recovery. Oxygen consumption is extended when an active recovery is undertaken, and assists in the removal of metabolic by-products.
Oxygen debt only occurs after the body has undertaken anaerobic exercise.
There are two parts to oxygen debt, fast and slow.
Fast (1st part): the replenishment of phosphocreatine (PC), this usually takes 2 to 3 minutes.
Slow (2nd part): the removal of lactic acid through buffering which is the absorption of H+ ions in the presence of hydrogen carbonate produced b the kidneys. The greater the accumulation of lactic acid, the larger the EPOC will be.
Recovery process during EPOC
Metabolic By-Products
H+ ions in plasma and muscle
The presence of hydrogen ions, not lactate, makes the muscle acidic, which will contribute to decreased muscle function. This acidic environment will slow down enzyme activity and ultimately the breakdown of glucose itself.
Inorganic Phosphate (Pi) and adenosine diphosphate (ADP)
The accumulation of Pi that occurs rapidly during high-intensity exercise would lead to decreased contractile force production whilst the accumulation of ADP is associated with the reduction in power output.
Recovery Strategies - Fuel Depletion (Refuelling)
PC is restored as soon as rest/recovery occurs (fast part of oxygen debt) and PC restoration is made easier by passive recovery. Low pH (accumulation of lactic acid) will slow PC restoration, as will slow supply of oxygen, having a high aerobic capacity can prevent this.
Glycogen depletion can be minimised by ensuring carbohydrate loading occurs 4-5 days prior to competition. High-GI foods and hypertonic drinks should be consumed after exercise to ensure rapid restoration back to glycogen pre-exercise levels.
Recovery Strategies for H+ Ions
It’s recommended that an active recovery should be undertaken because it:
- Prevents venous pooling (accumulation of blood in a part of the body)
- Maintains oxygen levels higher than if the person were to simply sit/lie down, and this speeds up removal of lactic acid that actually impedes recovery
- Creates a ‘muscle pump’ that increases rate of oxygen supply and waste removal via the circulatory system
- Massage is also a recovery strategy beneficial in breaking down hydrogen ions but doesn’t have the benefit of having a higher oxygen presence than rest. Contrast bathing leads to increased removal due to vasodilatation then vasoconstriction being repeated many times so is more a ‘venous pump’ than a ‘muscle pump’.
Recovery Strategies for Dehydration and elevated body temp
Recovery strategies for elevated body temperature and dehydration mainly involve ‘prevention’ and include the following:
- Hydrating before, during and after the event.
- Consuming sports drinks containing sodium to encourage fluid retention
- Carbohydrate loading which is associated with water absorption
- Ice baths/cool pools
Drinking ‘cool’ drinks rather than cold drinks
