PHYSIOLOGICAL REQUIREMENTS OF PHYSICAL ACTIVITY Foods Fuel and Energy Systems
A Maria Sharapova serve takes 1-2 seconds to perform. It’s fast & explosive. She might do this hundreds of time over a game. Plus she has to run fwd, bkwd and sideways for 1-2 hours. Her Muscles requires ENERGY to do this. Where does this energy come from?
Food Fuels our Body 1. CARBOHYDRATES (Glycogen) 2. PROTEIN 3. FATS
CARBOHYDRATES Pastas Cereals Rice Fruit/Veges Breads Sugar Carbohydrates are stored as Glycogen in Muscle & Liver CHO is the body’s preferred fuel during Exercise – breaks down easily, uses little oxygen
PROTEIN Fish Red Meat Poultry Eggs Dairy products GRAINS Protein is stored as MUSCLE and AMINO ACIDS around the body. 5-10% contribution to endurance events: Mainly used for growth/repair
FATS Butter Oils Margarine Nuts Cheese
Food that we ingest is stored and burnt to fuel our muscles This food must be converted into a chemical compound called ATP WithoutATP, Muscles cannot contract
A.T.P. • Adenosine triphosphate. • This is energy for muscle contraction. • Energy for movement of muscle fibres is stored in the muscle as a molecule of ATP. Adenosine P P P Adenosine triphosphate
To use the stored ATP • To release the energy, ATP is broken down into ADP + Pi (Adenosine diphosphate + Phosphate molecule) • The energy released allows for a muscle contraction. + P P Pi Adenosine Energy
Resynthesis of ATP • There is only enough stored ATP for about 1-2 contractions, soooo….we must resynthesise ADP back into ATP. • Fuel and energy for this comes from CHO, Fats, Proteins and Creatine phosphate. • These fuel sources resynthesise the free Phosphate molecule (Pi) back to the ADP to reform ATP.
CHO, Fats, Proteins, CP + P P Pi Adenosine Resynthesises the ADP back to ATP P P Pi Adenosine
ATP is used in all 3 energy systems. The type of energy system used and the interplay between them depends on the frequency, duration, intensity of the activity and fitness levels of the individual.
The 3 energy systems • The ATP – PC system • Alactacid system • Creatine phosphate system • Phosphagen system. • The Lactic Acid Systems • Anaerobic glycolysis system • Lactacid system • Aerobic System • Aerobic Glycolysis
ATP –PC system • ATP breaks down to ADP + Pi to release energy. • The ADP + Pi must be reformed to ATP for continued muscle function. • PC provides the energy for the free Pi to be re-attached to the ADP molecule to form ATP.
ATP –PC system cont.. • PC stored in the muscles breaks down anaerobically (without O2) to form Phosphate and creatine. This releases energy for the resynthesis of ATP. • It takes 2 PC molecules to resynthesise 1 ATP molecule (one PC = 0.7 ATP). • NOTE: The resynthesis of PC (Phosphate + creatine = PC) occurs in the recovery phase.
For activity lasting: 0-10 SEC ATP-PC SYSTEM 10-30/40 SEC LACTIC ACID SYSTEM 30 + SEC- 2MINS AEROBIC SYSTEM
ATP-PC SYSTEM CP instantly available, but runs out quickly Uses stores of CP (Creatine Phosphate) to REMAKE ATP Used for high intensity Jumps, Throws, Sprints Only have 10 seconds of CP in muscles If activity lasts longer than 10 sec, ATP must be REMADE by some other means…..
Summary • Each ATP molecule is made up of an adenosine part and three phosphate groups. When 1 mole(1) of ATP is broken down, 7 to 12 Kcal (2) of energy is released. • Besides ATP, there is still another high-energy compound called phosphocreatine (PC) inside the human muscle cells. When PC is broken down, energy is released for the resynthesis of ATP.
Summary Cont… • However, the total amount of PC stored in the human body is also extremely limited. There are altogether 450 to 510 mM PC, or 4.5 to 5.1 Kcal of energy in the human body. The energy released from the breaking down of ATP is also required to resynthesize PC. Nevertheless, this process will be carried out when the human body is in the recovery stage. • The complete ATP-PC system can only supply 5.7 to 6.9 Kcal of energy, which can maintain about 10 seconds of maximal efforts.
Summary cont… • The importance of the ATP-PC system is that it is the instant energy source in the human body. • The ATP-PC system does not require oxygen in the muscles for proper functioning. Besides, the required fuels (ATP and PC) have already been stored in the muscle cells • The chemical reactions involved when PC is broken down are fewer than the other two energy systems. • The ATP-PC system is particularly important for high-intensity and high- speed activities that need to be completed in a few seconds (e.g., starting, jumping, throwing, and weight lifting).
LACTIC ACID SYSTEM Body uses stored fuel of GLYCOGEN to REMAKE ATP Need Oxygen to do this properly About 2-3 hours of glycogen stored in body. Downside – by-product called Lactate. Hydrogen Ions also released which inhibit muscle contraction Happens because of lack of enough Oxygen to break down Glycogen 400m run, 800m at high intensity
AEROBIC SYSTEM Plenty of Oxygen available to remake ATP . So no LA or H+ is accumulated Used in longer, sub-max activities. Long run, swim, cycle. Like the LA system, the Aerobic uses Glycogen to remake ATP. Oxygen supply meets demand We use this system at REST (Now!) – except we burn… Will keep suppling ATP for as long as Fitness levels allow FAT!!!!
During REST Any rest, short OR Long, CP is being replenished, so we can ‘sprint’ again. BUT, need 3 minutes rest to get all CP back! Any Lactate and Hydrogen Ions are removed from muscles & blood stream too.
Things to remember: All 3 turn on at once no matter what the activity. However, depending on intensity and duration of the activity, ONE system will contribute more than the other TWO. The 3 Energy Systems are not like TRAFFIC LIGHTS. One does not switch off and another goes on.