THREE ENERGY SYSTEMS

The body needs energy for basic body functions and activity. The chemical compound adenosine triphosphate (ATP) provides the energy that allows muscular movement – from repetitious weight lifting, to walking, to subconscious movements like blinking

ENERGY CAN BE PRODUCED BY THREE METHODS: AEROBIC (USING OXYGEN) …..aerobic energy system ANAEROBIC (WITHOUT OXYGEN) ….creatine phosphate (ATP- PC) system ….anaerobic glycolysis (Lactic Acid)system

All 3 energy pathways can operate at one time, however, the contribution of each varies depending on the intensity (how hard) and the length of the activity, and also the fitness of the athlete. Stick the graph of energy system contribution into your workbook – from handout material

THE PHOSPHATE ENERGY SYSTEM – (ATP – PC) (ANAEROBIC) This system provides most of the ATP during powerful or explosive efforts. Once off activities, such as , kicking a goal, take off in long jump. Quick activities, such as, sprints (eg. FF in footy, GS in netball) RELATED TO (PROVIDES ENERGY FOR) THE FOLLOWING FITNESS COMPONENTS: Muscular strength, muscular power, anaerobic power, speed, agility.

*** Following 10-15 seconds of maximal effort, the phosphate system is largely depleted. The body then needs to reduce the intensity of the activity. At this point, the next energy system (the anaerobic glycolysis system or Lactic Acid system) takes over as the dominant provider of ATP. The phosphate energy system relies on muscle stores of ATP and a chemical compound called phospho-creatine (or creatine phosphate), to create maximal effort for the activity.

HOW ATP AND PHOSPHO-CREATINE PRODUCE ENERGY ATP supplies diminish in the muscles, leaving ADP + P. The breaking of the bond between phosphate and creatine produces energy to turn ADP + P back into ATP. Thus producing more energy for the working muscles. This system does not require oxygen, so is ‘anaerobic’ After 10-15 seconds of effort, the muscles’ stores of phospho-creatine are also depleted, the athlete must slow down or stop.

After approximately 10 seconds of maximal effort, the body can take 5 – 7 minutes to fully restore the ATP and phospho-creatine supplies. Obviously if the effort was much less than 10 seconds the recovery time would be shorter. List 5 activities from 5 completely different sports that would use the phospho-creatine system

THE ANAEROBIC GLYCOLYSIS SYSTEM aka: the lactic acid system, the lactacid system Provides the bulk of the energy for high intensity, just below maximal efforts (85 – 95%). Also when there has been insufficient time to replenish phospho-creatine in repeated maximal efforts. Dominant supplier of ATP during maximal efforts from 10-60 seconds.

THE ANAEROBIC GLYCOLYSIS SYSTEM IS CLOSELY LINKED TO: Anaerobic power, local muscular endurance, speed and muscular power. During the 400m sprint the phospho-creatine system allows for an explosive start, however, the anaerobic glycolysis system dominates for most of the race

HOW THE ANEROBIC GLYCOLYSIS SYSTEM WORKS Glycogen stores within the muscle create ATP (without the use of oxygen>>>anaerobic) Glycogen is converted into glucose, with the assistance of enzymes. The glucose is then converted into lactic acid. During this reaction energy is released to resynthesise ATP (turn ADP + P back into ATP) * * Because there is not much oxygen available, lactic acid is produced from pyruvic acid.

When lactic acid accumulates in the muscles, contractions are inhibited. The body can tolerate increasing levels of lactic acid, until the level is higher than the body’s ability to remove it. LACTATE THRESHOLD: WHEN LACTIC ACID LEVELS ARE GREATER THAN THE BODY’S ABILITY TO REMOVE IT. When an athlete passes this threshold, they must slow down. A fit 400m runner eg.Cathy Freeman may not hit their threshold until near the finish. An unfit 400m runner may hit the threshold much earlier.

How does the lactate threshold affect a runner (400/800m), compared to a team sport player? Provide 5 examples from different activities of the anaerobic glycolysis system being used.

THE AEROBIC ENERGY SYSTEM aka: aerobic glycolysis Relevant to all fitness components Provides the bulk of energy for sub maximal efforts which go beyond 2 minutes. Maximal activities longer than 30 - 60 secs.

During rest, fats are the primary fuel, during exercise carbohydrates are the primary fuel, depending on the duration and intensity of the exercise. Example: submaximal activities of low intensity where energy demands are low (lawn bowls, slow walking) fats provide the major fuel source. Submaximal / maximal activities of higher intensity (running, swimming and intense team sports) carbohydrates are the major fuel.

CHARACTERISTICS OF THE AEROBIC SYSTEM Much slower energy production than that of the anaerobic systems Individual reaches a ‘steady state’ after 2 – 5 minutes. This is when the respiratory system’s increased oxygen intake meets the activity’s oxygen demands. Aerobic production of ATP then plateaus at the required rate. You can tell you have reached a steady state when your breathing is steady. Dominant contributor of ATP during sub maximal conditions. Limited contribution of ATP production if lactate threshold is reached, due to the debilitating effects of lactic acid and hydrogen ions.

Pyruvic acid (which created lactic acid during anaerobic glycolysis) is further broken down in the citric acid cycle and the electron transport chain, inside the mitochondria.

Create a table with the characteristics of the 3 energy systems.