Anaerobic Energy Systems By Jake and Charlotte

Anaerobic Energy System Page 57 of Lab Manual 2 Types: - ATP-PC <8 sec - Lactic Acid OR Anaerobic Glycolysis <3min ATP-PC energy source is Creatine Phosphate Lactic Acid System uses glucose (sugar) for its energy

ATP-PC Energy System least complicated provides energy for activities of short duration (up to 10 seconds) and high intensity (85-100% of maximal effort) most evident in events such as 100m sprints, swimming, high jump without this system fast powerful movements would not be able to be performed

Lactic Acid System (Anaerobic Glycolysis) Its more complicated than the ATP-PC system far more powerful, providing energy for events of up to three minutes (400m, 800m) uses carbohydrates as its main fuel for rebuilding ATP

Anaerobic Energy System Highlight the ATP-PC System and Lactic Acid System

Definitions Speed: The ability of the body, or part of the body, to move as quickly as possible from one place to another Power: combination of speed and strength Work: Force expressed through distance, or a displacement, independent of time Velocity:

EPOC Excess Postexercise Oxygen Consumption:- elevated oxygen consumption above resting levels after exercise; at one time referred to as oxygen debt. Example: Running up a few flights of stairs in the education building to get to a class on time. This leaves you with a rapid heart rate and feeling short of breath. After a few minutes your pulse and breathing returns to normal. This is a great example of excess postexercise oxygen consumption at work in everyday life.

Sources of Fatigue FATIGUE We typically use the term fatigue to describe general sensations of tiredness and accompanying decrements in muscular performance. Most of the underlying causes of fatigue focuses on: the energy systems (ATP-PCr, anaerobic glycolysis & oxidation) the accumulation of metabolic by-products, such as lactate the nervous system failure of the muscle fiber’s contractile mechanism However, none of these alone can explain all aspects of fatigue, and other factors such as stress or environment are thought to contribute to fatigue. Many questions about fatigue remain unanswered!

PCr DEPLETION PCr (phosphocreatine) is an energy rich compound that plays a critical role in providing energy for muscle action by maintainig ATP concentration. PCr is used under anaerobic conditions to rebuild high-energy ATP as it is used. As PCr is depleted, your body's ability to quickly replace the spent ATP is hindered. ATP use continues but the ATP-PCr system is less able to replace it, therefore ATP levels are also decreased. It now appears that P is a potential cause of fatigue.

MUSCLE GLYCOGEN DEPLETION Muscle ATP levels are also maintained by the aerobic and anaerobic breakdown of muscle glycogen. In events lasting only a few seconds (eg.sprints), muscle glycogen becomes the primary energy source for ATP synthesis. The muscle depends on a constant supply of glyocgen to meet the high energy demands of exercise. However, glycogen reserves are limited and are depleted quickly.

NEUROMUSCULAR FATIGUE (NERVE IMPULSE) Evidence suggests that under some circumstances, fatigue may result from an inability to activate the muscle fibres, a function of the nervous system. Nerve impulses are transmitted across the neuromuscular junction to activate the fibre's membrane, and it causes the fibre's sarcoplasmic reticulum to release calcium. The calcium in turn, binds with troponin to iniate muscle contarction. Evidence suggests that fatigue maybe attreibuted to calcium retention within the sarcoplasmic reticulum, whihc would decrease the calcium available for muscle contraction. Depletion of PCr and build-up of lactate might simple increase the rate of calcuim accumulation with the sarcoplasmic reticulum. Remains speculative!

CENTRAL NERVOUS SYSTEM (CNS MUSCLE RECRUITMENT) Early studies showed that when a subject's muscles appeared to be nearly exhausted, verbal encouragement, shouting or even direct electrical stimulation of the muscle could increase the strength of muscle contraction. These studies suggest that the limits of performance in exhaustive exercise may, to a great extent, be psychological.

METABOLIC BY-PRODUCTS Sprints in running, cycling or swimming all lead to large accumulations of lactic acid. However, the presence of lactic acid shouldn't be blamed for the feeling of fatigue itself. When not cleared, the lactic acid dissociates, converting to lactate and causing an accumulation of hydrogen ions. This H+ accumulation causes muscle acidification, resulting in a condition known as acidosis. Activities of short duration and high intensity, such as sprinting, depend heavily on anaerobic glycolysis and produce large amounts of lactate and H+ within the muscles. Luckily, the cells and body fluids possess buffers, such as bicarbonate (HCO3), that minimalise disrupting influence of the H+. Without these buffers, H+ would lower the pH to about 1.5, killing the cells. Because of buffering, the H+ concentration remains low even during severe exercise, allowing muscle pH to decrease from a resting value of 7.1 to no lower than 6.6 to 6.4 at exhaustion.