Principles of Resistance Training - Bioenergetics (Draft) lyrics

Biological Energy Systems Three basic energy systems exist in human muscle cells to replenish ATP: a.The phosphagen system b. Glycolysis c. The oxidative system As it applies to exercise-related bioenergetics, two terms are usually used to describe how the three energy systems interact: 1. Aerobic 2. Anaerobic The phosphagen system and the first phase of glycolysis are anaerobic mechanisms that occur in the sarcoplasm of a muscle cell. The Krebs cycle, electron transport, and the rest of the oxidative system are aerobic mechanisms that occur in the mitochondria of muscle cells and require oxygen as the terminal electron receptor. Out of the thre primary macronutrients, only carbohydrates can be metabolized for energy without the direct involvement of oxygen. Which energy system is primarily in use at any one time is dependent on the intensity of an activity, as well as its duration. Phosphagen System This energy system relies on the hydrolysis of ATP and breakdown of another high-energy phosphate molecule called creatine phosphate (CP), also called phosphocreatine (PCr). Creatine kinase is the enzyme that catalyzes the synthesis of ATP from CP and ADP. ATP Stores The body can only store around 80 to 100 g of ATP at a time, and on top of this, your body will cease any non-essential functioning well before ATP stores are ever fully depleted. This is why the CP system is so essential to short-term exercise, as it rapidly replenishes ATP. Another important reaction for ATP replenishment in the short term is the adenylate kinase reaction. Control of Phosphagen System With enzyme-mediated reactions, such as the reactions of the phosphagen system, the rate of product formation is greatly influenced by the concentrations of the reactants.