Using creatine phosphate So all muscle cells contain a high-energy compound called creatine phosphate which is broken down to make more ATP quickly. Creatine phosphate can supply the energy needs of a working muscle at a very high rate, but only for about 8–10 seconds. Creatine phosphate (CP), like ATP, is also stored in small amounts within cells. It's another high-energy compound that can be rapidly mobilized to help fuel short, explosive efforts. To sustain physical activity, however, cells must constantly replenish both CP and ATP. For activities lasting more than 3 minutes, the aerobic system is the primary energy source, and in lower-intensity activity lasting longer than 20 minutes, beta oxidation provides the greatest amount of ATP. Pre-Event Example Meal (3-4 hours before): Baked potato. A bagel, cereal with low-fat milk, low-fat yogurt. Sandwich with small amounts of peanut butter or lean meat. 1-2 cups of cold water or sports drink.
Specifically, the body burns fat after first exhausting the contents of the digestive tract along with glycogen reserves stored in liver cells and after significant protein loss. After prolonged periods of starvation, the body uses the proteins within muscle tissue as a fuel source.
The easiest macronutrient to burn is sugar. Exercise lasting from 10 seconds to several minutes uses predominantly glucose in the form of pyruvate, and if the exercise is intense enough, in the form of lactate. After several minutes of work, the body will begin to burn fats for energy use.
Three energy systems function to replenish ATP in muscle: (1) Phosphagen, (2) Glycolytic, and (3) Mitochondrial Respiration. The three systems differ in the substrates used, products, maximal rate of ATP regeneration, capacity of ATP regeneration, and their associated contributions to fatigue.
Carbohydrates, such as sugar and starch, for example, are readily broken down into glucose, the body's principal energy source. Glucose can be used immediately as fuel, or can be sent to the liver and muscles and stored as glycogen.
The three main fuel sources in humans are carbohydrates, fats, and proteins. They are used preferentially under different conditions. In general, the body burns carbohydrates, then fats, and then proteins, in that order. It is important to realize that energy metabolism is not an "all-or-none" phenomenon.
The system is rapidly replenished during recovery; in fact, it requires about 30 seconds to replenish about 70% of the phosphagens and 3 to 5 minutes to replenish 100%.
The body uses three main nutrients to function— carbohydrate, protein, and fat. These nutrients are digested into simpler compounds. Carbohydrates are used for energy (glucose). Fats are used for energy after they are broken into fatty acids.
All of the energy systems work to generate ATP, or generate molecules that will further drive ATP production, and also deal with the hydrogen and heat that surfaces from such mechanisms. There are three energy systems: the immediate energy system, the glycolytic system, and the oxidative system.
Once we have depleted our ATP (through a 1 rep max attempt, for example), it takes at least 3 minutes of rest for muscles to recover the maximum amount possible of ATP and creatine phosphate. After at least 3 minutes have elapsed, your ATP-PC system will be ready for explosive movements again.
Aerobic glycolysis has a slow rate of ATP production and is predominantly utilized during longer-duration, lower-intensity activities after the phosphagen and anaerobic systems have fatigued. It is important to remember that all three of these systems contribute to the energy needs of the body during physical activity.
Glycolytic Pathway = Longer Intervals 400-meter sprint. Lifting weights for short periods. Sports requiring quick bursts of speed, such as basketball, High-intensity interval training programs.
Slow glycolysis uses carbohydrates as a substrate for creating ATP during medium- and low-intensity activities where pyruvate, the final product of glycolysis, is not converted to lactate but it is transported to mitochondria where they are subject to Krebs Cyclus.
Energy pathways. These are supply routes between producers and consumers (pipelines, shipping routes, electricity cables) Energy poverty. This is when a country or region has insufficient access to reliable sources of power. Energy surplus.