Chapter 4 Exercise Metabolism and Bioenergetics

Introduction: Exercise Metabolism and Bioenergetics: The constant supply of energy to function properly to maintain health and internal balance. The food we eat is what provides our cells with the needed energy to survive and maintain balance. But before food can become a useable form of energy is has to be converted into smaller units call substrates. (carbohydrates, proteins, and fats) The energy stored in these substrate molecules is then chemically released in cells and stored in the form of high energy compound called adenosine triphosphate. (ATP)

The Process: Bioenergetics: The study of energy in the human body Metabolism: All chemical reactions that occur in the to maintain itself. Metabolism is the process in which nutrients are acquired, transported, used and disposed of by the body. (more efficient this process is… the more energy (calories you are able to burn) Substrates: the material or substance on which an enzyme acts.

Fuel for Metabolism: Carbohydrates: A(n) important source of energy eventually broken down in the body to glucose, a simple sugar. Glucose: A simple sugar manufactured by the body from carbohydrates, fat, and to a lesser extent protein, which serves as the body’s main source of fuel. Glycogen: A complex carbohydrate molecule used to store carbohydrates in the liver and muscle cells. When carbohydrates are needed, glycogen is converted into glucose for use by the muscle cells. Fat: HDL, LDL, vitamin absorption, promotes health in the integumentary system. (skin, hair, nails) Protein: Amino Acids (building blocks of proteins) which rarely supplies much energy during exercise.

Energy and Muscle Contraction Adenosine triphosphate (ATP): Energy storage and transfer unit within the cells of the body. When chemical bonds that hold ATP together are broken, energy is released for cellular work (performing muscle contraction) Adenosine diphosphate (ADP): The product that is left behind from that cellular work being completed (muscle contraction completion). In order to harness enough free energy to reattach a phosphate group to an ADP molecule and restore ATP levels back to normal to perform more “work.”

Energy Conversion and Muscle Contraction:

Energy During Exercise At rest and during normal activities, fats contribute 80– 90% of our energy; carbohydrates provide 5–18% and protein 2–5%. During exercise there are four major endogenous (developing from within) sources of energy: muscle carbohydrate stores (glycogen), blood sugar, blood fatty acids, and intramuscular triglycerides (body-fat)

Anaerobic Exercise vs. Aerobic Exercise During anaerobic exercise, oxygen consumption is not sufficient to supply the energy demands being placed on your muscles. ... Aerobic exercise increases your endurance and cardiac health while anaerobic exercise will not only help you burn fat but also help you gain lean muscle mass

Metabolism During Steady-State Exercise Muscle metabolism, blood lactate, and oxygen uptake in steady state exercise at aerobic and anaerobic thresholds: At anaerobic threshold muscle lactate (and hydrogen ions) will increase and power output will decrease…but not as significantly when compared with values at an aerobic threshold.

Steady State Exercise Vs. Interval Training Exercise Steady State Exercise: when the removal of lactic acid by oxidation keeps pace with its production. A condition in which the formation of substances keeps pace with their destruction so that all volumes, concentrations, pressures, and flows remain constant. HIIT (high intensity interval training): a cardiovascular exercise strategy alternating short periods of intense anaerobic exercise with less intense recovery periods.

Excess Post-exercise Oxygen Consumption In recovery, oxygen (EPOC) is used in the processes that restore the body to a resting state and adapt it to the exercise just performed. These include: hormone balancing, replenishment of fuel stores, cellular repair, innervation (stimulate) anabolism. Post- exercise oxygen consumption replenishes the phosphene system.

Excess Post-exercise Oxygen Consumption New ATP is synthesized and some of this ATP donates phosphate groups to creatine until ATP and creatine levels are back to resting state levels again. Another use of EPOC is to fuel the body’s increased metabolism from the increase in body temperature which occurs during exercise.