Energy for Muscular Activity

Flashcards covering the biochemical principles of muscular energy production, the three primary energy systems, aerobic power determinants, and factors influencing physical performance.

ATP (Adenosine Triphosphate)

The primary energy compound produced from the breakdown of carbohydrates, fats, and proteins that fuels biochemical processes including muscular work, thermoregulation, and digesting food.

Hydrolysis of ATP

The breakdown of ATP's unstable phosphate groups by $H_2O$, releasing an inorganic phosphate ($P$) to form ADP and yielding $38\text{ to }42\,kJ$ (or $9\text{ to }10\,kcal/mol\text{ ATP}$) of energy.

Phosphorylation

The transfer of a free inorganic phosphate group ($P_i$) released from ATP turnover to another molecule to provide energy for muscle contraction.

ATP Resynthesis

The regeneration of ATP from ADP and $P_i$, which requires energy supplied by the breakdown of food molecules.

High Energy Phosphate System

An anaerobic pathway that uses stored ATP and PC to produce very large amounts of energy in a short time for activities lasting $7\text{ to }12\,s$, limited by high-energy phosphate concentration.

Anaerobic Glycolytic System

An energy pathway that uses stored glycogen and blood glucose to produce energy under inadequate oxygen conditions for activities lasting $12\text{ s to }3\text{ min}$, limited by lactic acid and $H^+$ ion buildup.

Glycolysis

An anaerobic process occurring in the absence of oxygen that yields 2 molecules of ATP and 2 molecules of pyruvic acid, with 2 molecules of lactic acid formed as a by-product.

Fast Twitch Fibres (Types II)

Muscle fibres utilized during high-intensity exercise that are primarily associated with the anaerobic glycolytic system.

Anaerobic Threshold

The exercise intensity point at which lactic acid begins to accumulate in the blood, causing discomfort and a burning sensation in the active muscles.

Lactic Acid

A compound that temporarily stores pyruvate and hydrogen ions produced during anaerobic glycolysis until they can be processed by the aerobic system.

Aerobic Oxidative System

An energy system utilizing glycogen, glucose, fats, and protein to provide a large output of energy over long durations while removing lactic acid, limited by oxygen availability and lung/blood flow capacity.

Slow Twitch Fibres (Type I)

Muscle fibres suited for sustained endurance activities that rely primarily on the aerobic oxidative system.

Oxidative Phosphorylation

A mitochondrial process comprising the Krebs cycle and electron transport chain that resynthesizes ATP, producing $36\text{ ATP}$ per glucose molecule and up to $169\text{ ATP}$ per fat molecule, yielding $CO_2$ and $H_2O$ as by-products.

Cori Cycle

The physiological cycle wherein lactic acid is transported from muscle to the liver to be metabolized back into pyruvate and subsequently into glucose.

Aerobic Power ($VO_2\,\max$)

The maximal volume of oxygen that can be consumed per kilogram of body mass during maximal physical exertion.

Arterial Oxygen Content ($CaO_2$)

A determinant of aerobic power that depends on adequate lung ventilation and the oxygen-carrying capacity of the blood.

Cardiac Output ($Q$)

The total volume of blood pumped by the heart, calculated as heart rate multiplied by stroke volume ($Q = HR \times \text{stroke volume}$).

Tissue Oxygen Extraction ($a\text{-}v\,O_2\text{ difference}$)

The difference between arterial and venous oxygen levels, determined by the rates of oxygen diffusion from capillaries and oxygen utilization in peripheral tissues.

Endurance Training

Exercise consisting of long durations performed several times per week that increases the maximal aerobic power of a sedentary individual by $15\text{ to }25\%$ regardless of age.

Somatic Factors

Biological and physical body attributes affecting performance, including sex, age, body distribution, state of health, drugs, strength, and fibre type.

Psychic Factors

Mental and psychological components affecting physical performance, specifically listed as attitude and motivation.

Environmental Factors

External surrounding conditions affecting physical performance, including diet, temperature, air pressure, air pollution, and noise.