chapter 4 terms

Lactic acid:

A chemical by-product of ATP production; at low levels, it can be reconverted into ATP, but at high levels it is detrimental to performance.

Catabolized:

A chemical process by which large complex molecules are broken down into simpler compounds; the simpler compounds can be oxidized, releasing energy.

Adenosine triphosphate (ATP):

A complex chemical compound formed with the energy released from food; produced in the mitochondria of cells, it is the main energy source of most cellular functions.

Emphysema:

A condition characterized by progressive destruction of the alveoli, making breathing, especially exhalation, difficult; with chronic bronchitis, known as chronic obstructive pulmonary disease (COPD).

Glucose:

A form of carbohydrate (simple sugar) circulating in the blood; used by the body for energy (ATP) production; derived from food sources.

Creatine phosphate:

A form of rapidly mobilized energy available to the skeletal muscles and the brain; also known as phosphocreatine.

Glycogen:

A form of stored blood sugar (glucose) typically derived from food; stored in limited amounts in skeletal muscle, liver, and brain.

Asthma:

A medical condition characterized by airway inflammation and constriction of breathing passages, which makes breathing difficult; in some cases, can be exacerbated by exercise.

Heart rate reserve (HRR) method:

A method of calculating target cardiorespiratory endurance exercise intensity based on a percentage range of heart rate reserve, which is the difference between resting heart rate and maximum heart rate.

Heart rate maximum (HR max) method:

A method of calculating target cardiorespiratory endurance exercise intensity based on a percentage range of maximum heart rate.

Cross-training:

A pattern of training that alternates different activities (modes of exercise) that develop the same fitness component; may be done to improve performance or to avoid or rehabilitate injuries.

Metabolic equivalents (METs):

A physiological concept expressing the energy cost of any physical activity relative to resting metabolic rate; the value of sitting at rest is defined as 1.0 MET; more vigorous activities have higher MET requirements.

Krebs cycle:

A process in the mitochondria in which carbohydrates, fats, and proteins are converted into ATP through cellular (oxidative) respiration; also known as the citric acid cycle or TCA.

Talk test:

A qualitative assessment of exercise intensity based on the ability to talk during exercise.

Target heart rate range:

A range of heart rates that reflect an intensity of exercise that will result in cardiorespiratory fitness improvement.

Rating of perceived exertion (RPE):

A scale that provides a subjective measure of exercise intensity; widely used in the absence of heart rate monitoring.

Adenosine triphosphate (ATP):

ATP is the main energy source for the majority of cellular functions. ATP is primarily produced in the mitochondria of the cell.

Cardiorespiratory fitness (CRF):

Ability of the respiratory and circulatory systems to provide the necessary oxygen to skeletal muscles to sustain regular physical activity; also known as cardiorespiratory endurance, aerobic endurance, and aerobic fitness.

Glycolysis:

An anaerobic chemical reaction that converts glucose into pyruvate, yielding a small number of ATP.

Pyruvic acid:

An end product of glycolysis; in aerobic metabolism, pyruvate is sent to the Krebs cycle to aid in the production of ATP; in anaerobic metabolism, pyruvate is converted to lactic acid.

Veins:

Blood vessels responsible for storing most of the blood at rest and for returning blood to the heart.

Chronic bronchitis:

Chronic or persistent inflammation of the bronchi in the lung.

Arteries:

Elastic vessels throughout the body that carry blood away from the heart; they are responsible for transporting oxygen-rich blood to the muscles.

Interval training:

Interspersing higher intensity bouts of exercise periodically throughout a workout in order to increase maximal oxygen consumption.

Anaerobic:

Occurring in the absence of oxygen.

Aerobic:

Occurring in the presence of oxygen.

Burnout:

Physical and emotional exhaustion from exercise.

Mitochondria:

Structures within cells in which most of the chemical reactions in cellular (oxidative) respiration occur; also known as cellular "power plants," as they are the location for most ATP production.

Volume of oxygen consumed (VO2):

The absolute amount of oxygen that can be consumed and used by an individual. Usually reported in liters per minute and highly correlated to body size.

Stroke volume:

The amount of blood pumped by the heart in each beat.

Cardiac output:

The amount of blood pumped by the heart per minute.

Vascular system:

The body's network of blood vessels (arteries, veins, capillaries); blood travels in the vascular system throughout the body, delivering oxygen and nutrients and picking up carbon dioxide and other waste products.

Lactate threshold (LT):

The exercise intensity at which significant amounts of lactic acid accumulates in the blood; at or above this intensity, performance suffers; LT can be increased through training.

Cardiorespiratory (CR) system:

The heart, lungs, and network of blood vessels.

ATP/PC energy system:

The immediate energy system that powers activities requiring an immediate burst of energy (no more than 10 seconds); powered by stored ATP and creatine phosphate.

Respiratory system:

The lungs, air passages, and breathing muscles; allows for gas exchange, with the body taking in oxygen and eliminating carbon dioxide.

Maximum volume of oxygen consumed (VO2max):

The maximum amount of oxygen that can be consumed and used by skeletal muscles, typically reported in terms of milliliters of oxygen consumed per minute per kilogram of body weight (ml/kg/min); considered one of the best measures of aerobic fitness.

Maximum heart rate:

The maximum number of beats per minute of the heart, which can be measured directly through laboratory testing or estimated according to age; the value typically decreases with age starting around 20 years.

Capillaries:

The smallest blood vessels, with walls so thin that substances can pass between the blood they carry and the surrounding cells and tissues; the site where oxygen and carbon dioxide are transferred between skeletal muscles cells and the bloodstream.

Anaerobic energy system:

The system responsible for initial production of energy; requires glucose but no oxygen, and produces a net of only two ATP molecules; can provide energy for only short periods of physical effort; also known as the glycolysis.

Aerobic energy system:

The system responsible for most energy production in the body through the Krebs cycle and the electron transport system; takes place in the mitochondria and requires glucose and oxygen; also known as aerobic respiration.

Electron transport system (ETS):

The transfer of electrons from a high-energy molecule to a lower-energy molecule in the production of ATP; takes place within the mitochondria.

Progression:

gradual increases in frequency, intensity, and duration of exercise in order for the body to adapt and increase fitness.

Alveoli:

tiny sacs in the lungs covered by blood vessels, serving as the site of gas exchange.