Exercise physiology Glossary

jacky

引自：Exercise Physiology: Theory & Application to Fitness & Performance, 7th Edition ( 2009 )



absolute V˙O2 the amount of oxygen consumed over a given time period; expressed as liters · min–1.

acidosis an abnormal increase in blood hydrogen ion concentration (i.e., arterial pH below 7.35).

acids compounds capable of giving up hydrogen ions into solution.

acromegaly a condition caused by hypersecretion of growth hormone from the pituitary gland; characterized by enlargement of the extremities, such as the jaw, nose, and fingers.

actin a structural protein of muscle that works with myosin in permitting muscular contraction.

action potential the all-or-none electrical event in the neuron or muscle cell in which the polarity of the cell membrane is rapidly reversed and then reestablished.

adenosine diphosphate (ADP) a molecule that combines with inorganic phosphate to form ATP.

adenosine triphosphate (ATP) the high-energy phosphate compound synthesized and used by cells to release energy for cellular work.

adenylate cyclase enzyme found in cell membranes that catalyzes the conversion of ATP to cyclic AMP.

adequate intake (AI) recommendations for nutrient intake when insufficient information is available to set an RDA standard.

adrenal cortex the outer portion of the adrenal gland. Synthesizes and secretes corticosteroid hormones, such as cortisol, aldosterone, and androgens.

adrenaline see epinephrine.

adrenocorticotrophic hormone (ACTH) a hormone secreted by the anterior pituitary gland that stimulates the adrenal cortex.

aerobic in the presence of oxygen.

afferent fibers nerve fibers (sensory fibers) that carry neural information back to the central nervous system.

afferent neuron sensory neuron carrying information toward the central nervous system.

aldosterone a corticosteroid hormone involved in the regulation of electrolyte balance.

alkalosis an abnormal increase in blood concentration of OH– ions, resulting in a rise in arterial pH above 7.45.

alpha receptors a subtype of adrenergic receptors located on cell membranes of selected tissues.

alveolar ventilation (V˙A) the volume of gas that reaches the alveolar region of the lung.

alveoli microscopic air sacs located in the lung where gas exchange occurs between respiratory gases and the blood.

amenorrhea the absence of menses.

anabolic steroid a prescription drug that has anabolic, or growth-stimulating, characteristics similar to that of the male androgen, testosterone.

anaerobic without oxygen.

anaerobic threshold a commonly used term meant to describe the level of oxygen consumption at which there is a rapid and systematic increase in blood lactate concentration. Also termed the lactate threshold.

anatomical dead space the total volume of the lung (i.e., conducting airways) that does not participate in gas exchange.

androgenic steroid a compound that has the qualities of an androgen; associated with masculine characteristics.

androgens male sex hormones. Synthesized in the testes and in limited amounts in the adrenal cortex. Steroids that have masculinizing effects.

angina pectoris chest pain due to a lack of blood flow (ischemia) to the myocardium.

angiotensin I and II these compounds are polypeptides formed from the cleavage of a protein (angiotensinogen) by the action of the enzyme renin produced by the kidneys, and converting enzyme in the lung, respectively.

anorexia nervosa an eating disorder characterized by rapid weight loss due to failure to consume adequate amounts of nutrients.

anterior hypothalamus the anterior portion of the hypothalamus. The hypothalamus is an area of the brain below the thalamus that regulates the autonomic nervous system and the pituitary gland.

anterior pituitary the anterior portion of the pituitary gland that secretes follicle-stimulating hormone, luteinizing hormone, adrenocorticotrophic hormone, thyroid-stimulating hormone, growth hormone, and prolactin.

antidiuretic hormone (ADH) hormone secreted by the posterior pituitary gland that promotes water retention by the kidney.

aortic bodies receptors located in the arch of the aorta that are capable of detecting changes in arterial PO2.

apophyses sites of muscletendon insertion in bones.

arrhythmia abnormal electrical activity in the heart (e.g., a premature ventricular contraction).

arteries large vessels that carry arterialized blood away from the heart.

arterioles a small branch of an artery that communicates with a capillary network.

articular cartilage cartilage that covers the ends of bones in a synovial joint.

atherosclerosis a pathological condition in which fatty substances collect inside the lumen of arteries.

ATPase enzyme capable of breaking down ATP to ADP + Pi + energy.

ATP-PC system term used to describe the metabolic pathway involving muscle stores of ATP and the use of phosphocreatine to rephosphorylate ADP. This pathway is used at the onset of exercise and during short-term, high-intensity work.

atrioventricular node (AV node) a specialized mass of muscle tissue located in the interventricular septum of the heart; functions in the transmission of cardiac impulses from the atria to the ventricles.

autologous transfusion blood transfusion whereby the individual receives his or her own blood.

autonomic nervous system portion of the nervous system that controls the actions of visceral organs.

autoregulation mechanism by which an organ regulates blood flow to match the metabolic rate.

axon a nerve fiber that conducts a nerve impulse away from the neuron cell body.

basal metabolic rate (BMR) metabolic rate measured in supine position following a twelve-hour fast, and eight hours of sleep.

bases compounds that ionize in water to release hydroxyl ions (OH–) or other ions that are capable of combining with hydrogen ions.

beta oxidation breakdown of free fatty acids to form acetyl-CoA.

beta receptor agonist (β-agonist) a molecule that is capable of binding to and activating a beta receptor.

beta receptors adrenergic receptors located on cell membranes. Combine mainly with epinephrine and, to some degree, with norepinephrine.

bioenergetics the chemical processes involved with the production of cellular ATP.

biological control systems a control system capable of maintaining homeostasis within a cell or organ system in a living creature.

blood boosting a term that applies to the increase of the blood's hemoglobin concentration by the infusion of additional red blood cells. Medically termed induced erythrocythemia.

blood doping see blood boosting.

blood packing see blood boosting.

Bohr effect the right shift of the oxyhemoglobin dissociation curve due to a decrease of blood pH. Results in a decreased affinity for oxygen.

bradycardia a resting heart rate less than sixty beats per minute.

brain stem portion of the brain that includes midbrain, pons, and medulla.

buffer a compound that resists pH change.

bulimia an eating disorder characterized by eating and forced regurgitation.

bulk flow mass movement of molecules from an area of high pressure to an area of lower pressure.

calcitonin hormone, released from the thyroid gland, that plays a minor role in calcium metabolism.

calmodulin part of second messenger system involving calcium that results in changes in the activity of intracellular enzymes.

capillaries microscopic blood vessels that connect arterioles and venules. Portion of vascular system where blood/tissue gas exchange occurs.

cardiac accelerator nerves part of the sympathetic nervous system that stimulates the SA node to increase heart rate.

cardiac output the amount of blood pumped by the heart per unit of time; equal to product of heart rate and stroke volume.

cardiovascular control center the area of the medulla that regulates the cardiovascular system.

carotid bodies chemoreceptors located in the internal carotid artery; respond to changes in arterial PO2, PCO2, and pH.

catecholamines organic compounds, including epinephrine, norepinephrine, and dopamine.

cell body the soma, or major portion of the body of a nerve cell. Contains the nucleus.

cell membrane the lipid-bilayer envelope that encloses cells. Called the sarcolemma in muscle cells.

cellular respiration process of oxygen consumption and carbon dioxide production in cells (i.e., bioenergetics).

central command the control of the cardiovascular or pulmonary system by cortical impulses.

central nervous system (CNS) portion of the nervous system that consists of the brain and spinal cord.

cerebellum portion of the brain that is concerned with fine coordination of skeletal muscles during movement.

cerebrum superior aspect of the brain that occupies the upper cranial cavity. Contains the motor cortex.

chemiosmotic hypothesis the mechanism to explain the aerobic formation of ATP in mitochondria.

cholesterol a twenty-seven-carbon lipid that can be synthesized in cells or consumed in the diet. Cholesterol serves as a precursor of steroid hormones, and plays a role in the development of atherosclerosis.

clo unit that describes the insulation quality of clothing.

concentric action occurs when a muscle is activated and shortens.

conduction transfer of heat from warmer to cooler objects that are in contact with each other. This term may also be used in association with the conveyance of neural impulses.

conduction disturbances refers to a slowing or blockage of the wave of depolarization in the heart, e.g., first-degree AV block, or bundle branch block.

conductivity capacity for conduction.

convection the transmission of heat from one object to another through the circulation of heated molecules.

Cori cycle the cycle of lactate-to-glucose between the muscle and liver.

coronary artery bypass graft surgery (CABGS) the replacement of a blocked coronary artery with another vessel to permit blood flow to the myocardium.

cortisol a glucocorticoid secreted by the adrenal cortex upon stimulation by ACTH.

coupled reactions the linking of energy-liberating chemical reactions to "drive'' energy-requiring reactions.

critical power a specific submaximal power output that can be maintained without fatigue.

cromolyn sodium a drug used to stabilize the membranes of mast cells and prevent an asthma attack.

cycle ergometer a stationary exercise cycle that allows accurate measurement of work output.

cyclic AMP a substance produced from ATP through the action of adenylate cyclase that alters several chemical processes in the cell.

cytoplasm the contents of the cell surrounding the nucleus. Called sarcoplasm in muscle cells.

Daily Value a standard used in nutritional labeling.

deficiency a shortcoming of some essential nutrient.

degenerative diseases diseases not due to infection that result in a progressive decline in some bodily function.

delayed-onset muscle soreness (DOMS) muscle soreness that occurs twelve to twenty-four hours after an exercise bout.

dendrites portion of the nerve fiber that transmits action potentials toward a nerve cell body.

dental caries tooth decay; related to sugar content in foods.

deoxyhemoglobin hemoglobin not in combination with oxygen.

diabetes mellitus a condition characterized by high blood glucose levels due to inadequate insulin. Type I diabetics are insulin dependent, whereas Type II diabetics are resistant to insulin.

diabetic coma unconscious state induced by a lack of insulin.

diacylglycerol a molecule derived from a membrane-bound phospholipid, phosphatidylinositol, that activates protein kinase C and alters cellular activity.

diaphragm the major respiratory muscle responsible for inspiration. Dome-shaped—separates the thoracic cavity from the abdominal cavity.

diastole period of filling of the heart between contractions (i.e., resting phase of the heart).

Diastolic blood pressure arterial blood pressure during diastole.

Dietary Guidelines for Americans general statements related to food selection that are consistent with achieving and maintaining good health.

Dietary Reference Intakes the framework for nutrient recommendations being made as a part of the revision of the 1989 RDA.

diffusion random movement of molecules from an area of high concentration to an area of low concentration.

direct calorimetry assessment of the body's metabolic rate by direct measurement of the amount of heat produced.

dose the amount of drug or exercise prescribed to have a certain effect (or response).

double-blind research design an experimental design in which the subjects and the principal investigator are not aware of the experimental treatment order.

double product the product of heart rate and systolic blood pressure; estimate of work of the heart.

dynamic refers to an isotonic muscle action.

dynamic stretching stretching that involves controlled movement.

dynamometer device used to measure force production (e.g., used in the measurement of muscular strength).

dysmenorrhea painful menstruation.

dyspnea shortness of breath or labored breathing. May be due to various types of lung or heart diseases.

eccentric action occurs when a muscle is activated and force is produced but the muscle lengthens.

ectomorphy category of somatotype that is rated for linearity of body form.

effect change in variable (e.g., V˙O2 max) due to a dose of exercise (e.g., 3 days per week, 40 min/day at 70% V˙O2 max).

effector organ or body part that responds to stimulation by an efferent neuron (e.g., skeletal muscle in a withdrawal reflex).

efferent fibers nerve fibers (motor fibers) that carry neural information from the central nervous system to the periphery.

efferent neuron conducts impulses from the CNS to the effector organ (e.g., motor neuron).

ejection fraction the proportion of end-diastolic volume that is ejected during a ventricular contraction.

electrocardiogram (ECG) a recording of the electrical changes that occur in the myocardium during the cardiac cycle.

electron transport chain a series of cytochromes in the mitochondria that are responsible for oxidative phosphorylation.

element a single chemical substance composed of only one type of atom (e.g., calcium or potassium).

endergonic reactions energy-requiring reactions.

endocrine gland a gland that produces and secretes its products directly into the blood or interstitial fluid (ductless glands).

endomorphy the somatotype category that is rated for roundness (fatness).

endomysium the inner layer of connective tissue surrounding a muscle fiber.

endorphin a neuropeptide produced by the pituitary gland having pain-suppressing activity.

end-plate potential (EPP) depolarization of a membrane region by a sodium influx.

energy of activation energy required to initiate a chemical reaction.

energy wasteful systems metabolic pathways in which the energy generated in one reaction is used up in another that leads back to the first, creating a futile cycle and requiring a higher resting metabolic rate.

enzymes proteins that lower the energy of activation and, therefore, catalyze chemical reactions. Enzymes regulate the rate of most metabolic pathways.

epidemiologic triad a model that shows connections between the environment, agent, and host that cause disease.

epidemiology the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems.

epilepsy a neurological disorder manifested by muscular seizures.

epimysium the outer layer of connective tissue surrounding muscle.

epinephrine a hormone synthesized by the adrenal medulla; also called adrenaline.

epiphyseal plate (growth plate) cartilaginous layer between the head and shaft of a long bone where growth takes place.

EPOC an acronym for "excess post-exercise oxygen consumption''; often referred to as the oxygen debt.

EPSP excitatory post-synaptic potential. A graded depolarization of a post-synaptic membrane by a neurotransmitter.

ergogenic aid a substance, appliance, or procedure (e.g., blood doping) that improves performance.

ergometer instrument for measuring work.

ergometry measurement of work output.

erythrocythemia an increase in the number of erythrocytes in the blood.

erythropoietin hormone that stimulates red blood cell production.

estrogens female sex hormones, including estradiol and estrone. Produced primarily in the ovary and also produced in the adrenal cortex.

evaporation the change of water from a liquid form to a vapor form. Results in the removal of heat.

exercise a subclass of physical activity.

exergonic reactions chemical reactions that release energy.

extensors muscles that extend a limb—that is, increase the angle at a joint.

FAD flavin adenine dinucleotide. Serves as an electron carrier in bioenergetics.

fasciculi a small bundle of muscle fibers.

fast-twitch fibers one of several types of muscle fibers found in skeletal muscle; also called Type II fibers; characterized as having low oxidative capacity but high glycolytic capacity.

ferritin the iron-carrying molecule used as an index of whole-body iron status.

field test a test of physical performance performed in the field (outside the laboratory).

flexors muscle groups that cause flexion of limbs—that is, decrease the angle at a joint.

follicle-stimulating hormone (FSH) a hormone secreted by the anterior pituitary gland that stimulates the development of an ovarian follicle in the female and the production of sperm in the male.

food records the practice of keeping dietary food records for determining nutrient intake.

free fatty acid (FFA) a type of fat that combines with glycerol to form triglycerides. Is used as an energy source.

G protein the link between the hormone-receptor interaction on the surface of the membrane and the subsequent events inside the cell.

gain refers to the amount of correction that a control system is capable of achieving.

General Adaptation Syndrome (GAS) a term defined by Selye in 1936 that describes the organism's response to chronic stress. In response to stress the organism has a three-stage response: (1) alarm reaction; (2) stage of resistance; and (3) readjustment to the stress, or exhaustion.

glucagon a hormone produced by the pancreas that increases blood glucose and free fatty acid levels.

glucocorticoids any one of a group of hormones produced by the adrenal cortex that influences carbohydrate, fat, and protein metabolism.

gluconeogenesis the synthesis of glucose from amino acids, lactate, glycerol, and other short carbon-chain molecules.

glucose a simple sugar that is transported via the blood and metabolized by tissues.

glucose polymer a complex sugar molecule that contains multiple simple sugar molecules linked together.

glycogen a glucose polymer synthesized in cells as a means of storing carbohydrate.

glycogenolysis the breakdown of glycogen into glucose.

glycolysis a metabolic pathway in the cytoplasm of the cell that results in the degradation of glucose into pyruvate or lactate.

Golgi tendon organ (GTOs) a tension receptor located in series with skeletal muscle.

graded exercise test see incremental exercise test.

gross efficiency a simple measure of exercise efficiency defined as the ratio of work performed to energy expended, expressed as a percent.

growth hormone hormone synthesized and secreted by the anterior pituitary that stimulates growth of the skeleton and soft tissues during the growing years. It is also involved in the mobilization of the body's energy stores.

HDL cholesterol (high-density lipoprotein cholesterol) cholesterol that is transported in the blood via high-density proteins; related to low risk of heart disease.

hemoglobin a heme-containing protein in red blood cells that is responsible for transporting oxygen to tissues. Hemoglobin also serves as a weak buffer within red blood cells.

hemosiderin an insoluble form of iron stored in tissues.

high-density lipoproteins (HDL) proteins used to transport cholesterol in blood; high levels appear to offer some protection from athero-sclerosis.

homeostasis the maintenance of a constant internal environment.

homeotherms animals that maintain a fairly constant internal temperature.

homologous transfusion a blood transfusion using blood of the same type but from another donor.

hormone a chemical substance that is synthesized and released by an endocrine gland and transported to a target organ via the blood.

hydrogen ion (H+) a free hydrogen ion in solution that results in a decrease in pH of the solution.

hyperbaric chamber chamber where the absolute pressure is increased above atmospheric pressure.

hyperoxia oxygen concentration in an inspired gas that exceeds 21%.

hyperplasia an increase in the number of cells in a tissue.

hyperthermia an above-normal increase in body temperature.

hypertrophy an increase in cell size.

hypothalamic somatostatin hypothalamic hormone that inhibits growth hormone secretion; also secreted from the delta cells of the islets of Langerhans.

hypothalamus brain structure that integrates many physiological functions to maintain homeostasis; site of secretion of hormones released by the posterior pituitary; also releases hormones that control anterior pituitary secretions.

hypothermia a condition in which heat is lost from the body faster than it is produced.

hypoxia a relative lack of oxygen (e.g., at altitude).

immunotherapy procedure in which the body is exposed to specific substances to elicit an immune response in order to offer better protection upon subsequent exposure.

incremental exercise test an exercise test involving a progressive increase in work rate over time. Often graded exercise tests are used to determine the subject's V˙O2 max or lactate threshold. (Also called graded exercise test.)

indirect calorimetry estimation of heat or energy production on the basis of oxygen consumption, carbon dioxide production, and nitrogen excretion.

induced erythrocythemia causing an elevation of the red blood cell (hemoglobin) concentration by infusing blood; also called blood doping or blood boosting.

infectious diseases diseases due to the presence of pathogenic microorganisms in the body (e.g., viruses, bacteria, fungi, and protozoa).

inorganic relating to substances that do not contain carbon (C).

inorganic phosphate (Pi) a stimulator of cellular metabolism; split off, along with ADP, from ATP when energy is released; used with ADP to form ATP in the electron transport chain.

inositol triphosphate a molecule derived from a membrane-bound phospholipid, phosphatidylinositol, that causes calcium release from intracellular stores and alters cellular activity.

insulin hormone released from the beta cells of the islets of Langerhans in response to elevated blood glucose and amino acid concentrations; increases tissue uptake of both.

insulin-like growth factors groups of growth-stimulating peptides released from the liver and other tissues in response to growth hormone. Also called somatomedins.

insulin shock condition brought on by too much insulin, which causes an immediate hypoglycemia; symptoms include tremors, dizziness, and possibly convulsions.

integrating center the portion of a biological control system that processes the information from the receptors and issues an appropriate response relative to its set point.

intercalated discs portion of cardiac muscle cell where one cell connects to the next.

intermediate fibers muscle fiber type that generates high force at a moderately fast speed of contraction, but has a relatively large number of mitochondria (Type IIa).

ion a single atom or small molecule containing a net positive or negative charge due to an excess of either protons or electrons, respectively (e.g., Na+, Cl–).

IPSP inhibitory post-synaptic potential that moves the post-synaptic membrane further from threshold.

irritability a trait of certain tissues that enables them to respond to stimuli (e.g., nerve and muscle).

isocitrate dehydrogenase rate-limiting enzyme in the Krebs cycle that is inhibited by ATP and stimulated by ADP and Pi.

isokinetic action in which the rate of movement is constantly maintained through a specific range of motion even though maximal force is exerted.

isometric action in which the muscle develops tension, but does not shorten; also called a static contraction. No movement occurs.

isotonic contraction in which a muscle shortens against a constant load or tension, resulting in -movement.

ketosis acidosis of the blood caused by the production of ketone bodies (e.g., acetoacetic acid) when fatty acid mobilization is increased, as in uncontrolled diabetes.

kilocalorie (kcal) a measure of energy expenditure equal to the heat needed to raise the temperature of 1 kg of water 1 degree Celsius; also equal to 1,000 calories and sometimes written as calorie rather than kilocalorie.

kilogram-meter a unit of work in which 1 kg of force (1 kg mass accelerated at 1 G) is moved through a vertical distance of 1 meter; abbreviated as kg-m, kg · m, or kgm.

kinesthesia a perception of movement obtained from information about the position and rate of movement of the joints.

Krebs cycle metabolic pathway in the mitochondria in which energy is transferred from carbohydrates, fats, and amino acids to NAD for sub-sequent production of ATP in the electron transport chain.

lactate threshold a point during a graded exercise test when the blood lactate concentration increases abruptly.

lactic acid an end product of glucose metabolism in the glycolytic pathway; formed in conditions of inadequate oxygen and in muscle fibers with few mitochondria.

lateral sac see terminal cisternae.

LDL cholesterol form of low-density lipoprotein responsible for the transport of plasma cholesterol; high levels are indicative of a high risk of coronary heart disease.

lipase an enzyme responsible for the breakdown of triglycerides to free fatty acids and glycerol.

lipolysis the breakdown of triglyc-erides in adipose tissue to free fatty acids and glycerol for subsequent transport to tissues for metabolism.

lipoprotein protein involved in the transport of cholesterol and triglycerides in the plasma.

low-density lipoproteins (LDL) form of lipoprotein that transports a majority of the plasma cholesterol; see LDL cholesterol.

luteinizing hormone (LH) also called "interstitial cell stimulating hormone"; a surge of LH stimulates ovulation in middle of menstrual cycle; LH stimulates testosterone production in men.

major minerals dietary minerals including calcium, phosphorus, potassium, sulfur, sodium, chloride, and magnesium.

mast cell connective tissue cell that releases his*****ine and other chemicals in response to certain stimuli (e.g., injury).

maximal oxygen uptake (V˙O2 max) greatest rate of oxygen uptake by the body measured during severe dynamic exercise, usually on a cycle ergometer or a treadmill; dependent on maximal cardiac output and the maximal arteriovenous oxygen difference.

mesomorphy one component of a somatotype that characterizes the muscular form or lean body mass aspect of the human body.

MET an expression of the rate of energy expenditure at rest; equal to approximately 3.5 ml · kg–1· min–1, or 1 kcal · kg–1· hr–1.

mineralocorticoids steroid hormones released from the adrenal cortex that are responsible for Na+ and K+ regulation (e.g., aldosterone).

mitochondrion the subcellular organelle responsible for the production of ATP with oxygen; contains the enzymes for the Krebs cycle, electron transport chain, and the fatty acid cycle.

mixed venous blood a mixture of venous blood from both the upper and lower extremities; complete mixing occurs in the right ventricle.

molecular biology branch of biochemistry involved with the study of gene structure and function.

motor cortex portion of the cerebral cortex containing large motor neurons whose axons descend to lower brain centers and spinal cord; associated with the voluntary control of movement.

motor neurons efferent neurons that conduct action potentials from the central nervous system to the muscles.

motor unit a motor neuron and all the muscle fibers innervated by that single motor neuron; responds in an "all-or-none" manner to a stimulus.

muscle action term used to describe muscle form development.

muscle spindle a muscle stretch receptor oriented parallel to skeletal muscle fibers; the capsule portion is surrounded by afferent fibers, and intrafusal muscle fibers can alter the length of the capsule during muscle contraction and relaxation.

muscular strength the maximal amount of force that can be generated by a muscle or muscle group.

myocardial infarction death of a portion of heart tissue that no longer conducts electrical activity nor provides force to move blood.

myocardial ischemia a condition in which the myocardium experiences an inadequate blood flow; sometimes accompanied by irregularities in the electrocardiogram (arrhythmias and ST-segment depression) and chest pain (angina pectoris).

myocardium cardiac muscle; provides the force of contraction to eject blood; muscle type with many mitochondria that is dependent on a constant supply of oxygen.

myofibrils the portion of the muscle containing the thick and thin contractile filaments; a series of sarcomeres where the repeating pattern of the contractile proteins gives the striated appearance to skeletal muscle.

myoglobin protein in muscle that can bind oxygen and release it at low PO2 values; aids in diffusion of oxygen from capillary to mitochondria.

myosin contractile protein in the thick filament of a myofibril that contains the cross-bridge that can bind actin and split ATP to cause tension development.

NAD coenzyme that transfers hydrogen and the energy associated with those hydrogens; in the Krebs cycle, NAD transfers energy from substrates to the electron transport chain.

negative feedback describes the response from a control system that reduces the size of the stimulus, e.g., an elevated blood glucose concentration causes the secretion of insulin which, in turn, lowers the blood glucose concentration.

net efficiency the mathematical ratio of work output divided by the energy expended above rest.

neuroendocrinology study of the role of the nervous and endocrine systems in the automatic regulation of the internal environment.

neuromuscular junction synapse between axon terminal of a motor neuron and the motor end plate of a muscle's plasma membrane.

neuron nerve cell; composed of a cell body with dendrites (projections) that bring information to the cell body, and axons that take information away from the cell body to influence neurons, glands, or muscles.

nitroglycerin drug used to reduce chest pain (angina pectoris) due to lack of blood flow to the myocardium.

norepinephrine a hormone and neurotransmitter; released from postganglionic nerve endings and the adrenal medulla.

normocythemia a normal red blood cell concentration.

normoxia a normal PO2.

nucleus membrane-bound organelle containing most of the cell's DNA.

nutrient density the degree to which foods contain selected nutrients, e.g., protein.

open-circuit spirometry indirect calorimetry procedure in which either inspired or expired ventilation is measured and oxygen consumption and carbon dioxide production are calculated.

organic describes substances that contain carbon.

osteoporosis a decrease in bone density due to a loss of cortical bone; common in older women and implicated in fractures; estrogen, exercise, and Ca++ therapy are used to correct the condition.

overload a principle of training describing the need to increase the load (intensity) of exercise to cause a further adaptation of a system.

oxidative phosphorylation mitochondrial process in which inorganic phosphate (Pi) is coupled to ADP as energy is transferred along the electron transport chain in which oxygen is the final electron acceptor.

oxygen debt the elevated post-exercise oxygen consumption (see EPOC); related to replacement of creatine phosphate, lactic acid resynthesis to glucose, and elevated body temperature, catecholamines, heart rate, breathing, etc.

oxygen deficit refers to the lag in oxygen uptake at the beginning of exercise.

oxyhemoglobin hemoglobin combined with oxygen; 1.34 ml of oxygen can combine with 1 g Hb.

pancreas gland containing both exocrine and endocrine portions; exocrine secretions include enzymes and bicarbonate to digest food in the small intestine; endocrine secretions include insulin, glucagon, and somatostatin, which are released into the blood.

parasympathetic nervous system portion of the autonomic nervous system that primarily releases acetylcholine from its postganglionic nerve endings.

partial pressure the fractional part of the barometric pressure due to the presence of a single gas, e.g., PO2, PCO2, and PN2.

percent grade a measure of the elevation of the treadmill; calculated as the sine of the angle.

percutaneous transluminal coronary angioplasty (PTCA) a balloon-tipped catheter is inserted into a blocked coronary artery and plaque is pushed back to artery wall to open the blood vessel.

perimysium the connective tissue surrounding the fasciculus of skeletal muscle fibers.

peripheral nervous system (PNS) portion of the nervous system located outside the spinal cord and brain.

pH a measure of the acidity of a solution; calculated as the negative log10 of the [H+] in which 7 is neutral; values that are >7 are basic and <7 are acidic.

phosphocreatine a compound found in skeletal muscle and used to resynthesize ATP from ADP.

phosphodiesterase an enzyme that catalyzes the breakdown of cyclic AMP, moderating the effect of the hormonal stimulation of adenylate cyclase.

phosphofructokinase rate-limiting enzyme in glycolysis that is responsive to ADP, Pi, and ATP levels in the cytoplasm of the cell.

phospholipase C membrane-bound enzyme that hydrolyzes phosphatidylinositol into inositol triphosphate and diacylglycerol that, in turn, bring about changes in intracellular activity.

physical activity characterizes all types of human movement; associated with living, work, play, and exercise.

physical fitness a broad term describing healthful levels of cardiovascular function, strength, and flexibility; fitness is specific to the activities performed.

pituitary gland a gland at the base of the hypothalamus of the brain having an anterior portion that produces and secretes numerous hormones that regulate other endocrine glands and a posterior portion that secretes hormones that are produced in the hypothalamus.

placebo an inert substance that is used in experimental studies, e.g., drug studies, to control for any subjective reaction to the substance being tested.

pleura a thin lining of cells that is attached to the inside of the chest wall and to the lung; the cells secrete a fluid that facilitates the movements of the lungs in the thoracic cavity.

posterior hypothalamus area of the brain responsible for regulation of the body's response to a decrease in temperature.

posterior pituitary gland portion of the pituitary gland secreting oxytocin and antidiuretic hormone (vasopressin) that are produced in the hypothalamus.

power a rate of work; work per unit time; P = W/t.

power test a test measuring the quantity of work accomplished in a time period; anaerobic power tests include the Margaria stair climb test and the Wingate test; aerobic power tests include the 1.5-mile run and cycle ergometer and treadmill tests in which power output and oxygen consumption are measured.

primary risk factor a sign (e.g., high blood pressure) or a behavior (e.g., cigarette smoking) that is directly related to the appearance of certain diseases independent of other risk factors.

progressive resistance exercise (PRE) a training program in which the muscles must work against a gradually increasing resistance; an implementation of the overload principle.

prolactin hormone secreted from the anterior pituitary that increases milk production from the breast.

proprioceptive neuromuscular facilitation technique of preceding a static stretch with an isometric contraction.

proprioceptors receptors that provide information about the position and movement of the body; includes muscle and joint receptors as well as the receptors in the semicircular canals of the inner ear.

protein kinase C part of second messenger system that is activated by diacylglycerol and results in the activation of proteins in the cell.

provi*****in a precursor of a vi*****in.

pulmonary circuit the portion of the cardiovascular system involved in the circulation of blood from the right ventricle to the lungs and back to the left atrium.

pulmonary respiration term that refers to ventilation (breathing) of the lung.

Quebec 10-second test a maximal effort 10-second cycle test designed to assess ultra short-term anaerobic power during cycling.

radiation process of energy exchange from the surface of one object to the surface of another that is dependent on a temperature gradient but does not require contact between the objects; an example is the transfer of heat from the sun to the earth.

receptor in the nervous system, a receptor is a specialized portion of an afferent neuron (or a special cell attached to an afferent neuron) that is sensitive to a form of energy in the environment; receptor is also a term that applies to unique proteins on the surface of cells that can bind specific hormones or neurotransmitters.

reciprocal inhibition when extensor muscles (agonists) are contracted, there is a reflex inhibition of the motor neurons to the flexor muscles (antagonists), and vice versa.

Recommended Dietary Allowances (RDA) standards of nutrition associated with good health for the majority of people. Standards exist for protein, vi*****ins, and minerals for children and adults.

relative V˙O2 oxygen uptake (consumption) expressed per unit body weight (e.g., ml · kg–1· min–1).

releasing hormone hypothalamic hormones released from neurons into the anterior pituitary that control the release of hormones from that gland.

renin enzyme secreted by special cells in the kidney that converts angiotensinogen to angiotensin I.

repetition the number of times an exercise is repeated within a single exercise "set."

residual volume (RV) volume of air in the lungs following a maximal expiration.

respiration external respiration is the exchange of oxygen and carbon dioxide between the lungs and the environment; internal respiration describes the use of oxygen by the cell (mitochondria).

respiratory compensation the buffering of excess H+ in the blood by plasma bicarbonate (HCO3¯), and the associated elevation in ventilation to exhale the resulting CO2.

respiratory exchange ratio (R) the ratio of CO2 production to O2 consumption; indicative of substrate utilization during steady-state exercise in which a value of 1.0 represents 100% carbohydrate metabolism and 0.7 represents 100% fat metabolism.

resting membrane potential the voltage difference measured across a membrane that is related to the concentration of ions on each side of the membrane and the permeability of the membrane to those ions.

resting metabolic rate (RMR) metabolic rate measured in the supine position following a period of fasting (4–12 hours) and rest (4–8 hours).

rest interval the time period between bouts in an interval training program.

reversibility a principle of training that describes the temporary nature of a training effect; adaptations to training are lost when the training stops.

sarcolemma the cell (plasma) membrane surrounding a muscle fiber.

sarcomeres the repeating contractile unit in a myofibril bounded by Z-lines.

sarcoplasmic reticulum a membranous structure that surrounds the myofibrils of muscle cells; location of the terminal cisternae or lateral sacs that store the Ca++ needed for muscle contraction.

satellite cells undifferentiated cell found adjacent to skeletal muscle fibers. These cells can fuse with existing muscle fibers and contribute to muscle growth (hypertrophy). It may also be possible that these fibers can differentiate and form a new muscle fiber following muscle injury.

Schwann cell the cell that surrounds peripheral nerve fibers, forming the myelin sheath.

second messenger a molecule (cyclic AMP) or ion (Ca++) that increases in a cell as a result of an interaction between a "first messenger" (e.g., hormone or neurotransmitter) and a receptor that alters cellular activity.

secondary risk factor a characteristic (age, gender, race, body fatness) or behavior that increases the risk of coronary heart disease when primary risk factors are present.

set a basic unit of a workout containing the number of times (repetitions) a specific exercise is done (e.g., do three sets of five repetitions with 100 pounds).

sex steroids a group of hormones, androgens and estrogens, secreted from the adrenal cortex and the gonads.

sham reinfusion an experimental treatment at the end of a blood doping experiment in which a needle is placed in a vein, but the subject does not receive a reinfusion of blood.

sham withdrawal an experimental treatment at the beginning of a blood doping experiment in which a needle is placed in a vein, but blood is not withdrawn.

sinoatrial node (SA node) specialized tissue located in the right atrium of the heart, that generates the electrical impulse to initiate the heartbeat. In a normal, healthy heart, the SA node is the heart's pacemaker.

SI units system used to provide international standardization of units of measure in science.

sliding filament model a theory of muscle contraction describing the sliding of the thin filaments (actin) past the thick filaments (myosin).

slow-twitch fibers muscle fiber type that contracts slowly and develops relatively low tension but displays great endurance to repeated stimulation; contains many mitochondria, capillaries, and myoglobin.

somatomedins groups of growth-stimulating peptides released from the liver and other tissues in response to growth hormone. Also called insulin-like growth factors.

somatostatin hormone produced in the hypothalamus that inhibits growth hormone release from the anterior pituitary gland; secreted from cells in the islet of Langerhans and causes a decrease in intestinal activity.

somatotype body-type (form) classification method used to characterize the degree to which an individual's frame is linear (ectomorphic), muscular (mesomorphic), and round (endomorphic); Sheldon's scale rates each component on 1–7 scale.

spatial summation the additive effect of numerous simultaneous inputs to different sites on a neuron to produce a change in the membrane potential.

specificity a principle of training indicating that the adaptation of a tissue is dependent on the type of training undertaken; for example, muscles hypertrophy with heavy resistance training but show an increase in mitochondria number with endurance training.

spirometry measurement of various lung volumes.

static stretching stretching procedure in which a muscle is stretched and held in the stretched position for ten to thirty seconds; in contrast to dynamic stretching, which involves motion.

steady state describes the tendency of a control system to achieve a balance between an environmental demand and the response of a physiological system to meet that demand to allow the tissue (body) to function over a period of time.

steroids a class of lipids, derived from cholesterol, that includes the hormones testosterone, estrogen, cortisol, and aldosterone.

stroke volume the amount of blood pumped by the ventricles in a single beat.

strong acids an acid that completely ionizes when dissolved in water to generate H+ and its anion.

strong bases a base (alkaline substance) that completely ionizes when dissolved in water to generate OH– and its cation.

ST segment depression an electrocardiographic change reflecting an ischemia (inadequate blood flow) in the heart muscle; indicative of coronary heart disease.

summation repeated stimulation of a muscle that leads to an increase in tension compared to a single twitch.

supercompensation an increase in the muscle glycogen content above normal levels following an exercise-induced muscle glycogen depletion and an increase in carbohydrate intake.

sympathetic nervous system portion of the autonomic nervous system that releases norepinephrine from its postganglionic nerve endings; epinephrine is released from the adrenal medulla.

sympathomimetic substance that mimics the effects of epinephrine or norepinephrine, which are secreted from the sympathetic nervous systems.

synapses junctions between nerve cells (neurons) where the electrical activity of one neuron influences the electrical activity of the other neuron.

systole portion of the cardiac cycle in which the ventricles are contracting.

systolic blood pressure the highest arterial pressure measured during a cardiac cycle.

tapering the process athletes use to reduce their training load for several days prior to competition.

target heart rate (THR) range the range of heart rates describing the optimum intensity of exercise consistent with making gains in maximal aerobic power; equal to 70%–85% HR max.

temporal summation a change in the membrane potential produced by the addition of two or more inputs, occurring at different times (i.e., inputs are added together to produce a potential change that is greater than that caused by a single input).

terminal cisternae portion of the sarcoplasmic reticulum near the transverse tubule containing the Ca++ that is released upon depolarization of the muscle; also called lateral sac.

testosterone the steroid hormone produced in the testes; involved in growth and development of reproductive tissues, sperm, and secondary sex characteristics.

tetanus highest tension developed by a muscle in response to a high frequency of stimulation.

theophylline a drug used as a smooth muscle relaxant in the treatment of asthma.

thermogenesis the generation of heat as a result of metabolic reactions.

thyroid gland endocrine gland located in the neck that secretes triiodothyronine (T3) and thyroxine (T4), which increase the metabolic rate.

thyroid-stimulating hormone (TSH) hormone released from the anterior pituitary gland; stimulates the thyroid gland to increase its secretion of thyroxine and triiodothy-ronine.

thyroxine hormone secreted from the thyroid gland containing four iodine atoms (T4); stimulates the metabolic rate and facilitates the actions of other hormones.

tidal volume volume of air inhaled or exhaled in a single breath.

tonus low level of muscle activity at rest.

total lung capacity (TLC) the total volume of air the lung can contain; equal to the sum of the vital capacity and the residual volume.

toxicity a condition resulting from a chronic ingestion of vi*****ins, especially fat-soluble vi*****ins, in quantities well above that needed for health.

trace elements dietary minerals including iron, zinc, copper, iodine, manganese, selenium, chromium, molybdenum, cobalt, arsenic, nickel, fluoride, and vanadium.

transferrin plasma protein that binds iron and is representative of the whole body iron store.

transverse tubule an extension, invagination, of the muscle membrane that conducts the action potential into the muscle to depolarize the terminal cisternae, which contain the Ca++ needed for muscle contraction.

triiodothyronine hormone secreted from the thyroid gland containing three iodine atoms (T3); stimulates the metabolic rate and facilitates the actions of other hormones.

tropomyosin protein covering the actin binding sites that prevents the myosin cross-bridge from touching actin.

troponin protein, associated with actin and tropomyosin, that binds Ca++ and initiates the movement of tropomyosin on actin to allow the myosin cross-bridge to touch actin and initiate contraction.

twenty-four-hour recall a technique of recording the type and amount of food (nutrients) consumed during a twenty-four-hour period.

twitch the tension-generating response following the application of a single stimulus to muscle.

type I fibers fibers that contain large numbers of oxidative enzymes and are highly fatigue resistant.

type IIa fibers fibers that contain biochemical and fatigue characteristics that are between Type IIb and Type I fibers.

type IIb fibers fibers that have a relatively small number of mitochondria, a limited capacity for aerobic metabolism, and are less resistant to fatigue than slow fibers.

underwater weighing procedure to estimate body volume by the loss of weight in water; result is used to calculate body density and, from that, body fatness.

U.S. Dietary Goals a series of nutritional goals to achieve better health for the American population.

vagus nerve a major parasympathetic nerve.

variable-resistance exercise strength training in which the resistance varies throughout the range of motion.

veins the blood vessels that accept blood from the venules and bring it back to the heart.

ventilation the movement of air into or out of the lungs (e.g., pulmonary or alveolar ventilation); external respiration.

ventilatory threshold (Tvent) the "breakpoint'' at which pulmonary ventilation and carbon dioxide output begin to increase exponentially during an incremental exercise test.

venules small blood vessels carrying capillary blood to veins.

vestibular apparatus sensory organ, consisting of three semicircular canals, that provides needed information about body position to maintain balance.

vital capacity (VC) the volume of air that can be moved into or out of the lungs in one breath; equal to the sum of the inspiratory and expiratory reserve volumes and the tidal volume.

web of causation an epidemiologic model showing the complex interaction of risk factors associated with the development of chronic degenerative diseases.

whole-body density a measure of the weight-to-volume ratio of the entire body; high values are associated with low body fatness.

Wingate test anaerobic power test to evaluate maximal rate at which glycolysis can deliver ATP.

work the product of a force and the distance through which that force moves (W = F × D).

work interval in interval training, the duration of the work phase of each work-to-rest interval.


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