Glossary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A band the dark band seen as part of the striation effect of skeletal and cardiac muscle

acceleration phase the second phase of a sprinting event

accumulation hypothesis an explanation of muscle fatigue in terms of the building up of metabolites such as lactate, hydrogen ions, inorganic phosphate, and ammonia, within muscle fibers

acetylcholine (ACH) a neurotransmitter widely distributed in body tissues with a primary function of mediating synaptic activity of the nervous system and skeletal muscles

acid a compound that yields positively charged hydrogen ions in solution

acquired immune deficiency syndrome (AIDS) a disease state caused by the human immunodeficiency virus and characterized by a severe depletion of helper T cells and major complications such as cancer or opportunistic infection

actin a type of contractile protein (myofilament)

action potential an electrical impulse transmitted across the plasma membrane of a nerve fiber during the transmission of a nerve impulse and across the plasma membrane of a muscle fiber during contraction

acute musculoskeletal injury injury resulting from trauma experienced during a single episode of training

adenosine diphosphate (ADP) a product of the hydrolysis of ATP

adenosine triphosphate (ATP) an energy-storing molecule in muscle that releases energy when it is hydrolyzed to adenosine diphosphate (ADP)

adenosine triphosphate–phosphocreatine (ATP–PC) system the anaerobic metabolic pathway that utilizes adenosine triphosphate (ATP) and phosphocreatine (PC) to meet the energy demands of short-term, high intensity exercise

adolescence the period of development between the onset of puberty and adulthood, characterized by a growth spurt

aerobic with oxygen

afferent neuron a neuron that conducts impulses from the periphery to the central nervous system; also known as sensory neuron

agonist the muscle causing a movement

alkaline reserve the ability of the plasma bicarbonate system to buffer fixed acids such as lactic acid

all-or-none law the fact that when a muscle fiber (or motor unit) responds to a single impulse at or above threshold value by contracting, the tension produced is independent of the intensity of the stimulus

allosteric inhibition process in which the end product of a series of enzymatic steps inhibits the activity of the enzyme

alpha motor neuron a motor neuron that transmits impulses from the central nervous system to the extrafusal skeletal muscle fibers

altitude acclimatization the increased ability to perform at high altitudes; accomplished by various systems of physical conditioning at progressively higher altitudes or a progressive conditioning program at the competition altitude

alveolar duct any of the small air passages in the lung that branch out from the bronchioles and lead to the alveoli

alveolar ventilation rate the rate of air flow to the alveoli

alveolus a small pouch in the lungs through which gas exchange between alveolar air and pulmonary capillary blood occurs (plural: alveoli)

amenorrhea absence of menstrual flow

amphetamine a sympathomimetic amine used in medicine as a central nervous system stimulant; sometimes used as an ergogenic aid

anabolic steroid a synthetically developed cholesterol- based drug that resembles naturally occurring hormones such as testosterone and has growth-promoting and masculinizing effects

anabolism “to build up”; refers to metabolic processes in which structures are created

anaerobic glycolysis the metabolism of glucose to lactate

anaerobic threshold the intensity of exercise just below that at which metabolic acidosis and the associated changes in gas exchange occur

anaerobic without oxygen

anatomical dead space the volume of the conducting portion of the airways of the lungs where no gas exchange occurs

androstenedione a weakly androgenic steroid precursor; sometimes used as an ergogenic aid

angina pectoris chest pain usually caused by myocardial anoxia as a result of atherosclerosis or coronary artery spasm

anovulation suspension or cessation of the production and/or release of an ovum

antagonist the muscle whose contraction opposes a movement

antibody a glycoprotein produced and secreted by plasma cells in response to bacteria, viruses, or other antigenic substances; also known as an immunoglobulin

antibody-dependent cell-mediated cytotoxicity (ADCC) the process of destroying cells by the binding of an antibody to an antigen on the cell surface and lysing those cells

antigen any substance, usually a protein, that causes the formation of an antibody that reacts specifically with that substance

arginine a semi-essential amino acid that is involved in a number of metabolic pathways and the production of biologically active compounds

arteriole a muscular vessel that lies between an artery and a capillary

arteriosclerosis hardening of the arteries

arteriovenous anastomose (AV shunt) short vascular connections between small arteries and veins, arterioles and venules, and metarterioles and venules

artery an elastic vessel that carries blood away from the heart

asthma a condition that involves chronic inflammation of the airways of the lungs and is characterized by obstruction of the flow of air due to bronchoconstriction, wheezing, coughing, shortness of breath, and tightness of the chest

atherosclerosis an abnormal condition of the vascular system characterized by yellowish plaques of cholesterol, lipids, and cellular debris in the inner layer of the walls of large and medium-sized arteries

athletic menstrual cycle irregularities (AMI) disruption in the menstrual cycle as a result of high-intensity athletic training programs

atrioventricular (AV) node a specialized mass of conducting tissue located at the base of the atria in the interatrial septum

atrium a chamber of the heart that receives blood from veins

autonomic nervous system the branch of the nervous system that regulates involuntary functions, including the activity of the cardiac muscle, smooth muscle, and glands

autorhythmicity self-excitation, a property of cardiac muscle

axon the portion of a neuron that conducts impulses away from the cell body

B cell a cell that resides in lymph nodes, spleen, and other lymphoid tissue and mediates humoral immunity

ballistic stretching a method of muscle elongation (stretching) involving high-force, short-duration, jerky or bouncy movements

basal ganglia paired masses of gray matter in each cerebral hemisphere

basal metabolic rate the rate of metabolism required for basic body functions during rest

base a compound that yields negatively charged hydroxyl ions in solution

beta oxidation an aerobic metabolic process in which long chain fatty acids are broken into two carbon acetyl coenzyme A molecules to enter the Krebs cycle

beta-alanine a nonproteogenic (not involved in protein synthesis) amino acid produced in the liver; the role of beta-alanine in exercise performance is related to its involvement in the synthesis of carnosine in skeletal muscle

beta-hydroxy-beta-methylbutyrate (HMB) a metabolite produced as a result of the breakdown of leucine; sometimes used as an ergogenic aid

Betz cells large pyramidal cells in the motor area of the precentral gyrus of the cerebral cortex; also known as Bevan–Lewis cells

bilateral deficit a decrease in the strength of a muscle group when the contralateral limb is concurrently performing a maximal contraction

blood doping a procedure involving the removal of blood 8 to 12 weeks prior to an athletic event, isolation and freezing of the red blood cells, and reinfusion of those cells during the week preceding the athletic event; also known as erythrocythemia

blood flow the amount of blood flowing to the various organs each minute

blood pressure the arterial pressure during systole over the arterial pressure during diastole

body building a competitive sport in which the participant uses several resistance training methods to develop muscle size, symmetry, and definition

body mass index (BMI) body weight divided by height squared (kg/m2)

Boyle’s law if temperature remains constant, the pressure of a gas varies inversely with its volume

bronchi two subdivisions of the trachea; conveys air to and from the lungs (singular: bronchus)

bronchioles one of the smaller subdivisions of the bronchial tubes, containing smooth muscle and elastic fibers, but no cartilage in its wall

buffer system an acid and its conjugate base (salt) that, when present in a solution, reduce any change in pH that would otherwise occur in the solution when acid or alkali is added to it

caffeine a central nervous system stimulant that increases sympathetic nervous system arousal and also acts as a diuretic; sometimes used as an ergogenic aid

capacitance vessels thin-walled vessels, such as veins, that are important in altering the capacity, or storage function, of the postcapillary system

capillary vessel with a single-cell layer wall that functions in gas exchange

carbohydrate sparing effect the result of the preferential use of fatty acids for ATP production in endurance trained individuals

cardiac contractility the ability of the heart to produce force per unit of time (power)

cardiac cycle the cyclic pattern of contraction and relaxation of the heart

cardiac muscle contractile tissue of the heart

cardiac output (CO) the amount of blood ejected by the heart each minute; heart rate times stroke volume

cardiac reserve the heart rate reserve and the stroke volume reserve; the ability of the heart to increase its cardiac output

cardiovascular disease an illness or disorder of the heart or blood vessels

catabolism “to break down”; refers to metabolic processes of breaking down

catecholamine a hormone secreted by the adrenal medulla that serves to increase the availability of fuel to the active muscles

cell-mediated immunity the mechanism of acquired immunity characterized by T cell lymphocytes and involving resistance to infectious diseases caused by viruses and some bacteria; also known as cellular immunity

central fatigue a decrease in motor performance due to mechanisms proximal to the motor neurons

central governor model a model postulating that the central nervous system regulates exercise performance to ensure that physiological failure does not occur during normal exercise

central nervous system the brain and spinal cord

chilblain one of the most common nonfreezing cold injuries; typically less severe than trenchfoot and can occur with only one to five hours of exposure of bare skin to cold

childhood the time between the first birthday and puberty, characterized by steady growth and maturation with particularly rapid progress in motor development

chilling a sudden decrease in body temperature; often occurs when there are intermittent periods of activity and rest

chronic musculoskeletal injury injury resulting from repeated microtrauma due to overuse

chronic obstructive pulmonary disease (COPD) Bronchitis and/or emphysema that is characterized by limited airflow to the lungs and is not fully reversible

chylomicron a small droplet of lipoprotein synthesized in the gastrointestinal tract and transported through the lymph vessels into the plasma and eventually to the tissues for use

claudication limping; usually refers to intermittent claudication

cluster designation (CD) a protein on the surface of an immune cell that is used to identify, classify, and study that cell

coefficient of oxygen utilization the proportion of oxygen transported by the blood that is given off to the tissues

coenzyme vitamin or vitamin derivative that transports hydrogen within the cell and affects the turnover rate of an enzyme in a metabolic pathway

cofactor metal that affects the turnover rate of an enzyme in a metabolic pathway

cold acclimatization the increased ability to withstand cold temperatures as a result of continued exposure to cold

collateral circulation a redundant blood pathway developed through enlargement of secondary vessels after obstruction of a main channel

complement protein any of nine proteins that are involved in the lysis of antibody-coated bacteria and other cells; stimulate phagocytosis and inflammation

complete protein a protein that includes all of the essential amino acids

complex carbohydrate a combination of three or more glucose molecules

concentric muscle action that involves the production of force while the muscle is shortening

conduction the transfer of heat between two objects that are in contact with one another

conductivity the ability of muscle tissue to propagate a stimulus throughout any one fiber in skeletal muscle and from fiber to fiber in smooth and cardiac muscles

contractility the ability of muscle tissue to contract

contraction phase the period of muscle twitch during which the muscle shortens (also called shortening period)

contract–relax (CR) stretching technique of isometrically contracting the lengthened muscle, then relaxing and further passively lengthening the muscle

contract–relax with agonist-contraction (CRAC) stretching technique identical to contract–relax except that during the final stretching phase the muscle opposite the one stretched is concentrically contracted

controlled frequency breathing (CFB) for swimmers, breathing is less than once per stroke cycle

convection the transfer of heat through a gas or liquid by the circulation of heated particles

cooling down low- to moderate-intensity activity performed after a physical activity

core strengthening a training program focused on the muscles that stabilize the trunk of the body, including abdominal, low back, and gluteal muscles, as well as flexibility of muscular attachments to the pelvis, such as the quadriceps and hamstring muscles

core temperature the temperature of the central nervous system and internal organs; reflected by the rectal temperature

coronary heart disease (CHD) a condition causing reduced flow of oxygen and nutrients to the heart; formerly known as coronary artery disease

creatine loading ingesting creatine monohydrate prior to a performance in order to increase muscle phosphocreatine stores

creatine a naturally occurring nitrogenous compound synthesized in the liver, kidneys, and pancreas; combined with phosphorus, it forms high-energy phosphate; sometimes used as an ergogenic aid

cross-bridge recycling the process of a myosin crossbridge swiveling inward, being released from the actin molecule, standing back up, rebinding to the actin molecule, and swiveling again; also called crossbridge recharging

crossed extensor reflex reflex extension of the contralateral (opposite) limb

cross-education effect the phenomenon of strength increases in a contralateral (opposite) limb as a result of unilateral training; also known as the cross-training effect

cruise intervals training performed at the lactate threshold, consisting of discontinuous work bouts lasting approximately 3 to 10 minutes with 1-minute rest intervals

cyclic AMP (cAMP) an activator of the enzyme phosphorylase kinase; formed from ATP by adenyl cyclase; also known as adenosine 3’:5’-cyclic phosphate and cyclic phosphate

degenerative disease any disease in which deterioration of a structure or function of tissue occurs; examples include cardiovascular disease, hypertension, and cancer

dehydroepiandrosterone (DHEA) a weakly androgenic steroid precursor; sometimes used as an ergogenic aid

dehydrogenase enzymes enzymes involved in oxidation and reduction reactions that catalize six reactions within glycolysis and the Krebs cycle

delayed onset muscle soreness (DOMS) the pain caused by microtrauma of the muscle felt 24 to 48 hours after an exercise bout

dendrite the portion of a neuron that receives impulses

depletion hypothesis a possible explanation of muscle fatigue; involves the concept of the depletion of glycogen, glucose, or phosphagen stores

detraining the secession, or stopping, of a training program; usually accompanied by a decrease in fitness

development 1. the differentiation of cells along specialized lines of function; 2. the evolution of competence in a variety of interrelated domains

diabetes mellitus a metabolic disorder characterized by elevated blood glucose levels

diastole the relaxation phase of the cardiac cycle

diastolic pressure the arterial blood pressure during diastole

diffusion gradient the rate of change of gas exchange; dependent upon the ease with which a gas can penetrate a membrane

disaccharide simple carbohydrate made up of two simple sugar molecules

disordered eating a disturbance in the behavior associated with taking in food; anorexia nervosa and bulimia nervosa are examples

drafting a racing technique in which an athlete performs directly behind another athlete to reduce wind and air resistance

duration how long exercise is performed each day

dynamic constant external resistance (DCER) muscle action a type of muscle action in which the external resistance remains constant throughout the movement; also known as isotonic muscle action

dynamic exercise exercise, such as running or cycling, that involves rapid contractions alternating with relaxations

dynamic flexibility a measurement of range of motion that reflects joint stiffness and resistance to limb movement

dyslipidemia an elevation of LDL or triglycerides, or a reduction in HDL; a major, modifiable risk factor for CHD

dysmenorrhea pain from uterine contractions or ischemia during menstruation

dyspnea labored breathing; shortness of breath

eccentric a muscle action that involves the production of force while the muscle is lengthening

economy of movement the efficiency with which a movement is performed; may be determined by measuring the oxygen cost

efferent neuron a neuron that conducts impulses from the central nervous system to the muscles and other effectors; also known as motor neuron

electromyography the recording of muscle action potentials (or their currents)

electron transport system (ETS) also called the respiratory chain; mitochondrial system in which large amounts of ATP are produced and oxygen is utilized

electronic integrators a tool that finds the average amplitude of summated muscle action potentials

embolus a blood clot or other mass that circulates in the blood stream until it becomes lodged in a vessel

end bulb the end of the neuron

end diastolic volume (EDV) the amount of blood in each ventricle of the heart at the end of diastole

end systolic volume (ESV) the amount of blood in each ventricle of the heart at the end of systole

endocrine pertaining to the system of ductless glands that secrete hormones into the blood and lymph

endolymph the fluid in the semicircular canals of the inner ear

endomysium the connective tissue sheath covering an individual muscle fiber

enzyme proteins that have specific properties and functions

ephaptic conduction rapid transmission of an impulse from cell to cell

epimysium the connective tissue sheath covering a muscle

epinephrine a hormone secreted by the adrenal medulla; serves to increase the availability of fuel to the active muscles

epiphyseal growth plate a thin layer of cartilage between the epiphysis, a secondary bone forming center, and the bone shaft; new bone forms along the plate

ergogenic aid a substance, such as a steroid, used by athletes with the expectation that it will provide a competitive edge

erythrocyte red blood cell

erythrocythemia a procedure involving the removal of blood 8 to 12 weeks prior to an athletic event, isolation and freezing of the red blood cells, and reinfusion of those cells during the week preceding the athletic event; also known as blood doping

erythropoietin a naturally occurring hormone produced by the kidneys in response to low hemoglobin levels; stimulates bone marrow to produce red blood cells; sometimes used as an ergogenic aid

esophagus the muscular tube in the neck, extending from the pharynx to the stomach; serves as a passageway for food

essential amino acid an amino acid that cannot be synthesized by the body and therefore must be supplied by the diet

estrogen a hormone secreted by the ovaries

eupnea easy, free breathing as observed in the normal subject under resting conditions

evaporation a change from liquid form into gas form; also known as vaporization

exercise intensity the workload of an exercise, measured in foot-pounds or kilogram-meters per minute

exercise-induced asthma (EIA) bronchoconstriction caused by exercise

exercise-induced bronchospasm (EIB) a prolonged contraction of the involuntary muscles fibers of the walls of the bronchi and bronchioles during exercise

exercise-related transient abdominal pain (ETAP) Pain that occurs in running or other repetitive movements that is felt in the lateral aspects of the mid abdomen, along the costal border and has been described as cramping, aching, or pulling when it is less intense, as well as sharp or stabbing, when the pain is more severe. Commonly referred to as stitch in the side.

exertional heat exhaustion The fatigue that develops during exercise in the heat; this fatigue may be caused by excess body heat and by dehydration

exertional heatstroke A potentially fatal disorder that occasionally follows heat exhaustion; characterized by an elevated core body temperature greater than 104°F; loss of consciousness (coma) following exertion; and clinical symptoms of damage to the central nervous system, liver, and kidneys

exertional hyperthermia An elevated core body temperature greater than 104°F that occurs during athletic or recreational activities; it is influenced by exercise intensity, environmental conditions, clothing, and equipment

exocrine pertaining to glands that secrete their products through ducts

expiration phase the process of breathing out

expiratory reserve volume the maximal amount of gas that can be expired from the end-tidal expiratory level

external respiration gas exchange in the lungs in which the blood in the lung capillaries takes up oxygen and gives up much of its carbon dioxide; also known as pulmonary ventilation

extrafusal muscle fibers (EF) a typical skeletal muscle fiber

extrapyramidal system the portion of the brainstem and spinal pathways that do not pass through the pyramids and are concerned with postural control

Fartlek training training that consists of an easy, continuous pace alternating with short, high-intensity bursts

fascia the fibrous connective tissue of the body

fasciculus a bundle of muscle fibers (plural fasciculi)

fast-twitch glycolytic (FG) fatigable muscle fibers that favor glycolytic (anaerobic) methods of energy production; also known as type IIb fibers

fast-twitch oxidative glycolytic (FOG) one of the three primary fiber types in human skeletal muscle; also called type IIa

fatigue the state following a period of mental or bodily activity characterized by a lessened capacity for work and reduced efficiency of accomplishment, usually accompanied by a feeling of weariness, sleepiness, or irritability; may also supervene when, from any cause, energy expenditure outstrips restorative processes

female athlete triad a syndrome that affects extremely physically active females, characterized by disordered eating, amenorrhea, and osteoporosis

Fick method an indirect method of estimating cardiac output by determining the rate at which oxygen is added to the blood as it flows through the lungs

FITT-VP principle of aerobic exercise prescription focusing on six components frequency of exercise, intensity of exercise, time (duration) of exercise, type (mode) of exercise, volume (amount) of exercise, and progression (advancement) or pattern of exercise

flexibility the range of motion at a joint or a series of joints

flexion reflex an involuntary flexion of a muscle in response to a stimulus; allows for the removal of the body part from the stimulus; a simple reflex

force–velocity curve the relationship of the maximum force produced at any given velocity

frank anemia the third and final stage of iron deficiency, characterized by inefficient cell metabolism and decreased oxygen transport

Frank–Starling law of the heart the principle that contraction force during systole is dependent upon the length of the cardiac muscle fibers at the end of diastole

frequency domain the domain of the EMG signal that is the rate at which a wave form fluctuates above and below the baseline

frequency how often exercise is performed; usually, the number of times per week exercise is performed

frostbite a damaging condition caused by the crystallization of fluids in the skin or subcutaneous tissues upon exposure to cold temperatures

functional residual capacity the amount of gas remaining in the lungs at the resting expiratory level; includes the expiratory reserve volume and residual volume

gamma motor neuron a motor neuron that transmits impulses from the central nervous system to the intrafusal fibers of a muscle spindle

gap junction a small channel within an intercalated disk; allows for ion exchanges between the cytosol of adjacent cells

Gay-Lussac’s law if volume remains constant, the pressure of a gas increases directly in proportion to its absolute temperature

globin the protein constituent of hemoglobin

glottis a slitlike opening between the true vocal cords

glucagon a hormone secreted by the pancreas that acts to raise blood glucose levels

glycogen depletion the exhaustion or emptying of stored glucose (glycogen) as a result of long duration activities such as distance running or cycling

glycogen supercompensation a procedure used to produce the maximum possible glycogen

glycogen the storage form of glucose

glycogenolysis the conversion of glycogen to glucose

glycolysis an anaerobic pathway that utilizes glucose for energy production

Golgi tendon organs a sensory receptor in the tendon of a muscle; it is sensitive to stretch and serves as a detector of tendon tension

gonads the gamete-producing organs; testes in the male and ovaries in the female

growth hormone a naturally occurring polypeptide secreted by the anterior pituitary gland; promotes increases in muscle mass directly by increasing amino acid transport and protein synthesis in skeletal muscle and indirectly by stimulating the production of insulin- like growth factor

growth an increase in the size of the body as a whole or the size attained by specific parts of the body

H band a lighter area within the A band seen as part of the striation effect of skeletal and cardiac muscle

heart murmur a sound created by blood that is not flowing smoothly through the heart

heart rate reserve the difference between maximum heart rate and resting heart rate; the ability of the heart to increase its rate of contraction; also known as heart rate range

heat acclimatization the increased ability to withstand hot temperatures as a result of continued exposure to heat

heat strain the effect of heat stress on the body; the elevation of core temperature, skin temperature, and heart rate

heat stress the sum of the metabolic and environmental heat loads; related to exercise intensity, environmental temperature, and evaporative potential of the environment

heat syncope dizziness associated with high environmental temperatures due to peripheral vasodilation, postural pooling of blood, diminished venous return, dehydration, reduced cardiac output, and/or cerebral ischemia; also known as orthostatic dizziness

helper T cell a type of T cell that stimulates the cytotoxic action of killer T cells and increases antibody production by plasma cells

heme the pigmented iron-containing, oxygen-carrying constituent of hemoglobin

hemochromatosis a rare disease of iron metabolism, characterized by excess iron deposits throughout the body

hemoglobin a complex protein–iron compound of erythrocytes that carries oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs

hemorrhagic stroke an abnormal condition of the brain that occurs when a vessel ruptures in the brain, causing ischemia of the brain tissue

Henry’s law the quantity of a gas that will dissolve in a liquid is directly proportional to its partial pressure, if temperature remains constant

high risk individuals with known cardiovascular, pulmonary, or metabolic disease or who exhibit certain symptoms

high-density lipoprotein a plasma protein made in the liver and containing about 50 percent protein with cholesterol and triglycerides; transports cholesterol and other lipids to the liver for disposal

high-velocity phase the third phase of a sprinting event

hormone a biological chemical that is secreted by an endocrine gland into the blood and lymph

human immunodeficiency virus (HIV) a retrovirus that causes acquired immunodeficiency syndrome (AIDS); cripples the immune system by decreasing the number of helper T cells

humoral immunity resistance to disease that exists in the blood and lymph

hunch guess

hypercapnic training a training method, such as controlled frequency breathing, in which ventilatory volume and partial pressure of oxygen decrease while the partial pressure of carbon dioxide increases

hyperglycemia elevated blood glucose levels

hyperlipidemia elevated lipids in the blood

hyperplasia an increase in the number of elements comprising a part (such as tissue cells)

hyperplastic obesity a condition of excessive body fatness characterized by an increase in the number of fat cells

hypertension elevated blood pressure; resting systolic blood pressure greater than 160 mm Hg or resting diastolic blood pressure greater than 95 mm Hg

hypertrophic obesity a condition of excessive body fatness characterized by an increase in the size of the fat cells

hypertrophy an increase in the size of existing parts (such as the size of the cells of a tissue)

hyperventilation an increase in lung ventilation without a corresponding increase in metabolic rate

hypocapnia abnormally low levels of carbon dioxide in the circulating blood

hypoglycemia low blood glucose levels

hypothermia severely reduced core body temperature

hypothesis a tentative supposition (based on prior observations) provisionally adopted to explain certain facts and to guide investigations

hypoventilation a reduction in lung ventilation without a corresponding decrease in metabolic rate

hypoxic training a training method in which the partial pressure of oxygen is subnormal

I band a lighter area between the A bands seen as part of the striation effect of skeletal and cardiac muscle

immune free from or resistant to an infectious disease

immunoglobulin a glycoprotein produced and secreted by plasma cells in response to bacteria, viruses, or other antigenic substances; also known as antibody

indicator dilution method an indirect method of estimating cardiac output by injecting dye (indicator) into a large vein or into the right atrium of the heart

infancy the first year of life, characterized by rapid growth in almost all bodily functions and physical characteristics

inspiration phase the process of breathing in

inspiratory capacity the maximal amount of gas that can be inspired from the resting expiratory level; includes the tidal volume and inspiratory reserve volume

inspiratory reserve volume the maximal amount of gas that can be inspired from the end-tidal inspiratory level

insulin a hormone secreted by the pancreas that acts to reduce blood glucose levels

integration the mathematical process of determining the area under a curve; used to find the mean amplitude of summated muscle action potentials

intensity a term used to describe the degree of physiological strain or challenge of exercise

intercalated disk a connective tissue structure located between adjacent cardiac muscle cells, allowing one cell to pull on the surrounding cells

interferon a cellular protein produced by cells infected by viruses; act on neighboring cells to prevent infection

intermediate-density lipoprotein a lipid–protein complex with a density between that of a low-density lipoprotein and a high-density lipoprotein

internal respiration gas exchange between the blood and cells; also known as tissue respiration

internuncial neuron a neuron that lies in the gray matter of the spinal cord, between a sensory and a motor neuron

interval training training consisting of short periods of work alternating with short rest intervals

intrafusal (IF) muscle fibers a small fiber located within the capsule of a muscle spindle

irritability muscle tissue’s responsiveness to stimuli

ischemia insufficient blood flow

isocaloric state state in which calories taken in equal calories expended

isokinetic muscle action that has a constant velocity of movement

isometric muscle action involving tension production without movement at the joint or shortening of the muscle fibers; also known as static muscle action

isotonic muscle action in which the external resistance remains constant throughout the movement, also known as dynamic constant external resistance (DCER)

jet lag the fatigue and sluggishness that travelers feel following long airplane flights across time zones

killer T cell a type of T cell that defends against invading organisms by producing lymphotoxins, interferons, macrophage chemotactic factor, macrophage invading factor, and macrophage migration inhibiting factor

kinesthesis The sense of movement and position of body parts in space

Krebs cycle an aerobic metabolic process that utilizes acetyl coenzyme A molecules to produce ATP; also known as citric acid cycle or tricarboxylic acid cycle

lactate threshold the measurement of the anaerobic threshold by blood lactate levels

lactate an end product of glycolysis; can lead to a decrease in cellular pH

latent iron deficiency the second stage of iron deficiency, characterized by an increased total iron binding capacity and reduced serum iron

latent period the short delay between the application of a stimulus and the beginning of muscular contraction

law of energy balance law describing the relationships between calories taken in and calories expended

Law of Mass Action the ability of a reversible reaction to be driven from an area of high concentration to an area of low concentration

law of partial pressures in a mixture of gases, each gas exerts a partial pressure, proportional to its concentration

leukocyte white blood cell; any cell of the immune system

leukocytosis an increase in the number of circulating white blood cells (leukocytes)

lipoprotein a compound containing lipid (fat) and protein; the form lipids take as they travel in the blood

lock-and-key method used to describe the specificity of fit involved in interactions such as those of antigen with antibody and hormone with receptor

long slow distance (LSD) training training at approximately 65 to 70 percent of VO2 max to develop the cardiorespiratory system, circulatory blood supply to the active muscles, and enhance the metabolic characteristics of the muscles

low risk men under 45 and women under 55 who are asymptomatic and have no more than one risk factor

low-density lipoprotein a plasma protein that contains more cholesterol and triglyceride than protein

lower motor neuron a neuron whose cell body is in the spinal cord

lung ventilation rate volume of breathing per minute

lymphocyte an agranular leukocyte formed in lymphoid tissue; includes T cells, B cells, and natural killer (NK) cells

lymphocytosis an increase in the number of circulating lymphocytes

lymphotoxin a cytotoxic polypeptide produced by killer T cells

macrophage activating factor a lymphokine released from a sensitized leukocyte that stimulates phagocytosis by macrophages

macrophage chemotactic factor a lymphokine released from a sensitized leukocyte that attracts macrophages to the site of an invasion by an antigen

macrophage migration inhibiting factor a lymphokine released from leukocytes that immobilizes macrophages after contact with an antigen, thereby preventing the macrophages from exiting the area

macrophage a large ameboid mononuclear phagocytic cell

making weight the effort to reduce body weight in order to qualify for a particular weight class in competition

maturation the tempo and timing of progress toward the mature (advanced) biological state

maximum heart rate (HRmax) the highest heart rate attainable during exercise; HRmax = 220 – age

mean power the total work performed during a maximal 30-second cycle ergometer test; reflects the capacity of the glycolytic energy production pathway

memory B cell a subclassification of B cell that recognizes and responds quickly to an antigen from a previous exposure

memory T cell a type of T cell that recognizes and responds quickly to an antigen from a previous exposure

menarche the first menstrual period or flow

metabolic equivalent (MET) 3.5 • mL • kg–1 • min–1; average resting VO2; used to describe the intensity of an exercise as a multiple of the resting VO2, for example, 1 MET, 2 MET, etc.

metabolism “to change”; includes the processes of anabolism and catabolism

metarteriole a small blood vessel that lies between an arteriole and a true capillary

mitochondria the organelle within the sarcoplasm that functions in aerobic energy metabolism and respiration (plural: mitochondria)

mode a term used to describe the type of exercise

moderate risk men over 45 and women over 55, or any person with more than one risk factor

monocyte an agranular leukocyte normally found in lymph nodes, spleen, bone marrow, and loose connective tissue

monosaccharide a six carbon atom sugar; glucose, fructose, and galactose

motor cortex the precentral gyrus of the frontal lobe of the cerebrum; contains nerve cell bodies whose axons form the descending pyramidal motor tracts

motor neuron a neuron that conducts impulses from the central nervous system to the muscles and other effectors; also known as efferent neuron

motor unit a motor neuron and all of the muscle fibers that it innervates

muscle (heat) cramps acute, painful, and involuntary muscle contraction due to dehydration, electrolyte imbalances, and/or neuromuscular fatigue

muscle action potential (MAP) the electrical charge that accompanies the contraction of muscle tissue

muscle atrophy shrinking of a muscle

muscle spindle a sensory receptor within skeletal muscle, containing intrafusal muscle fibers enclosed in a fibrous sheath; it is sensitive to stretch and serves as a detector of muscle length

myocardial infarction heart attack; death of heart tissue

myocardium heart muscle

myofibril the slender column-like structures that run longitudinally within the sarcoplasm of a muscle fiber

myofilament contractile protein

myoglobin an iron-containing structure that transports oxygen from the sarcolemma to the mitochondria of the skeletal muscle fiber, where it is used for aerobic metabolism

myoneural junction the intersection of a motor neuron and a muscle fiber; also known as neuromuscular junction

myosin ATPase an enzyme that breaks down ATP that is bound to the myosin cross-bridge, thereby liberating energy

myosin cross-bridge the portion of the myosin protein that binds with the binding site on the actin protein; also known as myosin head

myosin a type of contractile protein (myofilament)

myotatic reflex a simple, two-neuron reflex in which the tapping (or stretching) of a tendon results in the contraction of that tendon’s muscle

nasopharynx the cavity of the nose and the nasal parts of the pharynx

natural killer (NK) cell a non-T and non-B lymphocyte that is thought to be involved with immune surveillance against cancer by destroying certain cells before they can produce tumors

negative caloric balance state in which calories expended exceed calories taken in

neuromuscular fatigue a transient decrease in muscular performance usually seen as a failure to maintain or develop a certain expected force or power output

neuromuscular junction the intersection of a motor neuron and a muscle fiber; also known as myoneural junction

neuron a nerve cell

neutrophil a granular leukocyte formed in the bone marrow and released into the bloodstream

non-pathologic cardiac hypertrophy an exercise-induced increase in the thickening of the heart walls (primarily the left heart) as well as an increase in the diameter of the left ventricle

norepinephrine hormone secreted by the adrenal medulla and sympathetic nerve endings; serves to increase the availability of fuel to the active muscles

obesity an abnormal increase of fat in the subcutaneous connective tissues

oligomenorrhea irregular menstrual periods

orthostatic dizziness dizziness associated with high environmental temperatures due to peripheral vasodilation, postural pooling of blood, diminished venous return, dehydration, reduced cardiac output, and/or cerebral ischemia; also known as heat syncope.

osteoporosis a disease characterized by low bone mass and microarchitectural deterioration of bone tissue

overload a basic principle of resistance training, that in order to promote strength gains and hypertrophy, a resistance training program must demand more of a muscle or muscle group than it normally performs

overtraining the adverse effects on health and performance that often result from increasing the total volume of training too quickly

oxygen cost of breathing the percentage of metabolism devoted to the muscular work required for breathing

oxygen dissociation curve a graphic indication of the amount of oxygen released from hemoglobin as a result of changing carbon dioxide levels in the tissues

oxygenation the process of hemoglobin combining with oxygen

parasympathetic branch the division of the autonomic nervous system that originates in the brain and the sacral region of the spinal cord and is activated during times of inactivity and digestion of nutrients

parathyroid hormone (PTH) hormone secreted by the parathyroid gland, involved in calcium regulation

pathologic cardiac hypertrophy an increase in the thickness of the walls of the heart, usually caused by chronically high aortic pressure and not accompanied by an increase in ventricular chamber diameter

peak height velocity the greatest rate of growth in height; used to assess the adolescent growth spurt

peak power the greatest amount of work performed during a five-second period; reflects the efficiency of the phosphagen system (ATP and CP breakdown)

peak weight velocity the greatest rate of increase in weight; used to assess the adolescent growth spurt

perimysium the connective tissue sheath covering a fasciculus

periodization periodic changes in a resistance training program to minimize boredom and facilitate adherence; a basic principle of resistance training

peripheral artery disease (RAD) any abnormal condition that affects the blood vessels outside the heart

peripheral fatigue a decrease in motor performance due to mechanisms in the motor units

peripheral nervous system the nerves that lie outside the brain and spinal cord

phagocytosis the process by which unwanted particles are engulfed and destroyed by digestive enzymes

pharynx the cavity of the nose and the nasal parts of the pharynx

phenolic amine hormone a hormone that contains a phenol group attached to an amine

phosphagen depletion the exhaustion or emptying of phosphocreatine (PC) stores and extensive reduction of adenosine triphosphate (ATP) as a result of very high intensity physical activity

phosphagen the fuel source for the ATP–PC system of energy production

phosphatase the enzyme responsible for dephosphorylating glucose-6-phosphate, thereby creating glucose

phosphate loading sodium phosphate supplementation

phosphocreatine (PC) a high energy bond containing phosphagen that is utilized for rapid ATP production during short-term, high-intensity exercise; also known as creatine phosphate

phosphofructokinase (PFK) the rate-limiting enzyme of glycolysis

physiology of exercise and sport the study of the processes and functions of living organisms and their component parts during and after physical activity

physiology the study of the processes and functions of living organisms and their component parts

planimetry the use of an engineering instrument to trace a curve and find the area under it

plasma cell a subclassification of B cell that secretes, into circulation, antibodies that are specific to a particular antigen

plyometrics a type of training involving the stretching of a muscle through an eccentric (lengthening) phase followed by a forceful concentric (shortening) muscle action

polypeptide several amino acids linked together

positive caloric balance state in which calories taken in exceed calories expended

power density spectrum (pds) spectrum that describes the amount of power that exists in the EMG at each given frequency

power lifting a competitive sport in which an athlete attempts to lift a maximal amount of weight in specific lifts (squat, dead lift, and bench press)

power work divided by time

prelatent iron deficiency the earliest stage of iron deficiency, characterized by a decrease or absence of storage iron

premotor cortex the portion of the brain that is rostral to the motor area and contains the nerve cell bodies of the extrapyramidal system

pressure gradient the difference in pressure between two points

principle a settled rule of action based on theories that are well supported by research findings

professional a person who has “professed” or declared a commitment to a learned discipline with a well-defined body of knowledge

progesterone a hormone secreted by the ovaries

progression a basic principle of resistance training, that in order to maintain overload and continue to see adaptation from a resistance training program, it is necessary periodically to increase the volume of training

prohormone refers to androstenedione and dehydroepiandrosterone, precursors to testosterone and estrogen; sometimes used as ergogenic aids

proprioception feedback of sensory information regarding movement and body position

proprioceptive neuromuscular facilitation (PNF) a technique used for maintaining or increasing flexibility or restoring range of motion following injury

protein hormone a hormone that is a chain of amino acids

puberty the period of life during which the ability to reproduce begins or the time of sexual maturation

pulmonary vein vessel that carries oxygenated blood from the lungs to the left heart

pulmonary ventilation gas exchange in the lungs in which the blood in the lung capillaries takes up oxygen and gives up much of its carbon dioxide; also known as external respiration

Purkinje fibers specialized conducting cells of the heart that conduct the cardiac impulse throughout the ventricular myocardium

pyramidal system the corticospinal pathways that originate in large nerve cells that are shaped like pyramids and have axons that synapse with the motor neurons in the ventral horn of the spinal cord

pyramidal tracts descending motor pathways that originate in cell bodies of the motor cortex and synapse with motor neurons in the ventral horn of the spinal cord

pyruvate a metabolite of carbohydrate metabolism; sometimes used as an ergogenic aid

qualitative electromyography electromyography concerned with the wave form of the muscle action potential from single discrete motor units

quantitative electromyography electromyography concerned with the amount of electrical activity that is present in a given muscle under varying conditions

radiation the transfer of heat between objects that are not in contact with one another, by means of electromagnetic waves

rate coding the process of changing the firing frequency of motor units to produce varying amounts of tension in a muscle

rating of perceived exertion (RPE) a 15-point scale used to quantify an individual’s subjective opinion of exercise intensity

reactant a substance acted on by an enzyme to create a product; also known as substrate

reciprocal inhibition the neuromuscular function that serves to turn off one of a pair of muscles when its opponent is activated

recommended daily caloric intake the quantity of daily calories suggested for the maintenance of good nutrition for healthy persons in the United States

recruitment the calling into play of additional numbers, as in the additional motor units called into play in order to increase the tension production in a muscle

reflex an involuntary motor response to a sensory stimulus

relaxation period the lengthening period that follows the contraction phase of a muscle twitch

repetition (REP) training a type of training similar to interval training, but involving greater intensity, work bouts lasting approximately 30 to 90 seconds, and a work to recovery ratio of 15

repetition maximum (RM) load the maximum amount of weight that can be lifted for a specific number of repetitions

reserve of heart rate the ability of the heart rate to increase from the resting rate to the maximum rate

residual volume the volume of gas remaining in the lungs after a maximal respiration

resistance vessels muscular vessels, such as the small arteries and arterioles, which dilate or constrict to control the resistance to blood flow

resistance the sum of the forces that oppose blood flow, including blood viscosity, the length of the vessel, and the diameter of the vessel

respiratory center the nerve cells in the pons and medulla that are responsible for the automatic and rhythmic control of respiration

resting heart rate the heart rate measured when the body is at rest

righting reflex a series of reflex movements that cause a person or animal placed upside down to change to an upright position

runner’s wall fatigue experienced by long-distance runners at approximately 18 to 20 miles, probably caused by glycogen depletion in the quadriceps

sarcolemma the cell membrane of a muscle fiber

sarcomere the functional unit of the myofibril

sarcoplasm the cytoplasm of a muscle fiber

sarcoplasmic reticulum a network of tubules and sacs in skeletal muscle fibers that plays an important role in muscle contraction and relaxation by releasing and storing calcium ions; analogous to endoplasmic reticulum of other cells

second wind the psychological and physical relief felt by an endurance athlete upon making the necessary metabolic adjustments to a heavy exercise intensity

sensory neuron a neuron that conducts impulses from the periphery to the central nervous system; also known as afferent neuron

Setchenov phenomenon the fact that more work can be produced after a pause with diverting activity than after a passive rest pause

shortening period the phase of muscle twitch in which the muscle shortens (also called contraction phase)

simple carbohydrate one or two sugar molecules joined together

sinoatrial (SA) node a specialized mass of cardiac tissue in the wall of the right atrium; initiates the cardiac cycle; also known as the pacemaker of the heart

size principle the fact that the small motor neurons innervating slow twitch, oxidative fibers have the lowest threshold for activation and are therefore activated first during the recruitment of motor units for muscular contraction

skeletal muscle contractile tissue attached to the skeleton

sliding filament model the proposition that explains how protein filaments within the sarcomere move to cause muscle fiber contraction

slow-twitch oxidative (SO) fatigue-resistant muscle fibers that favor oxidative (aerobic) methods of energy production; also known as type I fibers

smooth muscle contractile tissue found in the walls of the hollow viscera and blood vessels

sodium bicarbonate a naturally occurring buffer in the blood; sometimes used as an ergogenic aid by athletes in an attempt to reduce lactic acid build-up during exercise

sodium phosphate a granular crystalline salt sometimes used as an ergogenic aid

somatic nervous system the branch of the nervous system that regulates voluntary functions

specificity of speed the fact that speed is not an overall characteristic of the individual but is specific to the limb and joint and direction of movement

specificity a basic principle of resistance training that suggests that the adaptations that occur as a result of a resistance training program will be specific to the characteristics of the program

speed the result of applying force to a mass; implies constant movement

sphygmomanometer a pressure cuff and mercury or anoid manometer used to measure blood pressure

spinal reflex a two-neuron reflex in which a sensory neuron receives a stimulus and carries an impulse to the spinal cord, and the impulse is transmitted to another neuron, which carries the impulse to a muscle or gland

sports anemia a decrease in blood hemoglobin levels that occurs in response to heavy endurance training in the absence of any recognizable disease process

spot reducing exercising a specific area of the body to decrease fat stores at that location; this is ineffective

sprint-assisted training a method of training that uses such techniques as assisted towing, downhill running, and high-speed treadmill running to improve sprint running performance

sprint-resisted training a method of training that uses resistive exercises to improve sprint running performance

start the first phase of a sprinting event

state anxiety the degree of a general feeling of impending danger or dread

static exercise exercise that involves holding a position, such as isometric contractions

static flexibility a measurement of the range of motion of a joint

static stretching a method of muscle elongation (stretching) involving low-force, long-duration (10 to 60 seconds) movements

steroid hormone a hormone that is derived from cholesterol and therefore exhibits a classic four-ring structure

stitch in the side pain in the lower, lateral thoracic wall that occurs during exercise; may be caused by ischemia of the diaphragm or intercostal muscles

strength training the use of resistance methods to increase one’s ability to exert or resist force; may include use of free weights, the individual’s own body weight, machines, and/or other resistance devices to attain this goal

stretch reflex the contraction of a muscle in response to being stretched

stroke volume (SV) the amount of blood ejected out of each ventricle of the heart with each cardiac contraction

stroke volume reserve the ability of the heart to increase its contraction strength, its filling pressure, and the distensibility of its ventricles

stroke an abnormal condition of the brain characterized by an embolus, thrombus, or hemorrhage, resulting in ischemia of the brain tissue

substrate a substance acted on by an enzyme to create a product; also known as reactant

summation of twitches the increase in tension produced in a muscle as a result of stimulation before the muscle is allowed to relax

suppressor T cell a type of T cell that regulates the action of killer T cells and the development of B cells into plasma cells

sympathetic branch the division of the autonomic nervous system that originates in the thoracic and lumbar regions of the spinal cord and is activated in emergency or stressful situations

synapse the junction between two neurons or between a neuron and an effector organ

syncytium a network of cells

systole the contraction phase of the cardiac cycle

systolic pressure the arterial blood pressure during systole

T cell a class of lymphocyte that upon presentation of an antigen by a macrophage, enlarges and divides into four subclassifications (killer T cells, helper T cells, suppressor T cells, and memory T cells)

Tanner scale a commonly used technique that uses a 1 to 5 scale in assessing puberty, based on the level of development of secondary sex traits

target heart rate the desired exercise heart rate for an exercise bout; usually obtained by multiplying the maximum heart rate reserve by a percentage within the range of 40 to 85 percent

task-dependency model a model that suggests the cause of neuromuscular fatigue is dependent upon the characteristics of the exercise task that is being performed

temperature regulatory center the area of the hypothalamus that controls body temperature; receives sensory input regarding environmental and core temperatures and then activates and/or inhibits the body’s heat production and conservation or heat loss mechanisms

tempo-pace training training consisting of continuous work bouts of approximately 20 minutes duration

testosterone a hormone secreted by the testes

tetanus a sustained muscular contraction caused by a series of stimuli so frequent that the individual muscular responses are fused

theory a position based on scientific evidence but insufficiently verified to be accepted as fact

thoracic wall compliance the relationship between force required (elastic force) per unit strength of the thorax

thromboembolic stroke an abnormal condition of the brain that occurs when a blood clot forms or an embolus breaks loose from somewhere in the body and blocks an artery in the brain, causing ischemia of the brain tissue

thrombus a blood clot

tidal volume the volume of gas inspired or expired during each respiratory cycle

time domain the domain of the EMG signal that involves determining the amplitude (voltage) of electrical current that exists during a specific period of time

tissue respiration gas exchange between the blood and cells; also known as internal respiration

torque rotary force production

total lung capacity the amount of gas in the lung after a maximal inspiration; includes the tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume

trachea the cartilaginous and membranous tube in the neck that extends from the larynx to the fifth thoracic vertebra, where it divides into two bronchi; serves as a passageway for air

trait anxiety the degree of a feeling of impending danger or dread at the present time

transverse tubules extensions of the sarcolemma that allow the action potential to move from the outside to the inside of a muscle fiber

trenchfoot one of the most common nonfreezing cold injuries; typically develops after many hours (usually >12 hours) of exposure to cold, wet conditions when socks and shoes are worn continuously. Symptoms include swelling and numbness of the feet.

triglyceride a fat compound consisting of glycerol and three molecules of fatty acid

tropomyosin a type of contractile protein (myofilament) that changes shape upon calcium binding with troponin, allowing actin and myosin to bind

troponin a type of contractile protein (myofilament) that binds calcium ions

turbinate pertaining to the thin, bony plates within the nasal cavity

type 1 diabetes mellitus a metabolic disorder characterized by elevated blood glucose levels, caused by the destruction of the beta cells of the pancreas and therefore a deficiency in the hormone insulin

type 2 diabetes mellitus a metabolic disorder characterized by elevated blood glucose levels, caused by a decrease in insulin receptor number or sensitivity

unilateral imagined training training that involves thinking about, but not actually performing, a resistance exercise with only one limb

upper motor neuron a neuron whose cell body is in the brain

upper respiratory infection (URI) any infectious disease of the sinuses, tonsils, nose, pharynx, or larynx

vagus nerve tenth cranial nerve; arises from the medulla oblongata and supplies the larynx, lungs, heart, esophagus, stomach, and most of the abdominal viscera

vein a thin-walled vessel that carries blood toward the heart

ventilation equivalent the number of liters of air breathed for every 100 ml of oxygen consumed

ventilatory threshold the measurement of the anaerobic threshold by expired gas samples

ventricle a chamber of the heart that pumps blood into arteries

venule a small vessel that lies between a capillary and a vein

very-low-density lipoprotein a plasma protein that is primarily composed of triglycerides with small amounts of cholesterol, phospholipid, and protein

vestibular receptor the portion of the inner ear that functions to provide a sense of equilibrium

viscosity the stickiness and thickness of a fluid

vital capacity the maximal amount of gas that can be expired with a forceful effort following a maximal inspiration; includes the tidal volume, inspiratory reserve volume, and expiratory reserve volume

VO2 reserve the difference between VO2 max and resting VO2

volume of exercise the product of the frequency,intensity, and time of exercise (frequency x intensity x time), which reflects the total amount of physical activity performed

warming up activities that increase general body temperature and the temperature of muscles involved in a physical activity, prior to the activity

weight lifting a competitive sport in which an athlete attempts to lift a maximal amount of weight in specific lifts (clean and jerk and snatch)

wind chill factor the effect of wind in reducing effective temperature

Z-line the membrane that separates sarcomeres