Glossary

abduction—To draw away from or deviate from the midline of the body; opposite of adduction; side movement away from the midline of the body; Example, a side leg raise moving the leg away from the body’s center.

abrasion—A scraping away of skin or mucous membrane as the result of an injury or by other mechanical means.

abs—Slang for rectus abdominus muscle.

Acceptable daily intake (ADI)—The amount of chemical that, if ingested daily over a lifetime, appears to be without appreciable effect.

acclimatization—The process of becoming accustomed (physiologically adapting) to an unfamiliar environment, for example, the body can adjust to a high altitude or a hot climate and increase its capacity to work in those conditions.

accommodative resistance—The application of a resistive force that controls the speed with which an individual is able to move, thereby allowing him to work at maximal resistance throughout the complete range of motion; this is very useful during rehabilitation, when injuries are present, and also in sports training for speed-strength; also referred to as isokinetic resistance; see also isokinetic resistance.

acesulfame K—Acesulfame K, or acesulfame potassium, is a low-calorie sweetener approved for use in the United States in 1988. It is an organic salt consisting of carbon, nitrogen, oxygen, hydrogen, sulphur and potassium atoms. It is 200 times sweeter than sucrose, has a synergistic sweetening effect with other sweeteners, has a stable shelf-life and is heat stable. It is excreted through the human digestive system unchanged, and is therefore non-caloric.

acetyl Co-A—Acetyl Co-enzyme A; a substance that is formed by an acetyl group attaching itself to coenzyme A (CoA); the acetyl group is formed either from pyruvate, the breakdown product of glycolysis (the breakdown of sugars), or beta-oxidation (the breakdown of fats), and is used to enter the Kreb’s cycle and generate energy in the form of ATP.

Achilles tendinitis—Inflammation of the Achilles tendon (tendon found at the back of the heel); rest and ice are the two recommended treatments for Achilles tendinitis.

acid-base balance—The mechanisms by which the pH of the body fluids are kept in a state of balance so that arterial blood is kept at a constant pH level of 7.35 to 7.45; The pH of blood is kept from becoming too acidic or alkaline through respiration, buffers, and work done by the kidney.

acromegaly—A chronic disorder developing in adult life characterized by increased massiveness of the bones, organs and other body parts and elongation and enlargement of the bones of the extremities and certain head bones, especially of the frontal bone and jaws, with enlargement of the nose and lips and thickening of the soft tissues of the face; caused by increased levels of growth hormone.

actin—One of the fibrous contractile proteins found in a myofibril.

active (dynamic) stretching—A technique in stretching muscle and tissue that requires muscle contraction through a range of motion; no outside force is involved.

active recovery—Performing light aerobic exercise, stretching exercises, or working other body parts to facilitate recovery after intense exercise to allow for more productive use of exercise time and to encourage blood flow to the muscles.

actomyosin—The protein complex involved in muscle contraction and relaxation which is composed of actin and myosin protein filaments.

acute—Having a rapid onset; sharp, severe; opposite of chronic.

adaptation—The ability of the body to adjust; Example, the body’s ability to adjust to hot or cold climates.

additives—Substances other than a foodstuff present in food as a result of production, processing, storage or packaging; Examples, preservatives, coloring, thickeners (gums), and binders.

additives (food additives)—Any natural or synthetic material, other than the basic raw ingredients, used in the production of a food item to enhance the final product. Any substance that may affect the characteristics of any food, including those used in the production, processing, treatment, packaging, transportation or storage of food.

adduction—To bring toward the midline of the body; opposite of abduction; Example, bringing the elbows together in front of the body like a chest press working the pectoralis muscle.

adenosine triphosphate (ATP)—A high-energy molecule from which the body derives its energy; produced aerobically and anaerobically, and stored in the body.

Adequate Intake (AI) —A value established through experimental or observational data that show a mean intake which appears to sustain a desired indicator or health when sufficient scientific evidence is not available to estimate an average requirement and no RDA exists. The AIs are part of the DRIs.

adherence—The degree to which an individual follows a given prescribed program; for example, the amount of activity engaged in during a specified time period compared to the amount of activity recommended for that time period.

adipose tissue—Fatty tissue; connective tissue made up of fat cells.

ADP—Adenosine di-phosphate, a high energy phosphate molecule involved in the production and storage of energy. The end product of the mono-phosphate reduction of ATP.

aerobic—With, or in the presence of, oxygen; Aerobic metabolism most efficiently produces the basic energy source, adenosine triphosphate (ATP). Walking, jogging, biking, an aerobic exercise class and any activity which maintains the heart rate in the THR zone for a minimum of 20 minutes is aerobic activity. Tennis and basketball are not considered aerobic activities.

aerobic exercise—Aerobic exercise refers sustained exercise that uses large muscle groups and places demands on the cardiovascular system.

aerobic exercise (training)—Exercise with the purpose of developing aerobic or cardiovascular conditioning; activities in which oxygen from the blood is required to fuel the energy-producing mechanisms of muscle fibers; Examples, running, cycling, rowing, cross-country skiing.

aerobic interval training—Training method characterized by intervals of high and low intensity of pre-determined duration; heart rate typically remains at 60-80% of MHR, with 2-15 minute intervals; used to develop the aerobic energy system.

aerobic threshold intervals—Used to develop ability to use oxygen while performing at a higher intensity; exercise is performed for a pre-determined time at anaerobic threshold, combined with a period of active recovery; This training can be modified in terms of intensity and duration of the exercise interval and the number of work intervals per workout.

afterburn—Calories used due to an increase in metabolic rate following exercise activities.

agonist (muscle)—Muscle that is directly involved in contraction; primarily responsible for movement; opposes the action of an antagonist (opposite) muscle. During a bicep curl, the bicep is the active muscle or agonist; compare antagonist.

allergen (food allergen)—A food allergen is the part of a food (a protein) that stimulates the immune system of food allergic individuals. A single food can contain multiple food allergens. Carbohydrates or fats are not allergens.

allergy (food allergy)—A food allergy is any adverse reaction to an otherwise harmless food or food component (a protein) that involves the body's immune system. To avoid confusion with other types of adverse reactions to foods, it is important to use the terms "food allergy" or "food hypersensitivity" only when the immune system is involved in causing the reaction.

all-or-none principle—The principle of muscle contraction that states that when a motor unit is activated, all of the muscle fibers in that given motor unit will maximally contract or not contract at all.

amenorrhea—The absence of menstruation; somewhat more common in women engaging in excessive exercise; thorough medical exam is required to determine the exact cause.

amino acids—Amino acids function as the building blocks of proteins. Chemically, amino acids are organic compounds containing an amino (NH2) group and a carboxyl (COOH) group. Amino acids are classified as essential, nonessential and conditionally essential. If body synthesis is inadequate to meet metabolic need, an amino acid is classified as essential and must be supplied as part of the diet. Essential amino acids include leucine, isoleucine, valine, tryptophan, phenylalanine, methionine, threonine, lysine, histidine and possibly arginine (conditionally essential). Nonessential amino acids can be synthesized by the body in adequate amounts, and include alanine, aspartic acid, asparagine, glutamic acid, glutamine, glycine, proline and serine. Conditionally essential amino acids become essential under certain clinical conditions.

AMP—Adenosine mono-phosphate, a phosphate molecule involved in the production of energy in the body. The end product of the mono-phosphate reduction of ADP or the di-phosphate reduction of ATP. Used to regenerate ATP levels.

anabolic androgenic steroids—A general class of hormones (or synthetic derivatives) of the male sex hormone testosterone which simulates testosterone’s tissue building and masculinizing properties.

anabolism—The metabolic processes which build up body tissue; Example, muscle-building; anabolism is the opposite of catabolism.

anaerobic—Outside the presence of oxygen; not requiring oxygen; Anaerobic activities produce higher levels of lactic acids and carbon dioxide than aerobic activities. Short duration activities, requiring bursts of energy, are usually anaerobic.

anaerobic exercise—Short-term, highly intense activities in which muscle fibers derive energy for contraction from stored internal energy sources without the use of oxygen from the blood; stored energy sources include ATP, CP, and glycogen; Examples, short burst, intense efforts, such as in sprinting or weightlifting.

anaerobic glycolysis—The metabolic pathway that uses glucose or stored glycogen for energy production without requiring oxygen; sometimes referred to as the lactic acid system or anaerobic glucose system, it produces lactic acid as a by-product.

anaerobic interval training—Training designed to teach the body to derive energy from the anaerobic system to improve muscular strength and speed and develop the athlete’s ability to remove lactate from the muscles; characterized by intervals of higher and lower intensity; Aerobic interval training typically exceeds 85% of MHR with 30 second to 4 minute intervals.

anaerobic threshold—The point during high intensity activity when the body can no longer meet its demand for oxygen and anaerobic metabolism predominates; also called lactate threshold.

anatomical planes—Three planes of the human body in the anatomical position: sagittal, frontal, and transverse.

anatomical position—Description of human body when body is erect, arms are down at sides, and palms are forward; used for describing positions on the body or directions of movement of the body.

anatomy—The study of the structure of an organism or its elements; Human anatomy refers to the study of the human body.

anemia—Anemia is a condition in which a deficiency in the size or number of erythrocytes (red blood cells) or the amount of hemoglobin they contain limits the exchange of oxygen and carbon dioxide between the blood and the tissue cells. Most anemias are caused by a lack of nutrients required for normal erythrocyte synthesis, principally iron, vitamin B-12, and folic acid. Others result from a variety of conditions, such as hemorrhage, genetic abnormalities, chronic disease states or drug toxicity.

anemic—Condition characterized by a reduction below normal of the number of red blood cells or hemoglobin in the blood, often displaying symptoms of fatigue.

angina—See angina pectoris.

angina pectoris—Pain in the chest due to insufficient blood supply and oxygen to the heart; can be characterized as a crushing pain or by a substantial "pressure" sensation within the chest, commonly radiating down the arm, up into the jaw, or to another site; Angina pectoris is caused by an obstructed coronary artery and insufficient oxygen to the heart muscle.

Anorexia Nervosa—An eating disorder characterized by refusal to maintain a minimally normal weight for height and age. The condition includes weight loss leading to maintenance of body weight 15 percent below normal; an intense fear of weight gain or becoming fat, despite the individual's underweight status; a disturbance in the self-awareness of one's own body weight or shape; and in females, the absence of at least three consecutive menstrual cycles that would otherwise be expected to occur.

Anorexia Nervosa—A psychological eating disorder characterized by refusal to maintain a minimally normal weight for height and age; This condition includes: weight loss leading to maintenance of body weight 15 percent below normal; an intense fear of weight gain or becoming fat despite the individual's underweight status; a disturbance in the self-awareness of one's own body weight or shape; and in females, the absence of at least three consecutive menstrual cycles that would otherwise be expected to occur. Metabolic abnormalities are commonly associated with this disorder and can sometimes be fatal.

antagonist—Muscle that works against or in opposition of an agonist muscle; while one muscle group flexes, another extends; During a biceps curl, the biceps is the agonist and the triceps is the antagonist; see also agonist.

anterior—Toward the front; frontal segment; Example: the quadriceps are anterior to the hamstring.

anthropometric measurements—Measurement and analysis of parts of the human body; Examples, skinfold, girth, and body weight.

antibiotics—Antibiotics are used in animal agriculture for two reasons. First, to improve the rate of growth and the feed efficiency of animals so they produce more meat or milk on less feed. The second reason is to prevent and treat diseases, just as in humans.

antibody—Protein produced by the immune system of humans and higher animals in response to the presence of a specific antigen.

antigen—A foreign substance (almost always a protein) that, when introduced into the body, stimulates an immune response.

antioxidant—Antioxidants protect key cell components by neutralizing the damaging effects of "free radicals," natural byproducts of cell metabolism. Free radicals form when oxygen is metabolized, or burned by the body. They travel through cells, disrupting the structure of other molecules, causing cellular damage. Such cell damage is believed to contribute to aging and various health problems. Antioxidants include vitamins A, C, E, and selenium. Other potential antioxidants include pycnogenol, nordihydroguairetic acid (NDGA), glutathione, superoxide dismutase, and others. Antioxidants are also referred to as free-radical "scavengers".

antisense—A piece of DNA that produces the mirror image, or antisense messenger RNA, that is exactly opposite in sequence to one that directs the cells to produce a specific protein. Since the antisense RNA binds tightly to its image, it prevents the protein from being made.

aorta—The main arterial vessel; arises from the left ventricle of the heart and carries blood to all parts of the body; The aorta is the largest artery in the body.

aponeurosis—A broad, flat tendinous sheet of connective tissue that extends from the fibrous wrapping of a muscle and connects that muscle to adjacent structures, usually the wrappings of another muscle.

arachidonic acid—An omega-6 essential fatty acid which is an important precursor to the formation of prostaglandins.

arrhythmia—Abnormal heart rhythm or beat.

arteries—Vessels that carry oxygenated blood away from the heart; the carotid artery is commonly used to monitor the heart rate.

arterioles—Smaller divisions of the arteries as they get farther away from the heart and lead to capillaries.

arteriosclerosis—The hardening, thickening or loss of elasticity of the wall of an artery; precedes cardiovascular disease such as stroke and coronary artery disease; Arteriosclerosis is sometimes referred to as "hardening of the arteries".

arthritis—Inflammation of one or more joints; a potentially painful disorder that limits comfortable range of motion; The exercise prescription for arthritis should include slow, controlled exercises that work the full range of motion; see also osteoarthritis and rheumatoid arthritis.

articulation—Place of union or junction between two or more bones; joint.

aspartame—Aspartame is a low-calorie sweetener used in a variety of foods and beverages and as a tabletop sweetener. It is about 200 times sweeter than sugar. Aspartame is made by joining two amino acids, aspartic acid and phenylalanine.

asthma—Asthma is a chronic medical condition, affecting approximately 10 million Americans (3 to 4 percent of the population). Asthma results when irritants (or trigger substances) cause swelling of the tissues in the air passage of the lungs, making it difficult to breathe. Typical symptoms of asthma include wheezing, shortness of breath and coughing.

asthma—An intermittent obstruction of the tubes that carry air to and from the lungs characterized by episodes of difficulty breathing; For some, asthma is brought on only by exercise. Symptoms of exercise-induced asthma are coughing and shortness of breath after only 8-12 minutes of exercise. Participants should consult a doctor and obtain an exercise prescription.

atherosclerosis—A condition that exists when too much cholesterol builds up in the blood and accumulates in the walls of the blood vessels, often referred to as ‘hardening of the arteries’.

atherosclerosis—The most common and serious form of arteriosclerosis; Fatty substances and other debris collect in the inner lining of the arteries, forming plaques that encroach upon the passageway and gradually obstruct the flow of blood. Atherosclerosis is associated with a high-fat diet.

athlete’s heart—An enlarged heart muscle found in endurance athletes; Athlete’s heart is the result of large, strong muscle fibers in the heart’s left ventricle, which are well conditioned by pushing out a great volume of blood.

atom—The smallest divisible unit of an element in nature in which that element still holds its natural properties as that element.

ATPase—Enzyme which acts to split the ATP molecule.

ATP—Adenosine triphosphate, a high energy phosphate molecule used to store and release energy for work within the body.

ATP—Adenosine triphosphate, a high-energy molecule from which the body derives its energy; see also adenosine triphosphate.

ATP-CP system—Energy system that utilizes ATP and creatine phosphate; see also adenosine triphosphate and creatine phosphate.

atrium—One of the two (left and right) upper chambers of the heart (Pl. atria); acts as a collection chamber for the heart prior to entering the ventricles to leave the heart .

atrophy—Decrease in the cross-sectional size of a muscle due to lack of use or disease; Example: the arm, after it has been in a cast for a period of time, is usually smaller than before it was broken.

Attention Deficit Hyperactivity Disorder (ADHD)—Commonly called "hyperactivity," Attention Deficit Hyperactivity Disorder is a clinical diagnosis based on specific criteria. These include excessive motor activity, impulsiveness, short attention span, low tolerance to frustration and onset before 7 years of age.

autogenic inhibition—Automatic relaxation reflex caused by excessive stimulation of Golgi tendon organs (GTOs).

avascular—Lacking in blood vessels or having a poor blood supply; not vascular; said of tissues such as cartilage and ligaments.

avulsion—The forcible separation or tearing of tissue from the body.

axis of rotation—The imaginary line or point about which an object, such as a body or a lever, rotates.