Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android


  • absorption The transfer of nutrients from the digestive system into the blood supply.

  • acceptable macronutrient distribution range (AMDR) The range of intake for a macronutrient that is associated with decreased risk of chronic disease while providing sufficient intake of essential nutrients.

  • acclimatization Physiological changes that occur in response to repeated exposure to an environmental condition such as heat or high altitude.

  • active dehydration Dehydration resulting from increasing exercise and heat exposure.

  • active transport The passage of a particle from an area of low concentration to an area of high concentration made possible through the use of ATP.

  • acute illness Sudden onset of a time-limited ailment.

  • adenosine triphosphate (ATP) The body’s usable energy source.

  • adequate intake The amount of intake believed to cover the needs of all healthy individuals in age- and gender-specific groups; used when insufficient evidence is available to establish an RDA.

  • adipocyte A fat cell.

  • adiponectin A hormone produced by fat cells; it increases insulin sensitivity and stimulates fat breakdown. Low levels may contribute to an increased risk for insulin resistance and diabetes.

  • adipose tissue Fatty tissue; connective tissue made of fat cells.

  • adipositas athletica A term describing athletes who try to gain body fat to increase insulation or increase body energy stores.

  • aerobic power The speed at which adenosine triphosphate (ATP) is generated; increased in endurance athletes due to metabolic adaptations.

  • aerobic respiration The 10-step metabolic process of breaking glucose down to intermediate pyruvate, which is converted to acetyl-CoA and enters the citric acid cycle. Occurs in the mitochondria and cytoplasm in the presence of oxygen; produces a net 36 ATP.

  • air displacement plethysmography (ADP) (brand name is BodPod) A device that uses the displacement of air to measure body volume and density; compare to hydrostatic weighing, which uses the displacement of water to estimate body composition.

  • alanine-glucose cycle The cycle of transporting pyruvate and nitrogen from the muscle tissues to the liver as the amino acid alanine. In the liver, the alanine unloads the nitrogen group to become pyruvate, which is converted to glucose through gluconeogenesis. This process moves the work of gluconeogenesis from the muscle to the liver.

  • aldosterone A hormone released by the adrenal gland that helps to maintain normal blood sodium levels by increasing the kidney’s reabsorption of sodium and decreasing the amount of sodium lost in sweat.

  • amenorrhea A female condition defined by at least 3 months without a menstrual period.

  • amino acids The basic building blocks of proteins. Each amino acid has an amino- or nitrogen-containing group and a unique R chain that determines its ability to be used in various processes. Also known as peptides.

  • amino acid pool The amino acids available in the body to be used for protein synthesis.

  • amylopectin A polysaccharide, highly branched chain of glucose molecules that is easily digested.

  • amylose A polysaccharide made of glucose molecules bound together in a linear chain that is mostly resistant to digestion.

  • anabolic steroids Synthetic drugs that mimic the effect ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.