Browse the journal
Follow journal articles connected to Alpekin knowledge topics.
Dynamic stretching is a stretching technique in which joints are moved repeatedly through a controlled range of motion using active muscular contractions, without holding a prolonged position at the end of the movement. The movements are …
An effector is a cell, tissue, or organ that produces a physiological response when it receives an appropriate signal. In the nervous system, effectors are the targets of motor, or efferent, pathways. Muscles and glands are …
Elastic recoil, in respiratory physiology, is the tendency of the lungs to return toward a smaller volume after they have been expanded during inspiration. As the lungs expand, mechanical energy is stored in lung tissues and …
Emulsification is the process of dispersing one liquid into another liquid with which it does not normally mix. In digestion, the term usually refers to the dispersion of dietary fat into small lipid droplets within the …
Endurance exercise is physical activity performed continuously or repeatedly over a relatively prolonged period, requiring the body to sustain muscular work over time. Activities such as distance running, cycling, swimming, and prolonged walking are common examples. …
Energy balance is the relationship between the energy a person obtains from food and beverages and the energy the body expends. When energy intake and expenditure are approximately equal over a given period, body energy stores …
Energy expenditure is the amount of energy the body uses to maintain physiological functions and perform physical activity. Total daily energy expenditure (TDEE) represents the energy expended over about 24 hours and is commonly described in …
Enterocytes are specialized absorptive epithelial cells that line the intestinal surface, particularly the villi of the small intestine. They make up the majority of cells in the small-intestinal epithelium and form a major interface between material …
Enteropeptidase is a digestive serine protease located mainly on the brush border of enterocytes in the duodenum and proximal jejunum. It is also historically called enterokinase. Its principal physiological function is to activate trypsinogen, the inactive …
The esophageal phase is the stage of swallowing in which a swallowed bolus is transported through the esophagus toward the stomach. It follows the pharyngeal phase, during which the bolus passes through the throat and enters …
The Estimated Average Requirement (EAR) is the average daily intake of a nutrient estimated to meet the requirement of 50 percent of healthy people in a particular life-stage and sex group. It is one of the …
Estrogen is a collective term for a group of steroid hormones that produce biological effects through estrogen receptors. The three major naturally occurring estrogens in humans are estradiol (E2), estrone (E1), and estriol (E3). Estradiol has …
Exercise is a form of physical activity that is planned, structured, repetitive, and performed with the purpose of improving or maintaining one or more components of physical fitness. Unlike incidental movement during everyday life, exercise involves …
Exercise prescription is the structured specification of an exercise program designed to achieve particular fitness, health, or functional goals. Rather than simply recommending that a person be more active, an exercise prescription defines how exercise is …
The external oblique is a paired skeletal muscle forming the most superficial of the three flat muscle layers of the anterolateral abdominal wall. It lies superficial to the internal oblique and transversus abdominis. The muscle originates …
The extracellular matrix, or ECM, is an organized network of proteins and polysaccharides located outside cells. Cells produce and assemble these molecules into structures that surround, support, and connect cells within tissues. The amount and composition …
FAD and FADH₂ are the oxidized and fully reduced forms of flavin adenine dinucleotide, a redox cofactor used by many enzymes. FAD contains a flavin group derived from riboflavin, or vitamin B2, linked to an adenine …
The FITT principle is a framework used to describe and organize the main components of an exercise prescription. FITT stands for frequency, intensity, time, and type. Together, these variables describe how often exercise is performed, how …
Fast glycolytic fibers are skeletal muscle fibers characterized by fast contractile properties and relatively high glycolytic capacity. In traditional physiological classifications, the term describes fast-twitch fibers with comparatively low oxidative capacity and rapid fatigue. In adult …
Fasting is the voluntary abstinence from some or all food, or from food and beverages, for a defined period. The term covers a range of practices that differ in duration and in whether water or limited …
Fat malabsorption is impaired absorption of dietary fat from the gastrointestinal tract. Normal fat absorption depends on several coordinated steps, including digestion of triglycerides, the action of bile acids, uptake of lipid digestion products by intestinal …
Fat oxidation is the metabolic process by which fatty acids are broken down and their chemical energy is used to support cellular energy production. In humans, a major pathway involved is mitochondrial fatty acid beta-oxidation. Fatty …
Fat-free mass (FFM) is the component of body mass that remains after fat mass is excluded. In the commonly used two-component model of body composition, total body mass is divided into fat mass and fat-free mass. …
Fatty acids are a class of organic molecules consisting of a hydrocarbon chain with a carboxyl group at one end. Naturally occurring fatty acids commonly have unbranched chains containing an even number of carbon atoms. Because …
Flexibility is a component of physical fitness traditionally related to the range of motion available at a joint or group of joints. It depends particularly on the properties of muscles and other soft tissues surrounding the …
Folic acid is the fully oxidized form of folate commonly used in fortified foods and dietary supplements. Folate, also known as vitamin B9, is a water-soluble vitamin that includes folic acid as well as naturally occurring …
A food allergy is an adverse health effect caused by a specific immune response that occurs reproducibly after exposure to a particular food. The substances that trigger these reactions are called food allergens and are usually …
Foodborne illness, also called foodborne disease, is illness caused by consuming food or drink contaminated with a harmful biological or chemical agent. Causes include bacteria, viruses, parasites, toxins, and other chemical substances. Although foodborne illness is …
Foodborne pathogens are disease-causing biological agents that can be transmitted to humans through contaminated food or beverages. They include pathogenic bacteria, viruses, and parasites. Examples include Salmonella, Campylobacter, Listeria monocytogenes, norovirus, hepatitis A virus, and foodborne …
Fortified foods are foods to which one or more nutrients have been deliberately added to increase their nutrient content. Fortification most commonly involves micronutrients such as vitamins and minerals, including iron, iodine, folic acid, vitamin A, …
Free radicals are atoms, molecules, or other molecular entities that contain at least one unpaired electron. Electrons commonly occupy orbitals in pairs, so an unpaired electron gives a radical distinctive chemical properties. The term “radical” is …
Frostbite is a localized cold injury in which body tissue freezes. It occurs when tissue temperature falls sufficiently for ice to form within the tissue, most often affecting exposed or poorly insulated areas such as the …
Fructose is a six-carbon monosaccharide, or simple sugar, with the molecular formula C6H12O6. It is a ketohexose, meaning that its open-chain form contains a ketone group. Fructose occurs naturally as a free sugar and is also …
Gastric distension is the expansion of the stomach as its volume increases, most commonly when food or liquid enters during a meal. As the stomach fills, its wall stretches and wall tension changes. These mechanical changes …
Gastric emptying is the process by which the stomach transfers its contents into the duodenum, the first part of the small intestine. The gastric emptying rate describes how quickly this transfer occurs. The stomach does not …
Gastrointestinal tolerance refers to how well a person can consume a food, ingredient, or nutrient without experiencing troublesome digestive symptoms. In nutrition research, it is commonly assessed using reported symptoms such as bloating, flatulence, abdominal pain …
Glucagon is a 29-amino-acid peptide hormone produced and secreted mainly by alpha cells in the pancreatic islets. It is an important regulator of blood glucose, particularly when glucose availability is low. Low blood glucose is an …
Gluconeogenesis is the metabolic pathway that produces glucose from noncarbohydrate precursors. It is particularly important when glucose is not being supplied continuously from food, such as during fasting. In humans, gluconeogenesis occurs mainly in the liver …
Glucose is a six-carbon monosaccharide, or simple sugar, with the molecular formula C6H12O6. It is an aldohexose, and the naturally predominant form is D-glucose. Glucose circulates in the bloodstream and can be obtained from the digestion …
The gluteal muscles commonly refer to three major muscles in the buttock region: the gluteus maximus, gluteus medius, and gluteus minimus. They extend from the pelvis to structures on the femur or the iliotibial tract and …
Gluten is a complex mixture of storage proteins found in wheat grain. Its two major protein groups are gliadins and glutenins, each of which contains many related proteins. These proteins are particularly rich in the amino …
The glycemic index (GI) is a measure that ranks carbohydrate-containing foods according to the blood glucose response produced by a fixed amount of their available carbohydrate. It is determined by comparing the blood glucose response to …
Glycemic load (GL) is a measure that combines the glycemic index of a carbohydrate-containing food with the amount of available carbohydrate in the portion consumed. It is intended to represent the potential glycemic impact of that …
Glycogen is a highly branched polysaccharide composed of glucose and is the principal storage form of glucose in animals. Its glucose units are joined mainly by α(1→4) glycosidic bonds, with α(1→6) bonds creating branch points. This …
Glycogen resynthesis is the rebuilding of glycogen stores after they have been depleted or reduced. Glycogen is a branched polymer of glucose stored mainly in skeletal muscle and the liver. In exercise physiology, glycogen resynthesis usually …
Glycogenolysis is the metabolic process by which glycogen, the stored polymer of glucose, is broken down to make its glucose units available for metabolism. It occurs mainly in the cytosol and is especially important in the …
Glycolysis is a metabolic pathway that converts glucose, a six-carbon sugar, into two molecules of pyruvate, each containing three carbons. It takes place in the cytosol and consists of ten enzyme-catalyzed reactions. Glycolysis captures some of …
A Golgi tendon organ, or GTO, is a sensory receptor associated with skeletal muscle that detects mechanical force or tension produced through the muscle-tendon system. Golgi tendon organs are located mainly at myotendinous and myoaponeurotic junctions, …
