Glossary of Relevant Terms - cont...

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On MuscleTalk there are a number of complex words, scientific terms and jargon and acronyms used in reference to bodybuilding, health and fitness. This section will help you define and understand the main ones. It is by no means finite and more will be added. If you have any words / terms you'd like explaining then please suggest them...

For information about technical terms relating to muscle and bone, see here.

Incomplete Proteins: Proteins that lack or are low in one or more essential amino acid.

Insulin: A hormone secreted by the pancreas and aids the body in maintaining proper blood sugar levels and promoting glycogen storage. Insulin secretion speeds the movement of nutrients through the bloodstream and into muscle for growth. It is also involved in amino acid uptake by muscle cells.

Insulin Index (II): Measures the speed of the rise in blood insulin levels in response to foods. II should be used alongside the GI to give a fuller picture of the glycaemic response. as sometimes they do not correspond.

Interval Training: See HIIT

In vitro: Refers to experiments done in the laboratory.

In vivo: Refers to experiments and what actually happens in the body as opposed to in the laboratory.

Ion-Exchange Filtration: A complex, thorough process of filtration used to obtain only the highest quality product. This is used in quality whey protein products.

Isolation: A technique that focuses work on an individual muscle without secondary or assisting muscle groups being involved, which provides maximal muscle shape. A good example is the seated dumbbell concentration curl.

Isotonic: A fluid where the osmotic pressure is equal to that of what it is being compared to, in this case, normal body fluids.

Ketones / Ketone Bodies: Intermediate products in fat metabolism. They are used as an energy source for critical organs and muscles during periods of fasting or very-low carbohydrate intakes.

Kilocalorie (kcal): The most commonly used unit of energy, more commonly just referred to as 'calories'. 1 kcal = 1,000 calories = 4.184kJ.

Kilojoule (kJ): The metric unit of energy (see Kilocalorie for conversion).

Krebs Cycle: The series of reactions catalysed by enzymes whereby pyruvate (formed from prior pathways) and other substrates are oxidised to CO2 and water generating ATP.

Lactate / Lactic Acid: Produced from glucose during anaerobic metabolism. When oxygen becomes available, lactic acid can be completely broken down to carbon dioxide and water. Lactic-acid build-up is a primary cause of muscle fatigue.

Lean Body Mass (LBM): See fat-free mass

Limiting Factor: A factor that prevents a process or reaction from taking place. For example, a lack of protein in the diet can be a limiting factor for muscle growth.

Linoleic Acid: An omega 6 polyunsaturated essential fatty acid. Good sources see Edible Fats & Oils

Linolenic Acid: An omega 6 polyunsaturated essential fatty acid. Good sources see Edible Fats & Oils

Lipid: Another term for fat related substances, including triglycerides, steroids, cholesterol.

Lipogenic: Making body fat.

Lipolysis: Refers to the breakdown of body fat by enzymes. This results in stored fat being used as fuel by the body.

Lipolytic: Describe something with fat-burning effects.

Low-Density Lipoprotein (LDL): A sub-category of cholesterol, typically thought of as bad cholesterol. Too high LDL levels have bee associated with heart disease.

Luteinizing Hormone (LH): A hormone that stimulates the testes to make testosterone in males, and in females induces ovulation.

Macromineral: A minerals required by the body in relatively large or gram quantities, e.g. calcium, phosphorus.

Macronutrient: A nutrients that we ingest in large quantities, including protein, carbohydrate, fat, and water.

Malabsorption: Inadequate absorption of nutrients from the digestive tract, resulting in deficiencies.

Mass: Refers to the results of training hard and eating correctly in order to add muscle bulk to a frame.

Meal Replacement Powder (MRP): A category of supplement which contains protein, carbohydrates, vitamins, minerals, and other key nutrients which are used to replace a regular-food meal for purposes of weight loss, weight gain, or increasing dietary nutrient intake. Meal replacement formulas are also referred to as total-nutrition products or engineered foods.

Metabolic Rate: Refers to the rate you convert energy stores into working energy in the body. It describes how fast your 'whole system' runs. Metabolic rate is controlled by numerous factors, including muscle mass, nutrient intake, exercise, age, disease state, use of drugs, and others.

Metabolism: Refers to the utilisation of nutrients and oxygen by the body. It's the process by which substances come into the body and the rate at which they are used.

Metabolites: Intermediates in metabolism.

Micronutrient: A nutrients which we ingest in relatively small amounts, including vitamins and minerals. Micronutrients are typically ingested in gram quantities or less.

Mineral: Naturally occurring, inorganic substance that is essential for human life and plays a role in many vital metabolic processes.

Mitochondria: Specialised structures within cells with specific capability to oxidise substances. They are the sites of most metabolic pathways, resulting in the production of ATP and energy.

Monosaccharide: The simplest form of carbohydrate, i.e. one sugar molecule. Examples are glucose and fructose.

Monounsaturated Fat (MUFA): A fatty acid which contains one open spot on the chain length. As a percentage of total fat intake these have been shown to be beneficial, and good sources see Edible Fats & Oils

Muscle Fatigue: The failure of a muscle to continue to perform work, caused by muscle ATP depletion.

Myosin: One of the contractile proteins of muscle fibres.