Fitness Glossary

As Many Reps As Possible

A workout protocol where you perform an exercise for as many repetitions as you can within a specified timeframe or until failure.

Anabolic processes build tissue such as muscle, while catabolic processes break tissue down for energy. Training and nutrition shift the balance between the two.

Adenosine Triphosphate

The primary molecule that stores and transfers energy within cells, fueling intense muscle contractions.

The cellular process of breaking down and recycling damaged components. Research suggests it can be upregulated by fasting and exercise as part of normal cellular maintenance.

Branched-Chain Amino Acids

Essential amino acids (leucine, isoleucine, and valine) involved in muscle protein synthesis. Largely redundant as a standalone supplement if you already eat enough total protein, since complete protein sources already supply them.

The proportion of a nutrient or supplement that is actually absorbed and available for the body to use, rather than passed through unused.

Basal Metabolic Rate

The number of calories your body burns at rest just to keep basic life functions (breathing, circulation) running.

BMD

A measure of the amount of minerals, mainly calcium, packed into bone. It is used as an indicator of bone strength, often assessed with a DEXA scan.

Plant extracts or herb-derived ingredients used therapeutically to promote health, reduce inflammation, or boost performance.

A form of strength training that uses the resistance of your own body weight rather than external weights.

Consuming fewer calories than you burn. A sustained deficit is the fundamental requirement for fat loss.

Consuming more calories than you burn. A modest surplus supports muscle gain when paired with resistance training.

The most abundant structural protein in the body, vital for maintaining skin elasticity, joint health, and connective tissue integrity.

A protein source that supplies all nine essential amino acids in adequate amounts, such as meat, eggs, dairy, and soy.

An exercise that works multiple joints and muscle groups at once, such as squats, deadlifts, and bench press. Efficient for building overall strength and mass.

The shortening phase of a muscle contraction, such as pressing the bar up in a bench press.

A hormone released in response to stress and exercise. Normal in acute amounts; chronically elevated levels are associated with poorer recovery and sleep.

An organic acid naturally occurring in the body that helps supply energy to muscle and nerve cells, widely used to boost athletic performance and cognitive health.

A planned reduction in training volume or intensity (typically for a week) to allow recovery and reduce accumulated fatigue before pushing again.

The indigestible part of plant foods that adds bulk, supports digestion and satiety, and helps steady the rise in blood sugar after meals.

Delayed Onset Muscle Soreness

The muscle pain and stiffness that typically begins 12 to 24 hours after a new or intense workout.

Performing a set to near failure, then immediately reducing the weight and continuing for more reps to extend a set past normal fatigue.

The lengthening phase of a muscle contraction, such as lowering the bar in a bench press. Eccentric loading is strongly associated with muscle damage and growth.

Minerals such as sodium, potassium, and magnesium that carry an electrical charge and support hydration, nerve signaling, and muscle contraction. Lost through sweat.

Every Minute On the Minute

A type of interval workout where you perform a specific task at the start of every minute for a set amount of time.

Excess Post-exercise Oxygen Consumption

The elevated calorie burn that continues after intense exercise as the body returns to baseline. Often called the "afterburn" effect.

EAAs

The nine amino acids the body cannot produce on its own and must obtain from food. They are required for building and repairing muscle.

GI

A ranking of how quickly a carbohydrate-containing food raises blood sugar. Higher-GI foods digest faster; lower-GI foods provide steadier energy.

The stored form of carbohydrate in muscle and liver. It is a primary fuel for higher-intensity exercise; depleting it is associated with reduced performance and "hitting the wall."

The community of trillions of microbes living in the digestive tract. Research suggests it plays a role in digestion, immune function, and overall health.

High-Intensity Interval Training

A cardiovascular exercise strategy alternating short periods of intense anaerobic exercise with less intense recovery periods.

Beta-hydroxy beta-methylbutyrate

A substance produced when the body breaks down leucine. It is used to prevent muscle breakdown and increase muscle mass.

A mild, acute biological stressor (like cold plunging or saunas) that triggers beneficial adaptive responses and improves overall resilience.

Heart Rate Variability

The measure of the variation in time between each heartbeat. A key indicator of nervous system readiness and physical recovery.

The increase and growth of muscle cells. Hypertrophy training focuses on building muscle size rather than pure strength.

A condition that occurs when the level of sodium in your blood is abnormally low, often caused by over-hydrating with plain water and flushing out electrolytes.

If It Fits Your Macros

A flexible dieting approach where you can eat whatever you want, provided you stay within your daily macronutrient targets.

How responsive your cells are to insulin. Higher sensitivity helps the body manage blood sugar; regular exercise is associated with improving it.

An exercise that targets a single muscle through one joint, such as a bicep curl or leg extension. Useful for bringing up lagging areas.

A metabolic state in which the body relies heavily on fat for fuel and produces ketones, typically brought on by very low carbohydrate intake.

The exercise intensity at which lactate begins to accumulate in the blood faster than it can be cleared, often experienced as a sharp rise in effort.

The amino acid most responsible for triggering muscle protein synthesis. Whey, eggs, and dairy are particularly rich sources.

Low-Intensity Steady State

A form of cardiovascular exercise where you maintain a consistent, low-to-moderate heart rate for an extended period of time.

Macronutrients

The three primary components of food that provide energy: Proteins, Carbohydrates, and Fats.

The number of calories that keeps your body weight stable. It sits between a deficit and a surplus and roughly equals your TDEE.

A training block of several weeks (often 3–6) focused on a specific goal, sitting between the weekly microcycle and the season-long macrocycle.

The tendency for the body to reduce energy expenditure during prolonged dieting, sometimes called adaptive thermogenesis, which can slow fat loss over time.

Vitamins and minerals the body needs in small amounts to function, as distinct from the macronutrients (protein, carbs, and fat) needed in larger quantities.

Consciously focusing on contracting the target muscle during a lift. Research suggests it can increase activation of that muscle, especially on isolation work.

The energy-producing structures inside cells that generate ATP. Aerobic training is associated with increasing their number and efficiency.

The active range of motion of a joint. It is how far you can move a joint using only your own muscular strength and neurological control.

mechanistic Target of Rapamycin

A cellular signaling pathway that helps regulate protein synthesis and cell growth. It is activated by resistance training, protein intake, and leucine.

Broadly, slow-twitch (Type I) fibers suited to endurance and fatigue resistance, and fast-twitch (Type II) fibers suited to power and maximal strength.

MPS

The process by which the body builds new muscle protein. Resistance training and adequate protein intake both elevate MPS, driving net muscle gain over time.

Non-Exercise Activity Thermogenesis

The calories burned from all the movement you do that is not sleeping, eating, or intentional exercise (e.g., walking, fidgeting).

The difference between the nitrogen you take in from protein and the nitrogen you excrete. A positive balance generally reflects net muscle-building conditions.

The absolute maximum amount of weight you can lift for a single, clean repetition of a given exercise.

Lower-than-normal bone mineral density that has not reached the threshold defined as osteoporosis. Resistance training and adequate calcium and vitamin D are commonly recommended for bone health.

A state of prolonged fatigue and declining performance that results from training beyond what the body can recover from. Adequate rest and deloads help prevent it.

Short chains of amino acids that act as building blocks for proteins like collagen and elastin, often used to promote skin health, muscle growth, or recovery.

The systematic planning of training in cycles that vary volume and intensity over time. It is used to keep progressing while managing fatigue and reducing plateaus.

Personal Record

Your best-ever performance on a lift or event — for example the most weight lifted for a given rep count, or a fastest time.

The gradual increase of stress placed upon the body during exercise training (e.g., adding weight, reps, or sets) to drive continuous improvement.

ROM

The full distance a joint can move through during an exercise. Training through a complete ROM is generally associated with better strength and muscle development.

A planned short-term increase in calories, usually from carbohydrates, during a diet to replenish glycogen and support long-term adherence.

A technique that extends a set by taking very short rests (roughly 10–20 seconds) between clusters of reps at a heavy load, allowing more total reps.

RHR

The number of times your heart beats per minute while fully at rest. A lower resting heart rate often reflects better cardiovascular fitness.

Gradually increasing calories after a period of dieting, aiming to limit fat regain while daily energy expenditure recovers.

Reps In Reserve

How many more reps you could have completed before failure. Training with 1–3 RIR is widely used to drive growth while managing fatigue.

Rate of Perceived Exertion

A 1–10 scale for how hard a set felt. An RPE of 8 means you had roughly 2 reps left in the tank — a common way to autoregulate training intensity day to day.

The age-related loss of muscle mass and strength. Resistance training and adequate protein are the most consistently recommended countermeasures.

Selective Androgen Receptor Modulators

A class of therapeutic compounds that have similar properties to anabolic steroids but with reduced androgenic properties. Often sold in the grey market.

The feeling of fullness and satisfaction after eating that reduces the drive to keep eating. Protein and fiber tend to be especially satiating.

The jiggly fat that lies directly beneath the skin. It is generally less harmful metabolically than visceral fat.

Performing two exercises back-to-back with little or no rest in between, used to save time or increase training density.

Total Daily Energy Expenditure

The total number of calories you burn in a given day, accounting for BMR, exercise, and daily movement.

Thermic Effect of Food

The amount of energy your body uses to digest, absorb, and metabolize the food you eat. Protein has the highest TEF.

The speed of each phase of a rep, often written as four digits (eccentric-pause-concentric-pause), e.g. 3-1-1-0. Slower tempos increase time under tension.

TUT

The total duration a muscle is under load during a set. Manipulating TUT (via tempo or pauses) is one variable used to drive hypertrophy.

How often you train a given muscle group or movement per week. Spreading weekly volume across more sessions is a common way to accumulate quality work.

How you divide your workouts across muscle groups or movements over a week, such as push/pull/legs, upper/lower, or a full-body split.

Continuing a set until you can no longer complete a repetition with good form. Effective for growth but costly in fatigue, so it is usually used selectively.

Exercises performed one limb at a time, such as single-leg squats or single-arm rows. Useful for exposing and correcting side-to-side imbalances.

A type of body fat that is stored within the abdominal cavity, wrapping around internal organs. High levels are linked to metabolic disease.

The maximum rate at which your body can use oxygen during intense exercise. It is a widely used marker of cardiorespiratory fitness.

The total amount of work performed in a training session or over a week, typically calculated as Sets × Reps × Weight.

A lighter preparatory set performed before your working sets to prime the muscles and joints and rehearse the movement pattern.

A fast-digesting complete protein derived from milk. It is rich in leucine and a popular choice around workouts for supporting muscle protein synthesis.

A mathematical formula used to compare the absolute strength of lifters across different body weight categories and genders.

Aerobic exercise performed at 60-70% of your maximum heart rate. It is highly effective for building an aerobic base and cellular endurance.