Whether you’re new to the gym or have been training for years, bodybuilding has its own vocabulary. This glossary explains the terms, abbreviations, and slang you’ll come across in training programs, supplement labels, and gym conversations — starting with the letters A and B. Browse alphabetically below, or jump straight to a specific term using the navigation links.
- Abdominal fat
- Fat deposited mainly on the abdominal area. A higher concentration of abdominal fat, sometimes called visceral fat, is associated with a greater risk of heart disease and metabolic conditions than fat stored elsewhere on the body. → Gender differences in fat distribution → Body fat calculator: 5 effective methods
- Abduction
- Movement of a limb away from the midline of the body, such as raising your arm straight out to the side, or lifting your leg sideways away from your body. The opposite of abduction is adduction. → The anatomy of the abductor muscles
- Abs
- A common slang term referring to the abdominal muscles, particularly the rectus abdominis — the muscle responsible for the visible “six-pack” appearance when body fat is low enough. → Rectus abdominis: functional anatomy guide
- Absolute strength
- The maximum weight a person can lift for a single repetition of a given exercise, regardless of their body weight. This differs from relative strength, which factors in bodyweight to compare strength between individuals of different sizes.
- Achilles tendon
- The tendon connecting the lower end of the calf muscle to the back of the heel. It is one of the strongest tendons in the body, but is also vulnerable to overuse injuries during heavy calf training, sprinting, or jumping movements.
- Active rest
- A recovery approach for a sports injury or after intense training in which light exercises are performed instead of complete inactivity, maintaining flexibility and blood flow without placing further strain on the affected area. → Deloading in weight training: is it necessary?
- Adduction
- Movement of a limb toward the midline of the body — for example, lowering your arm back down to your side after raising it out, or bringing your leg back in toward your body’s centre line. The opposite of abduction. → The anatomy of the adductor muscles for athletes
- Adenosine triphosphate (ATP)
- The molecular “currency” that provides energy in cells for everything from protein synthesis to muscle contraction. ATP is stored in limited amounts in muscle tissue and must be continuously regenerated through the body’s energy systems during exercise. → Understanding energy systems: aerobic vs. anaerobic
- Adipose tissue
- The body’s fat storage tissue, made up mostly of fat cells (adipocytes). Adipose tissue serves as the body’s main energy reserve and also provides insulation and cushioning for organs.
- Adrenal glands
- Two small endocrine glands located on top of each kidney that secrete cortisol, adrenaline, and other hormones involved in the body’s stress response, metabolism, and energy regulation during intense training.
- Advanced weightlifter
- A person who has trained with weights steadily and systematically for at least one full year, and who has typically developed a solid base of strength, technique, and recovery capacity beyond beginner and intermediate stages.
- Aerobic capacity
- Also known as VO2 max — the maximum rate at which the body can take in, transport, and use oxygen during intense exercise. It is widely used as a measure of cardiovascular fitness. → Test your aerobic capacity with the VO2 max calculator
- Aerobic exercise
- Prolonged, moderate-intensity exercise — usually performed continuously for at least 20 minutes — that the body can fuel using oxygen at a rate the cardiorespiratory system can keep up with. Common examples include walking, jogging, cycling, swimming, and rowing. → Aerobic vs. anaerobic: understanding energy systems
- Agonist muscle
- The muscle primarily responsible for producing a specific movement through concentric (shortening) muscle action. For example, during a biceps curl, the biceps brachii is the agonist muscle, while the triceps acts as the antagonist. → Biceps brachii: complete anatomy guide
- AMRAP (As Many Reps As Possible)
- A training protocol in which you perform as many repetitions of an exercise as possible within a set, or within a fixed time window, rather than stopping at a pre-determined rep count. Common in CrossFit-style programming and strength-testing protocols.
- Amenorrhea
- Absence of menstrual periods, often linked to very low body fat percentage or insufficient calorie intake relative to training demands. It is common in sports like gymnastics, bodybuilding, and track and field, but should not be dismissed as harmless — it can signal underlying hormonal imbalance and reduced bone density, and is worth discussing with a doctor. → Adjusting strength training around your menstrual cycle
- Amino acids
- Often called the “building blocks of life,” amino acids are biochemical compounds linked together by chemical bonds to form chains called polypeptides. Many polypeptide chains linked together in turn form a protein molecule — the basic material your body uses to build and repair muscle tissue. → Amino acid supplements for bodybuilding
- Anabolic
- A metabolic process in which smaller molecular units are assembled into larger ones. For example, the combining of individual amino acids into new protein strands — the foundation of muscle growth — is a form of anabolism.
- Anabolic steroid
- A class of synthetic drugs that mimic the effects of testosterone, encouraging the synthesis of new tissue — especially muscle — from nutrients. Anabolic steroid use carries significant legal and health risks and is banned in competitive bodybuilding and most other sports. → The complete guide to anabolic steroids in bodybuilding
- Anaerobic exercise
- Exercise that is higher in intensity than aerobic work, using up oxygen faster than the body can replenish it in working muscles. Anaerobic exercise draws on stored ATP, phosphocreatine, and glycogen for fuel. Weightlifting and sprinting are the most common anaerobic activities. → Aerobic vs. anaerobic: understanding energy systems
- Anatomy
- 1. The physical structure of the body. 2. The branch of science that studies the structure of the bodies of humans and animals — a key area of knowledge for understanding which muscles a given exercise actually targets.
- Androgen
- Any of a group of male sex hormones, including testosterone, that promote the development of male physical characteristics such as increased muscle mass and bone density.
- Ankle
- The joint connecting the foot to the leg, formed where the tibia and fibula meet the talus bone. Ankle mobility plays an important role in squat depth and overall lower-body lifting technique.
- Antagonist muscle
- The muscle responsible for actively opposing the concentric action of the agonist muscle during a movement. Although this seems counterintuitive, this opposing force is necessary for joint stability. For example, during a biceps curl, the triceps acts as the antagonist to the biceps. → Meet your arm muscles: triceps brachii
- Anterior
- An anatomical term referring to the front of the body, or to a structure located toward the front. For example, the “anterior deltoid” is the front portion of the shoulder muscle. The opposite term is posterior.
- Apple-shaped
- A descriptive term for a body type that carries fat deposits mostly around the abdominal area, as opposed to a “pear-shaped” body, which carries more fat around the hips and thighs.
- Arnold press
- A dumbbell shoulder press variation, named after Arnold Schwarzenegger, that begins with the palms facing the body and rotates outward as the weights are pressed overhead — targeting the front and side deltoids through a slightly longer range of motion than a standard shoulder press. → Arnold dumbbell press: complete guide
- Assistance exercise
- Typically a single-joint movement — such as the biceps curl, triceps extension, or deltoid lateral raise — that involves only one muscle group. Assistance exercises support and complement the larger compound lifts in a training program.
- Asymmetric training
- Also called unilateral training — any exercise that targets only one side of the body at a time. One-arm dumbbell curls, lateral raises, and triceps extensions are all examples. Asymmetric training can help correct muscle imbalances between left and right sides. → Unilateral training: pros & cons
- ATP
- Short for adenosine triphosphate — see the full entry under “Adenosine triphosphate (ATP)” above.
- Atrophy
- The wasting away of any part, organ, tissue, or cell — most relevantly for lifters, the loss of muscle fibre size and strength that occurs after a period of inactivity, illness, or injury.
- Back
- The group of muscles located on the dorsal (rear) side of the torso. The back-muscle complex includes the latissimus dorsi, spinal erectors, trapezius, rhomboids, and teres minor and major — together responsible for pulling movements and posture. → The anatomy of the back muscles
- Balanced diet
- A diet that supplies the right proportions of protein, carbohydrates, fats, vitamins, and minerals needed to support health, recovery, and training goals.
- Ballistic stretch
- A type of dynamic stretch involving bouncing movements that push a muscle beyond its normal range of motion. A ballistic stretch for the hamstrings might involve repeatedly bouncing down to touch your toes. Less commonly recommended today than controlled dynamic or static stretching.
- Bandage
- A long strip of fabric, often elasticated, wrapped around an injured part of the body for protection or support during recovery.
- Barbell
- One of the most basic and essential pieces of gym equipment, consisting of a long bar, collars, sleeves, and weight plates made of steel or iron. Barbells may be adjustable, allowing plates to be added or removed, or fixed with welded collars. They typically range from five to seven feet long and weigh between 25 and 45 pounds unloaded. → Dumbbells vs. barbells: what’s better for strength & size?
- Basal metabolic rate (BMR)
- The rate at which the body burns calories while awake but completely at rest, usually expressed in calories per day. BMR makes up the largest share of most people’s total daily energy expenditure and is a key starting point for setting calorie targets. → Calculate your BMR
- Basic exercises
- Also called compound exercises — movements that work more than one muscle group at the same time, forming the mainstay of a mass-building routine. Examples include the bench press, shoulder press, squat, deadlift, and bent-over row.
- BCAA (branched-chain amino acid)
- Short for branched-chain amino acid — see the full entry under “Branched chain amino acids” below. → BCAA supplements guide for bodybuilding
- Beginning weightlifter
- A person with less than six months of strength-training experience, typically still building fundamental technique and a base level of strength and coordination.
- Belt
- A wide leather or synthetic support, usually four to six inches wide, worn around the waist by lifters during heavy compound lifts. It increases intra-abdominal pressure to provide additional support to the spine and lower back. → Weight-lifting belt: should you use one?
- Bench
- A long, padded seat used for lying or sitting during exercises such as the bench press, dumbbell flye, or seated shoulder press. Benches may be flat, or adjustable to incline and decline positions.
- Bench press
- A compound pressing exercise performed lying on a bench, in which a barbell or pair of dumbbells is pushed up from chest height. It is one of the most common measures of upper-body strength and a staple chest-building movement. → Flat barbell bench press: complete guide
- Biceps
- The flexor muscle located on the front of the upper arm, made up of two “heads.” The biceps is responsible for bending the elbow and rotating the forearm, and acts as the agonist muscle during curling movements. → Biceps brachii: complete anatomy guide
- Bilateral
- Describing a movement performed using both limbs at the same time, such as a barbell squat or a standard barbell bench press. The opposite of unilateral, or asymmetric, training.
- Bioelectrical impedance analysis
- A method of estimating body fat percentage by sending a small, harmless electric current through the body and measuring resistance. Fat tissue conducts electricity differently than lean tissue, allowing an estimate of body composition. → Seven ways to measure your body fat percentage
- Biofeedback
- Any physiological or psychological signal given off by the body — such as fatigue, soreness, or motivation levels — that can inform training decisions. The most successful lifters tend to be those who learn to read these signals and adjust their training, eating, and recovery accordingly.
- Bis
- A gym slang term for the biceps muscles, as in “I’m training bis and tris today” (biceps and triceps).
- BMI (Body Mass Index)
- A measure of body fat based on height and weight, commonly used for general population health screening. BMI is a useful tool for the average person, but it should be interpreted with caution for athletes and bodybuilders with significant muscle mass, since it cannot distinguish muscle weight from fat weight. → BMI calculator
- BMR
- Short for basal metabolic rate — see the full entry under “Basal metabolic rate (BMR)” above.
- Bodybuilding
- A type of strength training combined with focused nutritional practices to deliberately shape the body’s musculature. Bodybuilding is also a competitive sport, with amateur and professional categories for both men and women, judged on muscularity, symmetry, and conditioning.
- Body fat percentage
- The proportion of your total body weight that comes from fat. For most bodybuilders, 8 to 10 percent is a typical off-season target for men, while 2 to 4 percent is closer to a competitive stage goal — figures for women are typically several percentage points higher. → Body fat calculator: 5 effective methods
- Bone density
- The amount of mineral content packed into a given volume of bone. Weight-bearing resistance training is one of the most effective ways to maintain and improve bone density, which becomes especially important with age.
- Box squat
- A squat variation performed by sitting back onto a box or bench set at a specific height, then standing back up. It is often used to teach proper squat depth, build explosive strength out of the bottom position, and reduce stress on the knees.
- Branched chain amino acids (BCAAs)
- The amino acids leucine, isoleucine, and valine, named for their branched molecular structure. They make up a large proportion of muscle tissue and are preferentially used by the body during intense exercise or calorie restriction. → Foods rich in BCAAs for muscle maintenance
- Bro split
- A popular training schedule that dedicates each workout to a single muscle group — for example, chest on Monday, back on Tuesday, legs on Wednesday — typically training each muscle group once per week.
- Bulking up
- Deliberately gaining body size and mass, ideally as muscle tissue, typically by eating in a calorie surplus combined with progressive resistance training. Historically this could mean gaining 30 to 40 pounds over a short period, though that aggressive approach has become less common as competitive bodybuilders now compete on a more frequent, year-round basis. → Bulking in bodybuilding: the complete guide
- Burn
- A slang term for the intense, painful sensation felt in a muscle that has been fatigued by high-repetition sets, usually associated with a buildup of metabolic byproducts in the working muscle.
- Bursae
- Small, flat sacs filled with fluid that cushion and reduce friction around joints, helping tendons and muscles glide smoothly over bone during movement.
- Bursitis
- Inflammation of a bursa, most commonly affecting the shoulder, elbow, or hip in lifters. It often results from repetitive overuse or poor technique and can cause pain and restricted range of motion during pressing or overhead movements.
- Buttocks
- The gluteal muscle group — the gluteus maximus, medius, and minimus — which extends and abducts the thigh at the hip joint and is a primary mover in squats, deadlifts, and hip thrust exercises. → Muscles of the gluteal region
