This section of the bodybuilding glossary covers M and N and brings together several terms that were already in use in earlier entries but were never properly defined on their own — including muscle failure and muscle imbalance. You’ll also find periodization concepts such as the macrocycle and mesocycle, nutrition fundamentals such as macronutrients and nutrient timing, and training concepts such as the mind-muscle connection and motor units. Browse the full list below, or use the navigation links to jump straight to a specific term.
- Macrocycle
- A phase of training periodization typically spanning six months to a year, though it can extend up to four years for Olympic-level athletes working toward a specific competitive peak. The macrocycle is usually broken down into smaller mesocycles and microcycles.
- Macronutrients
- The three primary nutrient categories the body needs in large amounts: protein, carbohydrates, and fat. Macronutrient ratios are a central focus of most bodybuilding and fat-loss nutrition plans. → Precise macronutrient (macro) calculator
- Maintenance calories
- The number of calories a person needs to eat daily to keep their body weight stable, neither gaining nor losing. Maintenance calories serve as the baseline from which a calorie surplus (for bulking) or deficit (for cutting) is calculated. → Total Daily Energy Expenditure (TDEE) calculator
- Mass
- A general term referring to muscle size, as in “muscle mass.” An especially large, heavily muscled bodybuilder is often described informally as “massive.”
- Max (one-rep max, 1RM)
- The maximum amount of weight a person can lift for a single, complete repetition of a given exercise with proper form. The one-rep max is commonly used as a reference point for setting training percentages and tracking strength progress over time. → One-repetition maximum (1RM): concept and calculator
- Maximal strength
- The greatest amount of force a muscle or muscle group can produce in a single maximal effort, typically trained using heavy loads and low repetitions. Maximal strength training is a primary focus of powerlifting and is also used by bodybuilders to support long-term muscle growth.
- Mesocycle
- A phase of training periodization usually lasting several weeks to a few months, sitting between the longer macrocycle and the shorter microcycle. A mesocycle often has a specific focus, such as a hypertrophy block or a strength-building block.
- Mesomorphs
- A body type characterized by a naturally larger bone structure, relatively low body fat levels, and an above-average rate of muscle growth. Mesomorphs are often considered to have the most genetically favorable build for bodybuilding. → The 3 somatotypes explained: ectomorph, mesomorph, endomorph
- Metabolism
- The sum of all chemical processes the body uses to convert food into energy and to build and break down tissue. Metabolism includes both anabolic (building) and catabolic (breaking down) processes, and its overall rate strongly influences calorie needs. → Biotin’s role in fitness, fat loss, and metabolism
- Microcycle
- A phase of training periodization typically lasting about a week, representing the shortest planning unit within a larger mesocycle.
- Mind-muscle connection
- The degree of conscious focus and neural engagement a lifter has on the specific muscle being trained during an exercise, rather than simply moving the weight. A stronger mind-muscle connection is often associated with greater activation of the target muscle, particularly on isolation exercises. → What is a mind-to-muscle connection?
- Mobility
- The ability to actively move a joint through its full range of motion under control, combining flexibility with strength and motor control. Mobility differs from pure flexibility, which refers more narrowly to the passive range of motion available at a joint.
- Motor unit
- A single motor neuron together with all the muscle fibers it controls. Motor units are recruited in order of size during muscle contraction, with smaller units activated first and larger, more powerful units recruited as more force is needed — a principle relevant to training intensity and fiber-type development.
- Multi-joint exercise
- Another name for a compound exercise — see the full entry under “Compound exercise” in the C-D glossary. → See “Compound exercise” in the C-D glossary
- Muscle
- Tissue made up of bundles of fibers attached to the skeleton, capable of contracting to move and stabilize the body’s joints and limbs. → Muscle anatomy basics: origin, insertion & innervation
- Muscle atrophy
- A decrease in muscle size and strength resulting from inactivity, illness, or injury — see the full entry under “Atrophy” in the A-B glossary. → See “Atrophy” in the A-B glossary
- Muscle failure
- The point during a set at which a muscle can no longer complete another repetition with proper, strict form, despite maximal effort. Training to muscle failure is a common technique for maximizing muscle stimulus, though it is not necessary on every set to continue making progress. → Lifting to muscle failure in weight training
- Muscle hypertrophy
- An increase in muscle fiber size resulting from resistance training — see the full entry under “Hypertrophy” in the G-H glossary. → See “Hypertrophy” in the G-H glossary
- Muscle imbalance
- A difference in strength, size, or development between opposing muscle groups, such as quads versus hamstrings, or between the left and right sides of the body. Left unaddressed, muscle imbalances can increase injury risk and limit progress on certain lifts. → Symmetrical muscular development
- Muscle memory
- The phenomenon by which a person who has previously built muscle and then lost it through inactivity can regain that muscle considerably faster than building it the first time. Muscle memory is thought to relate to retained satellite cell nuclei and ingrained neural movement patterns. → Muscle memory and its importance in bodybuilding
- Muscularity
- A term describing the degree of visible muscular definition a person displays. The lower a person’s body fat percentage, generally the greater their apparent muscularity, since less fat obscures the underlying muscle shape.
- Myofibrillar hypertrophy
- A type of muscle growth involving an increase in the size and number of myofibrils, the contractile protein structures within a muscle fiber. Myofibrillar hypertrophy is generally associated with heavier, lower-rep strength training, as distinct from sarcoplasmic hypertrophy.
- Nautilus
- A brand of exercise equipment invented by Dr. Arthur Jones, known for machines that use cams, pulleys, and weight stacks to provide variable resistance through a muscle’s full range of motion.
- NEAT (Non-Exercise Activity Thermogenesis)
- The energy expended through everyday activities that are not formal exercise — walking, fidgeting, standing, doing chores. NEAT can vary significantly between individuals and plays an important role in overall daily calorie expenditure, particularly during a cutting phase.
- Negative energy balance
- A state in which the body expends more energy than it consumes through food, forcing it to draw on stored energy reserves — primarily body fat — resulting in weight loss over time. It is the broader physiological concept underlying a caloric deficit. → Energy balance equation: the key to weight management
- Negative phase of repetition
- A term describing the eccentric portion of a muscle contraction. Deliberately emphasizing the negative, or eccentric, phase of a rep tends to cause greater muscle damage than the concentric portion alone — for example, the slow lowering of the bar to the chest during a bench press. → Exploring negative repetitions in strength training
- Negatives
- The portion of a repetition that moves in the same direction as gravity, with the lifter deliberately controlling and resisting it rather than letting it drop. In most exercises, negatives correspond to the lowering, or eccentric, half of the movement — for example, the downward phase of a biceps curl.
- Nervous system
- The body’s network of nerves and the brain and spinal cord that control them, responsible for sending the signals that activate muscle fibers during movement. Strength gains early in a training program are driven significantly by nervous system adaptations, before substantial muscle growth occurs. → Nervous system adaptations to strength training
- Neural adaptation
- Improvements in the efficiency and coordination of the nervous system’s signaling to muscles, which allow a lifter to produce more force without necessarily increasing muscle size. Neural adaptation explains much of the rapid strength gains seen in the early weeks of a new training program.
- Neuromuscular system
- The combined network of nerves and muscles that work together to produce and control body movement. The nervous system sends signals that determine which muscle fibers are activated, how forcefully, and in what sequence. → The nervous system: its critical role in athletic performance
- Neutral grip
- A hand position on a bar or handles in which the palms face each other, with the thumbs pointing upward — as used, for example, on a V-bar low pulley row or on parallel-bar dips. → Versatile neutral grip handles from Kensui
- Neutral spine
- The natural, slightly curved position of the spine that represents good posture and the strongest, most stable alignment for the back. Maintaining a neutral spine — rather than rounding or excessively arching — is important during most heavy compound lifts to reduce injury risk.
- Nitrogen balance
- A measure comparing nitrogen intake (mainly from dietary protein) against nitrogen lost from the body. A positive nitrogen balance, where intake exceeds losses, is generally associated with an anabolic, muscle-building state, while a negative balance suggests the body is breaking down more protein than it is replacing. → The concept of nitrogen balance: anabolism and catabolism
- Nutrient density
- A measure of how many vitamins, minerals, and other beneficial nutrients a food provides relative to its calorie content. Nutrient-dense foods — such as vegetables, lean proteins, and whole grains — deliver more nutritional value per calorie than heavily processed alternatives. → Nutrient-dense foods
- Nutrient timing
- The practice of strategically timing meals or specific nutrients — such as protein or carbohydrates — around training sessions, based on the idea that when nutrients are consumed can influence muscle growth, recovery, or performance. Its practical importance is generally considered smaller than total daily intake, but it can still offer a modest edge.
- Nutrients
- The various minerals, vitamins, proteins, fats, and carbohydrates the body requires for proper function, health, and growth. Nutrients are broadly divided into macronutrients, needed in large amounts, and micronutrients, needed in smaller amounts. → Micronutrients in bodybuilding: vitamins and minerals
- Nutrition
- The practice of combining foods in the right types and amounts so the body receives everything it needs for health and performance. In a bodybuilding context, good nutrition specifically means eating in a way that supports muscle growth while keeping body fat under control. → Bodybuilding nutrition fundamentals
