N-acetylcysteine – An antioxidant supplement sometimes used to reduce exercise-induced oxidative stress.

NAD⁺ – A coenzyme involved in energy production, especially in glycolysis and the Krebs cycle.

NASA Task Load Index (NASA-TLX) – A tool for measuring perceived workload in complex tasks or sports.

Natriuresis – The excretion of sodium in urine, important for fluid balance during exercise.

Negative feedback – A control mechanism where a change triggers a response that reverses the initial change.

Negligence – Failure to take proper care in training or coaching, possibly leading to injury.

Nerve conduction velocity – The speed at which electrical signals travel along a nerve.

Nervous system – The body’s control system for movement and physiological regulation.

Neuromuscular adaptation – Adjustments in the nervous system and muscles in response to training.

Neuromuscular block – Temporary muscle weakness due to impaired nerve signal transmission.

Neuromuscular efficiency – The ability to recruit motor units quickly and in a coordinated manner.

Neuromuscular fatigue – A decline in muscle performance due to impaired nervous system function.

Neuromuscular junction – The synapse where a motor neuron communicates with a muscle fibre.

Neurotransmitter – A chemical messenger used for communication between neurons or neurons and muscles.

Newtons (N) – A unit of force in the SI system, used in biomechanics.

Nitric oxide – A molecule that promotes blood vessel dilation, enhancing blood flow during exercise.

Noise (measurement) – Variability in data due to measurement or environmental errors.

Non-communicable disease – A chronic illness not passed between individuals, often linked to inactivity.

Non-linear pedagogy – A coaching approach that uses variability and exploration to develop skills.

Non-weight-bearing exercise – Physical activity performed without placing weight on the limbs, like swimming.

Norm-referenced test – An assessment comparing an individual’s performance to a group norm.

Norms (sport) – Average performance scores used as benchmarks for athlete comparison.

Normal distribution – A bell-shaped statistical distribution used to interpret performance data.

Nose breathing – Inhalation through the nose, which can improve oxygen uptake and humidity control.

NREM sleep – Non-rapid eye movement sleep, essential for physical recovery.

Nociceptor – A sensory receptor that signals pain in response to harmful stimuli.

Nordic hamstring curl – A strength and injury-prevention exercise targeting the hamstrings eccentrically.

Nose-brain link – The vagus nerve pathway linking nasal airflow patterns to brain activity.

Noys-Scale – A perceptual scale measuring discomfort or pain during exercise.

NREM stage 1 – The first light stage of sleep, important for transitioning into deeper rest.

NREM stage 2 – A sleep stage characterised by sleep spindles and K-complexes, vital for memory consolidation.

NREM stage 3 – Deep slow-wave sleep associated with physical restoration and muscle growth.

Null hypothesis – A statistical assumption that there is no effect or difference between groups.

Nutraceutical – A food or supplement that offers medical or health benefits beyond basic nutrition.

Nutrition periodisation – Planned adjustments in diet based on training phase and goals.

Nutrient density – Amount of nutrients per calorie in a food, important for athlete diet quality.

Nutrient timing – The strategic planning of nutrient intake around training or competition.

Nutrition label reading – Understanding food packaging to make informed dietary choices.

Nutritional ergogenic aid – A food or supplement used to enhance physical performance.

Nutritional status – An individual’s health condition based on nutrient intake and absorption.

Nutrient–exercise interaction – How food intake influences physiological response to training.

NREM cycle – A group of sleep stages that repeats throughout the night during restorative rest.

Nutrient partitioning – The distribution of dietary energy into fat storage or muscle fuel.

Neuromuscular blockade – Controlled paralysis used in medical or research settings, sometimes relevant to sport physiology.

Neuroplasticity – The brain’s ability to reorganise neural pathways in response to training or injury.

Neuromuscular recruitment – The process of activating additional motor units to increase force.

Neuromuscular synergy – Coordinated activation of muscle groups to produce efficient movement.

Neurophysiology – The study of nervous system function during movement and rest.

Neurotransmission – The process of signal transfer between neurons at synapses.

Neutral alignment – Proper joints positioning to support optimal movement and reduce injury risk.

Newton’s laws – Fundamental principles describing the relationship among motion, force, and mass.

Nociceptive pain – Pain caused by tissue damage, such as a sprain or muscle strain.

Nominal scale – A categorical scale with no natural order, used in sports data classification.

Nomothetic approach – A research method focusing on general laws rather than individual differences.

Non-declarative memory – Unconscious memory supporting skills and habits.

Non-exercise activity thermogenesis (NEAT) – Calories burned through daily movement excluding formal exercise.

Non-parametric test – A statistical test not assuming a normal data distribution.

Non-taxing activity – Low-effort movements used for active recovery during training.

Normative feedback – Performance feedback based on comparison to standard benchmarks.

Norm-referenced scoring – Scoring based on comparison to a reference group.

Notational analysis – Systematic recording of performance events to inform coaching.

N-type calcium channel – A neural ion channel involved in neurotransmitter release, impacting muscle activation.

Nutation – A small movement of the sacrum relative to the pelvis during gait or load bearing.

Nutrigenomics – The study of how nutrition influences gene expression in performance and health.

Neutraliser – A muscle that prevents unwanted movement while another muscle contracts.

Nerve root compression – Pressure on a spinal nerve causing pain or weakness, relevant in athlete assessment.

Nutrient absorption – The process of taking digested nutrients into the bloodstream.

Neuroendocrine response – The interaction between the nervous and hormonal systems during exercise.

NMES (Neuromuscular electrical stimulation) – The use of electrical currents to evoke muscle contraction for training or rehab.

Natural logarithm – A mathematical function often used to linearise physiological data for analysis.

Network density (social support) – Measurement of social connections supporting athlete wellbeing.

Neurovisceral integration – Connection between brain and heart function, relevant in stress and performance.

Neurovascular bundle – A network of nerves and blood vessels supplying muscles and joints.

Nitrate supplementation – The use of nitrate-rich foods like beetroot to enhance blood flow and endurance.

Night-time core temperature – Body temperature declines at night, affecting recovery and sleep quality.

Normalised power – A weighted average of power output accounting for variability, e.g., in cycling.

Normalised stroke volume – Stroke volume adjusted to body size, useful for comparing athletes.

Non-functioning pituitary adenoma – A benign tumour that may affect hormones relevant to athlete’s health.

NMJ safety factor – The variability between the strength of a neuromuscular signal and the threshold needed to activate a muscle fibre.

Neurogenic fatigue – Fatigue caused by decreased nerve signal generation, often seen in endurance events.

NMJ degeneration – The breakdown of neuromuscular junctions in chronic neuromuscular disease.

Neurocomputational models – Computer-based simulations of neural control during movement or coordination.

Neuromusculoskeletal biomechanics – The integrated study of nerves, muscles, and skeleton during movement.