Library · Reference
Protocol Glossary.
Every term, explained.
Science-backed definitions for every term in your health data: plain English and the mechanism behind it.
Know what the number means before you act on it.
/
291 terms across 10 categories
A to Z
From the numbers on your ring to the markers on your labs.
A
22 terms
- ActigraphySleepMovement-based sleep measurement across days and weeks
- Active RecoveryRecoveryLow-intensity movement that accelerates physiological recovery faster than rest alone
- Acute:Chronic Workload Ratio (ACWR)TrainingThe ratio that separates productive overload from injury risk
- AdenosineHormonesThe molecule that makes you sleepy: what caffeine is actually blocking
- AdiponectinHormonesThe fat cell hormone that fights insulin resistance
- Adrenaline (Epinephrine)HormonesThe acute alarm hormone that prepares the body for immediate action
- Aerobic BaseTrainingThe accumulated low-intensity fitness that lets you work harder, longer, and recover faster.
- Aerobic Threshold (AeT)TrainingThe Zone 2 ceiling: where fat starts ceding to carbohydrates
- Alcohol MetabolismNutritionHow your liver breaks down alcohol, and why the process disrupts recovery long after the drinking stops.
- AldosteroneHormonesThe hormone that controls your salt and blood pressure balance
- Allostasis vs. HomeostasisRecoveryHow the body maintains balance not by staying fixed, but by anticipating and adapting
- Allostatic LoadTrainingYour total accumulated stress burden: the body cannot separate the sources
- ALT & AST (Liver Enzymes)BiometricsYour liver's distress signal in a blood draw
- AmygdalaNeuroscienceThe brain's threat-detection center that triggers your fight-or-flight response
- Anabolic vs. Catabolic StatesHormonesBuild mode versus breakdown mode
- Anaerobic Threshold (AT)TrainingThe intensity ceiling where fat fuel gives out
- Anti-inflammatory FoodsNutritionFoods that lower the immune system background noise
- ApoB (Apolipoprotein B)BiomarkersThe best single number for cardiovascular risk
- ATP-PCr SystemTrainingThe immediate, oxygen-free energy system that powers your first 10 to 15 seconds of maximal effort.
- Attention and FocusNeuroscienceThe brain's capacity to lock onto one task while filtering out everything else competing for it
- Autonomic Nervous System (ANS)BiometricsThe body’s automatic regulatory control system
- AutophagyLongevityThe process cells use to recycle damaged proteins and worn-out parts, and a key link between fasting, exercise, and longevity.
B
15 terms
- Baroreflex Sensitivity (BRS)BiometricsHow quickly your body corrects blood pressure swings
- Basal Body TemperatureBiometricsThe one reliable way to confirm ovulation happened, one day at a time
- Basal Metabolic Rate (BMR)NutritionCalories your body burns at rest just to stay alive
- BCAAs (Branched-Chain Amino Acids)NutritionThree essential amino acids sold as a supplement, but incomplete without the other six
- BDNF (Brain-Derived Neurotrophic Factor)HormonesThe protein that grows your brain, most powerfully triggered by exercise
- Biological AgeLongevityHow old your body actually functions, based on measurable biomarkers, not the number of birthdays you've had.
- Block PeriodizationTrainingA model that sequences training into blocks, each concentrated on one physical quality, to build toward a single peak.
- Blood Pressure Variability (BPV)BiometricsHow much your blood pressure swings between readings, a separate risk marker from your average blood pressure number.
- Blood Sugar RegulationNutritionHow tightly your body controls glucose all day
- Blue Light ExposureSleepThe evening light signal that delays your biological clock
- Body CompositionNutritionThe ratio of fat mass to lean mass
- Body Fat PercentageNutritionFat mass as a fraction of total body weight
- Breathing Rate VariabilityBiometricsThe natural ebb and flow in your breathing rhythm, and what a flattened pattern can mean
- Burnout (Physiological Definition)RecoverySystemic physiological failure from chronic unrecovered stress load
- Buteyko MethodRecoveryA breathing retraining technique that reduces breathing volume and trains nasal, low and slow breathing to build CO2 tolerance.
C
27 terms
- Caffeine MetabolismNutritionHow your body processes caffeine and why the timing matters
- Caloric DeficitNutritionThe engine behind every fat loss outcome
- Caloric SurplusNutritionThe fuel requirement for building muscle
- Carb PeriodizationNutritionMatching carbohydrate intake to training demand day by day
- CBT-I (Cognitive Behavioral Therapy for Insomnia)SleepThe evidence-based cure for chronic insomnia
- Chronic Low-Grade InflammationBiomarkersA persistent, low level immune activation that lingers for months or years instead of resolving like a normal injury or infection response.
- Chronic StressStressStress that does not get the shutoff signal, so the body stays in resistance mode
- ChronotypeSleepYour biological preference for when to sleep and be alert
- Circadian PhaseSleepWhere you are in your 24-hour biological clock right now
- Circadian RhythmSleepYour body's internal 24-hour clock: the master scheduler of nearly every biological function
- CO2 ToleranceTrainingHow much carbon dioxide your body can tolerate before the brain triggers an urgent need to breathe.
- Cognitive FlexibilityNeuroscienceThe brain's ability to switch mental gears when the situation changes
- Cognitive LoadNeuroscienceThe total mental demand placed on working memory at once
- Cognitive ReserveNeuroscienceThe brain's buffer that keeps thinking sharp despite age or damage
- Cold ExposureRecoveryA deliberate thermal stressor that activates recovery and adaptation
- Complete Blood Count (CBC)BiometricsThe standard blood panel that screens oxygen transport, immunity, and clotting in one draw
- Compound vs. Isolation ExercisesTrainingLifts that move several joints and muscles at once, versus lifts that isolate one joint to train a single muscle directly.
- Compression TherapyRecoveryMechanical pressure that accelerates fluid clearance after training
- Concurrent TrainingTrainingThe interference effect between strength and endurance training
- Continuous Glucose Monitoring (CGM)BiometricsReal-time blood sugar dynamics on demand
- Contrast TherapyRecoveryAlternating hot and cold exposure in a single session
- CortisolHormonesYour body's primary stress hormone and morning alarm signal.
- Cortisol Awakening Response (CAR)BiometricsThe first hormonal signal that sets your day
- Cortisol-to-DHEA RatioHormonesThe biochemical score for how well you are aging under stress
- CreatineNutritionThe most evidence-backed supplement for strength and power output
- CRP (C-Reactive Protein)BiometricsYour body's systemic inflammation signal
- Cycle SyncingHormonesA method that matches diet, training, and habits to four cycle phases, part real hormone physiology, part unproven marketing template.
D
10 terms
- Decision FatigueNeuroscienceDeclining decision quality as cognitive resources deplete through the day
- Default Mode Network (DMN)NeuroscienceThe brain circuit that runs when you stop focusing
- Deload WeekTrainingThe planned reduction in training stress where adaptation actually lands
- DetrainingTrainingHow fast your fitness actually disappears when you stop
- DHEA (Dehydroepiandrosterone)HormonesThe adrenal precursor hormone that declines steadily with age
- Diaphragmatic BreathingRecoveryBreathing that engages the diaphragm and expands the belly, not the chest, to trigger a fast, voluntary calm-down of the nervous system.
- Dietary FiberNutritionThe part of plant foods your body cannot digest, which feeds gut bacteria, slows glucose absorption, and helps lower cholesterol
- DOMS (Delayed Onset Muscle Soreness)TrainingThe 24 to 72 hour soreness signal after novel or hard training
- DopamineHormonesThe motivation and anticipation signal, not the pleasure hormone
- DysbiosisNutritionA shift in the gut's bacterial balance, when diversity drops and opportunistic species crowd out beneficial ones.
E
11 terms
- Eccentric TrainingTrainingDeliberately overloading the lengthening phase of a lift to build strength and size faster than concentric work alone
- Energy AvailabilityNutritionCalories left for recovery after training cost
- Energy BalanceNutritionThe master equation of body composition
- Enteric Nervous System (ENS)NeuroscienceThe gut's own nervous system, embedded in its walls, that runs digestion largely independent of the brain.
- Epigenetic AgeBiomarkersA DNA methylation based estimate of how fast your body is aging, separate from your birth date
- EPOC (Excess Post-Exercise Oxygen Consumption)TrainingThe temporary afterburn cost of hard training
- Essential Amino Acids (EAAs)NutritionThe 9 amino acids your body cannot make and must obtain from food
- Estradiol (E2)HormonesThe primary estrogen that governs more than reproduction
- EstrogenHormonesThe hormone that shapes bone, brain, and recovery in both sexes
- Executive FunctionNeuroscienceThe brain's control system for thinking and behavior
- Exercise Energy Expenditure (EEE)NutritionCalories burned during formal exercise, often overestimated
F
12 terms
- Fasting GlucoseBiometricsYour baseline blood sugar after an overnight fast
- Fasting InsulinBiometricsThe single blood number that shows insulin resistance years before glucose does
- Fat AdaptationNutritionTraining your body to burn fat as its primary fuel
- FerritinBiometricsYour iron storage tank, and an inflammation marker
- Fight-or-Flight ResponseRecoveryYour body's hardwired emergency activation system
- Flow StateNeurosciencePeak performance where effort disappears
- Follicular PhaseHormonesThe first half of the cycle, from day 1 of bleeding to ovulation, when rising estrogen drives follicle growth and often climbing energy.
- Free T3 and Free T4HormonesThe active and storage forms of thyroid hormone your labs should show
- Free TestosteroneHormonesThe biologically active fraction that actually reaches cells
- FSH (Follicle Stimulating Hormone)HormonesThe pituitary hormone that drives egg and sperm development
- Functional MovementTrainingTraining the fundamental movement patterns your body needs for daily life, not gym gimmicks.
- Functional OverreachingRecoveryThe productive edge where fatigue becomes adaptation
G
14 terms
- GGT (Gamma-Glutamyl Transferase)BiometricsThe liver enzyme most sensitive to alcohol and metabolic stress
- GhrelinHormonesThe stomach hormone that drives hunger before meals and after poor sleep
- GlucagonHormonesInsulin's counterpart: the hormone that raises blood sugar when it drops too low
- GlucocorticoidsHormonesThe stress and metabolism hormone class cortisol leads
- Glucose VariabilityBiometricsHow much your blood sugar swings across the day
- Glycemic Index (GI)NutritionHow fast a food raises blood glucose
- Glycemic LoadNutritionHow much a food actually raises your blood sugar, factoring in both how fast its carbs digest and how much of it you eat.
- Glycolytic vs. Oxidative Energy SystemsTrainingTwo major pathways your muscles use to make energy: one fast and glucose-fueled, the other slower and oxygen-fueled.
- Glymphatic SystemSleepThe brain's waste clearance network, most active during deep sleep
- Grip StrengthBiometricsA simple squeeze that predicts how well you'll age
- Growth Hormone (GH)HormonesThe pituitary hormone that repairs tissue during deep sleep
- Growth Hormone Pulse (Sleep)SleepThe single largest release of growth hormone each day, timed to your first block of deep sleep.
- Gut MicrobiomeNutritionThe ecosystem in your gut that shapes your health
- Gut-Brain AxisNutritionThe two-way communication highway between gut and brain
H
20 terms
- Hallmarks of AgingLongevityThe twelve interconnected biological processes that scientists identify as the root drivers of aging inside every cell.
- HDL Cholesterol (HDL-C)BiomarkersThe "good cholesterol" that is more nuanced than its label suggests
- HealthspanLongevityThe number of years you live in good health, not just the number of years you're alive.
- Heart Rate Recovery (HRR)BiometricsHow quickly your heart rate drops after you stop exercising, a strong marker of cardiovascular fitness and autonomic health.
- Heart Rate Reserve (HRR)BiometricsThe usable range between rest and maximum effort
- Heart Rate Variability (HRV)BiometricsYour nervous system's daily readiness signal
- Heat Acclimation / SaunaRecoveryA controlled heat stress that builds cardiovascular resilience and growth hormone response
- Hemoglobin A1c (HbA1c)BiometricsA 3-month average of your blood sugar control
- HIIT (High-Intensity Interval Training)TrainingShort bursts of hard effort for cardiovascular adaptation
- HippocampusNeuroscienceThe brain's memory consolidation and learning center
- HOMA-IR (Homeostatic Model Assessment of Insulin Resistance)BiometricsThe earliest measurable signal of insulin dysfunction
- HomocysteineBiomarkersAn amino acid byproduct that signals B-vitamin status and vascular risk
- HormesisTrainingThe biological principle that small, controlled doses of stress trigger adaptive responses that make your body stronger and more resilient.
- HPA Axis (Hypothalamic-Pituitary-Adrenal Axis)HormonesThe three-gland stress response system that runs your cortisol
- HPG Axis (Hypothalamic-Pituitary-Gonadal Axis)HormonesThe command chain that controls sex hormones
- HRV BiofeedbackStressA paced breathing practice guided by a real-time heart rate variability readout
- hs-Troponin (High-Sensitivity Cardiac Troponin)BiometricsThe blood marker that detects damage to heart muscle itself, not just its risk factors
- Hydration and PerformanceNutritionHow fluid balance shapes endurance, strength, and focus during exercise.
- HypertrophyTrainingThe structural enlargement of muscle fibers in response to training stress
- Hypnagogic StateSleepThe threshold between waking and sleep onset
I
11 terms
- IGF-1 (Insulin-like Growth Factor 1)HormonesThe anabolic signal that turns growth hormone into muscle repair
- IGF-1 SignalingHormonesThe growth signal that converts effort into muscle
- Immune Suppression (Post-Stress)RecoveryThe temporary dip in immune defense that follows a demanding stress or training bout
- Inflammatory CytokinesBiomarkersThe signaling proteins immune cells release to trigger and coordinate the body's inflammatory response.
- InsulinHormonesThe master nutrient storage and signaling hormone
- Insulin ResistanceNutrition
- Intermittent Fasting (IF)NutritionCycling between eating windows and fasting periods
- InteroceptionStressThe brain's real-time sense of what is happening inside the body, from heartbeat and breath to hunger and muscle tension
- Intestinal Permeability (Leaky Gut)NutritionHow tightly your gut lining controls what crosses into your bloodstream, and what happens when that seal loosens.
- Iron Panel & FerritinBiometricsYour iron storage and delivery system, measured in full
- Isometric TrainingTrainingHolding a muscle contraction at a fixed joint angle, generating force without the muscle changing length or the joint moving
L
11 terms
- Lactate ThresholdTrainingThe intensity above which your pace becomes unsustainable
- LDL Cholesterol (LDL-C)BiomarkersThe most tracked lipid marker, and the most misread
- LDL Particle Size (LDL-P vs. LDL-C)BiomarkersWhy two people with the same LDL number can have very different risk
- Lean Body MassNutritionTotal weight minus fat, the mass that drives your metabolism
- LeptinHormonesThe fat-cell hormone that tells your brain how much energy you have stored
- Leucine ThresholdNutritionThe minimum leucine dose that triggers muscle protein synthesis, and why meal size matters
- LF/HF RatioBiometricsA window into your autonomic nervous system balance
- LH (Luteinizing Hormone)HormonesThe pituitary signal that triggers sex hormone production
- Linear PeriodizationTrainingA model that moves training from high volume and low intensity toward low volume and high intensity across phases, to peak strength once.
- Lipoprotein(a) [Lp(a)]BiomarkersThe inherited cardiovascular risk factor most panels skip
- Luteal PhaseHormonesThe second half of the cycle, from ovulation to the next period, when progesterone drives body temperature and, for some, PMS symptoms.
M
15 terms
- MagnesiumNutritionThe mineral that keeps your nervous system calm
- Max Heart Rate (MHR)BiometricsThe ceiling of your cardiovascular output
- MelatoninHormonesThe darkness hormone that tells your body when to sleep
- Memory ConsolidationSleepThe process that turns a fresh memory into a stable one, largely by replaying it during sleep.
- Menstrual Cycle PhasesHormonesThe four hormonal phases, follicular, ovulation, luteal, and menstrual, that reshape energy, temperature, and training capacity each month.
- Metabolic FlexibilityNutritionYour body's ability to switch fuel sources: the difference between steady energy and crashes
- Mind-Muscle ConnectionTrainingThe conscious practice of focusing on and feeling a target muscle work during a lift, which changes how many fibers in that muscle activate.
- MineralocorticoidsHormonesThe adrenal hormones that regulate fluid and electrolyte balance
- Mitochondrial BiogenesisTrainingGrowing new mitochondria: the cellular adaptation that drives aerobic fitness
- Mobility vs. FlexibilityTrainingTwo different physical capacities people use interchangeably, and only one of them requires strength.
- Motor Unit RecruitmentTrainingHow your nervous system scales force output
- mTOR PathwayBiomarkersThe cellular switch that decides whether your body builds new tissue or breaks old tissue down for recycling.
- Muscle Mass IndexBiometricsHow much lean muscle you carry relative to your height
- Muscle Memory (Myonuclei)TrainingWhy returning to training after a break is faster than starting fresh
- Muscle Protein Synthesis (MPS)TrainingThe cellular process that builds and repairs muscle
N
13 terms
- N1 and N2 SleepSleepThe lighter NREM stages where most of sleep actually happens
- NAD+BiomarkersA coenzyme every cell needs to convert food into energy and repair DNA, and one that reliably declines with age.
- NappingSleepPlanned short sleep that restores alertness without full recovery
- Nasal BreathingTrainingBreathing through your nose instead of your mouth, both at rest and during easy training.
- Natural Killer CellsBiomarkersThe immune system's rapid-response cells that hunt down infected and cancerous cells without needing to see them before.
- Nervous System FatigueRecoveryThe fatigue that hides beneath the muscle soreness
- NeurogenesisNeuroscienceThe birth of new neurons from stem cells, and what helps or hinders it in the adult brain
- Neuromuscular FatigueTrainingWhen your nervous system, not your muscles, is the limiter
- NeuroplasticityNeuroscienceThe brain's capacity to rewire in response to experience
- Non-Exercise Activity Thermogenesis (NEAT)NutritionThe calories you burn moving without trying to exercise
- Non-Functional OverreachingRecoveryWhen too much training stops paying off
- Non-HDL CholesterolBiomarkersA better total atherogenic burden marker than LDL-C alone
- NorepinephrineHormonesThe alertness and arousal signal for brain and body
O
6 terms
- Omega-3 Fatty AcidsNutritionAnti-inflammatory fats that support recovery, brain health, and cardiovascular function
- Omega-3 Index (EPA + DHA)BiometricsYour cell membrane fatty acid quality score
- One-Rep Max (1RM)TrainingThe ceiling that calibrates everything else
- Orthostatic Heart Rate TestBiometricsA 60-second morning recovery readiness check
- Overtraining SyndromeTrainingWhen accumulated stress outpaces recovery for long enough to break the system
- OxytocinHormonesThe social bonding and trust signal
P
18 terms
- Parasympathetic ReboundRecoveryThe nervous system shift that signals genuine recovery
- Passive RecoveryRecoveryComplete rest as a deliberate training input
- PeriodizationTrainingThe structured organization of training stress and recovery across time
- PhosphatidylserineNutritionA brain-dense phospholipid that blunts cortisol and supports cognitive recovery
- Plyometric TrainingTrainingExplosive stretch-shortening exercises like jumps and bounds that train muscles to produce force fast, not just powerfully
- Polyphasic SleepSleepSplitting sleep into multiple periods instead of one nightly block
- Polysomnography (PSG)SleepThe gold-standard clinical measurement of sleep
- Polyvagal TheoryRecoveryA framework for understanding how the nervous system governs safety, threat, and social connection
- Prebiotics vs. ProbioticsNutritionTwo different tools for gut bacteria: one feeds the microbes you already have, the other adds new ones temporarily.
- Prefrontal Cortex (PFC)NeuroscienceThe brain's executive control and decision-making center
- Premenstrual Syndrome (PMS)HormonesThe predictable dip in mood, energy, and comfort that follows ovulation and clears once a period starts.
- ProgesteroneHormonesThe calming counterpart to estrogen, with deep ties to sleep and recovery
- Progressive OverloadTrainingThe principle that drives all adaptation: consistently increase the demand to keep improving
- ProlactinHormonesThe pituitary hormone that suppresses sex hormones when elevated
- Protein TimingNutritionWhen you eat protein matters less than most think, but more than some claim
- Psychological SafetyNeuroscienceThe nervous system's automatic read on whether it is safe to rest, digest, and connect
- PsychoneuroimmunologyRecoveryThe science of how stress, emotions, and thought patterns directly change immune function, and immune signals shape mood in return
- Pulse Wave Velocity (PWV)BiometricsHow fast the pressure wave from each heartbeat travels through your arteries, a direct read on arterial stiffness apart from blood pressure.
R
13 terms
- Rate of Force Development (RFD)TrainingHow fast your muscles generate force, not how much they can produce
- Rate of Weight LossNutritionHow fast you lose determines what you lose
- Reaction Time and Processing SpeedNeuroscienceHow fast your brain detects a signal and turns it into a response.
- Readiness ScoreBiometricsOura's daily verdict on your capacity for stress
- Recovery ScoreBiometricsYour body's readiness verdict after last night
- Recovery WindowRecoveryThe post-training period when adaptation either happens or stalls
- Refeed DayNutritionA planned day of higher carbohydrate eating at roughly maintenance calories, placed inside a longer calorie deficit
- REM SleepSleepThe sleep stage where your brain consolidates memory and regulates emotion
- Respiratory RateBiometricsBreaths per minute: your body's quiet early warning signal
- Rest-and-DigestRecoveryThe parasympathetic state where recovery actually happens
- Resting Heart Rate (RHR)BiometricsHow hard your heart works when it doesn't have to
- RMSSD (Root Mean Square of Successive Differences)BiometricsThe beat-to-beat calculation that powers your HRV score
- RPE (Rate of Perceived Exertion)TrainingYour body's internal intensity gauge
S
38 terms
- SAID PrincipleTrainingThe principle that your body adapts specifically to the type, intensity, and pattern of stress placed on it, not to exercise in general.
- SarcopeniaLongevityThe age-related loss of muscle mass and strength that quietly predicts falls, frailty, and loss of independence.
- Satiety IndexNutritionA ranking of how full different foods leave you, scored against white bread at 100 percent
- SDNN (Standard Deviation of NN Intervals)BiometricsThe HRV metric Apple Watch uses, and why it reads higher than Oura
- Second Wind (Evening Alertness Peak)SleepThe late-evening burst of alertness that shows up right when you expect to feel sleepy
- Senescent CellsBiomarkersAged or damaged cells that permanently stop dividing but refuse to die, quietly driving inflammation as they accumulate with age.
- SerotoninHormonesThe mood and stability signal that lives mostly in your gut
- SHBG (Sex Hormone Binding Globulin)HormonesThe protein that determines how much testosterone your body can actually use
- Short-Chain Fatty Acids (SCFAs)NutritionThe fermentation byproducts that fuel your gut lining and calm inflammation
- Skin Temperature DeviationBiometricsYour body's overnight thermostat as a recovery signal
- Sleep and AgingSleepWhy sleep gets lighter, shorter, and more fragmented as you get older, and what still stays in your control
- Sleep and TestosteroneSleepMost of a day's testosterone is made overnight, timed to sleep stage rather than the clock.
- Sleep ArchitectureSleepThe internal structure of your sleep, not just how long, but how deep
- Sleep DebtSleepThe accumulated deficit between the sleep you need and the sleep you get
- Sleep EfficiencySleepThe percentage of your time in bed actually spent asleep
- Sleep FragmentationSleepRepeated brief awakenings that break sleep continuity without always waking you fully
- Sleep HygieneSleepThe daily habits that let your biology fall and stay asleep
- Sleep InertiaSleepThe grogginess and cognitive impairment that follows waking from deep sleep
- Sleep LatencySleepHow long it takes to fall asleep after getting into bed
- Sleep Pressure (Homeostatic Sleep Drive)SleepThe biological urge to sleep that builds every hour you are awake
- Sleep Regularity Index (SRI)SleepHow consistent your sleep timing is: the dimension duration misses
- Sleep Restriction TherapySleepThe counterintuitive insomnia treatment that works by reducing time in bed
- Sleep SpindlesSleepThe brain's memory consolidation signal during N2 sleep.
- Sleep StagingSleepHow scientists classify the layers of a night
- Sleep WindowSleepThe hours when your biology is aligned for sleep
- Slow-Wave Sleep (Deep Sleep)SleepThe deepest sleep stage, where your body actually rebuilds
- Social JetlagSleepThe circadian disruption of sleeping on a different schedule every week
- Soft Tissue Work / MassageRecoveryManual therapy that addresses the texture and mobility of muscle and fascia
- SpO2 (Blood Oxygen Saturation)BiometricsThe percentage of your red blood cells carrying oxygen
- Strain ScoreBiometricsYour daily cardiovascular load, accumulated
- Strength-to-Weight RatioTrainingHow much force you can produce relative to your own body mass
- Stress InoculationNeuroscienceRepeated, manageable exposure to a stressor that trains the nervous system to respond to future stress with more control.
- Stress MindsetStressThe belief that stress helps or harms performance, a belief that measurably changes how the body responds to it
- Stress Response (General Adaptation Syndrome)RecoveryYour body's blueprint for handling any stressor
- Subcutaneous FatNutritionThe fat stored just beneath the skin, distinct from the visceral fat around your organs
- SupercompensationTrainingThe overshoot above baseline that makes training produce fitness
- Suprachiasmatic Nucleus (SCN)SleepThe master clock that synchronizes every biological rhythm
- Sympathetic vs. ParasympatheticBiometricsThe two-branch system behind every readiness metric
T
17 terms
- Telomere LengthBiomarkersThe length of the protective DNA caps on your chromosomes, a marker of cellular aging that shortens with cell division and stress.
- Tempo TrainingTrainingControlling rep speed to change the training stimulus without changing the weight
- Tendon AdaptationTrainingHow tendons remodel their collagen structure in response to mechanical loading, distinct from muscle growth
- TestosteroneHormonesThe primary anabolic hormone governing muscle, energy, and drive
- Thermic Effect of Food (TEF)NutritionThe calories your body burns digesting what you eat
- Thyroid Hormones (T3/T4)HormonesThe metabolic rate regulators every cell depends on
- Time Under TensionTrainingThe total number of seconds a muscle spends under load during a set, a duration metric distinct from reps or weight
- Time-Restricted Eating (TRE)NutritionCompressing daily eating into a consistent window aligned to your clock
- Total Daily Energy Expenditure (TDEE)NutritionThe total calories your body burns in 24 hours
- Training FrequencyTrainingHow often you train a given muscle group or movement pattern each week, independent of total volume or load.
- Training IntensityTrainingHow heavy or hard a given set or session is relative to your maximum effort.
- Training LoadTrainingThe cumulative stress of your recent training
- Training VolumeTrainingThe total amount of work performed in training, most often counted as sets per muscle group or total load lifted.
- Triglyceride-to-HDL RatioBiomarkersA proxy for insulin resistance hiding inside a standard lipid panel
- TriglyceridesBiometricsThe most measured, most misunderstood number on your lipid panel
- TRIMP (Training Impulse)TrainingA single number for quantifying training stress
- TSH (Thyroid Stimulating Hormone)HormonesThe pituitary signal that runs your metabolic engine
U
3 terms
- Undulating PeriodizationTrainingA training structure that rotates load and volume across sessions or weeks so you develop strength, size, and power at the same time.
- Unilateral TrainingTrainingTraining one limb at a time instead of both together, to build per-limb strength and stability bilateral lifts miss.
- Uric AcidBiometricsA metabolic waste product that predicts more than gout
V
7 terms
- Vagal ToneBiometricsThe strength of your parasympathetic recovery signal
- Vasopressin (ADH)HormonesThe hormone that tells your kidneys how much water to keep
- Visceral FatNutritionThe metabolically active fat that surrounds your organs
- Vitamin DBiomarkersThe hormone your body makes from sunlight
- VO2 MaxBiometricsThe strongest single predictor of long-term health and longevity
- VO2 Max (Lab Protocol vs. Wearable Estimate)BiometricsWhy your watch's VO2 max number and a lab test can tell two different stories
- VO2 Max Training ZonesTrainingThe five-zone system for turning oxygen uptake into a training prescription
W
4 terms
- WASO (Wake After Sleep Onset)SleepTotal minutes spent awake after first falling asleep
- Weekly Energy BalanceNutritionWhat actually moves the scale over time
- Window of ToleranceStressThe zone of stress and arousal where you can think clearly, feel your emotions, and stay engaged without shutting down or spiraling
- Working MemoryNeuroscienceThe brain's mental scratchpad for active thinking
More terms added regularly, across every category.
Explore topics