The jargon, decoded. 80% science, 20% violence.
A
ADHD (Attention Deficit Hyperactivity Disorder)
Technical definition: Neurodevelopmental condition marked by dysregulated dopamine and noradrenaline, which makes it hard to hold attention on unstimulating tasks (base endurance, for instance). Cornerman note: Not a disease, different wiring. Your brain is a Ferrari with no brakes. On a track (sprints, VO2max work) you are unbeatable. In traffic (zone 2) you overheat. Learn to drive your machine instead of complaining about the traffic.
AMPK (Adenosine Monophosphate-activated Protein Kinase)
Technical definition: Key enzyme acting as a cellular energy sensor. Activated by an energy deficit (endurance exercise, fasting), it drives fat oxidation and mitochondrial biogenesis (via PGC-1α), and inhibits the mTOR pathway (muscle growth). Cornerman note: The survival-mode switch. When it is on, your body thinks it has to run a long way to find food, not build biceps. Ride hard straight after leg day and you shoot your own gains.
ATP (Adenosine Triphosphate)
Technical definition: The universal molecule for storing and moving energy inside cells. Breaking its phosphate bonds releases the energy that drives muscle contraction. Cornerman note: Your body’s cash. No ATP, you are a statue. All of training is just teaching your body to print those notes faster than you spend them.
C
Cardiac drift
Technical definition: Heart rate climbing steadily through an effort held at constant power. Two causes:
- Haemodynamic: falling plasma volume (dehydration) and blood shunted to the skin (thermoregulation).
- Metabolic: Type I fibres fatiguing, forcing recruitment of Type II fibres (less oxygen-efficient). Cornerman note: If your heart gains 10 bpm while your watts sit still, you are cooking, you are drying out, or your slow fibres are dead. Either way your efficiency is collapsing.
Catecholamines
Technical definition: Family of neurotransmitters (dopamine, noradrenaline, adrenaline) released by the adrenal glands and the brain under stress or hard effort. They raise heart rate, alertness and energy mobilisation. Cornerman note: Fuel for your brain. In zone 2 you do not make enough, and your brain falls asleep (see SSD). Sprint and you take a shot of it. That is why you feel alive at 180 bpm and dead at 120.
Cortisol
Technical definition: Glucocorticoid steroid hormone released in response to stress, physical or psychological. It is catabolic: it breaks tissue down to free up glucose. Cornerman note: Public enemy number one. A little is fine, it gets you out of bed. Too much (work stress plus too much training plus no sleep) and you eat yourself from the inside. Stressed all the time, you build nothing. You decompose.
Creatine
Technical definition: Nitrogenous organic acid that helps regenerate ATP during short, intense efforts (alactic anaerobic pathway). It also raises intracellular hydration. Cornerman note: Not doping, just basics. Skip your 5 g a day and you leave performance on the table out of pure ignorance. And no, it will not cost you your hair. Stop reading obscure forums.
Critical Power (CP)
Technical definition: Asymptote of the power-duration relationship (Monod & Scherrer, 1965). The highest power at which the body holds a metabolic steady state. Below it, the effort settles. Above it, fatigue becomes inevitable and time to exhaustion is finite, therefore calculable. Cornerman note: Your real wall, the one FTP approximates without ever seeing it. The two correlate but they are not interchangeable (Karsten et al., 2020): on a diesel they sit close, on a puncheur they split wide open. What separates them has a name, and you will find it under W.
D
Dirty Z2 (stochastic zone 2)
Technical definition: Endurance protocol where average power stays in zone 2, but is reached through intensity variation (sweet spot on the rises, Z1 on the descents) rather than a constant effort. Cornerman note: Poor man’s fartlek, for anyone dying of boredom at a flat 180 W. Physiologically it is less clean than robotic Z2, and it is infinitely better than not riding at all. It is the neuro-mechanical compromise. Cornerman concept: house model, not a clinical entity.
E
Effect size (SMD, Hedges’ g)
Technical definition: Standardised measure of how large a result is, independent of the unit used. It always comes with a 95 % confidence interval. Usual landmarks: 0.2 small, 0.5 moderate, 0.8 large. If the confidence interval contains zero, the effect cannot be told apart from no effect at all. Cornerman note: The tool that lets you read a study instead of believing it. When a headline says X beats Y, go find the effect size and its interval. Nine times out of ten the lower bound is grazing zero, and the announced superiority fits inside the thickness of the line.
F
FatMax
Technical definition: The exercise intensity at which fat oxidation rate is highest (Jeukendrup & Achten, 2001). Determined in a lab through gas exchange, it usually sits near the first threshold without landing exactly on it. Cornerman note: The point where you burn the most fat per minute. Watch the trap: most fat per minute, not most fat overall, and it was never a performance target in itself. Its real value is elsewhere. It is one of the rare individual landmarks that honestly marks the bottom of your zone 2, instead of a percentage pulled off a chart.
FTP (Functional Threshold Power)
Technical definition: The highest power a cyclist can theoretically hold in a quasi-steady state (no exponential lactate accumulation) for roughly 60 minutes. Cornerman note: The cyclist’s measuring contest. It is a useful number for calibrating your zones, and it has become a bragging tool. Spoiler: if your FTP is high but you blow up after 35 minutes (see TTE), you do not have a big FTP. You have a big ego on a badly paced 20-minute test.
G
Glycogen
Technical definition: Storage form of glucose in the liver and the muscles. The preferred fuel for high-intensity efforts. Cornerman note: Your premium unleaded tank. About 90 minutes of it flat out. After that the tank is dry and you bonk. Eat your carbs. Keto is for influencers who never push past 150 watts.
H
HRV (Heart Rate Variability)
Technical definition: The variation in time (in milliseconds) between two consecutive heartbeats. An indicator of autonomic nervous system balance (sympathetic vs parasympathetic). Cornerman note: Your fatigue dashboard. High HRV, you are a machine ready for war. Low HRV, your body is begging you to stay on the couch. Ignore a low HRV three days running and get your tissues ready, you are about to get sick.
Hypertrophy (myofibrillar vs sarcoplasmic)
Technical definition:
- Myofibrillar: increase in the size and number of contractile fibres (real strength, dense muscle).
- Sarcoplasmic: increase in intracellular fluid volume and glycogen stores (visual size, the pump look). Cornerman note: You want both. Myofibrillar so you are not a fraud when something heavy needs lifting, sarcoplasmic to fill the t-shirt. Do not be the guy with 45 cm arms who shakes under an 80 kg bar.
I
IF (Intensity Factor)
Technical definition: Ratio of a ride’s Normalized Power (NP) to your FTP. IF = NP / FTP. Cornerman note: The severity grade of your ride.
- IF < 0.75: a walk in the park (recovery/endurance).
- IF 0.85: starting to bite (tempo/sweet spot).
- IF 1.0: you rode at threshold for an hour (race).
- IF > 1.05 over an hour: either you are a mutant, or your FTP is set wrong (it is).
Intensity distribution (TID)
Technical definition: How total training time splits across the zones bounded by the two physiological thresholds. Three described models: polarised (around 80 % below the first threshold, little intermediate work, 15 to 20 % above the second), pyramidal (easy-dominant, a real intermediate share, little very hard) and threshold (large volume concentrated between the two thresholds). Cornerman note: The real argument in endurance training, and the one everybody holds a firm opinion on without having read the papers. The honest answer: in trained cyclists, no model beats another on actual performance. What decides is that the easy is genuinely easy and the hard is genuinely hard.
Intensity domains (moderate, heavy, severe)
Technical definition: Physiological taxonomy of intensity in three regimes, separated by two boundaries only. The moderate domain stops at the first threshold (LT1): lactate stays low and stable. The heavy domain runs from the first threshold to critical power: lactate rises, then settles at a high level. The severe domain starts above critical power: nothing settles any more, and oxygen consumption drifts upward until you stop. Cornerman note: The only split your body recognises. The five or seven zones in your app are labels laid on top: handy for talking to each other, useless for telling you which domain you are actually riding in. You prescribe a domain and a position inside it. The zone number stays a display.
J
Junk Miles
Technical definition: Training volume done at an intermediate intensity (often zone 3), too high to allow proper recovery or pure aerobic adaptation, too low to create enough metabolic stress to raise your threshold. Cornerman note: The purgatory of the mediocre athlete. It is the ride you do for fun, a bit hard but not too hard. Result: too tired for tomorrow’s key session, and nothing gained. Congratulations, you wasted your time. Cornerman concept: house model, not a clinical entity.
K
Kyphosis (thoracic)
Technical definition: Exaggerated convex curvature of the spine in the thoracic region. Cornerman note: The posture of the cyclist and the office worker. Shoulders forward, back rounded, victim silhouette. Fix it with thoracic extensions and face pulls, or you end up looking like Gollum.
L
Lactate
Technical definition: By-product of anaerobic glycolysis. Contrary to popular belief it is not waste, it is a fuel recycled by the heart and the muscles (the lactate shuttle) and a buffer against acidity. Cornerman note: Lactate is not what burns your legs, H+ ions are (acidity). Lactate is your friend, the firefighter trying to put the fire out. Stop saying your legs are full of lactic acid, you sound illiterate.
LT1 (first lactate threshold / aerobic threshold)
Technical definition: The intensity at which blood lactate rises detectably above its resting value, classically around 2 mmol/L. It is the upper edge of the moderate domain, and therefore the real ceiling of zone 2. Its ventilatory equivalent is the first ventilatory threshold (VT1). Cornerman note: The true ceiling of your easy, and it cannot be deduced from a percentage. Measured in fifty cyclists, the markers meant to find it vary by 6 to 29 % depending which one you pick. Two people can have their LT1 at 23 % and at 57 % of their peak power. So riding at 65 % of FTP means nothing until you know where yours falls.
M
Mitochondria
Technical definition: Cellular organelle responsible for cellular respiration and ATP production through the oxidation of fat and carbohydrate. Cornerman note: Your engine. The more you have, the more you are a Ferrari. Two corrections to what everybody repeats: zone 2 builds them, but no more than intervals or sprints, and per hour spent it builds distinctly fewer. What decides is the mitochondrial content you reach, and it is paid for in total load.
Mitochondrial content
Technical definition: The amount of mitochondria present in the muscle, measured indirectly through marker enzyme activity such as citrate synthase or succinate dehydrogenase, or directly by microscopy of mitochondrial volume. It is the variable studies actually measure when they talk about building mitochondria. Cornerman note: The only number that counts when someone sells you a mitochondrial stimulus. And when it gets measured, it rises the same way with continuous endurance, with intervals and with sprints. The method does not decide. The load does: intensity multiplied by time.
MLSS (Maximal Lactate Steady State)
Technical definition: The highest intensity at which blood lactate concentration stabilises instead of climbing indefinitely. Historically treated as the border between the heavy and the severe domain, it is determined through successive 30-minute stages, which makes it an expensive protocol in sessions burned. Cornerman note: The threshold everyone cites and almost nobody has measured. Set against critical power across ten studies, the mean difference is only 12 W, but the limits of agreement run from minus 19 to plus 44 W. And the answer depends on the protocol chosen: stage duration, lactate-rise criterion, number of breaks. Two labs, two answers, same cyclist.
mTOR (Mammalian Target of Rapamycin)
Technical definition: Major cellular signalling pathway regulating cell growth, proliferation and survival. The main trigger of protein synthesis (building muscle). Cornerman note: The get-huge button. It switches on when you lift heavy and eat protein. It switches off when you ride long (see AMPK). If you want muscle, cherish mTOR and stop disturbing it with pointless cardio.
N
Neuro-Mechanics
Technical definition: Training approach that treats the brain as a limiting biological component (“wetware”), on the same footing as the heart or the muscles. It builds neurotransmitter management (dopamine, noradrenaline) into effort planning. Cornerman note: Stop talking about mindset and willpower. Talk chemistry. Out of dopamine, you cannot push the pedal, even with legs full of glycogen. Neuro-mechanics is the art of hacking your own brain so it stops braking. Cornerman concept: house model, not a clinical entity.
NP (Normalized Power)
Technical definition: Algorithm that estimates the real physiological cost of a ride by accounting for variability. It crushes the zeros (coasting) and over-weights the intensity spikes (because they cost exponentially more). Cornerman note: The real power. Your average says 200 W but your NP says 260 W? You rode like an animal. Your body took the stress of 260 W, not 200 W. NP is what sets your actual fatigue.
O
Osmolarity
Technical definition: Measure of a solution’s concentration (particles per litre). To be isotonic (absorbed fast), a drink needs an osmolarity close to that of blood plasma (~290 mOsm/L). Cornerman note: Drink a syrup that is too sweet (>8 %) and it is hypertonic. Your body pulls water out of your blood to dilute it in your gut. Result: you dehydrate while drinking, and you finish in the toilet. Respect the dosages.
P
PGC-1α
Technical definition: Transcriptional coactivator that regulates the genes involved in energy metabolism. The master regulator of mitochondrial biogenesis. Cornerman note: The holy grail of endurance. It is the protein you are trying to make while you suffer on the bike. More PGC-1α = more mitochondria = more endurance. Chemical, not magical.
Polarised vs Pyramidal
Technical definition:
- Polarised: 80% of volume at low intensity, 20% at very high intensity. Almost nothing in the middle.
- Pyramidal: plenty of base, a fair amount of middle (sweet spot/threshold), little very high intensity. Cornerman note: The debate that excites physiologists. For you, an amateur with a job and 8 h of training a week? Polarised is often a fantasy. Pyramidal (and sweet spot) usually pays better on a tight schedule. Do not copy the training of a pro riding 25 h a week.
R
RDL (Romanian Deadlift)
Technical definition: Straight-leg (or near straight-leg) deadlift variation emphasising hip extension, targeting the hamstrings, the glutes and the spinal erectors. Cornerman note: The king of exercises if you would rather not have a flat arse and a wrecked back. A cyclist who skips RDLs is a back injury waiting to happen. Build your posterior chain, damn it.
RPE (Rate of Perceived Exertion)
Technical definition: Subjective effort scale (usually 1 to 10) used to self-regulate training intensity. Cornerman note: Your internal sensor. RPE 10 = “I can see the white light”. RPE 2 = “a stroll with grandma”. The problem is that most people lie. Your RPE 9 is often a real RPE 7. Learn to suffer for real before you use this scale.
S
Shrimp syndrome
Technical definition: Posture combining shoulder protraction, thoracic kyphosis and shortened pecs. Typical of cyclists, gamers and desk workers. Cornerman note: Look at yourself sideways in the mirror. If your shoulders sit further forward than your ears, you are a shrimp. It is ugly, it is un-aerodynamic and it is going to wreck your neck. Open your chest, pull some rows, stand up straight.
SSA (Abrasive Stimulation Threshold)
Technical definition: The minimum intensity (in watts or bpm) required for physical pain to outweigh the psychological pain of boredom in a fast-wired (ADHD) subject. Cornerman note: The point where your brain stops nagging you. Below it, you think about your tax return. Above it, you are in survival mode. For some riders zone 2 sits under the SSA, which makes it unbearable. You have to raise the watts to find quiet. Cornerman concept: house model, not a clinical entity.
SSD (Dopamine Saturation Threshold)
Technical definition: The point in time during a monotonous effort where endogenous dopamine production becomes too low to keep the prefrontal cortex engaged, producing a non-metabolic drop in power. Cornerman note: The boredom crash. Your legs are fine, your heart is fine, and you want to throw the bike in the ditch. That is not weakness, it is a neurotransmitter tank running dry. Cornerman concept: house model, not a clinical entity.
Sweet Spot
Technical definition: Intensity band sitting just under functional threshold (88-94% FTP). It offers a good balance between physiological stress and the fatigue it generates. Cornerman note: A lot of gain for not much pain. The magic band for anyone who cannot ride 4 h a day. It hurts, but you can hold it. That is where the diesel engine gets built.
T
TSC2 (Tuberous Sclerosis Complex 2)
Technical definition: Protein acting as a signal integrator. Activated by AMPK (energy stress), it inhibits mTOR. The molecular crossroads of the interference effect. Cornerman note: The cop who stops you being an elite marathoner and a pro bodybuilder at the same time. You work around him by spacing your cardio and your lifting.
TTE (Time To Exhaustion)
Technical definition: How long an athlete can actually hold their FTP. It generally runs from 30 to 70 minutes depending on training status. Cornerman note: The truth behind the number. A 300 W FTP is nice. Holding it for 28 minutes is a joke. You work on stretching the duration (TTE) before you go chasing more power.
V
Ventilatory thresholds (VT1, VT2, RCP)
Technical definition: Breaks in the slope of ventilation during an incremental test, used to locate the boundaries of the intensity domains without a blood sample. VT1 marks the first acceleration in ventilation and serves as the respiratory equivalent of the first lactate threshold. VT2, and the respiratory compensation point (RCP) that goes with it, aim at the upper boundary. Cornerman note: Convenient, non-invasive, and far rougher than you are told. Set against critical power across nine studies, VT1 underestimates it by 30 %, RCP overestimates it by 6 %, VT2 by 21 %. And VT2 is not even correlated with critical power. The marker you choose decides the answer you get.
VI (Variability Index)
Technical definition: Ratio of Normalized Power (NP) to average power (AvgP). VI = NP / AvgP. Cornerman note: The lie detector.
- VI = 1.00: you are a metronome (indoor trainer).
- VI < 1.05: a clean, steady endurance ride.
- VI > 1.20: chaos. Junk miles or a crit. If you meant to ride endurance with a VI of 1.25, you missed the session.
VO2 Max
Technical definition: The maximum rate of oxygen the body can consume during effort. The product of maximum cardiac output and the arteriovenous oxygen difference. Cornerman note: Your engine size. Largely genetic. You can improve it, but if you were born a Fiat Panda you will not finish a Ferrari. Sorry. That said, a well-tuned Panda beats a Ferrari driven by an idiot.
W
W/kg (watts per kilogram)
Technical definition: Ratio of the power produced to body weight. The main determinant of climbing performance. Cornerman note: Gravity’s pitiless law. You can hold 400 watts. At 110 kg you still get dropped on Alpe d’Huez by a 60 kg shrimp pushing 250. Either push harder or quit the beer. The maths do not lie.
W’ (W prime)
Technical definition: Finite quantity of mechanical work available above critical power, expressed in joules. Second parameter of the power-duration model. It drains above CP and recharges below. Cornerman note: Your anaerobic battery. Count 10,000 to 20,000 joules for an amateur. Far more for a puncheur, far less for a diesel climber. Two riders with the same CP and a different W’ are opposite animals: one holds the climb at a steady pace, the other puts 200 metres into you in a sprint then dies. Their FTP can be identical.
W’ balance (W’bal)
Technical definition: Second-by-second modelling of the state of the W’ reserve through a session. Discharge above CP, recharge below, with a recharge time constant slower than the discharge. Cornerman note: The live fuel gauge. A successful interval session takes the battery near zero on the last rep, not the second. Recoveries too short and the session dies halfway. Too long and you recharge everything, losing the cumulative stimulus. This gets calculated, not guessed.
Z
Zone 2
Technical definition: Low to moderate intensity, capped at the top by the first threshold (LT1), and approximated in practice at 55-75% of FTP or 60-70% of max HR. It stimulates fat oxidation and capillary development (Type I fibres). No consensus definition exists: a panel of fourteen experts had to publish a commentary in 2025 to try to fix one. Cornerman note: The ingredient everybody neglects because it is boring. If you cannot hold a conversation, you are going too fast. If you have an ego, you will go too fast. Two clarifications all the same: the percentages above are a stopgap, the only real landmark is your LT1; and the point of it is not being the best mitochondrial stimulus, it is being the only one you can repeat six times a week without paying for it.