GLOSSARY.

The highest average power a cyclist can sustain for approximately one hour, measured in watts. All seven training zones are calculated as percentages of FTP.

The maximum rate at which the body can consume oxygen during intense exercise. A key determinant of endurance cycling performance, typically measured in ml/kg/min.

A training intensity distribution where approximately 80% of training time is spent at low intensity (Zone 1-2) and 20% at high intensity (Zone 4+), with minimal time in the moderate 'grey zone' (Zone 3).

Training at 88-94% of FTP. Delivers a high training stimulus with manageable fatigue — the 'sweet spot' between threshold work and tempo riding.

Training at 56-75% of FTP — a conversational pace where the body maximises fat oxidation and builds mitochondrial density without accumulating significant fatigue.

Power-to-weight ratio — FTP divided by body weight in kilograms. The primary predictor of climbing speed and overall cycling performance on hilly terrain.

The exercise intensity at which lactate begins to accumulate in the blood faster than it can be cleared. Closely related to FTP and a key determinant of sustainable race pace.

The systematic planning of training into phases (base, build, peak, taper) to achieve peak performance at a target date. Each phase emphasises different physiological adaptations.

The stored form of carbohydrate in muscles and liver. The primary fuel for high-intensity cycling. Typical stores last 60-90 minutes of hard riding before depletion ('bonking').

A planned reduction in training volume (typically 40-60%) in the 1-2 weeks before a target event, while maintaining some intensity. Allows accumulated fatigue to clear without losing fitness.

Training at 91-105% of FTP. The highest intensity a cyclist can sustain for approximately 40-60 minutes. The primary zone for building time-trial fitness.

The gradual rise in heart rate during steady-state exercise at constant power. Typically 10-15 bpm over 2-3 hours. Indicates increasing physiological cost even though watts remain stable.

A planned recovery week with 40-60% reduction in training volume. Allows accumulated fatigue to clear while maintaining fitness. Typically scheduled every 3-4 weeks.

A weighted average of power that accounts for the physiological cost of variable-intensity riding. Always higher than average power for non-steady-state efforts.

A syndrome caused by insufficient caloric intake relative to exercise energy expenditure. Impairs performance, bone health, hormonal function, immunity, and mental health.

Pedalling speed measured in revolutions per minute (RPM). Most cyclists are most efficient between 80-100 RPM, though optimal cadence varies by terrain, power output, and individual physiology.

A single number quantifying the training load of a session, based on duration and intensity relative to FTP. 100 TSS ≈ riding at FTP for one hour.

Increasing carbohydrate intake to 8-12g per kg of body weight in the 24-48 hours before an event to maximise muscle glycogen stores.

The air resistance a cyclist must overcome, proportional to the square of speed. Above 25 km/h, ~80% of a rider's power goes to overcoming drag. The dominant performance variable on flat and rolling terrain.

A training session combining two disciplines back-to-back, typically cycling immediately followed by running. Essential for triathletes to practise the bike-to-run transition.

The duration a cyclist can sustain power at FTP before fatigue forces them to stop. Typically 30-70 minutes for trained cyclists. A key predictor of time-trial and breakaway performance.

A smart trainer feature that automatically adjusts resistance to maintain a target wattage regardless of cadence. Essential for precise indoor interval training.

The ratio of Normalised Power to FTP (NP/FTP). IF = 1.0 means you rode at your FTP. IF = 0.75 means an endurance ride. IF > 1.0 means you exceeded your FTP on average.

Exercising without eating beforehand, typically first thing in the morning. The 'train low' protocol deliberately restricts carbohydrate to stimulate fat oxidation and metabolic adaptations.

A subjective 1-10 scale of how hard an effort feels. Useful when power or heart rate data isn't available. Zone 2 = RPE 2-3, threshold = RPE 7-8, VO2max = RPE 9.

The foundational phase of a training plan emphasising high volume at low intensity (Zone 1-2). Builds aerobic capacity, mitochondrial density, and metabolic efficiency before intensity is added.

Structured periods of hard effort followed by recovery. The primary method for building VO2max, threshold, and anaerobic capacity. Examples: 4x4 min at 110% FTP, 2x20 min at 95% FTP.

A chronic state of performance decline caused by sustained training load without adequate recovery. Characterised by fatigue that persists despite rest, mood changes, elevated resting heart rate, and illness susceptibility.

The physiological principle where the body rebuilds stronger after a training stimulus, provided adequate recovery is given. The foundation of all training adaptation.

A chart of a cyclist's best power outputs across different durations (5s, 1min, 5min, 20min, 60min). Reveals rider type: sprinter, pursuiter, time triallist, or all-rounder.

The process of adjusting saddle height, reach, stack, cleat position, and cockpit dimensions to match a cyclist's body. Affects power output, comfort, injury risk, and aerodynamics.

Riding closely behind another cyclist to reduce energy cost by approximately 25-30%. The fundamental skill of group riding and racing.

The sudden, severe fatigue that occurs when muscle glycogen stores are depleted during exercise. Characterised by inability to maintain power, dizziness, confusion, and emotional distress.

The practice of progressively increasing carbohydrate intake during training rides to improve the gut's ability to absorb fuel at race intensity. Essential for achieving 60-90g/hr carb targets.

The highest power output that can be sustained without progressive fatigue. Closely related to FTP but derived from a mathematical model (power-duration curve) rather than a single test.

The exercise intensity at which lactate first rises above resting levels. Marks the top of Zone 2 and the transition from purely aerobic to partly anaerobic metabolism.

The gradual increase of training stress over time to drive continued adaptation. Applied by increasing volume, intensity, or frequency in structured increments.

The energy lost as a tyre deforms against the road surface. Lower rolling resistance = less wasted energy = faster at the same power. Affected by tyre pressure, width, compound, and surface.

A planned short-term state of accumulated fatigue from intentionally high training load. Performance drops temporarily but rebounds above baseline after recovery (supercompensation).

The deliberate distribution of effort across a ride or race. Negative split (starting conservatively and finishing strong) is the optimal strategy for most cycling events.

The maximal rate of lactate production in the body, measured in mmol/L/s. A high VLaMax favours sprinting and short efforts; a low VLaMax favours endurance and sustained threshold work.

Breakpoints in breathing rate during exercise. VT1 marks the first noticeable rise in breathing (bottom of aerobic threshold); VT2 marks the point where breathing becomes laboured (top of threshold/FTP).

The ratio of carbon dioxide produced to oxygen consumed during exercise. Indicates the fuel mix being used — RER 0.7 = pure fat, RER 1.0 = pure carbohydrate.

The elevated oxygen consumption that continues after exercise ends, as the body restores homeostasis. Often called the 'afterburn effect'.

The concentration of mitochondria (the cellular organelles that produce ATP from fat and carbohydrate) within muscle fibres. Higher mitochondrial density = better aerobic capacity.

The rate at which the body burns fat as fuel. FatMax is the intensity at which fat oxidation peaks — typically between 55-75% of VO2max for trained cyclists.

The fixed amount of work (in kilojoules) a cyclist can do above their critical power before fatigue forces a reduction. Alongside Critical Power, W' forms the two-parameter CP model.

A WKO5-specific metric representing the anaerobic work capacity above FTP. Conceptually similar to W' but calibrated differently.

The rise in heart rate over a steady-power effort, or the drop in power at a steady heart rate. High decoupling (> 5%) signals inadequate aerobic fitness for the duration.

The ability to maintain power output late in long rides — the fatigue resistance that separates strong amateurs from pros. Measured as power decline after 2000, 3000, 4000 kJ of work.

The point at which muscle and liver glycogen stores are exhausted, forcing a reliance on slower fat oxidation and causing a significant drop in sustainable power.

The total amount of energy a cyclist can produce from non-oxygen-dependent metabolic pathways. Expressed as W' or FRC, measured in kilojoules.

Training structured around short bouts of high-intensity work (typically above lactate threshold) separated by recovery. The broad category covers VO2max intervals, threshold work, and sprint intervals.

A specific type of HIIT consisting of very short (15-30 second) all-out sprints with long recovery intervals. Generates large VO2max and anaerobic adaptations in minimal time.

Training performed at intensities below the first lactate threshold (below VT1), typically zone 1-2. The foundation of the polarised training model.

A training model where high intensity precedes high volume — the opposite of traditional base-build-peak. Used when riders have limited off-season time or need early-season racing form.

A training approach that concentrates one training quality (e.g. VO2max, threshold, or endurance) into a 2-4 week focused block before moving to the next quality.

A classic micro-interval session: 30 seconds at VO2max (115-125% of FTP) followed by 30 seconds of easy recovery, repeated 10-20 times per set.

Threshold intervals that alternate between power above FTP (typically 105%) and power below FTP (typically 95%), without full recovery between. Builds lactate-shuttling capacity.

Very short intervals (15-40 seconds on / 15-30 seconds off) performed at high intensity for extended durations. Popular in elite training for accumulating time at VO2max.

The responsiveness of cells — particularly muscle — to insulin's signal to absorb glucose from the blood. Higher sensitivity means less insulin is needed to clear the same blood sugar, and more is available as muscle glycogen.

The preferred sugar ratio in modern endurance nutrition, enabling absorption rates of 90-120g of carbohydrate per hour by using two separate intestinal transporters in parallel.

A deliberate variation in day-to-day carbohydrate intake matched to training load — high-carb on hard days, lower-carb on easy or rest days — to balance performance and metabolic flexibility.

Dietary nitrate supplementation — most commonly via beetroot juice — used to improve oxygen efficiency, lower the cost of submaximal exercise, and extend time to exhaustion.

The performance-benefit curve of caffeine for endurance cycling. Research converges on 3-6 mg/kg body mass taken 30-60 minutes before exercise, with diminishing returns and rising side effects above 6 mg/kg.

The amount of sodium lost per litre of sweat — a highly individual metric ranging from around 200 mg/L to over 2000 mg/L, with direct consequences for hydration strategy and cramp risk.

The calories remaining for normal physiological function after subtracting exercise energy expenditure from dietary intake, expressed per kilogram of fat-free mass. Chronic EA below 30 kcal/kg FFM/day is the clinical cutoff for RED-S risk.

Exogenous ketone supplements (primarily ketone monoester) used by some pro cycling teams as a recovery and performance aid, raising blood β-hydroxybutyrate without requiring a ketogenic diet.

The distribution of daily protein intake across meals to optimise muscle protein synthesis. Research supports 20-40g of high-quality protein every 3-4 hours rather than large single doses.

The approximate 2.5-3g of the essential amino acid leucine required in a single meal to maximally activate muscle protein synthesis (via the mTOR pathway).

Creatine monohydrate — long known in power sports — is increasingly used by endurance cyclists for its cognitive, recovery, and glycogen-storage benefits, rather than as a sprint-power aid.

A training state where glycogen stores are deliberately depleted to amplify adaptations — commonly called 'train low, race high'. Must be programmed carefully to avoid RED-S.

The horizontal distance between the outside of the two crank arms, measured pedal-face to pedal-face. Determines how wide the rider's stance is on the bike.

The horizontal distance from the bottom bracket centre to the tip (or a reference point) of the saddle, measuring how far back the rider sits relative to the pedals.

The distance from the centre of the pedal axle to the centre of the bottom bracket. Standard road crank lengths range from 165mm to 175mm, with shorter cranks increasingly common for aero and biomechanical reasons.

The amount a tyre deflects under the rider's weight — expressed as a percentage of tyre width. The industry default is 15%, based on Frank Berto's research in the 1990s.

Two frame-geometry numbers that define the functional dimensions of a road bike independent of seat tube angle or top tube length. Stack is vertical; reach is horizontal.

The aerodynamic drag coefficient multiplied by the rider's frontal area — the single number that describes how much air resistance a rider generates at a given speed.

The ratio of chainring teeth to cog teeth, determining how far the bike travels per pedal revolution. Modern road bikes typically span from 1:1 (climbing) to 4.5:1 (flat TT).

The intentional flex engineered into a bike frame (particularly the seat stays, seat post, and fork) to absorb road vibration and reduce rider fatigue on rough surfaces.

The metabolic process of producing glucose from non-carbohydrate sources (amino acids, lactate, glycerol). Becomes significant when glycogen stores are depleted during long rides.

An amino acid supplement that increases muscle carnosine levels, buffering hydrogen ions during high-intensity efforts. Improves performance in 1-10 minute maximal efforts.

Consuming extra sodium (1,500-3,000mg) with fluid before a long event to expand plasma volume and delay dehydration.

The nutritional strategy in the 0-4 hour window after training. Priority: replenish glycogen (1-1.2g carbs/kg/hour), repair muscle (20-40g protein), and rehydrate (150% of fluid lost).

The rate of fluid intake during exercise, typically 400-800ml per hour. Overhydrating is as dangerous as underhydrating (hyponatraemia risk).

Volume of sweat produced per hour of exercise. Measured by pre/post-ride weighing. Typical range: 0.5-2.5 litres per hour.

The ability to oxidise fat at progressively higher intensities, sparing glycogen. Improved through zone 2 training and carbohydrate periodisation.

The fore-aft, lateral, and rotational placement of the cleat on the cycling shoe. Determines foot-pedal interface and knee tracking.

Outside-to-outside measurement of drop handlebars. Traditionally matched to shoulder width, but narrower bars (38-40cm) are increasingly popular for aerodynamic benefit.

Length of the stem connecting steerer tube to handlebars. Affects reach, handling, and weight distribution. Typical road: 80-130mm.

The projected area of cyclist and bike as seen from the front. The 'A' in CdA. Smaller frontal area = less air to push = faster.

Sustained riding at 76-90% of FTP (Zone 3). Harder than endurance, easier than threshold. Builds muscular endurance but sits in the polarised 'grey zone'.

Intensity distribution: most time in zone 1-2, moderate in zone 3, less in zone 4+. Forms a pyramid shape when plotted.

Training at the intensity where fat oxidation peaks — typically 55-75% of VO2max, corresponding to upper zone 2.

Measure of training load variability across a week. Mean daily load ÷ standard deviation. High monotony (>2.0) is a risk factor for overtraining.

Ratio of recent load (7 days) to chronic load (28 days). Above 1.5 = dangerous spike. 0.8-1.3 is optimal.

Weekly rate of increase in chronic training load (CTL). Above 5-7 TSS/day per week risks overtraining; 3-5 is sustainable.

Structured reduction in training load before a target event. Typical: 40-60% volume reduction over 7-14 days with maintained intensity.

The principle that training should progressively mimic target event demands. Climbing events need climbing intervals; crits need repeated sprints.

Non-cycling exercise (running, swimming, rowing) to maintain fitness, reduce overuse risk, and add variety — especially useful in the off-season.

Physiological adaptations from 7-14 days of heat training: expanded plasma volume, earlier sweating, lower core temperature. Improves performance in hot and temperate conditions.

Sleeping at altitude (1,800-2,500m) to stimulate red blood cell production. The 'live high, train low' model maximises haematological gains while maintaining training intensity.

Graph plotting maximum sustainable power against time (1 second to 4+ hours). Reveals strengths relative to overall profile.

42-day exponentially weighted average of daily TSS. Represents accumulated fitness.

7-day exponentially weighted average of daily TSS. Represents short-term fatigue.

Structured intensity ranges from FTP or lactate testing. Coggan 7-zone and Seiler 3-zone are the dominant frameworks.

Volume of blood pumped by the left ventricle per heartbeat. Higher = more oxygen per beat = lower HR at a given power.

Total blood volume pumped per minute. Stroke volume × heart rate. Primary determinant of VO2max.

Total haemoglobin in blood. More = more oxygen-carrying capacity = higher VO2max ceiling.

Liquid component of blood. Expands with endurance training and heat acclimation, improving thermoregulation and cardiac filling.

Fatigue-resistant fibres optimised for sustained aerobic work. High mitochondrial density, high capillary density, high fat oxidation.

Powerful, fast-contracting fibres that fatigue quickly. Type IIa are trainable toward endurance; type IIx are pure sprint fibres.

The process by which lactate from fast-twitch fibres is transported to and consumed as fuel by slow-twitch fibres, the heart, and the brain.

Primary ATP production pathway in mitochondria, using oxygen. Produces ~36 ATP per glucose — 18× more efficient than anaerobic glycolysis.

Anaerobic breakdown of glucose into pyruvate and ATP. Fast but inefficient (2 ATP per glucose). Dominant during sprints and above-threshold efforts.

Metabolic process breaking down fatty acids into acetyl-CoA for the Krebs cycle. The body's long-duration fuel pathway.

Number of capillaries surrounding each muscle fibre. Higher = better oxygen delivery + faster waste removal. Key zone 2 adaptation.

Glycogen stored within muscle fibres — primary fuel for moderate-to-high intensity cycling. Capacity: 300-400g in trained cyclists.

Glycogen stored in the liver (~100g / 400 kcal). Primary role: maintaining blood glucose for the brain. Depletes overnight and during fasted exercise.

Hypothesis that the brain limits exercise proactively to protect the body — reducing power before physiological systems actually fail.

Fatigue originating in muscles — fuel depletion, metabolite accumulation, contractile machinery failure. Distinguished from central (brain-mediated) fatigue.

Fatigue from reduced CNS motor neuron drive — the brain sends weaker signals despite muscles being capable of more work.

The nervous system's ability to recruit muscle fibres effectively. Higher efficiency = more power per unit of activation. Improves with training and strength work.

Oxygen cost of producing a given power. Better economy = less oxygen per watt = more sustainable power.

Orderly recruitment from smallest (type I) to largest (type II) motor units as force demand increases.

Central metabolic pathway in mitochondria processing acetyl-CoA from carbs and fat into electron carriers that drive ATP production.

Speed at which oxygen uptake rises at the start of exercise. Faster kinetics = quicker aerobic engagement = less anaerobic cost during transitions.