Triathlon Glossary: Terms, Units and Common Confusions

T1: the first transition, normally from swimming to cycling. T2: the second transition, normally from cycling to running. Both usually contribute to total race time.

Split: the time recorded for a segment or between timing points. Chip time: elapsed time using the event's individual timing detection. Gun time: time measured from the designated start signal. Check which the event uses for results and cutoffs.

DNS: did not start. DNF: did not finish. DSQ or DQ: disqualified under the applicable rules. These labels describe a result status, not why it occurred.

Wave start: groups start separately. Rolling start: athletes start progressively through a defined process. Read how triathlons work for the timing implications.

Sprint, standard, middle and full distance: common event categories; use the distance table and verify the actual course.

70.3 and 140.6: approximate combined mile distances associated with IRONMAN event branding. Age group: a competition category based on the event's age rules. Elite or professional: a separate competition status with its own eligibility.

Slot: a place offered for another event, commonly a championship. Roll-down: an allocation opportunity moving under the rules when an eligible athlete does not accept. Age grading: comparing performance using an age-related standard; it is not simply raw-time ranking.

Use the qualification explainer for the process and current-source checks.

RPE: rating of perceived exertion, a subjective effort scale. State which scale is used; a number out of ten is not the same as a number on another scale.

Easy or aerobic session: a manageable effort used for the stated training purpose; exact zone definitions vary. Interval: a defined work period separated from another by recovery. Tempo and threshold: coaching labels whose precise meaning depends on the system.

Brick: two disciplines linked in one session, commonly bike then run. Taper: reducing training load before competition. Periodization: organising emphasis over time. Recovery week: a period of reduced demand, defined relative to the preceding work.

Read training basics before treating these labels as fixed prescriptions.

FTP: functional threshold power, a practical cycling estimate usually expressed in watts. A test-derived FTP is not identical to every laboratory threshold. W/kg: watts divided by rider mass in kilograms, with the mass convention stated.

VO2 max: maximal oxygen uptake, often expressed as mL/kg/min. A watch estimate differs from a laboratory measurement. Heart rate: beats per minute, abbreviated bpm.

Cadence: pedal revolutions per minute on the bike or commonly total steps per minute while running. Swimming stroke-rate conventions can count arms or cycles. Pace: time per unit distance, such as min/km or min/100 m. Speed: distance per time, such as km/h.

Use the cadence explainer and pace calculator to avoid unit errors.

Chainring: the toothed ring at the crank. Cassette: the rear set of sprockets. Gear ratio: front teeth divided by rear teeth. Derailleur: the mechanism that moves the chain between gears.

Aero bars: extensions or supports used for a particular riding position, subject to event rules. Clipless pedals: pedals that retain a matching shoe cleat despite the confusing name.

Tubeless: a compatible tire system that holds air without a conventional inner tube, often using sealant. Hookless: a rim bead-interface design with specific tire and pressure requirements. Tubular: a different tire construction bonded to a compatible rim.

Psi and bar: pressure units. A maximum is a limit, not the target setting. Use tire-pressure guidance for the full system check.

Carbohydrate: a fuel nutrient counted in grams, often planned per hour during longer exercise. Serving: the amount defined by a food label, which may differ from a whole packet.

Electrolytes: minerals involved in fluid balance and other functions. Sodium: one electrolyte commonly listed in milligrams. Sodium grams and salt grams are not interchangeable.

Sweat rate: estimated sweat volume per unit time, commonly L/h; it does not measure sweat sodium concentration. Hyponatremia: abnormally low blood sodium, which can occur with excessive fluid intake during endurance exercise and requires appropriate medical assessment.

Aid station: official on-course support. Personal-needs bag: an event-specific system for collecting personal supplies where offered. Read race fueling and hydration for the practical decisions.

Find the original context in the plan, manual or athlete guide. Write the full term and unit, then ask what decision it is supposed to inform. A glossary definition cannot override the current event rule or manufacturer specification.

If two coaches use the same label differently, ask for the intended effort and recovery rather than arguing over the label. If a product uses “compatible,” verify the exact models and conditions.

Save the explanation you need beside your own plan. The useful result is understanding the instruction well enough to act on it, not memorising every abbreviation in the sport.

Consider the illustrative note “Bike 60 min easy, then T2 practice and 10 min easy run; record RPE.” Bike and run identify the disciplines; T2 means the bike-to-run transition; RPE means rating of perceived exertion. The note does not specify a universal numerical intensity scale, so check which scale the plan uses.

A note saying “3 × 5 min at threshold” still needs recovery duration, warm-up and cool-down instructions. Knowing the word threshold does not supply the missing session design. Likewise, FTP in watts is different from a pace in minutes per kilometre, even when both help describe intensity.

When a term remains ambiguous, copy the full sentence and ask the author, coach or organiser what it means in that context. This is especially important for rules: a glossary can explain a draft zone, but only the controlling rulebook specifies its dimensions, timing and penalties for your event.

Bilateral breathing: breathing to both sides during freestyle practice. It can be useful for awareness or adapting to conditions, but athletes do not have to breathe every third stroke to swim safely or efficiently. Sighting: a brief look forward to check direction in open water. Drafting in the swim: swimming behind or beside another swimmer to reduce disturbance; event conduct rules still apply. Wetsuit-legal: a status set by the governing body or organizer under its temperature and category rules; it does not mean every athlete must wear a wetsuit.

Swimskin: a close-fitting swim garment used in some non-wetsuit settings when permitted; it is not a wetsuit. Mass start, wave start and rolling start: different methods for sending athletes into the swim. The event guide explains which one applies and how timing is recorded. Buoy line: the course direction between marked turn or sighting buoys; a swimmer should follow the official course rather than infer a shortcut.

Definitions explain terms, not individual safety. Open-water conditions, supervision, visibility and health can change whether a swim is appropriate.

Aerobars or tri bars: extensions that allow a rider to rest forearms forward on a compatible bicycle. Their legality and configuration depend on race format and rulebook. Aero position: a posture intended to reduce frontal area; it must still allow safe control, breathing and access to brakes. Draft zone: a rule-defined space behind or beside another competitor in some non-drafting events.

Hookless rim: a rim profile without an inward-facing bead hook. It must be paired only with tires and pressures approved by the wheel maker. Tubeless-ready: a tire or rim designed for a tubeless setup when used with compatible components and instructions. Sealant: liquid used in some tubeless systems to help close small punctures; it does not repair every cut or remove the need for a fallback.

Drip wax, hot-melt wax, wet lube and dry lube: broad lubricant types with different preparation and maintenance instructions. Do not mix them without checking product compatibility. Chain wear: material wear measured with an appropriate tool or mechanic; noise alone does not establish how worn a chain is.

RPE: rating of perceived exertion, a personal description of effort. The scale used may be numeric or verbal; check how the plan defines it. Heart-rate zone: a range within a particular model, such as maximum-heart-rate or threshold-based zones. Zone labels differ between systems. FTP: functional threshold power, a cycling training estimate defined by a particular test or platform; it is not necessarily a laboratory threshold.

TSS or training stress score: a platform-specific estimate combining duration and intensity. CTL, ATL and TSB: terms used by some platforms for modeled chronic load, acute load and form or freshness. These are calculations with assumptions, not direct measurements of fitness, fatigue or injury risk.

Brick workout: a session that combines two disciplines, often a bike followed by a run, to practise the transition. Taper: a planned reduction in training load before an event. Deload or recovery week: a period with adjusted training to manage fatigue; its structure is individual rather than a mandatory universal ratio.

T1: swim-to-bike transition. T2: bike-to-run transition. Both usually count toward elapsed race time. Mount line and dismount line: marked points where athletes must get on or off the bicycle under the event’s rules. Their location and the related procedures are race-specific.

Cutoff: a deadline to complete a course segment or finish. Check whether it is tied to an individual start, wave start or time of day, and whether it includes transition. DNF: commonly “did not finish,” but official result labels and withdrawal procedures vary. Penalty box: a designated place where an athlete may be required to serve a rule penalty; the location, duration and process depend on the event.

Special-needs bag: a bag placed at a designated course point when an event offers that service. Aid station: an organizer-operated location with specified supplies. Its products, location and athlete access rules vary; do not assume another event uses the same setup.

Carbohydrate intake: the amount of carbohydrate consumed, often counted in grams. A label’s serving size may not equal a whole packet. Gut training: gradual practice with an athlete’s chosen fueling approach; it does not mean pushing through nausea or ignoring medical symptoms. Electrolyte: a mineral such as sodium that has physiological roles; a supplement is not automatically required during exercise.

Sweat rate: an estimate of fluid lost through sweat over a period under particular conditions. It can vary by temperature, clothing and effort and does not create one fixed race drinking target. Exercise-associated hyponatremia: a potentially serious low blood sodium condition associated with prolonged exercise and often excessive fluid intake relative to losses; symptoms require medical assessment.

REDs: Relative Energy Deficiency in Sport, a health framework describing consequences of inadequate energy availability. It can affect athletes of any gender. A glossary entry cannot diagnose REDs; consult a qualified clinician or sports dietitian for individual concerns.

Write the unit beside every number. Kilometres and miles, watts and watts per kilogram, milligrams and grams, minutes per kilometre and minutes per mile describe different quantities. A value without its unit or reference point may be impossible to interpret. Check whether a bottle label reports a serving, container or prepared mixture.

Distinguish a measured value from an estimate. A watch’s maximum-heart-rate prediction, a calculator’s finish time and a platform’s training-load score use models. Record the method and assumptions; do not treat the result as a direct observation of physiology. Use current manufacturer or event documentation for product specifications and race rules.

When an acronym is unfamiliar, look at the sentence around it and identify the decision it is meant to inform. If it changes a medical, safety or rule decision, find the primary source rather than relying on a generic definition.

Start with the source that controls the decision: an event rulebook for race conduct, a manufacturer manual for equipment, a clinician or professional organization for health guidance, and the method notes for a calculator. Check edition date, jurisdiction, category, units and assumptions. If two sources disagree, the responsible authority or qualified professional can clarify the scope.

A useful note contains the full term, plain-language meaning, unit, source and date checked. Keep a separate note for local rules that may change annually. Avoid copying acronyms into a plan without confirming their intended meaning; “zone 2” and “easy” are not interchangeable in every model.

For foundational context, see what is a triathlon, triathlon distances and the rules guide. The glossary supports those pages but does not replace them.

Training files often combine pace, speed, heart rate, power, distance and duration. Pace usually describes time per unit distance, such as minutes per kilometre or mile; speed describes distance per unit time. The values move in opposite directions, so a smaller pace number means faster running while a larger speed number means faster movement. Confirm whether an app displays kilometres or miles before comparing workouts.

Heart rate is typically reported as beats per minute. It is an estimate of internal cardiovascular response and can shift with heat, stress, sleep, medication, hydration and sensor fit. Power is a measure of mechanical output from a cycling meter or trainer, usually shown in watts. It depends on the device and conditions and should not be compared casually across different meters without understanding calibration and setup.

A percentage can mean different things depending on its reference. A workout at 80 percent of maximum heart rate differs from one at 80 percent of threshold power. A plan should state the basis. RPE, or rating of perceived exertion, is a subjective effort scale; check the scale definition because some systems use numbers while others use descriptive categories. “Easy” should be interpreted using the plan’s context and the athlete’s experience.

When a workout note is unclear, ask what the target measures, which units are intended, how long the effort lasts and what recovery follows. Do not convert a pace, power or heart-rate target from another athlete without accounting for individual testing and conditions. A useful training term is one that supports a clear decision, not one that looks precise.

Race terms can have operational meanings. A cutoff is a deadline set by the event, while a split is a recorded time at a timing point. A wave or rolling start describes an entry format, but the organizer’s procedure determines how timing begins. Transition can mean the change between sports or the designated area; an athlete guide may use it in a narrower way. Drafting refers to riding within a defined zone under a particular rulebook, and the distance and passing process depend on the event.

Health terms also require context. “Dehydration,” “heat illness,” “low energy availability” and “overtraining” are not interchangeable descriptions of feeling tired. An online glossary cannot diagnose a condition. If a term appears in a clinical report, supplement label or race policy, use the source document and ask a qualified professional when the meaning affects a decision.

Units need the same care. Milligrams and grams differ by a factor of one thousand; millilitres measure volume, while grams measure mass. A bottle’s volume does not tell you the amount of carbohydrate or sodium unless you check its label. A temperature in Fahrenheit is not directly comparable to Celsius. Confirm units before using a calculator or packing plan.

Use the original source for rules, medical advice and product specifications. A glossary is a starting point for understanding words, not authority for a race decision. When a term is used differently by two apps, coaches or governing bodies, record the definition in the relevant context. That habit prevents a familiar word from creating a mistaken assumption.