Age Group - Refers to non-professional participants in races.  So called because participants officially compete against other racers in the same age ( usually within 5 or 10 year brackets) and sex.

Aluminum - Light-weight metal used in bike frame construction.  Generally lighter than steel, but not as strong. Thus, "oversized" tubing is used to create strong yet light-weight bike frames.

Aero/Aerodynamic- A description usually applied to bikes, but is applicable to any design or modification that reduces wind-drag and results in an object traveling faster through air using the same amount of energy.

Aero Bars - Handle bars that stretch the rider out over the wheel and lowers the body closer to the bike frame, resulting in less  surface area and, thus, less wind-drag.

Aero Wheels - Generally, any wheel design that eliminates spoke count, presents a more narrow surface contact (i.e. the internal edges of the wheel are sharper, the blades are flatter) and creates less wind drag.

Aerobic- Exercising where the muscle cells have sufficient oxygen.

Anaerobic- Exercising (or performing any physical activity) where the muscle cells lack sufficient oxygen.  Example:  sprints. 

AT- Anaerobic Threshold.  This is the physical point in exercise where oxygen consumption results in lactic acid production exceeding lactic acid removal. 

ATP- Adenosine TriPhosphate is the basic compound that muscles burn to make energy (carbohydrates, fat, everything is broken down to this compound for energy production).

Biathlon - A dual-sport event, commonly existing of a bike and run race.  Can be any two sports.

Bi-lateral Breathing - The act of taking breathes from alternate sides of the body while swimming.  Most swimmers have a predominate side from which they take their breathes, but bi-lateral breathing helps increase balance in the water and is useful if waves are "breaking" over one side.

Brick- The combination of a Bike and Run work-out.  Used to simulate race conditions, allows racers to acclimate to the feelings of moving rapidly from a cycling motion to a running motion.

Cadence - The measurement of a certain revolution.  Generally applied to pedal rotations per minute, or in running, strides per minute. 

Carbon/Carbon Fiber - A very light and very strong material "adopted" by the cycling community to help create equipment while shaving weight. Used in manufacturing various pieces of equipment from bike frames, to cranks, to handlebars, to soles of cycling shoes, to wheels, etc. 

Chainrings- The discs with teeth on the bike that are turned by the pedals.  The chain wraps around the rings, locked in place by the teeth.  Rotation of the rings causing the chain to revolve which, in turn, rotates the rear wheel.

Clincher - A type of bike tire which has a u-shape on a cross-section.  The tube is inserted into the tire, and the tire is then mounted onto the wheel and held in place by hooking the beads (the ends of the "u") under lips going around the outside edges of the wheel. 

Cool Down - The period after a work-out where the person is still exercising, but at a slow and relaxed pace so as to allow the muscles to pump out some of the lactic acid.  

Cranks - These bike components are the "arms" between the pedals and the chainrings which transfer the pedal motion to the chainrings.

Cycle Computer - A device generally mounted onto the bike's handlebars which provides feedback to the rider, possibly including speed, cadence, distance, etc.

Derailleur - A bike component that rests over the chainrings (front derailleur) and over the gear cluster (rear derailleur).  the purpose is to lift and lower the chain onto a new gear ring.

Disc Wheels - A wheel that has no spokes, but is instead has a disc "face".  This design eliminates wind drag created by spokes - but it also catches cross-winds. 

Drafting - The act of following very close behind the person in front. In cycling this reduces wind resistance, thus making cycling easier and faster - it is also banned in most events (except the Olympics and draft-legal I.T.U. events).   In swimming, the act of swimming right behind the toes of another swimmer - cuts down on water drag.  Generally, this is legal in all races.  In running, following right behind another runner - also helps cut down on wind drag and is very helpful when running into headwinds.

Duathlon - A dual sport event generally consisting of three stages.  Most common structure is a run-bike-run format.

Ergo - A prefix used to describe equipment designed with the interaction of the human body in mind.  

Fartlek - Means "speed play" and is a form of speed workouts in running similar to interval training.

Gear Ratio - The number of teeth in the front chain ring - to - the number of teeth in the rear gear.  Generally, the larger the ratio, the harder the legs must work to turn the wheel; the smaller the ratio, the easier it will be to "spin".

Goggles - Eye coverings used in swimming; often fogs up during swims, kicked/hit off during mass starts; left behind after practice.  Good goggle fit is important for comfort and to avoid water leaking into the goggles and irritating the eyes.

Half-Ironman Distance - Refers to a race with the following events: 1.2 mile swim; 56 mile bike and 13.1 mile run.  Popular local races of this distance include Wildflower and the Half-Vineman.

HRM / Heart Rate Monitor - A device that, as the name implies, monitors the heart rate of the person wearing it during exercise. Gaining fast popularity in both training and racing.

Hypothemia - The condition where the body's core temperature falls dangerously low.  While this can occur in any of the three classic triathlon events, it is most common in cold water swimming.  A wetsuit and/or neoprene swim cap can help slow down hypothermia.

Intervals - A speed workout that is composed of running faster paces mixed with slower paces.

Ironman Distance - The race distance named (and trademarked) after the original Hawaii Ironman. Owned by the WTC, the name refers to a triathlon consisting of a 2.4 mile swim, a 112 mile bike and a 26.2 mile run (marathon). 

Ironman Qualifier - Designates a race which offers qualifying spots to the Hawaii Ironman World Championship.  These qualifying spots are generally handed out to age-group winners and top finishers.

ITB - Ilio-Tibial Band.  This is a long tendon band that stretches from the buttocks, down the outer length of the leg.  Since the band stretches across the outside of the knee, tension along the band may cause it to rub against the knee, resulting in inflammation - a painful  condition called ITB Syndrome.

I.T.U. - The International Triathlon Union.  This is a governing body that oversees and regulates races across the world.  Generally, I.T.U. points are used to determine world champions.

Kick Board - A floatation device used in swim training.  Generally held in front of the body to keep the torso afloat so as to allow the swimmer to concentrate on kicking exercises.

Lactic Acid - A by-product of muscles burning ATP for fuel. Causes the burning feelings in muscles and results in fatigue.

LSD - Long Slow Distances - used to describe longer runs art a slower pace.  Helpful in building a distance base.

Maximum Heart Rate - Literally the highest heart rate that a person's heart can beat. Gradually decreases with age.

Negative Split - The measurement where the second half of an event is completed faster than the first half (e.g. in a marathon, the first 13.1 miles at 1:45, while the second 13.1 miles are run at 1:42:30.)

Olympic Distance - A race consisting of the following events: a 1.5 km swim, a 40 km bike and a 10 km run. Named after the distances of the actual Olympic triathlon.

Pull Buoy - A swim training device.  Generally a figure-8 shaped floating material that is held between the swimmers thighs.  This allows the legs to be kept afloat without any kicking action, allowing the swimmer to concentrate on arm exercises.

Rollers -  An in-door cycling training device.  Consists of a rectangular frame with three cylinders. Allows a rider to set up her/his bike on a roller with the front wheel resting on one cylinder and the rear wheel resting between two cylinders.  As the wheels turn, the cylinders turn - allowing the rider to pedal the bike but remain stationary. The bike is not fixed to anything, the rider balances the bike while spinning on the rollers.  

Sew-Ups - See "Tubulars" below.

Sprint - Anerobic running, generally on track.  Can be maintained for short distances.

Sprint Distance - Generally, any race with distances that are shorter than an Olympic Distance.

Steel - Formerly, the most common material used in bike frames.  Classic frame-makers such as Pinarello, Colnago, De Rosa, etc. all used steel.  Now, as many manufacturers are trying to find ways to decrease the weight of bikes, lighter materials such as carbon, titanium and aluminum are being utilized.

Tangents - Generally referred to in road racing (bike or running), when the racer takes the straight line across a curve - thus eliminating the added distance created by the curve.  Maybe illegal in some races - depending upon course markings/rules.

Titanium - A light metal being used in bike manufacturing.

Tubulars / Sew-Ups - A type of tire which has the tube encased in the tire which is then "sewn" shut.  The whole tri/tube is then glued onto a tubular wheel set.

USAT - U.S.A. Triathlon - this is the United States' governing body of triathlons.  Generally will sanction races and provide guidelines/rules.  Also licenses race participants. 

VO2 Max - The maximum amount of oxygen that a human body can utilize in one minute.

Warm Up - A slow, easy pre-exercise workout that allows blood to flow into the muscles, making them more flexible and less prone to injury. 

Wind Trainer - An indoor training device for bicycles.  Generally, the rear wheel is locked into place onto a cylinder.  The front wheel can be left on or removed and the forks mounted to a clamp (depending upon make and model).  As the rider pedals, the wheel causes the cylinder to rotate.  Sometimes fans or magnets are connected to the cylinder to provide a means of resistance, thus making the work-out more challenging.