The biathlon is an athletic event that combines cross-country skiing with rifle shooting. The event's combination of cycles of rigorous cardiovscular exertion of skiing, followed immediately by the need for controlled breathing and steady nerves necessary for target shooting, is very challenging and demands a high level of physical fitness.

A biathlon is a form of duathlon, a generic term that refers to a sporting event that is made up of two different athletic disciplines. However, the term biathlon refers to the specific wintertime combination of skiing and rifle shooting. A summertime biathlon also exists, which comprises cross-country running and rifle shooting.

The origin of the biathlon was as a military training tool for soldiers in Norway's army. Centuries ago, when today's armored machinery was nonexistent, it was advantageous for Norwegian soldiers to learn how to quickly move about and do battle in the winter. Cross-country skiing would allow troops to move relatively swiftly and silently through rough terrain. When in position, they could use the rifles strapped to their backs for offensive or defensive action.

This military training grew to include competitions. The first-known example was in 1767, and involved border guards from Norway and Sweden. As time went on, these competitions expanded to include rifle and ski clubs throughout Norway and other Scandinavian countries, and Switzerland. Aside from the pleasure of competition, the sport kept club members, many of whom could be called up for active military service, fit and trained.

Biathlon first appeared at the Winter Olympics as a demonstration sport in 1924. Then, it was known as "military ski patrol." By the next Olympics in 1928, the sport had been approved as an official medal sport.

In the early appearance of the Olympic biathlon, only a few Scandinavian countries participated in the sport. As well, there were few agreed-upon rules. The biathlon languished and was dropped from the Olympics after the 1948 competition.

Rather than the signal of the sport's demise, its exclusion from the Olympics galvanized resolve to organize the biathlon. In 1948, the Union Internationale de Pentathlon Modern et Biathlon was formed to standardize the rules governing both the biathlon and pentathlon (a sport involving five track and field events).

A biathlon world championship was held in 1957, and the sport returned to the Winter Olympics in 1960 as a men's event and in 1992 as a women's event.

In its original form, the biathlon consisted of a skiing over a 12.2-mi (20 km) course with four target-shooting stops between the fifth and eighteenth kilometers. At the first and third stops, each competitor shot while lying down. Then, the target was 9.8 in (25 cm) in diameter with an inner 4.9 in (12.5 cm) diameter ring. At the second and fourth stops, shots were taken while the competitor was standing. Then, because aiming the rifle was more difficult, the target was larger; a 17.7-in (45 cm) outer ring with an inner ring of 13.7 in (35 cm) in diameter.

In more recent times, while the prone and standing shooting positions have been retained, the targets have been modified. As of the early 2000s, during each round of shooting, a competitor tries to hit five 1.7-in (45 mm) diameter targets positioned 4.5 in (115 mm) off of the ground and 164 ft (50 m) away, with only one shot per target permitted.

The object of the biathlon is to complete the course in as short a time as possible. Shooting accuracy contributes to a quick time; originally, a shot that hit the outer rings of either target added one minute to a competitor's time, while missing a target entirely added an extra two minutes. Currently for each one of the five targets missed, a competitor either has one minute added to the time or must ski around a 492-ft (150 m) penalty oval (each lap takes elite athletes from 20 to 30 seconds to complete), prior to reentering the race course. As well, a competitor is supplied with three extra rifle cartridges that he/she can use to hit a missed target without incurring a penalty. Once these extra cartridges have been used, penalty times/laps apply for any additional missed target.

During the cross-country portion of a biathlon, athletes must carry their rifle and ammunition. As with other athletic equipment, biathlon rifles have been especially designed for the competition. The rifle stock is typically hollow to reduce the gun's weight. No automatic or semiautomatic rifles are permitted; the rifle must be manually reloaded between shots.

Modern Olympics added more varied distances and team relay events to the biathlon schedule. These include a sprint of 6 mi (10 km) for men and 4.6 mi (7.5 km) for women; individual 12.4 mi (20 km; men) and 9.3 mi (15 km; women); races where competitors begin separately; mass start races of 9.3 mi (15 km; men) and 7.7 mi (12.5 km; women); relays consisting of teams of four competitors who each ski 4.6 mi (7.5 km) and have two target stops; and pursuit races of 7.7 mi (12.5 km; men) and 6 mi (10 km; women). In the latter, athletes begin the race according to their finishing times in a previous race, with slower competitors starting first. The object is to catch up and pass competitors during the race.

Biathlon largely remains a sport of more northerly nations, although at the 1987 Calgary Olympics one competitor represented Puerto Rico.

SEE ALSO Beta-blockers; Shooting.