Swimming plan: Swimming

Swim styles
In competitive swimming, four major styles have been established. These have been relatively stable over the last 30–40 years with minor improvements. They are:

• 
  Butterfly
  
• 
  Backstroke
  
• 
  Breaststroke
  
• 
  Freestyle
  

In competition, only one of these styles may be used except in the case of the individual medley, or IM, which consists of all four. In this latter event, swimmers swim equal distances of butterfly, then backstroke, breaststroke, and finally, freestyle.^[13] In Olympic competition, this event is swum in two distances – 200 and 400 meters. Some short course competitions also include the 100-yard or 100-meter IM – particularly, for younger or newer swimmers (typically under 14 years) involved in club swimming, or masters swimming (over 18).
Dolphin kick
Since the 1990s, the most drastic change in swimming has been the addition of the underwater dolphin kick. This is used to maximize the speed at the start and after the turns in all styles. The first successful use of it was by David Berkoff. At the 1988 Olympics, he swam most of the 100 m backstroke race underwater and broke the world record in the distance during the preliminaries. Another swimmer to use the technique was Denis Pankratov at the 1996 Olympics in Atlanta, where he completed almost half of the 100 m butterfly underwater to win the gold medal. In the past decade, American competitive swimmers have shown the most use of the underwater dolphin kick to gain advantage, most notably Olympic and World medal winners Michael Phelps and Ryan Lochte; however currently swimmers are not allowed to go any further than fifteen metres underwater due to rule changes by FINA.^[14] In addition, FINA announced in 2014 that a single dolphin kick can be added to the breaststroke pullout prior to the first breaststroke kick.^[15]
While the dolphin kick is mostly seen in middle-distance freestyle events and in all distances of backstroke and butterfly, it is not usually used to the same effect in freestyle sprinting. That changed with the addition of the so-called "technical" suits around the European Short Course Championships in Rijeka, Croatia in December 2008. There, Amaury Leveaux set new world records of 44.94 seconds in the 100 m freestyle, 20.48 seconds in the 50 m freestyle and 22.18 in the 50 m butterfly. Unlike the rest of the competitors in these events, he spent at least half of each race submerged using the dolphin kick.^[16]
Competition pools
A simplified diagram of the World Aquatics long course swimming pool standard, used at the World Championships and Summer Olympics
World Championship pools must be 50 metres (160 ft) (long course) long and 25 metres (82 ft) wide, with ten lanes labelled zero to nine (or one to ten in some pools; zero and nine (or one and ten) are usually left empty in semi-finals and finals); the lanes must be at least 2.5 metres (8.2 ft) wide. They will be equipped with starting blocks at both ends of the pool and most will have Automatic Officiating Equipment, including touch pads to record times and sensors to ensure the legality of relay takeovers. The pool must have a minimum depth of two metres.^[17]
Other pools which host events under World Aquatics regulations are required to meet some but not all of these requirements. Many of these pools have eight, or even six, instead of ten lanes and some will be 25 metres (82 ft) long, making them Short course. World records that are set in short course pools are kept separate from those set in long course pools because it may be an advantage or disadvantage to swimmers to have more or less turns in a race.
Seasons
Competitive swimming, from the club through to international level, tends to have an autumn and winter season competing in short course (25 metres or yards) pools and a spring and summer season competing in long course (50-metre) pools and in open water.
In international competition and in club swimming in Europe, the short course (25m) season lasts from September to December, and the long course (50m) season from January to August with open water in the summer months. These regulations are slowly being brought to competition in North America.
As of right now, in club, school, and college swimming in the United States and Canada, the short course (25 yards) season is much longer, from September to March. The long-course season takes place in 50-meter pools and lasts from April to the end of August with open water in the summer months.
In club swimming in Australasia, the short course (25m) season lasts from April to September, and the long course (50m) season from October to March with open water in the summer months.
Outside the United States, meters is the standard in both short and long course swimming, with the same distances swum in all events. In the American short course season, the 500-yard, 1000 yard, and 1650-yard freestyle events are swum as a yard is much shorter than a meter (100 yards equals 91.44 meters), while during the American long course season the 400 meter, 800 meter, and 1500-meter freestyle events are swum instead.
Beginning each swimming season racing in short course allows for shorter distance races for novice swimmers. For example, in the short course season if a swimmer wanted to compete in a stroke they had just learned, a 25-yard/meter race is available to them, opposed to the long course season when they would need to be able to swim at least 50 meters of that new stroke in order to compete.
Officials
There are several types of officials,^[18] which are needed to manage the competition.^[19]
Referee: The referee has full control and authority over all officials. The referee will enforce all rules and decisions of World Aquatics and shall have the final answer to all questions relating to the actual conduct of anything regarding the meet, as well as the final settlement of which is not otherwise covered by the rules. The referee takes overall responsibility for running the meet and makes the final decisions as to who wins each race. Referees call swimmers to the blocks with short blasts of their whistles. This is the signal for the swimmers to stand next to their blocks. Then the referee will blow a long whistle that will tell the swimmers to step on the block. For backstroke events, the long whistle is the signal for the swimmers to jump into the water. The referee will then blow another long whistle, signalling the swimmers to grab the gutter or the provided block handle. Finally the referee will hand over the rest to the starter by directing their hand to the starter.
Starter: The starter has full control of the swimmers from the time the referee turns the swimmers over to them until the race commences. A starter begins the race by saying, "Take your mark." At this point, the swimmers will get into stationary positions, sometimes known as "point zero", in which they would like to start their race. After all swimmers have assumed their stationary position, the starter will push a button on the starting system, signaling the start of a race with a loud noise (usually a beep or a horn) and flash from a strobe light. A starter sends the swimmers off the blocks and may call a false start if a swimmer leaves the block before the starter sends them. A starter may also choose to recall the race after the start for any reason or request the swimmers to "stand", "relax" or "step down" if they believe that (a) particular swimmer(s) has gotten an unfair advantage at the start.