1. What's that white powder the gymnasts use? Alex Livesey / Getty Images That's magnesium powder. It gets rid of the moisture on the gymnasts' hands and reduces their risk of falling. The chalk reduces friction with the bars, pommels, and everything else the gymnast might come in contact with, keeping their hands dry and slippery. 2. In the long jump, how is distance measured? The sand pit is always a complete mess after they jump. Adrian Dennis / AFP / Getty Images It's actually pretty simple: what counts is the beginning of the mark they leave. In other words, the part that is closest to where they jumped from. That's why athletes jump with their arms and legs facing forward. None of the marks they leave beyond that matter, only the one they leave where they first land. 3. Can synchronized swimmers even hear the music that's playing during their routines? Christophe Simon / AFP / Getty Images Yes, they can. There are speakers placed underwater specifically for this purpose. Margaux Chretien, a French swimmer who tested Rio's pools for the Olympics, says that "listening to music underwater isn't like using headphones, but it still allows you to hear clearly." 4. Why do some swimmers slap themselves? Tap to play or pause GIF Tap to play or pause GIF youtube.com For many swimmers, this is just a ritual to calm their nerves. Others say that slapping themselves also releases endorphines, and boosts circulation. 5. And why do some swimmers wear two swimming caps? Christophe Simon / AFP / Getty Images The idea is to keep their goggles on tight. The second cap goes on top of the rubber straps and holds them on the swimmer's head. This tactic also keeps the goggle straps from getting tangled with the swimmers' hair. 6. What are those bruises the American athletes have? Lam Yik Fei / Getty Images Though they may look like bruises, the purple spots that appear on some athletes, like Michael Phelps, are from a treatment known as "cupping." Basically, it's a technique that dates back millennia in which small suction cups are placed on the athlete's skin to stimulates blood flow and relax muscles, naturally accelerating recovery. 7. What is the temperature of the water in Olympic pools? Richard Heathcote / Getty Images According to IOC standards, Olympic pools must maintain a water temperature between 82°F and 84°F. 8. Why is the turf on field hockey fields blue? David Rogers / Getty Images Hockey fields are covered by synthetic grass. The blue color was used for the first time at the 2012 games in London to increase the visual contrast with the yellow ball, which helps players, referees, and spectators see the ball. Up until the 2008 games in Beijing, the sport was played with green turf and a white ball. 9. What's up with scoring in tennis games: 15, 30, and 40? Toby Melville / Reuters Though the scoring of tennis may seem bizarre (15, 30, 40, and then game), it traces back to the hands of a clock, which divide each hour into quarters: 15, 30, 45, and 60. The numerical system used since ancient times to measure time inspired the counting used in the scoring of "jeu de palme" (palm game), a medieval precursor to tennis played with a ball and the players' hands, which was scored as 15, 30, 45, and 60.The modern version of tennis, which was developed in France during the 19th century, used this already familiar sequence, but 45 was changed to 40, supposedly to make scoring easier (or possibly because dropping a syllable made it easier to say). During the last century, American tennis authorities suggested changing the scoring system for games to 0, 1, 2, 3, and 4, but it never stuck. 10. Why isn't American football an Olympic sport? Otto Greule Jr / Getty Images Most football players play in America. The sport just isn't very popular anywhere else, so the US would always have a natural advantage. Also, the IOC decided to drop both baseball and softball as Olympic sports, and even though it currently has "provisional status," football probably doesn't stand a chance. 11. What the hell is freestyle swimming? Odd Andersen / AFP / Getty Images Freestyle swimming is just what it sounds like: athletes can swim using any style they choose, even the "doggy paddle" if they wanted to. In the trials for the individual medley or the relay medley, freestyle swimming refers to any swimming stroke OTHER THAN the backstroke, breast stroke, or the butterfly. 12. What does the Olympic symbol signify? Ruben Sprich / Reuters The five interconnected rings represent the union of the five continents of the world, though no one ring represents a specific continent. The colors (yellow, blue, black, green, and red over a white background) were chosen due to their frequent use in the flags of the various countries of the world. 13. What does "pyre" refer to? Ivan Alvarado / Reuters The Olympic "pyre" (or "flame") comes from the Greek word pýr, which means "fire". Traditionally, it's a structure usually made out of wood, where human bodies are burned as part of a ritual. Today, in most dictionaries, the word is listed as synonymous with a "fire pit". 14. What is a modern pentathlon? Issei Kato / Reuters The origin of the pentathlon comes from the military competitions of Ancient Greece. The Spartans used this competition to select the best soldiers using athletics, and the winner of the pentathlon was considered the champion of the Olympiad in ancient times. In ancient times, it basically consisted of long jump and high jump trials, throwing the discus and the javelin, races, and wrestling. Competitors were eliminated after each stage, until only two remained to wrestle against one another, with the winner emerging as champion.The Modern Pentathlon is an adaptation created for the modern Olympics and is inspired by a military simulation whose goal is to recreate a scenario where a soldier has to deliver a message behind enemy lines. It begins with an equestrian stage, then includes marksmanship, fencing, swimming, and ends with a race on foot. 15. Why are gymnasts so short? Dylan Martinez / Reuters There are a lot of thoughts about why gymnasts are so short. One theory is that gymnasts are doing it to themselves. At the ends of our bones there are plates of cartilage known as "growth plates". If these structures suffer from impacts due to intense or repeated exercise, it may lead to the deceleration of bone growth. Since this is an activity that causes impact in the musculoskeletal system, competitive gymnasts may impede their own growth. 16. Why are there two bronze medals in judo? Pascal Le Segretain / Getty Images This is a bit confusing, but it's mostly due to the type of tournament bracket used. It has to do with the fact that there is a playoff between the athletes who lose in the quarter finals, and the winner of that competition receives a bronze medal, in addition to the traditional competition between the losers of the semi finals. The winner of that match wins another bronze medal as well. It also applies to boxing and wrestling too. 17. Can judo be used for personal defense? Elsa / Getty Images Yes. Judo is a martial art that can be used to attack or to defend, using only your own body. Historians studying the technique say that the initial version of the sport that we now know today began in the 16th century in Japan. In 1882, professor Jigoro Kano studied the ancient techniques of self defense, applying the laws of Newtonian mechanics (action and reaction), and choosing to systematize them into a new system called "judo", or "the soft path" - from the words "ju" (soft) and "do" (path, or way). Kano eventually became one of the members of the International Olympic Committee in 1909, but it wasn't until the Tokyo Olympics of 1964 that the technique was definitively included in the games. 18. How much does a gold medal weigh? Damien Meyer / AFP / Getty Images The gold medals used in Rio 2016 weigh 500 grams (or just over a pound). The current composition of the gold medal is 92.5% silver, 6.16% copper and only 1.34% gold, which is only used to coat the medal. This means that each athlete who makes it to the highest spot on the podium will take home 6.7 grams of 24 karat gold. 19. How much is a gold medal worth? Odd Andersen / AFP / Getty Images Somewhere between $560 and $590. But the medals have an enormous value on the collectors' markets. One of the gold medals won by the legendary sprinter Jesse Owens, in defiance of Adolf Hitler during the 1936 Olympics, was auctioned off at $1.5 million in 2013. 20. Do gold medalists also win money? Johannes Eisele / AFP / Getty Images That depends on which country they are from. Brazil pays 100,000 reals to any athlete who wins a gold medal. For silver medals, the payoff is 50,000 reals, and 30,000 reals for the bronze. In Argentina, each medal pays roughly 275,000 Argentine pesos.The country that offers its athletes the most money for bringing home the Olympic gold is Italy, paying out around $185,000 USD. Russia, a fierce competitor for Olympic medals, pays $61,000 USD for each athlete who makes it to the top spot on the podium.The US, one of the major global powers in sports, offers a prize of $25,000 USD to each Olympic champion.