Why do speedskaters hold their hands behind their backs?

Why do speedskaters hold their hands behind their backs?

Speed Skating - Winter Olympics Day 1

SOCHI, RUSSIA - FEBRUARY 08: Sven Kramer of the Netherlands competes during the Men's 5000m Speed Skating event during day 1 of the Sochi 2014 Winter Olympics at Adler Arena Skating Center on February 8, 2014 in Sochi, Russia. (Photo by Quinn Rooney/Getty Images)

Sven Kramer of the Netherlands competes in the men's 5000 meters speed skating race during the 2014 Sochi Winter Olympics

Sven Kramer of the Netherlands competes in the men's 5000 meters speed skating race during the 2014 Sochi Winter Olympics, February 8, 2014. REUTERS/Laszlo Balogh (RUSSIA - Tags: OLYMPICS SPORT SPEED SKATING)

Bart Swings of Belgium competes in the men's 5000 meters speed skating race during the 2014 Sochi Winter Olympics

Bart Swings of Belgium competes in the men's 5000 meters speed skating race during the 2014 Sochi Winter Olympics, February 8, 2014. REUTERS/Phil Noble (RUSSIA - Tags: OLYMPICS SPORT SPEED SKATING)

Havard Bokko of Norway competes in the men's 5000 meters speed skating race during the 2014 Sochi Winter Olympics

Havard Bokko of Norway competes in the men's 5000 meters speed skating race during the 2014 Sochi Winter Olympics, February 8, 2014. REUTERS/Phil Noble (RUSSIA - Tags: OLYMPICS SPORT SPEED SKATING)

Speed Skating - Winter Olympics Day 1

SOCHI, RUSSIA - FEBRUARY 08: Mathieu Giroux of Canada competes during the Men's 5000m Speed Skating event during day 1 of the Sochi 2014 Winter Olympics at Adler Arena Skating Center on February 8, 2014 in Sochi, Russia. (Photo by Quinn Rooney/Getty Images)

Patrick Meek of the U.S. skates during the men's 5,000m speed skating race at the Adler Arena during the 2014 Sochi Winter Olympics

Patrick Meek of the U.S. skates during the men's 5,000m speed skating race at the Adler Arena during the 2014 Sochi Winter Olympics February 8, 2014. REUTERS/Issei Kato (RUSSIA - Tags: OLYMPICS SPORT SPEED SKATING)

Sven Kramer of the Netherlands competes in the men's 5000 metres speed skating race during the 2014 Sochi Winter Olympics

Sven Kramer of the Netherlands competes in the men's 5000 metres speed skating race during the 2014 Sochi Winter Olympics, February 8, 2014. REUTERS/Brian Snyder (RUSSIA - Tags: SPORT OLYMPICS SPORT SPEED SKATING)

Russia's Denis Yuskov skates during the men's 5,000m speed skating race at the Adler Arena during the 2014 Sochi Winter Olympics

Russia's Denis Yuskov skates during the men's 5,000m speed skating race at the Adler Arena during the 2014 Sochi Winter Olympics February 8, 2014. REUTERS/Phil Noble (RUSSIA - Tags: OLYMPICS SPORT SPEED SKATING)