Watch | Why are these Russians playing chess in icy water?

Russian swimmers are playing chess in frigid waters to build up their stamina and concentration.

In a lake in Russia's Ural mountain region on Saturday, these swimmers plunged into water of around 5 degrees Celsius for a chess game that tested their mental and physical strengths.

Speed was a key factor for success in an icy water chess game, the players said, as the sub-zero temperature encouraged them to make the next move within seconds. Each game lasted about 10 minutes.

The swimmers said they hoped to hold more similar events in the future.