President Dmitri A. Medvedev of Russia, angered over his country?s disappointing performance at the Winter Games, began calling for athletic officials? heads. ?Those who are responsible for training for the Olympics must take responsibility,? Mr. Medvedev said on Monday. ?They must have the courage to submit their resignation,? he said. ?And if they do not have this resolve, we will help them.? Such language from the typically measured Mr. Medvedev underscores the extent of the frustration here with Russian athletics just four years before Russia hosts the next Winter Olympics in the resort town of Sochi.