Athletes should wrap themselves in an electric blanket instead of doing a physical warm-up before a race, as their performance improves if the muscles are artificially heated, researchers believe.

Muscle power went up between 8 and 10 per cent for every 1C rise in temperature, Anthony Sargeant, of Manchester Metropolitan University, said. And heating muscles artificially was better than a physical warm-up in some respects, because the muscles became hotter without the risk of fatigue, the study, published in New Scientist, found.

The researchers asked six volunteers to pedal an exercise bike at two different speeds without any special preparation, and to repeat the exercise after a 30-minute leg bath in water heated to 42C. The researchers calculated how efficiently the cyclists' muscles were working by monitoring their breathing.

Athletes gave the idea a cool reception. The British sprinter Linford Christie, who won Olympic gold in 1992, said: "I wouldn't recommend it. Before a race, you don't want to be sitting down, you need to be on the move."