great runner," says Anderson. Using a heart monitor is a good way to prevent yourself from training too hard on your easy days. "Keep your heart rate below 75 per cent of your maximum heart rate– or 70 per cent of your heart rate reserve – and let your

or so higher. "In the opening stages of a marathon, the heart rate of both men and women should climb to the plateau of about 140bpm, working at about 70 per cent of your maximum effort, a guide we use for testing new athletes' fitness," says Pedlar

great runner," says Anderson. Using a heart monitor is a good way to prevent yourself from training too hard on your easy days. "Keep your heart rate below 75 per cent of your maximum heart rate– or 70 per cent of your heart rate reserve – and let your