Rocket boosters? Tiny electric motors? Cutting the course? The World Cup women’s field is going to have to come up with something, because it’s pretty clear that plain old training and technique isn’t going to be enough to beat Norway’s Marit Bjoergen any time soon. In Saturday’s 10 k classic in Davos, Switzerland, Bjoergen won for her fourth time in five races this year, skiing to a 30-second victory over her Polish rival Justyna Kowalczyk....


