JACKSON, N.H. — Two years ago, Martin Bergström quit skiing. A month ago, Petra Hyncicova took three weeks off skiing following U23 World Championships due to a painful bursa between her Achilles tendon and heel bone. Less than a week after resuming training, Hyncicova, a 22-year-old Czech Republic native and University of Colorado-Boulder (CU) junior, raced to two National Collegiate Athletic Association (NCAA) Skiing Championships titles — the first of her career — in Jackson,...