A torn ACL (anterior cruciate ligament) is one of the worst forms of knee sprains, accounting for one-third of skiing accidents every year. While much of the blame lies with improperly adjusted bindings, which are responsible for nearly half of such injuries, inadequate physical fitness also plays a part.
To decrease the risks of knee injuries, do yoga. Yoga improves flexibility in the pelvis and lower back, and also sharpens the capacity to concentrate. More importantly, it increases stability in the knees by working the flexibility and strength of secondary muscles that are less used in sliding sports. For example, the sequences of postures that emphasize flexibility and openness of the hips, the psoas, and the upper torso, combined with other specific postures that improve suppleness in such overdeveloped muscles as the quadriceps, are extremely beneficial.
By practicing yoga regularly, your body will be better prepared to take those ski slope turns with strength and stability. I recommend a regular practice of just 10 minutes each day to transform your body and your active leisure pursuits in the winter!