Have you seen people running marathons and they need to run it backwards halfway because of too much pain in knees?
This is because of overdoing forward motion. Ortopedists and physiotherapists often find such customers and interestingly this is related to strength exercises for skiing: when people overdo going forward, they forget the other motion that is going backwards. Skiing requires balance between backwards and forwards particularly in lower legs. Going only forward can compromise your balance so integrating both directions to training is healthy way to improve the strength for skiing because the strength must be balanced.
One of the easiest way to work the "ankles and muscles foot to knee" is to go backward: backward running works the muscles such as calves, shins and front thighs. Going backwards also improves the balance in lower legs. More benefits. Then combine this with things such as Backward skating, Backward slalom skinng like here and have some fun.
You need to find balance in many levels such as muscular level, neural level and coordination. It is a bit like frontstroke and backstroke in swimming.
More balance workouts.
- Motivating instructions on balance from novice to advanced here on roller skating