Originally Posted by CTKook
Just thinking aloud about what would be functional for skiing: skis are actually pretty stable fore and aft, stand on a fairly stable surface (the snow), but are subject to catching or losing edges side to side; skiing also involves support of a lot of centrifugal force when turning and absorption (or not) of up & down forces through A&E or pumping.
IMHO, there are a number of balance/core/recovery skills that are helpful, at least to ski racing, specifically 1) lateral balance, as sometimes you get into seriously funky positions as (for example) your outside ski breaks away and you fall onto the inside ski, and the better your lateral balance is, the better you can adjust and recover, using both skis (or the one that's still under you and tracking); 2) fore-and-aft balance, as you are more forward and more back at different phases of a slalom turn (or, like me, have to recover from having gotten too far back for optimal skiing.) There are some pretty exciting fore-and-aft challenges in skiing through cut up heavy snow on top of ice/hardpack, or late in the season when you hit that warm slush manmade snow glue while flying along.
One thing I find is that when I'm completely on one ski, I have trouble committing forward enough for optimal turning. Even so, skiing from time to time only on one ski (making turns in both directions) is a great balance training exercise on snow (as long as you're doing it where the hill is sufficiently flat.)
My thoughts about other important aspects of balance that relate to skiing are (1) you have to balance while resisting a load (Ron LeMaster says that when a racer goes from 60 degree inclination to 70 degree inclination, he is managing 3 Gs of force instead of 2 Gs. For a 180 lb skier, that means bearing a load of 540 lbs, briefly, about 80% or more just on the slightly flexed outside leg); (2) your most important balance challenges are when your legs are tired--whether that's at the end of the race or the end of the day, that's when you can get hurt; (3) there is a dynamic (rather than static) aspect to skiing's balance challenges, as you get more or less resistance and you get bounced around, all while trying to balance; (4) many of the balance challenges against a load involve eccentric resistance (not the pushing up phase of a squat, the sinking down phase); and (5) (at least for ski racers) some of the balance and combined load/balance challenges occur when you have a very deeply flexed inside knee.
So I try to do a lot of my weightlifting for my legs with a balance component (squat rack instead of smith machine or leg press; walking lunges, lifting the back leg to hold it up and briefly pausing while standing on the other leg before lunging forward again; step ups with the left leg, then raise the right knee to make my right thigh parallel to the floor, standing on the left leg only.) And I do some excercises with a balance component at the end of the workout, when my legs are already tired. (Tucks and haybalers on a bosu, flat side up.) Balance challenges are also nice for recovery phases between heavy lifts, keeping your heart rate up. (Juggling while kneeling on a fitball or standing on a foam roller.) Sometimes to get the most out of a workout, with the least recovery time, I alternate a heavy leg exercise with an upper body exercise, with a balance challenge.
There are a lot of ways to mimic the adjustment to outside forces/dynamic aspect, I think, including by tossing a medicine ball from hand to hand while balancing, having someone toss you a medicine ball while balancing, or even holding a dog toy between your bare toes and playing tug with a small dog, while standing on your other foot. (Or you can combine this--stand on a bongo board tossing a medicine ball from hand to hand while said small dog jumps up on you to get at the ball....)
IMHO, some of the best ways to train balance eccentricly is through plyometrics--jumping exercises, where the biggest challenge is to absorb the forces at landing and then explode back up again. (Although squats and especially lunges also have an eccentric component.) I do a lot of side to side skier hops--jump right, landing only only on your right foot (keeping the other above the ground), then jump to the left, landing on your left foot and repeat. I also jump over a long broom handle balanced on the corner of a low table and a cone for a combined jumping/landing/leg retraction/agility drill--at every landing, I have to gather myself to accurately jump to clear the broom handle and land not too close but not too far on the other side. (The number of times you can consistently clear it is also a nice marker for fitness/training level/agility as the season progresses...)
Finally, I think the deeply flexed knee issue is worth some thought, at least for ski racers. That's why I do deep squats on a flat surface, and deep sumo squats on a bongo board, and haybalers on a bosu (flat side up) or bongo board with a medicine ball, taking it from low outside my left ankle (with deeply flexed and angulated knees) to high above and outside my right shoulder (with straight legs.) That seems to mimic the balance and load challenge with flexed and angulated knees, like a slalom race.
Anyway, those are my eccentric thoughts on eccentric balance training with a crossover to skiing.