I just saw Xue Kela raise a good question: A question about the knees
http://bbs.lvye.cn/thread-760134-1-1.html
It’s about a girl’s situation, but it applies to guys too. I happened to have injured my medial and lateral knee ligaments one after another not long ago and am currently doing rehabilitation training, so I’ll share some experience with everyone:
    Xue Kela, our class rep, realized that strengthening muscles to protect vulnerable knees is a very wise idea. Muscle training doesn’t cost much even if you go to the gym, let alone DIY methods at home that cost nothing. Finding more ways to strengthen regularly means fewer injuries and fewer hospital visits — that’s doing a good deed for yourself and your family.
--------------------------------------------------------------------------------------------------
Here’s a reply to the class rep:
Kela, us amateurs don’t have the brutal training load of professional teams. As long as you put in the effort with exercises, knee problems can definitely be resolved 100%.
In skiing, the knees mainly face two demands: support and balance.
1. The quadriceps and ligaments assist each other. Wall squats can strengthen the quadriceps, but they’re boring and progress is slow. Unless it’s post-surgery rehab or you’re aiming for special strength levels, doing them daily is fine — no need to obsess over them.
    There’s a quick-fix method: there’s a leg machine at the gym where you sit and lift weights with your legs. This works extremely fast and targets the quadriceps directly. I’ll post a picture of it later.
2. Training smaller muscle groups helps protect the medial and lateral ligaments to support balance. Few people pay attention to this. Though small muscle groups can’t give you heavy-lifting power, they effectively provide protective support, assist balance, and prevent injury. I learned this from playing badminton. There are many methods: standing on one foot, standing on one foot on a soft mat, lightly hopping forward/backward/left/right on one foot, or standing on one foot with eyes closed. Any movement that disrupts your static balance can engage the small muscle groups by restoring balance. Do this kind of training occasionally for fun, and don’t do too much. After a few months, you’ll find amazing effects by the next ski season — you’ll make unexpected breakthroughs on the snow.
    Having good balance ability and being good at balancing is also a form of strength — it’s like using a small force to move a big one. Amateur skiing is essentially a game of balance. Four ounces of balance beats an unbalanced thousand pounds...
------------------------------------------------------------------------------------------------------
Now adding some points not covered in the reply post:
1. Equipment issues
[attach]1424771[/attach]


These are the pieces of equipment I’m using for my current rehab training. Actually, even when I wasn’t injured, I’d occasionally use them to strengthen myself, though the schedule and training volume weren’t as targeted as they are now.
First row A1-A3: stationary bike, treadmill, and sit-ups — everyone knows these...
Second row B2-B3: leg abduction/adduction, which trains the inner and outer thigh muscles. Well, not the main focus, but if you play slalom skiing, you’ll notice that the muscles you tire out during long, continuous, fast short-radius turns are similar to those trained with this equipment. Hehe... got sidetracked...
Third row C1, C2: these are the key ones. They’re for lifting the lower leg forward and backward. C1 definitely works your quadriceps — using this to train your quads leaves no wasted time at all. All the effort goes where it counts. Of course, muscle strength distribution should stay balanced: if your quads get stronger, the corresponding muscles at the back of your thighs also need training — that’s where C2 comes in.
    For lazy folks or those wanting to save time, C1 and C2 are recommended. But if you’ve managed to get to the gym, you wouldn’t just use two machines and leave, right? That’d be such a waste...
    For those not wanting to spend money, you can DIY at home: sit on the bed, prop your knees against the edge, tie a sandbag, dumbbell, wine bottle, rice bucket, or even a beauty magazine (something with a bit of weight) to your foot, lift your leg, hold it for a while, then lift again — that’s the C1 exercise... Then roll over, face the bed, lift your leg backward in a reverse calf raise, kick, hold for a while, then kick again — that’s the C2 exercise...

    These are all exercises for major muscle groups. There are tons of small muscle group exercises too, and they’re quite fun. Try walking a balance beam on a roadside curb, single-leg hopping in the park or at home, or standing on one foot on a thick mat at home like a stork. Basically, put yourself in situations where it’s hard to maintain balance, then work to regain it. You’ll feel slight soreness in the outer leg muscles and around the knees — stop right away, rest a bit, feel better, then continue...
    These exercises may seem inconspicuous, but their effects are no less than those of major muscle group training. Moreover, activating the small muscle groups can better prevent injuries and improve power output...
    If you want to go more advanced, spend a bit of money — buy a slackline and mess around with trees in the park. Try to find thick trees; don’t bully the little ones. Or try a trampoline or longboarding — anything that challenges your balance will help improve your skiing ability...

    One last thing: skiing is a game of body balance. For those who can’t ski dozens of days in a season to improve their skills, you can absolutely make up for the lack of ski time by significantly boosting your overall physical abilities in the off-season. Because when your explosive power, endurance, balance, and agility improve, a move you’d take a month to master might only take you a day. That’s why those who exercise often improve quickly in skiing...

    I’ve said a lot — not sure if it’ll help anyone. My ligament injury didn’t actually affect my skiing, but to fully recover without future issues, I took half a ski season off to rest completely. After fully healing the ligaments, I signed up for a one-month gym membership. It’s been over a week now, and my muscle strength is recovering quickly. I’ve fully regained my normal athletic feeling. In another three weeks, I’ll finish my self-designed rehab training... Having a completely injury-free body is every skier’s happiness... I managed it, and so can you...

Also: these insights apply only to alpine skiing — I don’t snowboard, so I can’t say how well they translate.

Class rep Xue Kela, the message was too long, so I answered in a separate post. I also have other questions for you — I’ll send you a private message later.
――――――――――――――――――――――――――――――――――――――――--
    Plus a summer alternative to skiing: longboarding. I originally got into it for fun, but another main reason was to handle deep powder snow. Back then, the options I thought of were: trampoline, skateboard, and slackline. Slackline is too niche — using it in the park would probably embarrass the old folks watching... Trampoline has dedicated spaces, no fear of an audience, and skateboards can be practiced in secluded spots. Especially the soft, wobbly, uneven feel of a trampoline is very similar to riding on high-mountain powder snow, and the instability of wobbling on a skateboard going downhill is very similar to skiing ungroomed mountain snow. So I thought I could use these two methods to break through my own limits. Damn it, if my absolute ability improves, at least understanding ski techniques won’t be wasted effort. So I got interested...
    Later, I discovered longboarding — it’s longer and wider than a skateboard, with huge wheels. Especially, it’s super easy to pick up — just 10 minutes, and the feeling of gliding forward with your hips pushed out is very similar to alpine skiing. You can also ride on one foot, which further improves your skiing technique (if I can ride on one foot, two feet on skis will be no problem)...
    Then I found it can substitute for wall squats because one-foot sliding for an hour is equivalent to an hour of wall squats with added dynamic balance training... It works really well. Recommended.
This is a video of my own longboard practice, for your reference...

I’d like to recommend this longboard to those who enjoy squats or wall sits — it’s definitely a lot more fun...