Flexing and shortening the outside leg in order to release the ski, also referred to as "flexion release", "flex to release", "retraction" or "down-unweighting", is an effective method of releasing the outside ski. These movements reduce the weight on the outside edge, allowing it to be released and un-tipped (to flatten the ski), as the turn ends. During transition, both legs are shorter rather than longer, a result of this flexing.
The flexing and shortening the leg to release will avoid an excessive up and down motion of the body and also, allows the skier to retain maximum control over the skis, by keeping them in contact with the snow (or close enough) and in fact, most releases include some flexing of the outside leg. The opposite type of transition, by extension or hopping up tends to disconnect the skier from the snow and delay engagement in the next turn.
Flexing to release results in a typical lower stance during the transition, as you see in the rather extreme example above, which will also result in what seems like a very aft position on the skis, requiring a strong recentering and coiling, like below.
This type of release is very good for absorbing the energy of high performance turns, as you can see here - even with that deep flexion, the skis still come off the snow:
The flexion is normally followed by tipping and an extension of the new outside leg into the new turn, where it allows early tipping of the skis into the new turn, as you see below dynamically, in slow motion:
Biomechanically, flexed joints allow mobility and separation, this is a big reason behind the efficiency of the flexed release.
An extension or push-off by contrast does not allow early engagement of the skis at the top of the turn, as the skier's hips would be "too high" and disconnected from the snow, especially in short technical turns!
Other benefits of flexion include establishing early "inclination" into the next turn, as the hips are lower and we don't have to "wait" for the hips to come down from a high position, we just extend the legs into the new turn and quickly establish inclination at will.
If not done properly, the flexing will induce some artifacts (like being back, squatted with less range of motion etc) which the skier needs to know how to avoid and deal with. This is why many coaches don't coach this movement, because they don't know how to deal with the likely side-effects which will appear as soon as they start working on this. In turn, they're happy to allow it to appear in some strong skiers, which discover it "via luck". Many other skiers do not discover this, so we think it's much better, overall, to educate coaches and learn how to coach it effectively.
The most important part of this type of release is the flexing and shortening of the outside leg. The long leg will flex when relaxed or retracted after the high pressure at the apex. Sometimes, a strong retraction is required, that is an extreme case, we can call that retraction. It is common in bumps and other situations where the skier has to react fast.
The flexion and absorption of the forces of the turn also provides another benefit: it is smoother and easier than a hop or a hard hit and also more relaxed and takes less effort. Although quite a few skiers find it tiring in the beginning, that is also common, as skiers mis-time the relaxation until "getting it".
In the release below, the body is not impulsed "up" much but the hips still come higher in relation to the boots, because they were very low to the snow at the apex (the hips actually stay more or less level while the boots move further down the slope, if you look at how the slope influences the geometrical relationships below):
So, when looking at a skier releasing, it is better to look for extending legs (long or getting longer), or legs that stay the same, or legs that get shorter (flexing), to determine the release type and how the body is impulsed. In the release above, notice how the outside leg is long at the apex and relaxes and becomes short (bent or flexed) when the skis are flat on the snow.
In Ted's release below for instance, the leg shortens just the same but the hips do not actually come any higher - this is simply a matter of timing (when do you start to shorten the leg? before or after the hips got some impulse up?) and of the slope - above we have a flatter slope while Ted is on a steeper part of the course, so his feet drop fast enough so the hips do not rise anymore.
Did you push them higher on a flatter slope? Did the steep slope fall away from you very fast, so the hips remained at the same level but are now higher from the snow? Not that relevant! What is relevant for performance skiing, is retaining the ability to contact and pressure the snow at will, which only works if the hips are lower than maximum extension and if the knees are bent (the more bend the more range of motion, until some threshold of diminishing returns, say around a 90 degrees squat).
There is a range of movements between passively relaxing the legs and allowing the energy of the turn to push the boots up OR gravity to pull the body down. At the other extreme we have a full retraction, where the boots are retracted towards the body.
Some of these may be referred to sometimes as "down unweighting" and in the extreme case, retraction release, when there is a strong retraction of the boots.
The extreme ranges of flexing or retraction shown here enable high performance skiing, but in reality, the range of flexion will depend on terrain, turn shape etc. As a matter of principle, however, any flexion during the release is better than none and leads to better, smoother skiing.
Retraction releases usually interfere with speed control. Speed control when using retraction releases is a higher level skill (we cover that at the black levels).
This type of release is also referred to as "down-unweighting" and contrasted to "up-unweighting" aka the push-off, where the hips are pushed "up" to unweight the skis.
We prefer the description relax to release because it is very specific as to what the skier does and it does give us a better image as well as a better cue while working on our skiing.
Between a full extension, or "hop and over" transition and a pure "flexed release" there is a large gray area which causes much discussion and confusion.
For instance, some may consider the 4th release in the sequence below to not be a "flexed release" although the knees are clearly bent and the leg clearly shorter than at the apex:
In our mind, that's clearly a relaxed and flexed release, the only difference from the others is that Odermatt managed to get a useful impulse forward in the direction of the ski, just before relaxing and flexing the leg.
Are all transitions where the legs are short when the skis are flat, are all those "flexed releases"? Most are, that is the signature of a flexed release, short legs when the skis are flat, but some are not so black and white. There is some gray area there, where the skier may actually push a bit into the skis and then relax. We call that "juicing" - see this turn from Marcel's free ski run and contrast that particular release with the others in that same run:
At time mark 1:21, that release looks somewhat different than the others, he looks undecided and just tips over while the leg stops relaxing at some point. That's part of that gray area: did he flex the leg? Of course! Did that release the ski? For the most part, yes, because the force was reduced a lot with this flexing. Is that a pure/clean flexed release? Not quite, because the ski was not really released before changing edges, there was a bit of weight there.
Anyways, for our purposes, we contrast the flexed release with the "hop up and over" so we consider all these to be "flexed releases". Some are better and more black and white, while others not so much! Such is skiing - color is everything!
Another sequence is quite common, which includes flexing just a little to end the turn, then extend before changing edges, but not quite go through transition with long legs. This is closer to an extension, because you go through the transition with a net impulse "up" and there was a push and extension somewhere in-between, so I would not consider that movement pattern to be a "flexed release", at least not a clean one. For instance this video - good skiing and although there is quite some flexion to end the turn, if you look closer, it is subtle, but the movement pattern that actually releases the skis is a small extension, this is fairly common:
That pattern, flex-extend-flex, is called "flex to end the turn" as opposed to "flex to release" as the extension disengages the ski, not a pure flex to release. And you can contrast that subtle hop, with these clean flexed releases that Marcel shows in most of his turns, freeskiing or racing:
Or racing, where he switches gears from just a relaxed flexing to more of a retraction release, to keep up with the rythm (retraction relese is the same mechanics, wiht the addition of a strong retraction effort, after the passive flex - same pattern, different muscle activation):
And there you really have it: while there are many variations, some good, some not, it's all about the dominating movement pattern during the transition. What started the release process, what caused the ski to release etc.
Sessions to work on this skill:
More to read:
"by keeping them in contact with the snow" Ehm... In the 3rd frame of your release both skis are out of contact with the snow.
"and delay engagement in the next turn" Ehm... in your slow motion video, your engagement is super late, well below the fall line. And next, instead of resisting to the force, you flex the outside leg and you topple down, the hips raise violently and you literally "take off", unweighting the ski in the entire first part of the turn. Resulting in a late engagement of the new outside ski.
Yup, correct on both counts - that is not a particularly great demonstration of those points... I will leave it as a "bad" example. The skis do not have to be in contact with the snow to affect control, just close enough, but more importantly, the skiers needs to have the range of motion to be able to use them - I updated the content to reflect that better.
Here's a more appropriate slow motion I'll use to exemplify those two points:
Odermatt extends completely through transition (where he has the space to do so), without having any problem since he is one of the best skiers in the world. Just to cite one... I have several example of great skiers who extend through transition. I mean: it's ok to stay flexed, it makes sense for some kind of turns, but if you say it is the "effective way" to ski, and the "other way" is ineffective... Well, the evidence tells me it's not like that. It has pros and cons...
We need to be careful about what we are looking at when drawing generalized conclusions about skiing. Ski jumping is different than speed events, which is different from technical skiing. If you look at any (modern) technical event skiing, including Odermatt in GS, the default transition is a flexed release, with both legs bent significantly, often looking like a squat, in fact the more technical the event, the more squatted it looks like and therein lies the story behind it. For instance https://youtu.be/KO0lxVIq1ls - a random race of this skier, just freeze-frame whenever the skis are flat on the snow and count how many times he looks flexed or even squatted versus extended with both long legs. He's squatted some 90% of the time... you can also look at Brignone, she's another example that some use to try to show that WC racers extend rather than flex on average, but while she does ski somewhat taller than others, that idea that she is extending to release is not true, when slowing down every transition.
For example, here are the first four transitions in Odermatt's race:
I know that flexing is a somewhat controversial topic and there are many forums online where you can debate various points of view on skiing - this website is not created as a forum for debate, the comment section here is meant to help clarify the content and resolve specific questions not addressed in the content - thank you for pointing out some of the issues with the content. In our view, this is the most effective release, this is why it's the "go to" release in all technical skiing. See http://www.effectiveskiing.com/wiki/carving-blog/Low_in_transition for instance, looking at what the best in the world are doing.
I am not saying that the flex to release transition is wrong. I am just saying it is not the only one possibile, nor the most effective... or why are they using it on steep, icy slope? It would have no sense. If you show us some of the transitions of Odermatt in the steepest part of the slope in Solden, you will see a lot of "full extended" transitions. (PS: the 4th frame, to me is not a flexed position... ;)) What Odermatt shows it is clearly an "up and forward" transition.
I did not want to be otherways polemical, it was just to understand why the "flex to release theory" fails to explain some evidence and some inconsistency. I remain with my doubt and with my "two way" transition depending on the situation. ;) Cheers.
In the 4th transition above, the knee is bent almost 90 degrees - that makes it a flexed release: whenever the leg relaxes and flexes to release the ski, that is a flexed release. An extension release by contrast will require a flexion then followed by a push before the skis are flat, which is most often not even a release, since you need the skis pressured to "push".
If you look at that one transition on the steep section when he appears long at 0:29, we can see that he needed more deflection across the hill to make it across to the blue gate, so he had to stand longer on the outside ski under the gate, result being that, as the steep hill falls away quickly, the feet need to stay planted while the hips catch up in "falling" to get pressure by the lower gate, resulting in that longer leg during transition, sure. He wasn't pushing himself up or forward, was just standing on the ski as the hill falls away quickly, trying to get more deflection.
All skiers can do anything at some time or another, especially WC racers that push it to the limit. The question is always, not what they end up doing here and there because of terrain or tactics (like having to skate uphill etc), but what is the "go-to", the "default", the most effective movement pattern or technique.
Also, specifically to flexing, you can look at it this way: extension comes naturally, as we walk, run etc, we flex at the end of the "stroke" and then extend to push our hips forward. That push is not needed in skiing, as we have gravity, which requires technique to use. The flexion is the counter-intuitive movement pattern that we need to work on and master, while the extension is embedded in our brains.
A lot of coaching and also race coaching is focused on "pushing hips forward" which requires an extension, but this is not what we see most of the time at the higher level. Extension does help get one forward, but it has a lot more drawbacks which make it ineffective. Look at the Release topics, a lot of biomechanics of why the extension is ineffective are discussed throughout. For instance it reduces mobility and range of motion: you cannot tip on edge a long leg - you need to let the hips fall inside instead etc.
The legs soon or later always relaxes to release the pressure even if you extend. So every release is a "flexed release".
No, well-spotted: that one is not a good example of flex to release. His leg doesn't really relax and shorten until late, there actually is a quick relaxation to get out of big angles but then he stiffens up and gets a late impulse there and only then flatten the ski - so not quite an extension either but close, like he's undecided. It would be a good demo if his leg stayed relaxed through flat, once he starts releasing. Most other turns in that run are good examples though!
This is good to help clarify the concepts here! Again, a flexed release is one where the release process starts with relaxing and flexing the outside leg, which continues to relax and flex through flat (when legs are equal lengths and skis are flat on snow). If you relax/stiffen/relax/stiffen, that's not a flexed release, at least not a "clean" one - that sounds more like a push off than relaxing the leg.
Some forms of pushing are more subtle, like this one you brought up here and they're discussed at the performance levels, when flexing and relaxation are studied in depth - the reason that's the exception during this run is because it stands apart from the way he skis, it is different from all other releases in this run, where he's flexing and relaxing to release. These forms of pushing are common when the balance is not sufficiently developed at a performance level, the skier is undecided or there is some tactical reason for it or when someone is still learning how to release well. I think we have enough videos and photos here now to explain the differences. Just the presence at some point of a flexed leg doesn't make it a flexed release, it doesn't mean the leg was flexed to release specifically. The presence of a push-off or stiffening at any point during the release process also makes that at least a poor flexed release if not something else. One does not have to be squatting to have a good release - even a small relaxation at the right time goes a long way.
Interesting question: should this be called "relaxation release"? The extension is not a problem, pushing off is. I will rename a few topics, with this in mind.
I don't find it true however that the leg always flexes in any transition. On the contrary, the most common transition is a low-level push-off followed by pivoting with long legs.
It's so awesome to watch Marcel Hirscher play on skis like that. Bottom line though - if I want to ski like Marcel, I analyze and try to emulate in my skiing the 95% of his turns in this video which share the same movement pattern, at least as far as the release goes, not the one turn that's a little different.