At a PSA Nationwide Seminar I attended yesterday I was so happy when the presenter gave me the opening for this post. He said, "without good extension, a skater has no power and no control."
I tell my students that extension is the end of any movement. That means that you have to find the end of each movement, and take it all the way to that point, then let it stop there for a moment.
One of the biggest "tells" of an inexperienced skater is that their movements never seem to have a "there." They'll leave a slightly bent knee, or any unpointed toe, a mushy jump set up, or step out of a landing too quickly. You can spot the strong, experienced skaters by their moments of stillness-- watch the end of a cross-over or a stroke. A good skater will wait just a hair before shifting to the next position. They're wringing every bit of power out of each push, each check, each moment at its very end.
Extension is one of the hardest things to teach low level skaters, because it's fussy and confusing. Kids today have zero muscle tone; I'm continuously astonished at the poor mid-body (core) control that children have. They're super smart these days, but they're a bunch of marshmallows when it comes to strength. And extension requires strength-- strong extension is actually a form of weight bearing exercise, focusing on proper muscle contraction (think about it-- your extended knee is caused by the flexing, not the extending, of the quad muscles).
The classic extension moves in skating are stroking, cross overs, and spirals, and every Moves in the Field test features these moves with a major focus on extension. I would like to see, and be able to spend more time on, the concept of extension in Learn To Skate/Basic Skills classes, but the set curricula of these programs neither emphasize nor support using class time for this, and the "move to the next level" mentality of coaches, parents, and management at most rinks cannot support holding someone back at Alpha/Basic 4 because of poor extension. As one cynical coach said to me "means more lessons when they start learning Moves." (Think about this, parents-- if you would stop getting your knickers in a twist over your kid passing Alpha, maybe you'd be saving money down the line in private Moves lessons. Just sayin'.)
You can teach extension from the very youngest children, though. With tots, have them stretch their hands over their heads, then run your hands just out of reach and have them stretch up as high as they can trying to touch you. With beginners, have them do "penguin walking" where the knees are stiff, the heels are together and toes apart-- this teaches them the muscles they need to contract to extend their knees as well as keeping them off their toe picks. You can also play swizzle games for extension-- doing swizzles with knees only bent, and with knees only straight; the widest and/or longest swizzle you can make and still pull back in, holding deep half-swizzle pumps. Holding half swizzle pumps and undercut pumps is also a good way to teach extension in cross overs.
Extension doesn't happen only in the legs, of course. All the extremities need to have that sense of length--arms, legs, neck. I call a nicely extended neck "snotty skater girl" position, and when I say that, every kid automatically does it right. I love using ballet arms to teach extension. Have the skaters do swizzles, with a different ballet position, one through five, for each push. With more advanced skaters try this with stroking, which then adds extension of the leg.
The best place to teach extension, however, is off-ice, where you remove forward movement as a factor. I think with recreational skaters we spend so much time telling them to bend their knees that when we suddenly say, okay now unbend it, it just does not compute.
Extension is what makes skating beautiful. Personally, I think of all the artistic athletic forms-- skating, gymnastics, ballet-- skating has the most aesthetically pleasing tradition of extension. There's none of the hyper-extended sensibility of ballet, and until recently, none of the contortionist excesses of gymnastics.
Extension in skating is simply where the movement ends. Hold that moment; it's lovely.