I've been meaning to come back to this topic. Found some time tonight.
I didn't want to just continue on from the Identifying Turns and MITF from the Sine Qua Non thread thread because that started in the middle of the topic instead of starting with the basics. I thought it might be useful to organize the thread more systematically. I'll start by copying an edited version of my last post in that thread, which should really be the beginning of the discussion.
Other skaters: Please suggest edits if you think I got something wrong or didn't explain clearly.
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Blades are the basis
The sport of figure skating is based on all the different ways that the human body can manipulate a pair of narrow blades fastened lengthwise along the bottom of the foot.
Figure skating blades are sharpened with two edges, one toward the inside side of the foot (inside edge) and one toward the outside of the foot (outside edge) with a narrow groove running between the two edges. Most figure skating skills are based on gliding forward or backward on one edge at a time, which produces a curved movement over the ice. These curves, and the curved tracings that the blades carve into the ice itself, are also referred to as “edges.”
Gliding on two feet at the same time in most cases removes most of the challenge of maintaining balance that the sport is based on. Gliding forward or backward on both edges of the blade at the same time results in straight-line motion. Blades moving sideways across the ice act as brakes, slowing or stopping the gliding motion. Stepping or hopping on the serrated teeth (toepicks) at the front of the blade allows for staccato motions in contrast to the basic gliding motion. Such moves can all be used for choreographic variety. But the fundamental techniques of figure skating consist of gliding on one edge at a time and transitioning from one edge to another.
Balance Glide Flow Edges Curves are all words that describe the fundamentals of good skating that the sport has always held among its highest values.
Speed and centripetal and centrifugal forces allow skaters to control their balance on the thin blades in positions that often cannot be sustained while standing still, on or off the ice. Deep lean over the edges, usually with deep knee bend to control, is highly valued.
Two edges on each foot (inside and outside) times two feet (right and left) times two directions of travel (forward and backward) yields a total of eight different edges: right forward inside, right forward outside, left forward inside, left forward outside, right backward inside, right backward outside, left backward inside, left backward outside. These are often abbreviated RFI, LBO, etc.
Each curve travels in either a clockwise (RFO, LFI, LBO, RBI) or counterclockwise (LFO, RFI, RBO, LBI) direction.