The release and transfer are arguably the most important parts of the turn - as they will set up the next turn as well. The purpose of the release is to end the previous turn and release the edges from the previous turn, carving or not.
In general, the release movements start with the ankles to flatten the skis, then knees and hips and so on but sometimes the "COM is released first" i.e. the relaxation of muscles will "release" the upper body before the skis.
At the most basic level, edge release starts in the ankle and progressively moves up the skiers kinetic chain. USSA GS Technique and Tactics
There are a few ways to release the skis, which can be combined with the subtle ankle movements above:
The extension release is the most frequently seen in recreational skiing while the others are typical for expert and high performance skiing and racing.
One of the important elements of a release is to extract energy from the turn - this is related to floating.
Some perceive the flexed release as wasting the energy of the turn. That is in fact one of its advantages and why it is used in performance skiing and high-level racing. In high-performance skiing, we generate a lot of energy, as you see in the frames above: even with the strong absorption and the boots still came off the snow.
The energy generated in a turn is in direct relationship to the edge angles at the apex and carving. The energy is highest in a carved turn on ice at maximum edge angles and lower in skidded turns at low edge angles (the skidding dissipates energy as the snow can't "push back") on soft snow.
Extension releases may be useful in low-energy turns, skidded and pivoted and/or without much edge angles, where little energy is generated in the turn and the skier ads to it with pushing "up".
It is a high level skill to extract as much energy from the turn, in the desired direction, as needed but not more! This is generally what we refer to as Impulse.
The Speed control with retraction releases is a high level skill (we cover that at the black levels). Easy speed control is why an extension with skidding is often used on steeper slopes.
There is a large spectrum of releasing, between extension and flexing, between pushing hard on the skis at the end of the turn to throw the body upwards, versus a complete flexing and relaxing of the legs, to allow it to fall downwards. Weight transfer could start late or early as well...
When characterizing a release, we will look for the dominant characteristic. Here is how the types of releases contrast or combine:
Another way to look at this is how the muscles are being used:
If we resist the forces of the turn with a longer outside leg, we use isometric and perhaps eccentric contractions.
From here, two options are available:
The COM release is sometimes seen in speed skiing. The basic idea is that the body is released before the skis, generally via relaxation of specific muscles. At the same time, the skis are rolled off the edge, but it may result in something resembling an A-frame around the transition.
Related to up-unweighting, this is based on a push and/or an extension of the legs, especially the outside leg, which will tend to push the hips and body "up". This will afterwards take weight off the skis and allow them to be released from the previous turn. Afterwards means when the pushing is completed, usually around skis flat.
It is an older technique, called "up-unweighting" and usually followed by a pivoting of the skis - while the skis are disconnected from the snow and any rotation efforts or momentums easily affect their rotation.
Typically, the skier in this case will flex the outside leg throughout the turn (giving into pressure) and then extend/hop at the end of the turn, to release the edges, hence the name "up-unweighting".
This type of release is very common but less effective, as it usually leads to excessive up and down movements as well as a loss of control (while the hips are "flying" up and down, all you can do is wait for them to come down, to get pressure back on the skis).