For the stride (or jump) to be most effective, the center of gravity (in the middle of the pelvic area) should be lined up with the direction of the force when viewed from any direction.  Powerful skaters "load up" their bent leg by correctly getting their center of gravity over their leg.

In the drawings below, the skater on the left is displaying efficient force production, while the skater on the right is displaying inefficient force production.
 

A powerful skater, like Troy Riddle, extends on each stride in a sequential way.   First, the gluteal muscles of the hip extend the upper leg and abduct (push to the side), while the quadriceps (thigh muscles) begin to extend the knee joint.   Finally, the calf muscles extend the ankle to get the last toe kick - - and we see the results of this with powerful skaters as they "spray" the ice with each stride.

The same sequence of power occurs in a one-legged jump to the side, like on the Russian Box.  That's why jumps like this are a great training tool for skating.

For the stride (or jump) to be most effective, the center of gravity (in the middle of the pelvic area) should be lined up with the direction of the force when viewed from any direction.  Powerful skaters "load up" their bent leg by correctly getting their center of gravity over their leg.

Weaker skaters will often lean forward or to the side at the hips, so the force line does not pass through the center of gravity.

This sounds more complicated in words than it is in action, but remember this important concept and try to feel the proper sequence of power when you're doing training jumps or working on your skating stride: Efficient skating (or jumping) requires the center of gravity to be in line with the force.