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Jump similarities: Study case with Sofia Samodelkina

Sofia Samodelkina is a promising Russian skater, almost 15years old from Moscow. During the 2021 Denis Ten memorial, she landed her quad toe-loop and salchow in her Free Skating, and this competition was only open to junior skaters.
Her salchow and toe-loop look similar. Let’s have a look!
There are six different jumps: three jumps that use the left foot to create the rotation/torque, three that use the right foot.
Salchow and toe-loop use the left foot to stop the skating motion.



This screenshot shows the entrance of the jumps. For the salchow (on the left side), Sofia ends the 3-turn, and she is on her right foot in the inside forward edge. For the toe-loop (on the right side), she will execute a 3-turn in the outside forward edge. Sofia is on her left foot.
No matter which foot Sofia is, she has got the same upper-body posture with the same opening of her shoulders.



The exit 

The exit of their turns is quite similar. On the right side, Sofia’s right hip is closed, ready to do the change of foot. Her body weight is more located on her toes (forward, compared to the left side). The movement she will do during the change of foot explains this difference.



Force production phase

On the right side (4T), Sofia’s upper body moves forward to incline around 62°. That’s huge. But she will keep this angle.
On the left side (4S), unlike the preparation of the quad toe-loop (4T), she keeps her upper body longer at the same inclination angle (26°), then she will incline more forward, around 42°.



Two feet / Toe-pick



Swing move

She straightens her upper body up. This move is part of her extension phase; it requires a perfect rhythm, but that’s explosive. We can notice that on the left side, her right knee is already going up.




Even with a different jump direction and camera angle, the take-off postures are almost similar. She has a little bit more pre-rotation on with her 4T (Right side). The difference in the direction of the 4T is due to the angle of her hip opening.



Air posture

Sofia’s body angle in the air is around 5° for both jumps. Her hands meet up on her right axis, her rotation axis.




On both sides, she is a bit too forward. Her body angle is around 6°.



The knee-up technique is rarely used, even if jumping with your arms up brings your free leg higher than jumping with your arms on your trunk.

4S Data, Flight time: 0.601s / Angular velocity of the snap: 29.263rad/s

4T Data, Flight time: 0.584s / Angular velocity of the snap: 27.695rad/s