Figure skates are not exactly the easiest things to jump in. They are stiff and restrict the motion of your foot and your ankle. Which makes me wonder how this affects the way the rest of your leg moves while jumping.
Haguenauer, Legreneur, and Monteil (2006) examined national and international figure skaters jumps comparing their barefoot squat jump, weighted squat jump (to control for the additional weight of figure skates), and jump while wearing skates. Each skater’s ankle, knee, and hip angles were similar at the start of the jump across all three conditions, indicating that the three were indeed comparable. But the height was affected in each case. On average the weight decreased jump height by 2.1 cm and wearing skates decreased the height by an additional 3.4 cm. This might not seem like much but it could make the difference between getting credit for doing a jump or being downgraded to a lower jump (fewer rotations). This is a significant point difference in the current judging system.
So skates have the potential to reduce the vertical height of the jumps but how. It can’t just be the weight because the weighted condition has a decrease but not as big of a decrease. Further, there was no change in the jump mechanics with just the extra weight attached. So then where does the extra loss come from? The results indicate that there is a decrease in the work down at the knee and ankle joints, the hip did the same amount of work across all conditions.
The loss in work at the ankle appeared to be related to the limited motion of the ankle caused by the skate. In other words, if you just do a jump in bare feet, your ankles will extend (think pointing your toe) more than they will in skates. This particularly affects the last moments of take-off, which makes sense because skates limit your ability to reach the full extension which you only do just before take-off. Without reaching full extension the muscles that extend your foot can’t generate as large a force, decreasing the jump height.
The decrease in work at the knee is a little less obvious. When wearing skates, the knee action starts later, compared to hip action. In other words, the knee starts to extend later and decelerates earlier when wearing skates. According to the researchers, this most likely happens because the foot can’t extend which affects when the knee begins to work. Interestingly though, compared to other research, the participants in this study tended to do less work with their knees even in the barefoot jump which possibly indicates that the skaters modify their jump in general because of their training in figure skating.
Obviously, decreasing the weight of figure skates could help skaters to jump higher and perhaps achieve cleaner jumps (fully rotated) or perhaps even more rotations. But perhaps there are also gains to be made in skate design?