Interesting. Does this explain why Yuna was suffering from injuries a few seasons ago? I hear her back still hurts at times, so that's a possible reason for wanting to retire after the Olympics.
Actually, it's quite the opposite. Just look at Yuna's Biellman position and spiral positions. She is much more flexible now than, say, 2006-2007 seasons.
The best thing to do is to actually go back and look at Yuna's skating. If you look carefully, you will see that Yuna's back remains fairly flexible, while her ankles and knees are now less flexible (almost immovable) compared to before.
This goes to show that if Yuna retires soonish after the Olympics, which is what has been indicated/hinted, it will not be because of her back so much, but more because I feel that her technique on her toe jumps incurrs great burden on the whole of her physique. She may be smiling as she lands those jumps, but I wouldn't underestimate the shock that those combinations give to her system.
In order to be able to land those triple-triple, she has to practice them, say, 5~10 times a day, 5 days out of the week. If she practices them 5 times a day, then that's 25 triple-triple combos per week, if 10 times, 50 combos per week. That's 100~200 combos a month she's practicing, meaning she's done 3600~7200 combo jumps in the past three years. (This is a very conservative estimate.)
Just go to an ice skating rink and try banging your toe into the ice with the intent to cause a force that would propell you into the air enough to complete three rotations. Next, jump into the air as high as you can (while skating backward if you can) and try landing it on one feet. In one combination, she does that twice, meaning she's forced herself to go through that 7200~14400 times in the past three years alone, so that she can do it in competition.