But can anyone tell me why many good athletes can't deal with quads. Deniss's fall seemed extremely painful and I was worried! And what about 3A? It seemed so strange.
I'll try to share some of my observations.
There are three important elements of a jump: height (the higher a jump is, the easier is to do multiple rotations), rotation speed (the faster rotation is, the easier is to do more rotations), safe landing. And:
1. the smaller a skater is, the higher they can jump in relation to their height
2. the slimmer a skater is (has smaller girth), the faster rotation can achieve
3. the shorter legs in relation to their height a skater has, the safer their landing is.
I would say that Deniss' body features are quite the opposite to the above: he's quite tall (for a skater), broad-shouldered and his legs are one of the longest in the business.
Is it to overcome? Sure, Adam Rippon has similar body feature and could jump 4T and 4Lz. Was it easy? No, and his rate of execution wasn't really high. And his frustration that his body betrayed him was immense.
The solution is to maximize the legs' strength and to build a muscle corset and that's what Deniss has been visibly working on.
But there're more problems.
Muscles are heavy, so a skater weight increase. Weight changes (even by half a kilo) makes significant impact on jumps (the same for height). Some skaters can deal with it quite easily, some not.
Younger skater can learn new jumps easier. Recently quite young kids are taught quads (while Deniss was taught 3A only at 15/16 and when other skaters got their quads, he was seriously injured and had to work hard to got his triples back; and then was the Olympics year and the priority was to skate clean and safe). Ghislain Briand (who is one of the best jump coach and was invited to Champery last year) said (reportedly) that if a skater doesn't jump quads till the age of 18, it's almost impossible to teach them later. On the other hand there were many skaters who started to jump quads in their 20. So... time will tell.
The jump fear makes skaters to avoid/pop difficult jumps. Fear of pain, fear of injury, or just fear of failure. It's very common and many skaters deal with it, of various reasons. I don't say that it's Deniss' case, but living in Switzerland as a foreigner with no regular income makes Deniss' situation quite difficult when it comes to medical treatment costs so he can be careful because of that. Stephane's been calling it "a blockade". In Innsbruck Deniss fell several time really painfully but he didn't pop so I hope his blockade is a past.
Last but not least factor: amount of training. The more the better one can tell, but how many exercises a skater can do with no overloading/injury/stress fracture etc.? Stephane seems to be careful and concerned coach so he put some limits while (as I saw at EC) Deniss would like to practice more. So I must say I was relieved seeing Deniss healthy and in good shape at Cup of Tyrol...
OK, I'm sorry for this excessively long post, but AgnesR's question was something I was thinking of for many months lately... For me Deniss' skating is so outstanding that I personally don't need any quads... On the other hand, his quads landed in practice are HUGE and really beautiful! Wish him to land them all at competitions since now.
Oh, and 3A. I'm not sure why, but apparently extensive work on quads makes 3A harder to jump than previously.