Developing Static-Active Flexibility (ie, holding a high kick)

I'm a martial artist, and I'm doing GST primarily to improve my art.  My current goal is to be able to hold my kicks high, but I can't find too much information on how to do this.

 

Currently I'm just holding my leg out as high as I can at various angles and position, holding for 5sec or a cramp, whichever comes first.  I then do 3-5 sets for each kicking position.  After a month of this, I've started cramping less, I can hold my leg lower for far longer than before, but my max height has remained the same.  I'm not sure, is there anything else I can or should be doing?  Does anyone have any experience developing this type of static-active flexibility?  Or perhaps the big question, will going through the Foundation courses help improve this?

 

I'll just mention in passing that I can easily kick over my head even without a warmup.  I'm close to both the front and side splits, and if I round my back I can get my head to touch the ground in a pancake.  The flexibility isn't an issue.  I have long, heavy legs, though, which may be holding me back.  I've played with this skill before, but now it's my current focus, and I'd welcome any tips or resources anyone has.  Thanks.

I would recommend a local beginner ballet class and PNF while you wedge yourself in a doorway with one leg high in the positions you are working on alternating contract release cycles, note you can engage either by pressing against the doorway or by trying to lift your foot off the doorway.  The advantage to doing the cycles in the doorway is that while you are resting you won't have to lower  your leg.  Your dynamic flexibility isn't important for holding kicks high, to be able to hold really nice high kicks I think your static flexibility is lacking, you want over-splits, pancake on 2 yoga blocks.

 

 

I was looking for this same information and stumbled across this article which has helped me. However I haven't been consistent due to my work schedule which has held me back a bit. I did see an increase in height and less cramping.

Check out the link below. It's about strengthening your hip flexors which take over when your leg is a certain height. I chose to focus on my glutes as well to get more hip extension. I didn't want any imbalances from doing this.

 

https://www.gymnasticbodies.com/forum/topic/16509-has-anyone-seen-this-ballet-article/