I can't do proper karate kicks. How can I improve my legs for this?

[Gianni]

Hello. I'm 18 years old and I practice karate, Tai Jutsu and Judo. My legs aren't really willing to cooperate during training.

An important detail is that my feet are not oriented forward. When in a relaxed state, they both point out about 45 degrees, forming an angle of 90 degrees when placed together. Perhaps this is important for later parts of this question.

When I do a standard forward karate kick (mae-geri), I cannot extend both my legs to a fully stretched position. They always stay at a slight angle. How can I make this part (the back side of my legs) more flexible in order to do this properly?

When I do a side kick (mawashi-geri) I can't aim high. Waist level is a challenge already. It feels as if there's a cable running from the inside of my feet, to my inner thighs on both sides. How can I stretch this part of my legs? When I try to do a split (feet facing forward), my knees start to feel pressure and strain. This isn't overly painful, but I'm afraid of injury. Ideas please?

When I do a backside kick (Ushiro-geri) I can aim fairly high, but again, my leg contracts very quickly after reaching the top of the kick. This makes it feel as if I can not put force into that kick, unless I would severely bend forward whilst doing it, causing balance to be 0. Ideas please?

This has been troubling me for ages and makes me fear of not being able to get my Dans one day. Please tell me what I can do about these issues and what techniques work best.

Many, MANY thanks!

[Ben]

Its really simple, stretching, A quick warm up, then 10 minutes stretching every day, pushing yourself harder each time, you'll be there very quickly. Sit on the floor, spread your legs apart, as wide as possible, and reach down one leg, holding a position where you feel tension for 30 seconds, then swap. You'll notice mae geri kicks will be the easiest to get high, the most difficult i would say is kekomi geri, it requires you to almost do the spilts. You may think 'yeah, but my legs wont bend out properly', to compensate for this, you will need to be more flexible on the backs of your thighs, good luck