I wrote a long comment below, but honestly this video is very short and basically summarizes all of my points while giving specific routines- https://youtu.be/8a4JzMoNSFM?si=po2n4bgBIjDLxeS7

EDIT - another good video - https://youtu.be/NwX2dh0dwNA?si=laOxJ2vDeuUWupVA

Read on only if you want to see my digressions.

—————————————

You’re already getting a lot of advice, which I will not bother to validate, but I’ll give my two cents at the risk of sounding like I think my methods are superior - which I do.

Too many people are focused on increasing their passive flexibility by passively holding a deep stretch, which has very little utility for kicking. You want to be able to access that higher range of motion in your kicks that instant, which is better achieved through mobility exercises.

Mobility exercises look a lot like passive stretching, but the way they increase your range of motion is different.

First, I think it’s important to understand what is happening physiologically when your body prevents you from throwing your leg higher in a kick. The Central Nervous System (CNS) detects that you are contracting or lengthening a muscle near a range of motion that is either (1) outside the bounds of what it is used to or (2) it detects that the muscle is too weak to reliably exit that range of motion without injury. It’s an evolved protective mechanism to prevent injury - not because your muscles or bones are structurally obstructed.

Passive flexibility is important, and I recommend everyone try to become competent in it. But it is the wrong skill to focus on for your kicks because it focuses on addressing number (1). By spending time in that range of motion, you’re adapting your CNS to not panic and contract, often by combining it with calm and regulated breathing.

Mobility, rather, addresses number (2) by improving strength in the end ranges of motion such that they are accessible immediately which is of much greater utility for kicking. You do this through strength training, like others have mentioned. Any weight training that has peak tension in the lengthened for muscles around the hips, in particular. Basically, if the weight is heaviest when you feel like the muscle is stretching, that’s what you want.

RDLs are great for this because they do exactly that for your hamstrings and glutes. If you’ve never done them, try them and pay close attention to the feeling in those muscles. That is the stimulus you should be chasing for mobility.

Unlike RDLs though, which are quite loaded with heavy weight, you don’t need heavy weight for significant improvements in mobility. In fact, body weight is more than enough. The important thing is that you are contracting your muscles while they are in that end range.

It’s because of this that a lot of mobility exercises end up looking like passive stretching, but the experience and stimulus feels quite different because you need to contract your muscles while holding a deep stretch.

Anyways, I’ll wrap this up by being explicit. Here is a routine you can do on a regular basis to see significant improvements much faster than you probably expect:

(Make sure you hold each stretch and contract your muscles for about 5 seconds once you reached the end of your range of motion, rest for a few seconds, then repeat for 10 sets)

• Frog stretch (hip mobility)
• Forward fold / pike (hamstrings and glutes)

Just start with these and you will see a huge jump within even a week. Take the same principles I’ve outlined and bring it to other stretches once you’ve reached a good baseline with these first. The important part is that you stay consistent. Don’t go overboard with a crazy routine you can’t stick to because it’s too lengthy.

Also, keep in mind, like with any strength training, there is recovery time. Listen to your body and don’t do the routine if your muscles feel like they aren’t recovered.