I am 21 years of age. I have been learning taekwondo for a year. However, I am still unable to achieve a complete split. What are exercises that I can do to increase my flexibility to reach a complete split?
You increase flexibility by stretching. You prevent injury through strength training. The great danger in splits, especially the middle split you need to work on for sidekicks is that if your cross-ligaments in your knee are week, all the strain will go there and you'll hyper-extend or tear them and have knee problems for the rest of your life. You need to warm up sufficiently before you even THINK of doing stretches to improve your flexibility. You can either achieve this by going for a short run and a couple of light stretches, OR you can cheat like I did and take a nice, long, hot bath (30min +-).
When you're good and ready, get into a middle split. Go as far as you can without pain. No one cares about how much pain you can take. This is about improving flexibility. When you start feeling pain, tense your leg muscles, squeeze for 5 seconds, then release and split a little further. Keep doing this until clenching and releasing doesn't make the pain go away anymore. It's also beneficial to LIGHTLY pound your inner thighs and hamstrings with your fists. I don't know why this works, but it does and there is science behind it which you can read on your own time.
With that out of the way, I want to point out two things:
When performing the flexibility exercise you want to be best at (split), keep in mind the following tips.
This is part of a full article I've written that can be found in my website: FLEXIBILITY IMPROVEMENT – KEY PRACTICAL KNOWLEDGE (martial arts)
" (...) HEALTH HABITS The following three health habits are truly essential for the development of flexibility: a) Drink plenty of water (2 L per day, for example). b) Don’t smoke. c) Don’t drink alcohol.
(...) STATIC DRILLS REPETITIONS Major mistake I generally see is repetitions that don’t last longer than 10 seconds! You won’t get improvements from those exercises in the same way you shouldn’t expect cardiovascular improvements from a light 1 minute jog!
Another common mistake is for people to bounce when they’re close to stretch limit, in order to surpass their limit with each impulse… This increases the probability of injury significantly and is therefore not recommended! Instead, do a single continuous push until you reach your limit and hold there.
For each type of exercise, just do 2-3 repetitions, each lasting at least 30 seconds, in only one continuous stretch motion that will reach the limits of what you can do. Discomfort is expected, but don’t take the exercise to where you feel unbearable pain, as that would lead to almost certain injury! Between each repetition, relax for a few seconds in a comfortable position.
(...) HOW OFTEN ARE FLEXIBILITY DRILLS REQUIRED In martial arts -> Every single training session should have a flexibility drills included. (...) "
I agree with Robin that squats and deadlifts are important. but i disagree that if you can't squat your own body weight you shouldn't be doing martial arts.
Squats are actually great for improving your hip flexibility, most people think they are only for strengthening, but they definitely improve your hip and ankle flexibility. Just make sure your form is good or you'll do more damage then good!
My favourite way to improve flexibility, which I have talked about in a few questions here, is active stretching, or stretching with a partner also known in more science like terms as isometric stretching. Here's a link to an answer to another questions: Is stretching with a partner beneficial, dangerous, or both?
For doing the splits, I would work on the one standing against the wall primarily. Doing the butterfly stretch won't hurt either.
To do the first one:
Make sure you do both sides b/c the stretch is difference depending which leg is in the air!
Also: Make sure you're very warm before doing any flexibility work. working on flexibility cold is not very helpful, and can be quite harmful.
Deadlifts and squats. Thomas Kurz (who demonstrates some very impressive splits at a moderately old age) says that if you can't deadlift and squat your own bodyweight (minimum), you really shouldn't be training for martial arts or flexibility.