How bad posture robs your technique

It is surprising how bad posture in karate can have such a large 
impact on your technique. We have all heard the instructions coming up 
through the ranks of tuck your stomach in, don't stick out your butt, 
etc. The difficulty is that it is harder to see bad posture in the 
mirror while wearing your gi top. Also the tendency is for technique 
to deteriorate as you try and speed up. 

What should good posture be? 

1. First you need to have a straight vertical spine. 
2. Shoulders need to be directly above your hips. 
3. Stomach should be tight. Think about lifting your rib cage or  tucking tummy under the ribs. 
4. Pelvis needs to be rotated to be under your torso. This is a hard one to get correct but, try tucking that butt in and under your hips. 

Now practice this in front of mirror preferable with your gi top off
so you can see your body posture. When you run a hand up the back of
your spine and it is straight you probably have got it right! 

Now given the above points on what good posture is what does bad
posture lead to. This should help give you the warning signs. 

1.) Typical student would have either their butt, sticking out, their
shoulders back behind their hips, or both 

2.) Bad posture causes the student to loose the connection of his
lower body to his upper body since you cannot engage your core muscles
to stitch the top and bottom together

3.) Because of #2 you punch only with your shoulders and arm muscles.
Possibly leading to rolling your shoulder (that feeling when you
shrug)  Weakening your technique.

4.) Your center of gravity (CG) gets messed up and is not over your
hips. This makes it hard to move into the next technique.

5.) You may also it difficult to stick a technique. What I call the
jello effect. Why because your core muscles are not engaged and
helping to lock muscles from foot to hand when you kimae.

6.) Power comes from the hips. Well that this is true, if posture is
not correct allowing your core to be engaged as you move forward your
upper body lags behind. With good posture and a strong core your CG
stays over your navel as you move through the technique increasing
speed, balance, and power.