Chudan Uchi-Uke is effective against kicks, punches and knife thrusting attacks. The following key points should be remembered:

• Speed is more desirable than power. All the power in the world wont help your block of you don't react fast enough. Try to redirect the strike rather than stop it.

• Never over-extend a block. Reaching too far with a strike will waste energy and make you vulnerable to secondary strikes.

• Move your body. Don't stand still when blocking. use angles to increase the effectiveness of the block.

• Always exhale when blocking. This increases power to the technique and helps protect you by contracting the abdominal muscles.

• Execute the block in such a way that contact is closer to the elbow than the wrist. 

Practice blocking techniques in front of a mirror. This way you can see what you are doing.  I carry this over into my dojo and when working with students, I will perform the mirror image of what I am teaching. 

 From the Forward Leaning Stance (Zenkutsu-Dachi) - Right hand is in the chamber (by the rib cage, fist closed / palm up), left arm is bent, fist at shoulder height, slightly away from the body, the elbow is at the side of the body (fist closed / palm in).  Bring the right arm across the body from right side to left, belt height, then on a 45-degree angle upward to the right, stopping shoulder height, palm above and forward of the elbow.  Simultaneously, move the left hand to the right shoulder (fist closed / palm in), then retract it into the left chamber.  The right hand passes in front of the left hand. Repeat for opposite side.

 Remember, without safety, there can be no Jujitsu.