In Okinawa karate, we emphasize proper transfer of energy from a punch, block, or kick, to the interior of the body of an attacker. This is sometimes called chinkuchi. Chinkucki is a subtle, but important, characteristic of Okinawa karate that takes time to develop and understand. It is something one needs to learn to order to develop a killer punch referred to as a one-punch knock out! To punch, block and kick in Okinawa karate, relax except for the fraction of a second when you make contact. Keep in mind that Okinawa karate systems train for combat, while most Japanese karate trains for tournaments. So, there are differences. To develop chinkuchi, learn kime. Kime and chinkucki, are about acceleration - something every karate practitioner needs. I can not emphasize this enough! Movements in karate need to be: (1) relaxed! (2) accelerated! (3) focused at the last possible moment, (4) accelerated! and (5) focused! I know I listed accelerated and focus twice, but this is because these are so important and DIFFICULT to get American martial artists to develop. Study Chinto (aka Gankaku in Japanese) kata performed by Akamine Hiroshi. Watch his kata for focus and acceleration (see about 4 minutes into the video) - it is nearly perfect. Watch it and periodically video tape yourself to see if you are gaining similar acceleration and focus in technique. A fast transfer of momentum implies the amount of force transferred to a target will be large all at once - this is the secret of one-punch knock outs.
Another important characteristic of Okinawa karate is mochimi. Mochimi refers to relaxation and flexibility. Punches, blocks and kicks should be performed relaxed and should contract only at the point of impact (not while you 'launch' your fist), and finish relaxed, which is different from Japanese karate where striking techniques are stiff throughout the process.
Newton's second law of motion states that Force is equal to Mass multiplied by Acceleration (F=m.a), indicating that heavier fighters can strike with greater force than light fighters based on mass alone. But because of the magic of karate, through proper training, a light-weight fighter can increase the force of strikes by acceleration, and by wisely using body mass with timing and shuffle steps (i.e., tsugi-ashi or yori-ashi), grabs, posture, hip rotation, and shoulder movement. Few of us are as endowed in the martial arts as Bruce Lee with perfect balance, body movement and acceleration. Even so, we can greatly improve our abilities with daily practice and good instruction.
To use mass effectively, execute every technique with good biomechanics and put more body weight into your punch just like the featherweight Bruce Lee (note how he moved forward to effectively use his body mass).
To increase mass participation with acceleration, practice kata (your body memory tool) at least twice: first, concentrate of mass participation practicing kata at slow to moderate speed: next concentrate on acceleration (you don’t need to move between steps fast, it’s your punches, blocks, and kicks that need to be accelerated to the max, with focus). If you have enough energy left after running through your kata twice (you should feel considerable energy spent), you can run through the kata a third time focusing on mass and acceleration working together.
When you practice for mass participation, work on hip rotation, foot movement, stance, breathing and the mechanics of blocks, strikes, kicks, and slow the kata down (but you SHOULD hear the sound of your gi sleeve snap on your wrist and forearm and on your ankle and shin when you kick). Acceleration, on the other hand, is the rate of change of speed. In other words, it's about how quickly you increase the speed of your mass in the shortest time possible. Next time you see a hummingbird, watch how quickly it accelerates. In one second, it can cover 50 of its body lengths; whereas, a Euro-fighter jet’s top speed will only cover 39 of its body length in one second (Scott, 2009). To improve acceleration, relax your body and muscles in your arm, then accelerate your punch as fast as possible, with focus - I recommend video-taping yourself and watch for ways to increase power and speed. Also dedicate time to improving your biomechanics and acceleration with properly timed release of breath.
When you punch, stand with your back straight, keep your spine and neck erect. Avoid leaning forward, as this will upset balance. Focus on hip movement - you must use hips properly to increase kinetic energy of your strikes. And of course, breathe. Learning to breathe (kokyu) correctly will influence your punching power, speed, stability, and endurance (Jutras, undated).
