Being too eager to respond to opponent’s action, whether it means the attack or block that is too early, gives the other side strategic advantage.
Video below this article
What it means is that initiating (attacking) side can invest less energy in order to receive more energy from blocking side in return. In other words the attacking side uses less commitment to fully engage the other which brings similarity to typical Sasoi-waza (one of the forms of set up).
In our drill the attacking side maintains full control over the technique and withdraws from it upon the contact with the blocking arm (pic 1). The energy of initial punch is then used for the block and another attack (pic 2). It is important to remember that average punch lasts close to 0.2 sec which may seem short but leaves enough time for skilled karateka to adjust to changing circumstances. Naturally it requires synchronized action of mind, body and breath.