A common misunderstanding within the Southern Shaolin arts is that we need to tense the arm/torso at the point of impact to transmit power into the opponent. This is not correct; the type of power we are aiming to transmit to the opponent is hindered by tension and muscle contraction.
So what do we do?
Southern Shaolin systems like our Tiger Crane Combination are based on the energetics & internal dynamics that was introduced by Bodhidharma. Bodhidharma’s teaching introduced the idea of creating power not through contracting the big muscles but by getting them out of the way as much as possible and engaging the Fascia & Sinew channels that run around the body like guitar strings. The training when done correctly should begin to develop these channels and link them up together; so that plucking one end of the string causes an effect in the other end. To get this we need to inflate & stretch. Our Suang Yang Form, which is a Shaolin soft fist emphasises this inflation of the body and this stretch constantly.
So instead of contracting and tensing on impact, which will give you a kind of brittle hardness. Try to find the stretch in the movement, this will give you a more taut and elastic type of hardness and then your body will be able to transmit the kind of power Shaolin Kung Fu is famous for, which we call Jin or Geng.