Most Chinese styles use a calm approach to power development. We try to keep unnecessary muscles from being involved in the technique, in order to avoid inhibiting the prime movers behind a certain technique from achieving its result. Essentially, a straight punch is a triceps-driven technique and the Chinese style of punching allows the triceps to do its job without the inhibition of significant biceps involvement in this punch.
Most other techniques can be viewed in a similar fashion – you have muscles which are vital to the effective execution of a technique and muscles which can be not, or which are even counter-productive when involved in that technique. No matter which martial arts style you do, try to avoid unnecessary muscle involvement.
Many Chinese styles use more “follow-through” in their techniques and achieve their power by driving the entire body weight through a target zone at speed. The arm is totally relaxed until contact is made and the body is still driving deeper into the target when attention is brought to the technique using a trigger.
The body has more inertia to overcome before it can move with the descending line of force and, as a result, the power is more completely absorbed by the body rather than being partially dissipated by the body moving more freely with the punch, as with a horizontal line of force.