Punch led kicks, that carry through to punch combos; will keep energy more flowing and continuous. Seasoned Goju fighters will do this with a front punch, followed by a back leg front kick, carrying the reverse punch.

The hand-elbow-shoulder combinations are balanced by foot-knee-hip movements and spins so areas traveled can be coordinated to the swing of the velocity changes of the inertia and potential energy generated. Tiger Tae Kwon Do hand combinations are synchronized well with spin and turn-back side thrust kicks.

An externally hard; hand-elbow-shoulder combination is a skeleton based, erector set that's primary force is lever and axis/joint leveraged. In mathematics this concept is rudimentarily measure by many triangle-rectangles in 'step-theory'. The more accurate mathematically theory of differential/integral calculus; requires an understanding of the flowing concepts of wave theory. An internal blow flows like water, with the force more efficiently delivered like a whip. Once applied, the internal conforms to the target better.

A hard-external arm blow must usually chambered/pocketed first to get it's full power; whereas an internal blow can attain killing power in two inches or less. If and when the blow misses, the hard/external fighter's movement must go the longer route back and forth to the initial launch point of the chamber/pocket. For example, most karate the chamber/pocket area for the front punch is either with the fists at the waste, or tucked up higher along the body's side ranging all the way up to the armpit, for some styles.

Internal blows can be a 'continuous and returning fist', maintaining their momentum and power as they travel and change direction, so you get many 'second chances if the first attempt does not connect. A karate front snap punch, has all the force released at the end of the blow, and is jerked/snapped back, so there is nothing left of the power generated; they have to reload! If you want to rely on that, then go ahead, not me.

From: http://www.jadedragonalaska.com/mart...l-benefits.php