Discussions on hikite are like discredited political philosophies. You think that empirical evidence has consigned them to history and then they flare up again, fuelled by the ‘true believers’ devotion to outdated treatises or the misguided analyses of the long-dead.
2020 saw another such flare up with many prominent and respectable individuals in the practical karate spectrum voicing opinions. I chose to steer clear, not seeing the need to express an opinion on what I felt was obvious. I suspected that ‘Covid Boredom’ and mischief rather than ignorance may have been responsible for the topic crawling from the grave once more. At the request of Les Bubka (author of the thought provoking Anxious Black Belt) I’ve finally been coaxed into stating my views in time for Halloween.
Retracting one arm does not increase the speed and therefore the power of extending the other arm. Whether the (non-striking) arm is pulled back or already held at the hip or in front of the chest / face makes no difference to the velocity of the other hand. It may feel more powerful, but any empirical test with hundreds of experienced subjects from multiple disciplines striking impact measuring equipment will demonstrate that this is not the case.
Leaving one arm fully extended while striking with the other may limit hip, torso, chest and shoulder movement and thus striking arm extension, resulting in reduced speed and therefore reduced power. As a result, if you have an arm already extended you should bring it back to enable full body movement to generate a powerful strike with the other hand. It is not the retraction that makes the extension more powerful, it is not having the ‘non-functional’ arm extended that enables better muscle recruitment for power generation in the striking arm. The simplification of this to ‘pull the arm back for more power’ may have been lost in translation.
Pulling a target onto a strike will increase its speed at the point of impact (and therefore the energy transferred) as the speed in the force calculation is the sum of both the striking object and the target moving towards it. HOWEVER, the distances involved are so small that very little target speed is generated and the shortened distance made by the striking limb results in it achieving a lower speed and thus the overall effect (in terms of power) is negligible and may actually be less powerful. Far more significant is the effect of any pulling on the state of the target, since third party induced movement may result in loss of muscle tension resulting in the strike having a greater effect; furthermore seizing a target increases the chances of the strike hitting the target and may enable greater accuracy.
I hope that is simple enough to understand.
Sometimes I think my martial arts friends are pulling my leg.