LaoDan wrote:The researchers only show vectors of force from the front foot. While they may have also collected data from the rear foot, it is not shown in the video. I take the shaded square in the drawn version to indicate the force plate, which is only under the front foot of the ball and stick illustration. I do not see any force plate indicated for the rear foot.
After further review yes, it looks like only one force plate. All similar studies I seen measure both front and rear feet and usually use two force plates.
LaoDan wrote:While they do use the terminology of pushing off, I think they are trying to describe the energy from the front foot rather than the push off with the rear foot. I think that pushing off of the front foot is a potentially misleading use of the terminology (e.g., as pointed out earlier, the torso is not raising up significantly = no bounce and no pushing off; also "pushing off" is mopre commonly used to describe the action of the rear foot). The force is being driven DOWN into the floor/force plate by the front foot.
Chen starts in orthodox stance with left arm raised,
rear foot pointing forward and bending over. He
pushes off the rear foot, torques his body, turns his front foot to a 45 degree, straightens his back, then lands. Once the foot lands, issuing of fist is finished, then retracted. The front foot does not move, pivot, bounce or push off.
Excerpt from "
Tai chi master studied for power to control body:"
Jessica Rose, PhD, assistant professor of orthopedic surgery, on May 7, 2008 wrote:"It seems to be an almost perfect example of translating the angular momentum of his body into the linear momentum of the strike," said Rose. "The power begins first in the trailing foot and is then rotated through the body in a super-fast pivot, then transferred to the striking arm."
The video did a subpar job in explaining Chen's movements. When measuring striking power, a study
should measure the strike at impact, not only ground reaction force when front foot lands. Chen could be leaking power into the ground. In the rear straight, the front leg is used as a pivot point
before rotation and punch is completed.