[Jeff]

DG

I can actually understand the idea of a mental trigger - where one focuses one's mind on a certain body part when starting the downswing (despite HK's statement that the listed triggers are release triggers and not downstroke triggers).

Having watched that TT video many times, this is my personal perception of what TT is doing in his right arm throw action.

As you stated, it doesn't start with a body pivot action, although the body pivots reactively in response to the right arm throw action. I think that TT throws the right forearm to start the downswing - in other words, I think that his mind is focused on the right forearm. Now, that doesn't mean that the right forearm muscles activate the downswing's right upper limb action. It means that he throws his entire "right forearm" down-and-out. The first downswing muscle motion is the activation of torso muscles that adduct the right upper arm (pull the right upper arm closer to the body) so that the right elbow approximates the right hip area. Then, fractionally later, the right triceps muscle contracts vigorously to straighten the right elbow thereby throwing the right hand (and therefore club grip and left hand) down-and-out towards the ball. During this downswing motion, the right forearm muscles do not contract in order to move the right wrist/hand/fingers. The right forearm muscles only develop increased isometric tone in response to the mental thought triggering the downswing - the mental thought of "throwing the right arm" down-and-out.

Jeff.