good thread ...the key factor for training pre-punching positions ,tan and jum , good elbow positions.
The main muscle is the pectoralis major to maintain the elbow of tan 'touching' the c~line....and trying to 'x' the c~line when doing jum-sao using the same P/major only with more contraction force . Done correctly your whole arm should be loose / relaxed.
The focus of SLT is to do this action of bringing the elbow in for pre-punch training position utilizing the outside forearm of tan ,outside gate /outside of the forearm, but maintaining the tan on the c~line. Same for the Jum-sao but using the inside gate / inside of the forearm....both focusing the hand at the opponents head [ as a reference point] while maintaining the elbow in its prechambered poistion... this is what the late WSL would refer to as being its [elbow] master not its minion....in other words dont fight thinking about your elbows just let it come naturally from chisao /gor sao training...
Dan chi is the redundant stepping stone of training the elbows 2 stage process developing this simultaneous P-major contraction with a forward strike ...1st its a 1-2 action as tan hits , to develop the elbow wrist line to target...jum responds by holding center [ forward energy] as the hand is pointing to the head...if students retract the jum arm I tell them to try hitting me as I hit with tan to get the little idea....after a while the process is ingrained to use the 'elbow' not the wrist...and the punch deflects the line of incoming force as it travels to target or is stalemated in the middle somewhere leading onto further concepts...jutsao ...gum ...etc...jum becoming a 1 count strike using inner energy to maintain center while hitting.
The tan is same but using the outside of its forearm, elbow touching the c~line to maintain its deflecting /striking action...if the elbow moves out it can be shown to block itself while trying to hit and easily trapped due to its angle and weak shoulder muscles as its support....it too becomes a 1count strike ...add jum and you get a 1-2 punch that can be doing more than the guy your fighting bargained for
SLT is this elbow in training period to develop the needed endurance of the pec/elbow/wrist lines for freefighting...if your elbows come out while doing chisao/fighting and your being taken advantage of ...more SLT / danchisao....the SLT done without this thinking can be a waste of time and turn into 'application ' fighting due to inability to work the elbow theory and arm chasing with your hands , when the forearms are meant to be a second set of hands....ie jum sao is like paksaoing with the forearm while punching with the fist ....tan is the same only from the outside of the forearm...attacking forwards as it does....not 1-2 hit. ie As the tan elbow 'spreads & hits' off the c~line [ linsildida ] but the punch goes to target
all from ELBOW thinking...or not .
Combine the 2 actions derived from elbow and you have a flanking attack using tan and jum to hold your defensive line whil attacking all out full speed...simple coaching methods can reinforce the elbow , like feinting while throwing a punch at a regular pace to see if the jum action is chasing the arm [shown by x-ing ones own center ] or maintining elbowline / hand to target regardlees of the feint...using pec contractions and elbow control ....it takes a little practice !