What happens internally with "tension and relaxation"?

Youtube video:

What happens with "tension and relaxation"internally?

So, what happens in the body when you do “Internal Movement” from the core with tension and relaxation (explained for Chinese and Western)?

Jim R. said: If you see Master Hwa's Youtube video in this post, there is less oxygen needed for relaxed muscles and hence the rate of breathing is slow. Since the heart is not required to be beating so fast to supply oxygen out to tense muscles, heart rate and blood pressure decline. Thus the normal blood flow will return to the belly and digestion resumes where the belly is calmed and also the hands and feet are warmed up. As a result, this series of body adaptations all occur and fall naturally into place as the voluntary muscles are being directed into a state of relaxation, and changes in mood will follow which makes the body feel calm and refreshed. A student of Master Hwa's said that she felt "heat" when she practiced but she said others faces turned red and perspired.

Master Hwa said:  “The Chinese way of explanation is that the abdomen is “Sea of Qi”. When one learns to connect one’s body so that Qi can flow without blockage during movements, Qi will fill every part of the body, Most obvious are fingers (hot and tingling). One will also feel hot and sweaty in the head. But, it should not be a flush red face, it should be a nice healthy color. Cardio exercise will result in a flush red face.”

Jim R: A Western explanation is that our internal movements are penetrating deep into the abdomen and the back, stimulating the function of the organs and promoting blood flow in those areas which result in the heat in the fingers, hot and sweaty in the head. Since most often, these movements are carried out slowly, the heartbeat does not increase significantly.

Video of "joint" (square) form

Video of "joint" (square) form

There would be injury to the knee if the person in this video only attempted to turn the foot. When one turns the lower body as shown in the video the turning is done from the CORE not from the leg, foot, etc. In the Tai Chi classics this is an adage of "hand follows foot, elbow follows knee, shoulder follows hip".  This video of my longtime student and a certified teacher Jason executing just the 1st 15 movements of the "Square" Form, sometimes referred to as "Joint" Form. Although there is incredible "articulation" of joints, it's real purpose is to teach students how attain a “delineation” and to move one part of the body while keeping the other still...a difficult task for beginners. Jason used my letter about his Tai Chi expertise to assist in gaining entrance to the D'Youville College Masters Degree Program. 3 years later he used Tai Chi and Heart rehabilitation as his Thesis for a Master's degree in Occupational Therapy. He is now a practicing OT in Colorado Springs, CO. His movements are very good, but the amazing thing was he learned the entire footwork of the 108 movement Square form FIRST at my urging. With his good work, I hope my present-day students can now see the importance of why I teach them lots of footwork first.