This video explores how we might use the "reinforced chest block" as a transitional position to set up a basic throw in Pinan Shodan/Heian Nidan. In Matsubayashi, after the chest block position, we pivot around 225 degrees to face the corner, so to speak, instead of a full 270 degrees. I think that is because it ends in the classic position for the judo throw (Shoshin Nagamine, founder of Matsubayashi, also trained in judo and taught judo to fellow police officers in Okinawa). Reverse punch is the "blow before the throw," the reinforced chest block is the set up position, and the pivot into low block is the throw. We drill the application from both the haymaker punch and a basic clinch. Then, we apply the high block that follows the low block (throw) as a contingency plan in case the throw fails, and we train it with moderate to low complacency to experience how difficult it can be to throw someone in a live scenario.
I have some student footage as well. Remember, these are absolute beginners (David Bowie just popped into my head...LOL), and had been training at this point only 10 weeks or so. Instructional context: a college physical education course (we meet twice a week for 50 minutes).