I've always wondered why we put our hand on our chest when doing shuto –

 

 

This video of John Kerker shows an excellent example application!

Note the check of the punch at the very beginning - it is easy to miss

John Kerker Ideally in a real situation the hand pulling to the sternum and the hand striking happen at the same time if you watch Dan's chin you see how the left hand pulls him and accelerates his chin down and forward, for that split second he has no control and that's when he would get hit.....for safety and demonstration purposes the striking hand delays