One thing I found peculiar but I’m now starting to understand a bit more is the importance of circulation. These dudes developed a system of isolating and contracting various muscles not only to gain strength and gain muscle but also to improve circulation.
Great video...compelling and informative! I did isometrics while preparing for OCS and it was a great help.
Oh, and one more thing (AS Lt. Columbo would say...)
You have a great smile...smile more!