This book was written by Pavel Tsatsouline, a fitnes instructor who introduced SPETSNAZ training techniques from the former Soviet Union to US Navy SEALs , Marines and Army Special Forces, and shortly thereafter to the American public.
Some info we know, but I think that is worth reading.
https://www.lbs.co.il/data/attachment-files/2014/12/19913_Pavel_Tsatsouline_-_Power_To_The_People.pdf