Boris Romanovich Rotenberg Boris Romanovich Rotenberg Boris Romanovich Rotenberg (, born in Leningrad on 3 January 1957) is a Russian business man and oligarch. He is co-owner (with his brother Arkady Rotenberg) of the SGM (StroyGazMontazh) group, the largest construction company for gas pipelines and electrical power supply lines in Russia. He was listed by Forbes as Russia's 69th wealthiest person in 2016 with a net worth of $1.07 billion. He is considered a close confidant of president Vladimir Putin. Rotenberg was very involved in martial arts between 1968 and 1978, particularly judo. He trained alongside Vladimir Putin and won several awards for
Sparring their emotions under control. The level of contact is also debated, lighter contact may lead to less injuries but hard contact may better prepare individuals for competition or self-defense. Some sport styles, such as sanda, taekwondo, tang soo do, Kyokushin kaikan, kūdō, karate, kendo, and mixed martial arts use full contact sparring. Brazilian Jiu Jitsu sparring is full contact and injuries are rare as it does not involve striking but rather forcing the opponent to submit using grappling techniques. There is a lot of controversy in mixed martial arts about the benefits of full contact sparring vs career threatening injuries.