1980s: Kickboxing

In 1981 Gruner left the military with the aim to train full-time in order to compete professionally as a kick boxer.^[7]

In 1984, he began fighting as a professional kick-boxer. By 1985, his successes in the ring were allowing him to train and fight full-time.^{[7][5][better source needed]}

Kickboxing titles

• 1985 W.A.K.O. World Championships -75 kg^[11]

Gruner retired from professional kickboxing in 1987 and pursued an acting career, following the lead of bodybuilders Reg Park and Arnold Schwarzenegger.^[1][6][8]

To promote himself, Gruner plastered posters of himself around Cannes during the 1987 Cannes Film Festival, which caught the attention of a producer. Gruner was invited to Los Angeles for screen tests.^{[citation needed]}

1990s: Acting

Gruner joined Imperial Entertainment Corporation (Turner Classic Movies - TCM) and began acting in action movies.^[6] He has appeared in martial arts magazines, such as Budo Journal, Combat, Impact, Inside Karate, Inside Kung Fu Yearbook and many more.^[12]

In 1989 he starred in his first movie; the urban action movie Angel Town.^[10] Although the film was not well received, Gruner was recognized his presence, with his acting compared favourably to that of Dolph Lundgren.^[13]

In 1992, Gruner starred as "Alex Raine" in Albert Pyun’s cyberpunk 1992 science fiction thriller Nemesis.^[2][14][3] The critics appreciated that Nemesis was filled with amazing stunts, thrilling action sequences, and innovative special effects that were pushing at the time the film industry limits of Blade Runner and Terminator 2.^[15] Both Nemesis and Angel town have been extremely popular in video,^[16] and Nemesis is one of the movies Gruner is most proud of.^[8] In this movie, he offers action, drama, fighting, and gunfights and had to drop down to a 4% body fat to be at his peak physically.^[15]

In 2010, Gruner acted as "Corsair Duguay" in Tales of an Ancient Empire, also named Abelar: Tales of an ancient Empire. In this movie, he had the pleasure to be reunited with Albert Pyun, his mentor in Nemesis.^[8]

Gruner has also played roles in Automatic (1994), Savate aka The Fighter (1995), Mercenary (1996), Savage (1996), Mars (1997), T.N.T. (1997), Mercenary 2:Thick & Thin (1998), Interceptor Force (1999), Velocity Trap (1999), The White Pony (1999), Crackerjack 3 (2000), Kumite (2000), G.O.D. (2001), Extreme Honor (2001), The Circuit (2001), Power Elite (2002), Interceptor Force 2 (2002), The Circuit 2: The Final Punch (2003), Deadly Engagement (2003), SWAT: Warhead One (2004), Crooked (2005), The Circuit 3: the street Monk (2006), Blizhniy Boy: The Ultimate Fighter (2007), Lost Warrior: Left Behind (2008), Skorumpowani (2008), Brother's War (2009), One Night (2010), Tales of an Ancient Empire, also named Abelar: Tales of an ancient Empire (2010), Re-Generator (2011), Cyborg: Rise of the Slingers (2013), Sector 4: Extraction (2014), EP/Executive Protection (2015), The whole World at our Feet (2015), Assassin X also named The Chemist (2016), Beyond the Game (2016), Showdown in Manila (2016), Darkweb (2016), Iron Cross: The road to Normandy (2018), and Amour (2019).

Gruner has been announced as "Jagger" in Escape from Paradise (2019), and as "Duguay" in Cyborg Nemesis: The dark Rift (2019), as well as in The Target (2019).

2000s: Television

Already in 1999, Gruner appeared as "Dieter Vanderval" in the episode titled Wildlife of a television series named Martial Law.

In 2001, he appeared multiple times as "Tawrens" in 26 episodes of the television series Code Name: Eternity.

In 2005, NBC contracted Gruner for producing a TV series named The Pros, a way of life. This was a project that Gruner himself had started in videos since 2003. It shows what happens behind the scene, and the life, training, and discipline of professional athletes.^[10] He had already done episodes on boxers, surfers, and MMA fighters,^[8] when NBC finally decided to shelve the TV series, and it was never published by them.^[6] A video published by Gruner is available.

He was also contracted to play "Ivan" in the television series Seven Days published in 2019.

2010s: Directing

Gruner first involvement as a director was in 2002 with Interceptor Force 2.

In 2011, he premiered his first feature film as a screenwriter, a director, and an actor,^[6] entitled Re-Generator. This film was previously titled 'One Night', a project Gruner had been working on since 2010.^[17]

In 2014 he featured as a director in Sector 4: Extraction, a direct-to-video release.

In 2015, Gruner released one more film as a director, a producer, a screenwriter, and an actor: EP/Executive Protection.

Film producing

Rather early in his career, Gruner got involved in the production of some of the films in which he was appearing as an actor. This is the case for Savage (1996), Mercenary (1996), Mercenary 2: Thick & Thin (1998), Interceptor Force (1999), The Circuit (2001), and Crooked (2005).

But it is only starting from the 2010's, at the exception of Interceptor Force 2 in 2002, that he accumulated his involvement both as a producer, as an actor, and as a director in One Night (2010), Re-Generator (2011), Sector 4: Extraction (2014), and EP/Executive Protection (2015).

He has also been involved as a producer only in Front line (2015). And he was both an actor and a producer in Iron Cross: The road to Normandy (2018).

Screenwriting

Gruner has had quite a taste for screenwriting and co-writing the stories of some of the movies in which he appeared as an actor.

He wrote the stories of T.N.T. (1997), Interceptor Force 2 (2002), Crooked (2005), One Night (2010), Re-Generator (2011), and EP/Executive Protection (2015).

He also co-wrote the story and the screenplay of Lost Warrior: Left Behind (2008), and co-wrote the story of Sector 4: Extraction (2014).

Body-guarding

Gruner occasionally does body-guarding for celebrities. It can be more comfortable for some clients to have a fellow star, who understands stardom's pressure and demands, who also fulfills the role of a bodyguard. Gruner indeed not only has one of the highest special forces military training one can receive,^[10] but also provides body-guarding training at his academy. One of such body-guarding clients is the famous Canadian singer Celine Dion.^[18][19][20]

Training videos

Gruner has been producing training videos for martial arts, combat skills, body-guarding, and survival techniques since 2012.^[5] He commercializes those under the various brands of "Gruner Tactical Training Academy" and "O.G Training". More recently, he has been producing a survival reality show video series under the name "Survival X" in 2018.

Personal training

Gruner has always kept a side activity as a personal trainer in various martial arts such as kickboxing and mixed martial arts.^[10][6] He usually dedicates this personal training time to competing martial artists, as well as retired champions.

Athletic fashion brand

He has also created his own "O.G" trademark athletic fashion brand. Several collections were produced, including "The Lone Operator" collection, and the "Pro Series" collection in 2018.

Helicopter piloting

Gruner is a licensed helicopter pilot, which allows him to mix this activity with film producing requirements at times. For example, he worked for ABC News in Los Angeles where he did many chase videos, and saw a lot of damages and lethal encounters.^[10] Moreover, he was also the helicopter co-pilot in the 1999 movie Storm.^[21]

He regularly flies helicopters and considers it a big part of his life. For Blue Hawaiian Helicopters, he regularly flew tours on Hawaii Big Island. For Maverick Helicopters, he also flew tours over the Grand Canyon.^[10]

Films

Television

Documentaries

Stunts