"Get back to the beast mode!" an observer shouts in the face of a sweating athlete. "Stop wallowing in self-pity!"

In a nearby competition, a participant grimaces in pain at the end of his workout. Moments later he is laughing and happy, being clapped on the back by his colleagues.

To outsiders, there's something martial going on as 40 male and 30 female athletes struggle through the fourth edition of the "Battle of Rostock," a CrossFit competition organized by the local CrossFit Box Sturmflut (German for storm flood).

CrossFit, a regimen developed by former gymnast Greg Gassman in California, aims to optimize physical competence in 10 areas: cardiovascular and respiratory endurance, stamina, strength, flexibility, power, speed, coordination, agility, balance and accuracy.

In Europe, the trendy sport has spread rapidly. In 2012, there were just 21 CrossFit boxes — or groups — in Germany. In three years, that increased to nearly 200.

On the program in Rostock are competitions such as the farmer's carry, which involves kettlebells. Many exercises are performed with weights. It takes at least three workouts to qualify for the finals. In each workout, two or three different exercises are combined, aiming for either overall speed or AMRAP — as many reps as possible.

Other workouts include front squats with a barbell, double jump ropes, deadlifts with a barbell, medicine balls, handstand pushups, running races and sled pushes. The final includes a clean-and-jerk barbell competition with increasing weights and a handstand walk.

"My box is like a family for me," CrossFit athlete Hauke Tesnau from Lueneburg said after finishing three workouts at the competition. He did not make the eight-man final, but was not expecting to. "No matter how far you go, you are fired up by all this. It helps the inner pig dog to go to its limits."

Tesnau added that "the mental challenge is extreme in sports. The head says 'no,' but the body does it."

Those behind the Battle of Rostock say it has quickly become one of the biggest CrossFit events in northern Germany.

"Next year we will host the competition on the beach!" promised organizer Sebastian Ladwig.