Among barbarians it was common to use extreme stretching for super endurance and immunity to bone-breaking, a very useful perk in wrestling.
To prove his or her unbreakability was the noble goal of every barbarian youth who kept developing their bodies since they were kids.
Some youths liked to brag about how flexible they are and what amazing stretches they were able to pull last night, too bad nobody was around to see them!
But many were honest and worked hard to inspire others and often pushed their bodies through breathtaking and scary feats. Not only involving strong assistants but even horses and tamed beasts, folding under huge stone plates and getting pulled beyond their limits by large buckets full of rocks (so called "School of Rocks").
"What doesn't kill us, makes us stronger!" And every youth strived to do their best because crying and whining would end up turning them into mere dancers and entertainers, weaklings whose only purpose in life would be to become living decorations and toys for someone stronger.
Many of these skills were applicable in real battle. Mounted archers had the ability to twist their bodies and shoot straight behind themselves without changing the horse's direction.
The best of them could twist their torso 360 degrees and keep riding the horse with their body twisted to boost the morale of their own troops. "We can do it!"
For barbarians the body was a mere toy to their strong will and in many ways they believed it helped them to be successful warriors and dominate over a huge territory.