Anger release bar

Strange stuff!
Does 'punch at' imply some sort of near hit or maybe maximum force allowed?
What if someone comes in who is capable of delivering a serious belting...
I wonder if insurance will cover that?
Or do they have waivers, stating you're working at your own risk?

Story:
Stressed-out Chinese can now unleash pent-up anger at a bar that lets customers attack staff, smash glasses and generally make a ruckus, a Chinese newspaper reported Monday.

The Rising Sun Anger Release Bar in Nanjing, capital of the eastern province of Jiangsu, employs 20 muscled young men as "models" for customers to punch and scream at.

The owners said that since he opened the bar in April, most of the patrons have been women, especially those working in karaoke bars and massage parlors.

Source