Yes it's all about acceleration as has been answered above. Given enough power, the guy could break the bar, assuming the guy has mass and the bar is not infinitely strong of course.

Reminds me of the age old puzzle of the lorry carrying a flock of birds crossing a bridge : the bridge weight limit is 10,000Kg, lorry weighs 9,990Kg, birds weigh 20Kg - how can the lorry cross the bridge safely?

Still doesn't decrease the weight of the vehicle, the air pressure from the birds wings is still pushing down on the load bed of the truck.

The only way is to take the birds out, drive the truck over, walk back and fetch the birds.

Besides Weight limit is not the breaking limit of the bridge.