Abstract: A tumbling strip including a plurality of panels, each panel having a channel defined along a centerline thereof. The plurality of panels are arranged such that the channels in each of a pair of adjacent panels are aligned with one another. A plurality of inserts are provided within the channels so that the tumbling strip has an increasing resistance to deformation as an amount of deformation of the tumbling strip increases. A fastening assembly selectively attaches adjacent panels in the plurality of panels to one another. An adjustable support assembly provides a variable amount of support for the tumbling strip so that the rebounding action of the tumbling strip can be varied depending on the amount of support provided by the adjustable support assembly.