An energy-absorbing pad structure includes an energy-absorbing pad that is encapsulated by a polymeric film. The polymeric film is sufficiently air-permeable to permit air to escape during rapid compression of the pad structure, such as from a high-speed dynamic impact, but nonetheless is water resistant under ordinary conditions. It is desirable that the polymeric film is made from an elastic polymer. The air-permeability can be provided from a series of perforations such that the film's elastic quality tends to contract the perforations thereby impeding the progress of water through them under normal conditions. The energy-absorbing pad can be a semi-rigid viscoelastic foam.