Additionally, as illustrated in Fig. 2B, indentations, weld areas, or other recessed structures on the top and/or bottom surfaces of the gas- filled bladder 122 may be filled with foam or other impact-attenuating material (the fill material shown in Fig. 2B at reference number 208, e.g., the material of the midsole or other impact-attenuating member, when the foam or other material making up these