Abstract: A dumbbell structure arranged for compacted configuration for ease of storage and transport is provided, wherein each dumbbell of the dumbbell apparatus includes respective first and second cylindrical housings having accordion pleated flexible side walls interconnected by an intermediate tubular housing, wherein each dumbbell is arranged for expansion for filling with dense material such as sand or fluid in use through a fill conduit in the first cylindrical housing of each dumbbell. The structure is arranged to further include a support web having a resilient central core to afford rigidity to the tubular housing when mounted thereabout.