Except for space walking (astronauts lose bone in space), I can't think of an exercise that would cause osteopenia to be worse.
Ngaphandle kokuhamba esithubeni (ii-astronaut ziye ziphelelwe ngamathambo zisesithubeni), ayikho eminye imithambo endiyicingayo enokubangela ukuba mandundu kwesifo sokuphela kwamathambo.