A "dowel rod" refers to a long cylindrical wooden stick or metal rod that is used for support or to connect parts of furniture or objects together. Full definition
Insert a plastic dowel rod into the top of the cake at about 3 inches into the top of the cake, remove the dowel and gently remove the cake inside the dowel, you'll need the top of it to seal the hole after inserting the jam. (thesweetsensations.com)
Do 1 - 2 sets of 10 - 15 reps. To test your core stability, place a small dowel rod on the small of the back and try to keep it straight and steady. (personalfitnessadvantage.com)