March parkrun's shed was broken into overnight.
The volunteer group said that lanyards have been stolen and that equipment and water bottles was thrown over West End Park.
"It's so disappointing that someone finds this amusing," said Claire Smith, event director for the junior parkrun.
As a result of the break-in, volunteers had to "use their own time this morning to tidy this up", she added.
She added that the volunteer group doesn't have the funds to replace these items.
Therefore, they will have to request new lanyards and whistles from parkrun, and print new sheets.
"It's a real shame that someone had felt the need to do this."
Cambridgeshire Constabulary said: "We were contacted today (Monday July 29) with reports a storage shed in City Road, March, had been broken into overnight.
"Equipment belonging to a running club was removed from the shed and left around the immediate area.
"Anyone with information should contact police via the force website using reference 35/55158/24. Anyone without internet access should call 101."
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