The run through Leeds' Temple Newsam Estate includes the ominously named "cardiac hill." Here are the top 10 best photos from Sunday's event as taken by the YEP's Simon Hulme.
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Despite Covid 773 runners took part on Sunday, not far off their best turnout of 839.
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Most competitors seemed to be taking the mud in their stride.
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Some even relished the challenge.
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The event was sadly cancelled last year due to Covid-19 restrictions but the runners were out in force on Sunday.
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Organiser Stuart Gall explained that many use the race as a chance to run off any excess Christmas pudding.
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Some runners struggled to maintain their footing as they battled through the mud.