A pair of US marathon runners have been photographed slowing down to help assist a fellow runner cross the finish line.

Philadelphia resident Chelsea Coyle documented the stunning act by two competitors during the annual Philadelphia Marathon in a post to Facebook on Sunday which was later shared to the Love What Matters page .

“Today, I saw one of the most beautiful acts of kindness I've ever witnessed,” she wrote.

“The man in the middle was really struggling and fell during the Philadelphia Marathon, and these two incredible men picked him up and helped carry him across.

“With all the awful things we hear going on in the world, it was definitely nice to see great people doing something beautiful."

Her post has since received thousands of reactions and hundreds of shares, with many celebrating the men’s decision to put aside their own competitive interests in the name of helping a fellow runner.