gruelling

1. (horse racing) A race in which the animal being raced finishes in a state of physical exhaustion.Examples: "The expenses are considerably reduced, and one or two men are prevented from carrying off nearly all the races ; for though " the spirit" may be ever so " willing," the " flesh is weak," and cannot stand more than five or six gruellings in a single day."; "Miss Harriet just got there first from Vauban, the latter being leg weary from his previous gruellings ; the bitch scored four more before giving way to the dog, who made some nice driving points ; Miss Harriet, coming again, finished a good trial an easy winner."; "The course was given to the black puppy, but his chance was generally considered to have been utterly destroyed by the two gruellings he had received."