Here is a standard waiver used on many race forms. Waiver could be modified, but is not necessary. Many race directors or organzations involved with events, such as sponsors, towns, volunteers.
In consideration of your accepting this entry, I, the below signed, intending to be legally bound, for myself, my heirs,my executors and administrators, waive and release and any all rights and claims for damages I may have against the race, and sponsors and their representatives, successors and assigns for any and all injuries suffered by me in said event. I attest that I will participate in this event as a footrace, that I am physically fit and sufficiently trained for the completion of this event. Furthermore, I hereby grant full permission to use my name and likeliness, as well as any photographs and any record of this event in which I may appear for any legitimate purpose, including advertising and promotion.