Exculpatory Clauses Don't Provide Total Exculpation in New York
Thank you for providing the name of your (your friend's?) state.
The release of liability form should be personally reviewed by a New York attorney to determine if your friend has signed away his right to sue and collect damages from the company that organized the race.
It appears he has an action to pursue against the driver of the vehicle that hit him, at any rate, so consultation with a personal injury lawyer would be smart anyway.
As I understand things, your friend, based in New York, signed a form release that purported to exculpate the sponsor of a race held in New York from any liability in connection with the race.
Although the New York courts have upheld exculpation clauses in cases where what was involved was merely simple negligence, that does not necessarily mean "game over" if the facts support a showing that what was happened involved more than simple negligence.
Although New York law will uphold liability disclaimers or purported limitations on liability in the face of ordinary run of the mill negligence if (and it's a big "if") it can be shown that what was involved amounts to gross negligence or willful misconduct, as a matter of public policy, the exculpation or limitation on liability will not stand.
An example might be useful. Let's say the sponsor of the race hired a reputable company to put up warning signs and provide crossing guards at each dangerous intersection the race path would cross, but just before the race was to cross, one of the crossing guards had a heart attack, was taken from his post by ambulance, and then your friend was hit by a car that crossed the intersection. The race's sponsor did what a reasonable sponsor would do and likely would not be found negligent. (The driver of the car, on the other hand undoubtedly would be found negligent for not looking out for pedestrians and controlling his car.) Contrast that with the situation where the race sponsor knew there was a dangerous intersection, but failed to put up warning signs or post a guard. That might amount to gross negligence.
Your friend should see a lawyer who handles auto accidents or personal injuries in NY, and discuss it. Such lawyers almost always work on a contingency fee basis and are paid only a portion of the recovery they obtain for their clients.