The Boston Athletic Association (BAA) has warned participants in next Monday's Boston Marathon against posting close-up photos of their bib numbers on social media sites like Facebook and Twitter, or risk having their results wiped out.

The warning stems from incidents last year in which some runners made copies of legitimate bib numbers presumably seen on social sites, then were found out when officially registered runners went to look up their photos online after the race -- only to find other people wearing their numbers. Among the culprits, the wife of social site Foursquare's owner (when she was found out, Foursquare's Dennis Crowley issued a public apology on her behalf).

Such sketchy tactics for taking part in the race are largely a result of the fact that qualifying for the marathon through athletic achievement or by obtaining a charity number has become increasingly tough, and was especially so last year in the wake of the bombings, which rallied so many to want to take part in the event. Race officials, citing security and crowding concerns, also cracked down on the tradition of bandit runners, those who run without being registered.

The BAA warns participants in its runners' handbook that: "The B.A.A. asks participants not to post close-up pictures of their bib number on social media before the race to avoid fraudulent bib duplication. If an athlete is found to have duplicated a bib number, or if his/her bib number has been duplicated by another party, the athlete will be subject to disqualification. Upon receiving a bib number by way of qualifying, as a guest, or as a fundraiser for charity, the athlete takes sole responsibility for their bib number. The B.A.A. will disqualify anyone found to have duplicated a bib number, or been the source of a duplicated bib number."

Naturally, the marathon has become an exceedingly social media swamped event, with charity number participants using online sites to drum up donations and with many others relentlessly sharing status updates on their training in advance of the Patriots' Day race. Runners also share their bib numbers online so that friends and family can track them online on race day. I had a first-hand look at technology running wild at last year's marathon ("Inside the Boston selfie-thon"), as a volunteer clock watcher at Mile 22 of the course.

The reality is that the BAA itself uses the Web excessively and effectively, through its mobile app, website and social media presence. ("If you have any questions regarding this year's Boston Marathon, be sure to visit our FAQ section at www.baa.org, or connect with us on social media.") And so do safety officials, such as the Boston Police, who have given numerous presentations in recent years about their use of social media and how it helped them to track down the bombers.

But the BAA has made it clear this year that runners need to display at least some restraint in showing off online before the race.