Running USA reported on road race participation numbers.
2016 State of the Sport – U.S. Road Race Trends
The second running boom appears to be backing off as runners retreat from non-traditional races.

2015 U.S. Road Race Trends – By the Numbers

After experiencing 300% growth from 1990 to 2013, U.S. running event finishers in 2014 and in 2015 declined. In 2015, there were a total of 17,114,800 U.S. running event finishers, down from 18,750,000. This represents a decline of 9%.

Total number of U.S. running events reached 30,300. In 2015, the 5K maintained the #1 position of all race distances with 7.6 million finishers, claiming 45% of all finishers.

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What does this have to do with gun owners? Compare the numbers.

First, these studies and organizations can only track people that are willing to be trackable, meaning only road race participants signing up for and actually participating and then completing a registered road race. Not on how many pairs of running shoes are sold and owned or how “pro-running” a person says he is, but rather, on actual, measurable participation. This participation can not be measured unless a person registers for and participates in a race where someone is bothering to keep tally. It doesn’t count if you buy every running shoe and accessory in existence and then jog alone or with a few friends. This data doesn’t consider a person as a road race participant unless they enter and actually complete a formal road race.

The shooting equivalent to this is participating in sanctioned, registered, or approved events, some sort of activity that a national organization can track. Note that most NSSF and NRA studies are estimates based on surveys, numbers based on unverifiable claims made by cold calling strangers on the phone, and do not measure actual participation.

This requires organized participation from both the runners and race organizers. And this number dropped to 17.2 million, down from 18.6 million and suffering a 9% decline from previous years.

That’s over 17 million people signed up and completing a formally-held road racing competition. Running enjoys about four times more competitive road racers than the NRA has total members.

The shooting equivalent to a “race finisher” runner is a person participating in sanctioned, registered or approved events often enough to hold a classification or some other equivalent. Using the running world’s definition, only two percent of the NRA membership are “race finisher” shooters. Even after adding in the other alphabet soup organizations (ATA, NSSA-NSCA, IHMSA, USPSA, IDPA, PRS, WA1500, ICORE, IBS, NBRSA, PRS, NRL, ASSA, SASS, etc.) and adding in shooting class attendees (Gunsite, Thunder Ranch, along with a plethora of small and mobile trainers) gun owners have perhaps 0.25 million “race finisher” shooters.

If we’re generous and double this already-generous overestimate, gun owners have 0.5 million “race finisher” shooters, 34.2 times less than road races.

These are the real reasons running gets media coverage and shooting does not.

Report referenced:
http://www.runningusa.org/state-of-sport-us-trends-2015