(CNN) Jessica Rudd has been running for 10 years and says she gets rude comments or some other form of harassment from men at least once a week.

The Atlanta Ph.D student runs 30 to 35 miles a week -- more if she's training for a big race -- and often while alone. When someone harasses her, she grits her teeth and tries to ignore them.

"It's hard to always tell if it's meant to be funny ... but almost always it comes off as sketchy," Rudd, 33, told CNN.

There's a world of difference between catcalls or wolf whistles and the fatal violence that befell Mollie Tibbetts , who disappeared last month after going out for an evening run in Brooklyn, Iowa. Authorities say her suspected killer, Cristhian Bahena Rivera, followed her in his car as she ran along a country road before assaulting her.

But Tibbetts' case has raised safety questions for women runners, a startling number of whom say they have faced harassment, or worse, from men who seem to view an athletic woman in shorts or jogging pants as an invitation for lewd or frightening behavior.

Survey finds widespread harassment

In 2016 Runner's World asked its readers, "How often, if ever, does a stranger whistle at you, comment on your body, needlessly honk at you, or give you other similar unsolicited sexual attention?"

According to court documents, Rivera said in an interview that when he approached Tibbetts, she pulled out her cell phone and said she was going to "call the police" and that made him get angry.

CNN contributor Symone D. Sanders argued this week that the main safety issue in the Tibbetts case was not Rivera's status as an undocumented farm worker from Mexico but his "toxic masculinity" and the suspect's unwillingness to take no for an answer.

Mollie Tibbetts was murdered b/c she told a man to leave her alone while she was jogging. Her murderer happens to be undocumented. This isn't about border security. This is about toxic masculinity. Mollie Tibbetts lost her life b/c a man couldn't take her saying no. Full stop. — Symone D. Sanders (@SymoneDSanders) August 22, 2018

The Runner's World survey found that violence against women joggers is rare. Only 3% said they had been grabbed, groped, or otherwise physically assaulted -- but that doesn't make the other behavior less frightening.

-- 30% of women said they have been followed by a person in a car, bicycle or on foot

-- 18% said they have been sexually propositioned

-- 5% said they have been flashed

And 54% of women said they were concerned at least sometimes while running, or getting ready to run, that they could be physically assaulted or have unwanted physical contact.

To protect themselves, many women told Runner's World they'd changed their running routes, brought their phones with them or told loved ones where they'd be running.

Running coach Eladio Valdez told CNN affiliate WDAF that women should be aware of their surroundings and try to run with a buddy.

"You find people to run with, even just one person, that will dramatically lower the risk of anything happening. And if you do like to run by yourself, pick well lit, highly populated roads with other pedestrians or cars," he said.

'It's probably best to just keep running'

Rudd said she hasn't changed her training patterns because of the Tibbetts case. But she always takes precautions to stay safe.

She doesn't run in unfamiliar areas after dark and she won't run alone in places that may be dangerous. On a recent work trip, she used an app to find a recommended route and checked with the hotel concierge to make sure it would be safe.

The Atlanta woman says she's usually too focused on her runs to react to abuse, so she tries to tune it out.

What's really upsetting to her is when men -- or women who don't run -- downplay the harassment or ask why she would put herself in bad situations by running alone.

"I don't necessarily want to get in my car and drive 30 minutes to meet other people at six in the morning," she said. "I just want to open my door and run outside and get it done."

Rudd said the harassment she faces is usually verbal, but sometimes a man will try to touch her butt or block the sidewalk so she has to run in the street to avoid "accidentally" brushing against him.

That sometimes makes her want to turn around and sock the man, but she fears it could provoke an even more violent response.

"So you just keep running like it didn't happen, and then you're mad at yourself because you wish you did something else," she said. "But it's probably best to just keep running."

Rudd says she doesn't bother changing her running route after someone bothers her because "I would have nowhere to run if I did that."

"I could run on Peachtree Street in broad daylight in front of police officers and a guy on the street will (still) say something to me," she said. "Most of the time, no reaction is the best reaction, so I just try to tune it out."