Parental grumbling about high school coaches is getting louder and more disruptive, fueled by growing use of Facebook and Twitter to spread displeasure with decisions as basic as about who plays and who starts.

Two longtime coaches who resigned last month both blamed, in part, parents using social media to amplify their vitriol. Coaches who counsel their players on the long-term damage caused by careless social media behavior are now increasingly reaching out for help to counter parents in need of similar restraint.

The shift comes as parents are becoming more forceful advocates for their kids, with coaches finding themselves targets of instantaneous and often emotional social media outbursts.

“In our estimation, it’s created a hostile working environment,” said John Erickson, executive director of the state coaches’ association.

Tony Scheid, who coached the Stillwater High School girls’ hockey team to two state championships in his 14 seasons, resigned on April 8 and lamented the rise of what he called “the public relations’’ side of coaching.

“Decisions that are part of good coaching almost inevitably will lead to hard feelings,’’ Scheid wrote in a letter to Superintendent Denise Pontrelli. ‘‘Increasingly, this criticism has been voiced and amplified in mass e-mail communications and social media.”

Ten days later, Brad Grimmius also cited parental pressures when he resigned after six years as head football coach at Worthington High School in southwestern Minnesota. Grimmius, a head coach for 14 years, said his wife read negative Facebook posts, which have since been deleted.

Carl Pierson, the Waconia High School girls’ basketball coach, recalled the reaction after he made changes to his starting lineup three seasons ago. A Wildcats assistant coach told him, “Stay off Facebook because they are trashing you all over town.”

Finding lasting examples of social media abuse is challenging. Private Facebook groups require approval to see behind the curtain, and 140-character Twitter posts, or tweets, can be deleted. But the concern is real.

“It’s a significant issue, and it needs to be discussed more,” said Kevin DeShazo, founder of Fieldhouse Media, an Oklahoma City firm that trains colleges and athletes on social media. DeShazo has engaged high school coaches on the topic and speaks at high schools in Oklahoma and at national workshops for activities directors.

“A parent going on social media to complain makes it worse for everyone, especially the kids,” DeShazo said.

Navigating with caution

Tom Dasovich embraced social media as boys’ basketball coach at Henry Sibley and Minnetonka high schools, citing the positives of distributing information to players and sharing success with a broader audience. Now the activities director at Watertown-Mayer High School, Dasovich encourages coaches to “not stick their heads in sand” and embrace social media. But he knows the climate can be difficult at times. “When someone rips Richard Pitino, at least he’s making a couple million dollars,” he said.

At Hopkins High School, boys’ basketball coach Ken Novak Jr. “is making about $4,000 after taxes,” he said. “High school coaches shouldn’t be immune to criticism, but for some parents, there’s no separation from the coaches on TV to the ones in their community.”

Dasovich said that he speaks at preseason all-sports parent meetings and that he hopes to have further conversations with individual teams.

At Prior Lake High School, activities director Russ Reetz is already there. Most Lakers coaches have a social media presence, and Reetz offers guidance on proper use.

“There is trolling, people that post things to get you to bite,” Reetz said. “Some coaches are desperate to respond and defend against something controversial. But we talk about ignoring the user or blocking them.”

Erickson, of the coaches association, concurred. “We encourage coaches to never get involved in a back-and-forth,” he said.

Reetz said he and his peers need more leadership on handling social media, because “there are more and more active, disgruntled parents than there was even five years ago.”

DeShazo said social media concerns no longer are just about young athletes sending inappropriate messages. Engaging parents is critical.

“What’s unique at the high school level is how personal it gets,” DeShazo said. “These parents are picking up their kids after practice each day and in the stands every game. We’re in the era where every kid deserves to start. But there must be a culture of respect even if parents disagree with coaches’ decisions.”

Tipping point disrupted

A survey of the Minnesota Girls Hockey Coaches Association last year indicated that members wanted to hear more about social media, said Jessica Christopherson, the group’s president. Scheid’s resignation brought more attention to the topic, which will be part of the fall meeting.

“I encourage using social media, but it’s out of control,” said Christopherson, who formerly coached at Coon Rapids High School. “Negative posts are one more way communities and programs become divided.”

Waconia’s Pierson, who wrote “The Politics of Coaching: A Survival Guide To Keep Coaches From Getting Burned,’’ said he talks at clinics about a coach’s approval rating.

“No matter what, 25 percent of the parents in your program are not happy. But if that number goes over 50 percent, it’s going to be tough for you to push your agenda. Social media can tip the balance,’’ Pierson said.

“We coach because we love the kids and the game more than we hate the constant criticism. But there is a tipping point for some coaches. Eventually, they decide the criticism isn’t worth the positives that come with coaching.”