The answer is surprising and tends to catch them off guard. Being the self-deprecating type, Hasenfratz tries to downplay the fact that open heart surgery and the subsequent recovery caused him to miss the entire 2009-10 and 2010-11 NHL seasons.
"He's picking up his pace and he's in as good of shape as he's been in all the years I've known him. He's showing the good qualities of an official. He's coming back."
-- NHL director of officiating Terry Gregson
Over the years, the monitor would help to detect a potentially life-threatening condition.
"For $110, it probably saved me, probably saved me my life," Hasenfratz said. "I'm the luckiest guy in the world that I wore a heart monitor one time."
A life-saving procedure
Hasenfratz was a third-generation police officer in his native Regina, Sask., who always had an abiding love of hockey. His father Tony organized a large local youth tournament, which was where Mike got his start as an official at age 13.
He achieved his dream of working in the NHL in 2000 and, as the League prefers for its officials to live in cities with NHL teams, he relocated to Nashville on the recommendation of Brent Peterson, a member of the Predators' organization whom Hasenfratz knew from Canada's Western Hockey League. Entering this season, Hasenfratz had worked 541 regular season games and 31 in the playoffs.
But back in 2009, he had to put his career and, in some ways, his life on hold. Five years ago, the heart monitor found that Hasenfratz had a higher heart rate than normal and he was sent for further testing. An echocardiogram revealed that his descending aorta was abnormally wide.
A normal measurement is 1.7 centimeters. At the time, Hasenfratz's was 2.3. By 2009, it had grown to 5.3 centimeters -- a potentially life-threatening situation. So on Oct. 15, 2009, Hasenfratz, at age 43, underwent a procedure at the Cleveland Clinic to replace his aorta with a synthetic one.
He knew the surgery would cost him a season, but he had no idea how much longer it would actually take him to get back on the ice. The 6-foot-4, 230-pound Hasenfratz said that for the first few months after the surgery, he could not lift more than 10 pounds. In retrospect, he said he had no idea what he was getting into.
"I didn't realize how serious it was," he said. "I just didn't know."
In the first few months after the surgery as Hasenfratz was recuperating, NHL director of officiating Terry Gregson flew to visit him. Gregson could see how eager Hasenfratz was to return.
"One of the things I try to do or do do is don't put any pressure on them to get back," Gregson said. "Mike explained to me how much he missed it. I said, 'That's fine, Mike, but we're not back to a health level.'"
That health issue ultimately proved an arduous and, at times, contentious one on Hasenfratz's path to recovery. As Hasenfratz worked to regain his strength, he suffered a complication. Fluid had gathered around his heart and needed to be drained. He underwent a second procedure to remedy that condition in fall 2010, which ended up nulling that second season for him.
The inactivity caused his muscles to atrophy and Hasenfratz to put on weight, consequences he would have to overcome in time.
The NHL first began a fitness program for its officials in the mid-1980s. Administrators began keeping data from these sessions and followed officials through their careers so that when they began to slip as they aged, the League could help them to improve in the categories where they needed to.
When play resumed after the work stoppage of 2004-05, its officiating standards and conditioning program ramped up several notches. With the rules changes and interpretations that were enacted, the speed of the game took off. Officials had to keep pace.
To create the program, the League brought in Dave Smith, who served as head trainer and conditioning coach for both the New York Rangers and Florida Panthers. Smith now serves as the monitor for the officials' health and wellness program.
To get himself back into shape, Hasenfratz began traveling to Buffalo, where Smith is based, to work out and to try to show that he could meet the protocols set for him. The protocols were based on data Smith and his group had collected on Hasenfratz during his first nine seasons in the League.
Smith said that he had to alter not only Hasenfratz's body, but also his mentality.
"I had to change him around to not have him look at me like I'm holding him back," Smith said. "But I'm actually only working for one reason. I told him, 'Look, I don't care if you never officiate again. I want to make sure you have a good life. That's more important to me than going on the ice. You gained weight, and the weight you gained is not lean muscle.'"
Smith said that just because Hasenfratz was medically cleared didn't mean he could go back to work.
"I try to get through to people: Just because the doctor clears you, he's giving you the medical OK, but that doesn't mean that you're, functionally, in the sports world, ready to go," Smith said. "That's a hard thing for people to understand."
Smith refused to risk Hasenfratz's health until his conditioning improved.
"His heart rates were going off the wall," Smith said.
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"I don't think I'm hiding anything: Mike got a little upset with us and thought maybe we were setting a little too stringent guidelines and everything," Gregson said. "But like I tell people, I'm not asking a guy his age to go and sit behind a desk -- and there's nothing wrong with that -- but there's such a huge physical element to our job that I can't just a have a man-on-the-street-type standards. We have our own standards and they have to be met."
Smith wanted Hasenfratz to drop about 15 pounds while meeting some rigorous performance standards. Eventually, Smith got through to Hasenfratz that they were on the same side. Hasenfratz said he realized in the end that he had to get himself out of a "victim cycle."
By June 2011, Smith visited Nashville with his stopwatch and other materials in that hope that the trip would represent Hasenfratz's final test. Hasenfratz passed.
Smith said he got goose bumps.
"I can't tell you the feeling he had and the feeling I had," Smith said. "It was like, 'We've done it.' 'No, no, Mike, you did it. You did it. I was just here to help you and now we can go back and tell the people you're ready to make a comeback.'"
Back on the ice
Gregson said that when he officiated, coming back for the first preseason games in September after three or four months off was like "standing in the fast lane of the highway." Hasenfratz was doing so after two years off.
An important milestone -- and scary moment -- came in Hasenfratz's first regular season game between Dallas and Chicago on Oct. 7. Jonathan Toews put a big hit on a Stars defenseman and Hasenfratz took a misstep. The defenseman crashed into Hasenfratz's chest.
"I guess there was a little skepticism in my own head that, 'Can I take a hit?'" Hasenfratz said. "I'm not a small person. So anyways, I took the hit and I immediately grabbed my chest and just brushed my hand down and went, 'OK. I'm all right.' I ended up with bruised ribs."
One of the most emotional moments came on Dec. 3 in a game in Edmonton, the closest city to much of Hasenfratz's family in Saskatchewan. His sister, Brenda Bennett, and her husband attended. Hasenfratz's daughter also was there.
Bennett said that growing up in Regina, hockey was part of the family fabric. The "Hockey Night in Canada" theme song evoked happy memories of her brother and her father arguing about the game. But during her brother's two years off, she did not watch hockey because it made her sad.
"It was a big deal and my son was going through cancer treatments," she said. "His goal was to be well enough that he could get to watch my brother. …We were all thrilled to be there."
Gregson said he has observed Hasenfratz on a couple of occasions this season. Gregson said he noticed some positioning issues, but that overall Hasenfratz has adapted to the speed of the game.
"He's picking up his pace and he's in as good of shape as he's been in all the years I've known him," Gregson said. "He's showing the good qualities of an official. He's coming back."
While booing officials comes with the thankless job, Hasenfratz explained why it's is so exhilarating to him.
"It's so exciting every night, going on the ice and hearing the crowd and dealing with the play and everything," he said. "End of the day, there's a minute left and the goalie is pulled and you're the down-low referee and you've got the weight of the world on you. Right now, that's what we live and die for right there.