Researchers Draw Conclusions on 2011 Rhabdo Outbreak

By Erin Jordan, Reporter


By Ellen Kurt

IOWA CITY, Iowa -- Much has been written about the 2011 hospitalization of 13 University of Iowa football players for a potentially-fatal muscular breakdown following an extreme workout.

But in a paper published this month in the Clinical Journal of Sport Medicine, UI physicians describe the incident and share findings that include speculation about which types of athletes might be more susceptible to rhabdomyolysis and whether protein shakes might counteract the condition.

“There’s very little in the literature of clusters of exertional rhabdomyolysis among athletes,” said Dr. Loreen Herwaldt, a UI physician in infectious disease and epidemiology. “There’s new information in this paper.”

When Hawkeye football players got sick in January 2011, the story made national news because of concerns about students being pushed too hard in practice. Sports fans wondered if the players had consumed drugs, alcohol or energy drinks that increased their risk of rhabdo.

UI President Sally Mason appointed Herwaldt and others to investigate the incident.

That group concluded UI coaches didn’t know rhabdo was a risk when they scheduled an intense squat workout on Jan. 20, 2011. The workout had been done in previous years, but never on the first day back after a three-week break.

“There was no malice, no abuse of players,” Herwaldt said. The investigation also found the players did nothing – and ingested nothing – that caused the condition.

But the physicians decided to study the incident further to see if they could prevent future outbreaks. Ten of 13 players who were hospitalized allowed Dr. Kyle Smoot, a team doctor, to review their medical records, which were compared with training logs and statistics about the players.

The athletes got sick within days of the workout in which they were asked to do 100 back squats at 50 percent of their one-repetition max, the paper explains.

The players reported dark, tea-colored urine and severe muscle soreness and swelling.

UI Hospitals doctors diagnosed the players with exertional rhabdomyolysis, an exercise-induced muscle fiber breakdown that causes release of muscle elements into the bloodstream. Complications of the ailment can include kidney failure, cardiac arrhythmia or even death.

Rhabdo usually affects untrained people who exert themselves, often in hot weather. The UI athletes were far from “untrained,” but they hadn’t had a team workout since before winning the Dec. 28, 2010, Insight Bowl against Missouri.

Researchers found rhabdo was not associated with age, height, weight, body-mass index, race/ethnicity, position or number of semesters playing football. But the risk did increase the longer it took the players to complete the 100 back squats.

For athletes in “skilled” or “semi-skilled” positions, which include receivers, defensive backs, linebackers and fullbacks, their risk of rhabdo increased significantly as the percent of body weight lifted increased, the study found. Linemen did not experience an increased risk for increased weight.

Researchers theorized that the players who do more running and jumping have more fast-twitch muscle fibers, which need regular training to remain at top condition.

“After three weeks off, at a molecular level, their cells potentially could have been detrained,” Herwaldt said. “A number of players said if we would have waited a week or two (for the squat workout), it wouldn’t have been a problem.”

The number of protein shakes the players drank after the workout also factored into risk for rhabdo, the study found. The researchers’ statistical analysis suggested for each protein shake consumed the odds of rhabdo decreased by about 30 percent.

“We still don’t know if that’s a real association,” Herwaldt said, adding that some colleagues have criticized the finding. “It needs more prospective study. If there is something that can protect athletes from this kind of muscle damage, it’s worth pursuing.”

UI researchers struggled, at first, to find a journal willing to publish the paper, Herwaldt said. Some strength and conditioning advocates believed the UI coaches put the players at unnecessary risk with the intense workout.

“We had some reviewers who took that same position,” Herwaldt said. “They were angry the coaches were not blamed and punished.”

UI coaches and trainers have discontinued the squat workout.

The UI study has limitations, including the fact that researchers only tested hospitalized players’ blood for creatine kinase, a marker for rhabdo. The risk factors for players with mild cases were not examined. Only two players had drug screens immediately after the squat workout, which meant researchers had to rely on later drug tests.

“Is it the end-all, be-all? No,” Herwaldt said of the study. But the UI’s openness about the incident has helped other universities whose players have been sickened, she said. “We wanted to get it out in the open and do a transparent investigation.”
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