Exertional Rhabdomyolysis

I hope the blog readership has had a chance to take a look at the most recent issue of CJSM.  The September 2013 edition of the Journal has studies looking at conditions from concussion to osteoporosis and at sports from football to ballet.  It is a varied mix, and a testament to the wide range of conditions primary care sports clinicians treat and study.

The great Nile Kinnick,
University of Iowa
1939 Heisman trophy winner,
World War II hero

I spent a good amount of time in August talking about concussions, and I could easily continue this thread throughout September.  I started off the month, in fact, with a look at my friend Bill Meehan’s recent work on the “The Presence of Undiagnosed Concussions in Athletes.”  I thought I’d take a break from that topic, and look at a less common but also potentially dangerous condition:  exertional rhabdomyolysis.  It’s a particularly relevant topic at this moment, as exertional rhabdo often times strikes untrained athletes working out in hot and humid environmental conditions, and it’s an unseasonable 95 in Columbus Ohio today, where I am writing this post.

A Cluster of Rhabdomyolysis Affecting a Division I Football Team,” a study by Smoot, MK, Amendola, A, Cramer, E et al., looks at an ‘outbreak’ of the condition in January 2011 at the University of Iowa’s football (american) team after some intense off-season lifting workouts.  Ironically, we had a cluster of our own in Columbus, Ohio, home to Iowa’s Big Ten rival Ohio State, just this spring, in the women’s sport of lacrosse.  The LAX players were hospitalized after team members performed a new 20 minute workout involving repetitive pushups, situps and chin ups, without break.  Six female athletes were hospitalized for as much as a week.  The local newspaper reported,  “Five returned to play last season, all except sophomore Kelly Becker of Dublin…..who has since transferred to Michigan.”

The author’s son,
letting it all hang out
in the ‘Big House’
Ann Arbor, MI

Ok, stop!!  If that doesn’t suggest to you the gravity of the situation, nothing will.  As a consequence of her experience as an athlete who developed exertional rhabdo, a young woman traded in being a Buckeye for a Wolverine.  The ultimate protest!!!!

Returning to the study…..The authors set out to look for what might be risk factors for exertional rhabdo (ER) in collegiate football players.  They begin by doing a brief and excellent overview of the signs and symptoms, defining characteristics, and known risk factors for ER.  They proceed then to describe the workout the 16 football players did (e.g. 100 back squats at 50% of one rep maximum) and how the young men presented with ER.  Thirteen players were hospitalized for ER after this workout.

The authors were given permission to look at the medical records of 10 of the 13 cases. Nine of the 10 had urine screens negative for drugs (one had a positive opiate screen, but his urine had been collected after being administered narcotic analgesics); one of the 10 had sickle cell trait; and two of the 10 had consumed creatine before the workout.

The University administration and Athletic department conducted an epidemiologic investigation of all 13 cases, and interviewed strength and conditioning coaches and athletic trainers involved in the workout.  Using the data gathered in this process, the study authors were able to calculate odds ratios (ORs) and other statistical measures for various risk factors that may predispose to ER.  Presence of sickle cell trait and use of creatine notably were not among the determined risk factors.  The authors did determine that the risk of ER increased with time and number of sets needed to reach 100 back squats (OR 1.11 and 1.33 respectively).  Self-report of working out to ‘muscle failure’ or doing extra back squats were both more likely in affected players than in unaffected players (P = 0.006).  Interestingly, drinking protein shakes post-workout was protective:  there was a decreased risk (OR = 0.7) in those who consumed protein shakes, with the odds decreasing about 30% per shake.

I thought this was a very well designed study, and I enjoyed the epidemiological investigation and biostatistical methods underpinning the authors’ work.  I learned a great deal about ER, the condition itself, as well.   It is a useful fact to be reminded, as the authors state in their discussion, of “The association of ER with the high-volume, high-intensity, repetitive back squat assignment….(workouts) that require athletes to suddenly increase the volume or intensity of an exercise with eccentric predominance are particularly high risk.”

Be particulalry careful out there if you’re working out today or tomorrow in this midwest heat wave (are you listening University of Iowa?  Ohio State?)  🙂  And think about drinking a post-workout glass of chocolate milk.

Until I catch up to you next time, enjoy the new CJSM issue and let us know what you think, either here on the comments page or on twitter @cjsmonline.