Some extreme cross-training workouts have come under scrutiny for being too much for some bodies to safely handle. (Photo by CrossFit.com)

In 2005, Makimba Mimms, a former Navy systems technician, began a workout at Manassas World Gym in southern Virginia with Javier Lopez, an employee there to oversee the routine.

Nearly three years later, in a lawsuit filed against Lopez, Manassas and the training routine he followed, Mimms recalled the workout’s catastrophic results: His “muscle fiber broke down,” he “sustained blood in his urine,” suffered “strains of the lumbosacral spine” and “strains of both quadriceps.”

Mimms had pushed himself to the point of fatigue in a cross-training routine meant to test the limits of his capabilities — a catchphrase commonly used at workout facilities across the country. He wound up with permanent damage to his muscles — and a $300,000 judgment in his favor.

Today, awareness about the damage, known as exertional rhabdomyolysis, or rhabdo, still remains strikingly low, even as many extreme cross-training exercises have caught on as fitness’s latest fad. It is the whispered condition in the weight room, always afflicting a friend of a friend — “Did you hear about so-and-so?” — but rarely confronted directly.

Exertional rhabdo is a skeletal muscle breakdown that results from a workout that goes beyond what the body can handle. The symptoms can surface immediately (muscle collapse) or days later (confused with delayed onset muscle soreness or fatigue), but could result in kidney failure, heart arrhythmia, shock and permanent muscle damage; it’s often associated with heat stroke or dehydration. For extreme cases, hospitalization is required immediately.

The damage is almost always from “the same dumb thing,” said Dr. Randy Eichner, a former University of Oklahoma team physician who has studied the condition, in an email. “Too much, too fast, too soon of an exercise too novel.”

In January, 13 football players at the University of Iowa were hospitalized after an offseason workout that included 100 sets of squats, along with pull-ups and dumbbell curls. After they were tested, rhabdo was seen as the culprit.

In the wake of that news, other reports surfaced.  Seven members of the University of South Carolina swim team were hospitalized after a practice in 2007; 12 high school football players after a workout in Oregon in 2010; a 13-year-old boy after doing too many pushups in Michigan in March.

And while collegiate or high school-level athletes expect to be tested physically, and are typically well supervised, others — like the hundreds of thousands of viewers who watch cross-training routines via YouTube — may not be.

High-intensity workouts like “P90X,” “CrossFit” and “Insanity” market themselves as transformative fitness systems that can tighten abs and harden muscles in the comfort of your local gym or your living room. But unlike the Bowflex or other popular home gyms, the newer workouts emphasize speed, repetition and variety — rapid cross-training exercises meant to “confuse” the muscles and thus help build them.

Studies have also shown a link between rhabdomyolysis and those who display a sickle cell trait or SCT, a genetic disorder found in about 8 percent of African-Americans and 1 percent of white Americans. As a result, the NCAA requires all Division I athletes to be screened for SCT unless they have been tested before or sign a release to decline testing.

For Division I athletic trainers like Jim Gossett of Columbia University, a 27-year veteran and a spokesperson for the National Athletic Trainers Association, the measure does not necessarily change much: They test, evaluate and know their athletes well enough to understand most risks anyway. But, Gossett said, the same is not the case at most neighborhood gyms and workout centers where recreational athletes aren’t tested and supervisors aren’t equipped to handle an outbreak.

“I would think the majority do not” know enough about rhabdo, Gossett said. “They probably don’t know the characteristics of their clients.”

Some people mistake their pain for delayed onset muscle soreness, or DOMS. “Maybe because the line between damaging rhabdo and ‘beneficial’ DOMS after a workout is a fine one,” Eichner suggested.

Jacob Donich-Croll, a former rower for Trinity College in Hartford, Conn., belongs to a CrossFit affiliate around Washington, D.C., and, even after a four-year collegiate athletic career, considers it the hardest workouts of his life.

“There is really nothing like it,” Donich-Croll said. “The first time I did it I didn’t finish the workout and was in great shape. Unless you train like that, you just can’t prepare for it.”

His first workout — called the “Daniel,” after former Army sergeant Daniel Crabtree, who was killed in combat in Iraq in 2006 — consisted of 50 pullups, a 400-meter sprint, 21 thrusters (like a front squat and push press in one), an 800-meter sprint, 15 more thrusters, another 400-meter sprint and 50 more pullups. “As fast as you can,” Donich-Croll said.

CrossFit was founded by a former college gymnast and celebrity trainer named Greg Glassman in 2001. Glassman has written about the risks of rhabdo on his website, and in 2005 he said that CrossFit was responsible for at least five known rhabdo cases.

“We now find ourselves obligated not just to explain CrossFit’s potency but to warn of its potential lethality,” Glassman wrote.

But some medical professionals find it difficult to simply point a finger at these new exercise routines.

“Based on our research, we believe that if you took blood samples of most athletes after their workout, games, practices etc., they would have the blood markers” for rhabdo, said Lacy Puttuck, an exercise therapist at the Institute of Sport Science and Athletic Conditioning, a sports research and education facility in Las Vegas. “With most case studies that we have looked at, there are other factors involved,” including dehydration, poor nutrition or genetics.

The catastrophic injuries in Iowa, Oregon and to Mimms in Virginia drew the spotlight and raised some alarm. But the silent threat in the workout room remains mysterious to many looking to push their bodies.

“People are always looking for the latest greatest thing,” Puttuck said. “That’s just the fitness industry in general. Every week it’s something new.”

Email: zss2111@columbia.edu