New to spinning? Diving headfirst into a half-marathon with little training? Sit all week and then jump into all-out exercise on the weekends? Then there’s a 12-letter word that needs to be on your radar: rhabdomyolysis.
Often referred to as “rhabdo,” this serious syndrome can occur by overtraining beyond your body’s current ability. And although considered rare and more often associated with “crush” injuries like car accidents and building collapses, reports of kidney-damaging rhabdo after a single spinning class are gaining the attention of medical researchers and the media alike.
A study featuring case reports of spinners developing exertional rhabdomyolysis, many after taking their first class, highlights the fact that going too hard too fast can lead to serious side effects. This is especially true for a subset of people who are often beginners and/or out of shape. Reports show that active-duty soldiers, firefighters and others with particularly taxing professions and training protocols face a risk of rhabdomyolysis; research also suggests that CrossFit workouts, running and P90X are other among other reasons people land in the hospital for rhabdomyolysis. (1, 2)
In fact, the rhabdomyolysis-CrossFit connection is actually celebrated with an infamous “uncle rhabdo” cartoon that features an exhausted, overtrained clown hooked up to a dialysis machine. (3, 4) You do not have to push to the point of rhabdo to get incredible fitness results.
Now, in no way to do I want to deter you from working out. Quite the opposite, given the incredible (and sometimes even surprising) benefits of exercise, including high-intensity interval training HIIT workouts. But this does warrant some simple precautions to take to avoid this kidney-damaging ailment. And, of course, don’t push too hard too fast when you’re starting a new workout routine.
What Is Rhabdomyolysis?
Rhabdomyolysis: A Brief History
When it comes to the history of rhabdomyolysis, it appears the condition was first described in the Bible’s Book of Numbers in the Old Testament. In this instance, the Jews suffered a “plague” while consuming large amounts of quail during the exodus from Egypt. The belief is that the quails ingested poisonous hemlock, which triggered rhabdomyolysis in the humans feasting on the game bird. (5)
But it wasn’t until doctors published literature on “crush syndrome” that we started to really understand the link between muscle damage and acute kidney damage. This research was the result of understanding how World War II-era bombing in London crushed victims’ muscles and triggered acute kidney damage. Today, we know rhabdomyolysis is major cause of acute-onset kidney failure. (6)
What is rhabdo in medical terms? It’s a complex condition involving the rapid breakdown of skeletal muscle that causes muscle proteins and other muscle constituents to leak outside of cells and into the bloodstream. This leakage includes:
- Myoglobin (The term myoglobinuria refers to myoglobin present in urine.)
- Creatine kinase (CK)
- Lactate dehydrogenase
A rise in free ionized calcium inside cells is a classic trait of the syndrome. Researchers say this can be triggered by:
- Energy depletion
- Direct plasma membrane rupture
This increase in cell calcium levels sets off a series of cellular side effects, including mitochondrial dysfunction and abnormal reactive oxygen species. Ultimately, this results in muscle cell death.
Doctors use a combination of clinical symptoms plus tests to look for myoglobin and excess creatine phosphokinase (CK) levels to diagnose the serious syndrome. (7)
Rhabdomyolysis can cause a wide range of impacts on your body. On one end of the spectrum, someone may experience no symptoms of illness but have elevated creatine kinase levels. On the other hand, some people experience life-threatening symptoms linked to extreme elevations in creatine kinase, electrolyte imbalance, acute renal failure and disseminated intravascular coagulation. (8)
Rhabdomyolysis CK levels vary, but generally levels above 5,000 U/l reveal serious muscle injury. For comparison, normal levels fall in the range of 45–260 U/l. (9) In severe cases, CK levels in rhabdomyolysis labs can rise over 100,000 U/l. Often, these “worst case” exertional rhabdomyolysis cases involve a de-conditioned person excessively training while dehydrated and/or under heat stress. Not being properly acclimated to a particular climate and lack of a proper diet can also contribute. (10)
Is rhabdomyolysis permanent? While overtraining beyond one’s capability is one common cause of exercise-induced rhabdomyolysis, there are actually more than 100 different triggers. It’s also possible to experience rhabdo with or without acute renal failure. Quick identification and treatment can often eradicate long-term problems, although recovering may take several weeks even in cases of severe muscle weakness without kidney damage.
Rhabdomyolysis Risk Factors and Causes
Anyone taking up exercise for the first time or training hard outside in the heat should take extra precaution to understand the risk factors, causes and symptoms of rhabdomyolysis.
The condition impacts roughly 26,000 people a year in the U.S., although many experts believe it’s much higher than that, with milder, more asymptomatic cases unreported. (11)
While some people show no symptoms and simply have elevated creatine kinase levels, others experience life-threatening complications like cardiac arrest, arrhythmias, compartment syndrome, disseminated intravascular clotting and acute kidney damage.
Risk Factors of Exertional Rhabdo
- Overtraining, especially when you’re de-conditioned, training beyond your ability too fast or returning to heavy workouts after time off (examples: after an injury, vacation or winter/spring break)
- Strenuous workouts in hot, humid weather
- Training in full gear (think two-a-day football practices with full pads and helmets or firefighters in full-gear trainings)
- Being a large football player — the National Academy of Sports Medicine points out a study identifying the sweat rates of certain football players, and sweat rates in large lineman can hit 3.9 liters an hour and up to 14 liters per day. Due to high intensity activity and abundant fluid loss, football players run a high risk of dehydration and subsequent exertional rhabdomyolysis (14)
- Performing exercise to muscle failure during the eccentric phase — an example of this would be the quadriceps eccentrically lengthening during the downward phase of a squat
Exercise isn’t the only cause of rhabdo. In fact, rhabdomyolysis and statins drugs are linked. Other rhabdomyolysis risk factors include:
- Certain prescription and illegal drugs (see the list of drugs that could contribute to the development of rhabdo)
- Heavy alcohol or drug use
- Prolonged bed rest
How do you get rhabdomyolysis? In the case of the spinning-rhabdo cases we highlighted earlier, the culprit is overtraining that leads to catastrophic muscle breakdown. This is known as exertional rhabdomyolysis.
A study published in the American Family Physician lists the following as physical causes of rhabdo: (15)
- Physical overexertion in untrained athletes
- Intense exercise, such as marathon running
- Heat-related causes, including heat stroke
- Malignant hyperthermia, a disease triggered when someone experiences a fast rise in body temperature and severe muscle contractions when given general anesthesia
- Crush injury (car accident, earthquake or war injuries, for example)
- Getting struck by lightening
- Extensive third-degree burn
- Neuroleptic malignant syndrome
- Ischemic causes
- Ischemic limb injury
- Exertional causes
- Pathologic muscle exertion
- Heat dissipation impairment
- Physical overexertion in persons with sickle cell disease
As you can see, there are many different rhabdomyolysis causes, but the most common include:
- “Crush” injury, such as those seen in vehicle accidents, war-time bombings or earthquakes
- Strenuous exercise
- Certain medications (this is just one of the many dangers of statins)
- Drug/alcohol abuse
Some causes of the condition have roots in infectious, inflammatory, metabolic or endocrine sources, including:
- Infections (According to the American Family Physician study, some viral and bacterial infections that can trigger rhabdo include but aren’t limited to influenza virus B, parainfluenza virus, adenovirus, coxsackievirus, echovirus, herpes simplex virus, cytomegalovirus, Epstein-Barr virus, HIV, Streptococcus, Salmonella, Legionella, Staphyloccus and Listeria species)
- Snake bites
- Electrolyte imbalances, including hyponatremia, hypokalemia, hypophosphatemia, hypocalcemia and hypernatremia
- Diabetic ketoacidosis
Some cases arise from genetic conditions that lead to metabolism issues related to fats, carbohydrates or purine-rich foods.
According to John Sauret, MD, rhabdomyolysis complications can be broken down into “early” and “late” categories.
- Hepatic inflammation
- Cardiac arrhythmia
- Cardiac arrest
- Acute renal failure
- Disseminated intravascular coagulation
- Early or late complication
- Compartment syndrome
Symptoms of Rhabdomyolysis
According to Merriam-Webster, the rhabdomyolysis definition is: “The destruction or degeneration of muscle tissue (as from traumatic injury, excessive exertion, or stroke) accompanied by the release of breakdown products into the bloodstream and sometimes leading to acute renal failure.” (16)
But the exact symptoms one experiences sometimes depend on the causes of rhabdo. Still, here are some of the hallmark signs of the condition. Note: Not all symptoms are always present in each case of rhabdomyolysis.
Symptoms of rhabdo include:
- Peeing brown or cola/tea-colored urine
- Muscle pain in the limbs (present in about 50 percent of cases) (17)
- Irregular heartbeat
- Bruising/muscle tenderness
- Decreased (or completely absent) urine production, typically 12 to 24 hours after the rhabdo-triggering incident
How to Avoid Rhabdomyolysis, AKA ‘Rhabdo’
When a rhabdomyolysis diagnosis is suspected, the main focus is to avoid damage to the kidneys. Patients tend to have much better outcomes when the syndrome is identified and properly treated fast. Rhabdomyolysis treatment involves:
- Large quantities of IV fluids
- Dialysis, if necessary
- Once urine starts flowing again, doctors routinely use sodium bicarbonate and mannitol. Even though these are commonly used, they are poorly supported by the latest evidence.
- Rhabdomyolysis recovery, including getting over muscle tenderness and weakness, can last several weeks, even in milder cases. The same goes for a trainer taking on a new fitness client. Mild cases of this syndrome do not require medical treatment and recovery time is usually about a week.
Rhabdomyolysis Prevention Tactics
- Avoid strenuous workouts in hot, humid weather unless you are acclimated to do so.
- Trainers and coaches should consider removing full-gear workouts during hot, humid weather.
- Maintain proper hydration and rest periods when you are training. Don’t just drink water, but electrolyte-rich drinks, too.
- If you are on statin drugs, regularly get your CK levels tested. And eat more cholesterol-lowering foods to try to normalize your cholesterol levels without drugs.
- Athletes can help avoid hyponatremia (low sodium levels) by consuming enough top sodium foods.
- When working out, drink water and use electrolyte replacement fluids for workouts lasting more than an hour or workouts in very hot weather.
- If you’re in the market for a personal trainer, make sure the trainer understands rhabdo. I suggest looking for trainers with at least a bachelor’s degree in exercise science and with certifications from organizations like the National Academy of Sports Medicine (NASM), National Strength and Conditioning Association (NSCA) or the American College of Sports Medicine (ACSM).
- Coaches should not start a training season using strenuous, repetitive exercises the trainees aren’t used to.
Rhabdomyolysis symptoms warrant an ER visit and should be taken seriously. Even those presenting symptoms without cola-colored “brown pee” could be suffering from rhabdo.
The good news is quick identification and treatment (usually involving higher levels of IV fluids) can often bring the body back into balance without long-term damage.
Rhabdo complications can be very serious and sometimes fatal, though, so proper prevention and identification of the symptoms is important. More common “early” complications involve severe hyperkalemia, which can trigger cardiac arrest. Acute renal failure is considered the most serious “late” complication. It occurs in about 15 percent of rhabdo patients.
Final Thoughts on Rhabdomyolysis or ‘Rhabdo’
- Rhabdomyolysis, also known as “rhabdo,” is a life-threatening, sometimes fatal condition that requires immediate medical attention.
- Rhabdomyolysis is the result of catastrophic muscle damage that can result from a number of factors, including but not limited to drug and alcohol abuse, statin medications, overtraining, heat stress, dehydration, snake bites, prolonged bed rest, infections, and metabolic and endocrine issues.
- When overtraining triggers rhabo, it’s known as exertional or exercise-induced rhabdomyolysis.
- Diagnosing the condition usually involves a doctor taking clinical symptoms into account, recent events and lab work to look for elevated CK levels and the presence of myoglobin from major muscle breakdown.
- Standard treatment partially depends on the cause and severity of the syndrome, but large amounts of intravenous fluids are generally included in treatment.
- Symptoms of the rhabdo include muscle pain and weakness, particularly in the shoulders, legs and/or back, cola/tea-colored urine, irregular heartbeat, weakness, vomiting, confusion, and low-level urine output (or none at all).
- There are many ways to prevent this condition, including proper hydration, electrolyte drinks, avoiding training in full gear in hot, humid weather, easing into exercise and getting your CK levels checked when you’re on statin drugs.
- If you anticipate more strenuous exercise, weigh yourself just before you start workout out and right after. Make sure you replace any lost fluids with electrolyte-rich drinks.
- Although dehydration and heat stress can contribute to the syndrome, rhabdo can develop in the absence of these two things, too.
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