It's safe to assume that most know me as that guy who reviews dietary supplements. But, there is another topic I'm very passionate about: rhabdomyolysis (“rhabdo”). I call rhabdo a cancer in the fitness community and I believe it's on the rise. Here, I want to alert you about a growing trend I've noticed over the last few years: rhabdo caused by indoor spinning classes. My hope is what you are about to read will save you pain, mental stress and avoid costly hospital bills caused by this little known side effect of working out too hard. Hopefully this never happens to you. Also see my review of rhabdo and personal training.
What Is Rhabdo?
Rhabdomyolysis (say “rab-doe-MY-O-lie-sis) translates into “muscle fiber death.” When the muscles fibers die, the contents of those cells leak into the bloodstream. While many things can cause muscle fibers to die, when physical activity is the cause, it's called exercise-induced rhabdomyolysis.
Rhabdo needs to be treated medically because in severe cases it can lead to kidney failure and heart attacks. I've been told of people who have died from rhabdo caused by exercise. Fortunately, the overall rate of death (from all causes) appears to be low, about 8% by some
estimates, but that is still too high for me.
The following are things that can occur when someone has rhabdo. Because rhabdo can vary in its severity, (ranging mild to severe) not everyone who has the condition will have all these symptoms and signs.
|Muscle weakness||Muscle swelling||Muscle pain|
|Fatigue||Inability to lift/move limbs||Fever|
|Dark colored urine||Reduced urination||Kidney failure|
|loss of consciousness||Heart attack||Liver problems|
Of these symptoms above, the following are often particularly recognized as indicating rhabdo:
- Muscle pain/weakness/ lack of ability to move arms or legs
- Muscle swelling
- Dark colored urine
To this list I'd also add in recent participation in an exercise that you were not used to doing or have not done in a long time. As you will see below, this is one of the key indicators in who is most likely to develop rhabdomyolysis.
What Are Case Reports?
Most of what you will see below comes from case reports. These are reports of a single person who got medical attention for some issue. The doctors overseeing the treatment thought the case was important enough to alert the medical community about. And so, they summarized what happened and submitted it to a medical publication.
The more case reports submitted on a topic, the greater the possibility that a trend might be occurring. I believe the trend is that indoor cycling classes are causing more rhabdo than in years past.
Case reports are not the same thing as large scale clinical trials but because there is no government or medical agency activity tracking rhabdo in the general public they a valuable tool to educate others about this condition.
What Is Creatine Kinase?
Creatine kinase is an enzyme that doctors can use as a measure of muscle damage. The more damage, the higher the levels go. Exercise increases CK levels as does damage like rhabdomyolysis. Another name for this enzyme is creatine phosphokinase (CPK).
In the reports below, I'll mention creatine kinase levels. I'll do this because it's been my experience that people who've been hospitalized get clobbered with info about their CK levels. It's basically all they hear about. It's usually the first thing they tell me when they recount what happened to them. So I'll list the CK levels so people can compare their levels to.
Normal creatine kinase levels can vary but some estimates put the normal level between 38-234 u/L. Your doctor can give you a more specific level for you. Generally, creatine kinase levels of at least 5 times normal usually indicates rhabdo but this is just a rule of thumb.
In this review, when I use the word “spinning” I'm not specifically referring to Spinning (as in Johnny G Spinning) but rather to indoor cycling classes as a whole. Even though spinning refers to a specific type of cycling program (the name is actually trademarked), the word has also become par of the common language (like Xerox, Kleenex, etc.). It's a general term these days.
Case reports such as those cited below often use the word “spinning” in their titles but the researchers often don't specially mention a class brand name (Soul Cycle, Johnny G, Mad Dogg etc.). As such, I wonder if they are just using a generic name?
I bring this up so people don't think I'm specifically singling out Spinning. I'm not.
Rhabdo From Spinning: The Evidence
What follows are several case reports of people who developed rhabdo after taking indoor cycling classes.
In 2004, doctors reported on a fit, 34 year old woman in the Scotland who complained of leg swelling and pain 2 days after taking a spinning class. The woman reported that she had worked out 2-3 times per week but that this was the first indoor spinning class she ever did.
After 4 days of medical treatment, her creatine kinase level dropped from 409,000 u/L to 29,000 u/L. Fortunately, her kidney function was good and after 4 weeks, her CK levels were back to normal and she recovered fully. This is often cited as the very first case of spinning-induced rhabdo ever reported in the medical literature.
Doctors in 2010 reported the case of a 63 year old woman who developed rhabdo a day after riding her stationary bike at home.
This woman was described as a “recreational athlete” but they gave no description of her previous physical activities. They did say she had a “strong” family history of type II diabetes and high blood pressure and began biking at home to help those reduce her risk of those disorders.
Her CK level at hospital admission was 38,000 u/L. After 2 days of reviving IV fluids, she was released. Because cycling at home is becoming popular, health professionals should educate consumers to reduce accidental self induced rhabdo.
Doctors in Israel, reported the case of a 21 year old woman in 2011 who developed rhabdo after taking a 45 minute “spinning” class for the first time.
After 5 days of suffering with the pain and dark colored urine, she went to the hospital. Her CK levels at admission to the hospital was 132,000 u/L. This woman was generally healthy, taking no medications and recently completed her mandatory military service.
She did have a genetic disorder called tomaculous neuropathy (HNP). It is unknown if HNP played a role in rhabdo development. She was active but never attended an indoor cycling class before. Within 24 hours of receiving treatment, her urine started to return to its normal color. After 6 days in the hospital, she was released. Her CK levels had decreased to 3781 u/L.
In 2012, a report was published in the Journal of Family Practice that outlined two cases of rhabdo in healthy people:
The first case involved a healthy but sedentary 38 year old man who took part in his very first indoor cycling class. He reported feeling fine during the class and only felt mild fatigue afterward.
The next day he played 18 holes of golf in a humid, hot environment, after which he admitted to drinking a few beers afterward and not drinking much during golf. These events likely contributed to his development of rhabdo.
He was released after spending 4 days in the hospital.
In the second case report, a healthy 26 year old woman took part in her very first indoor spinning class. About 30 minutes into the class, she experienced discomfort and two days later sought medical help due to the increase in thigh pain and dark color of her urine. Her creatine
kinase level was 86,000 u/L at admission to the hospital. After 4 days in the hospital, she was discharged as her CK levels were dropping (CK was 11,000 u/L at discharge. Two weeks later, CK levels were 772 u/L).
In a 2014 report, a 26 year old woman developed rhabdo after her very first indoor cycling class. From the report, she was apparently healthy and had worked out 3 times a week for the previous 5 months without problems. The spinning class lasted 30 minutes and included a 10 minute warm up period. The woman did report having low fluid intake on the day of the class.
The pain in her thighs had persisted for 5 days before she sought medical treatment. After 3 days of treatment with IV fluids, her symptoms began to subside. After a month, all of her blood levels (creatine kinase etc.) returned to normal values.
In another report from 2014 titled Spinning-induced Rhabdomyolysis and the Risk of Compartment Syndrome and Acute Kidney Injury, doctors report on 2 cases of cycling-induced rhabdomyolsys.
Case 1 involved a healthy 24 year old woman who was admitted to the hospital 4 days after taking her very first a spinning class. She was experiencing thigh pain in both legs that were tender to the touch and had dark colored urine. Her legs were painful when she tried to move them.
She reported experiencing thigh soreness and cramps immediately after the class which progressively got worse. Her thigh muscles were “tight as as drums” she told the doctors.
Her heart rate at the hospital was 122 bpm and her blood pressure was 133/99. Both of these values are higher than normal and might be related to the distress and pain she was experiencing. Her creatine kinase level was 161,000 u/L when she was admitted to the hospital (700 times higher than normal!).
Because of her worsening of symptoms, this woman required surgery of her thighs to reduce the pressure that was building up in them (this symptom is called compartment syndrome). The study linked to shows a picture of this. Eventually her kidneys recovered and she was released.
Case 2 relates the story of a 24 year old man who had some leg issues present from birth. He went to the hospital 2 days after taking a spinning class for the first time. At hospital admission, he reported worsening thigh pain and dark colored urine. His creatine kinase level was 14,000 when he was admitted. After 5 days of receiving medical treatment and reduction of his symptoms, he was released from the hospital.
Between 2014-2015, researchers in Korea identified 11 cases of indoor cycling-induced rhabdo. All the cases involved women (average age 23) with no risk factors for the disorder. Their most common complaint at the hospital was thigh soreness and dark colored urine. Most of the people reported dark colored urine 2-3 days after the exercise class, which was the first time they took part in spinning.
Their average creatine kinase level was over 11,000 u/L and the average length of time spent in the hospital was 7 days. After medical treatment, all women recovered.
In 2015, news organizations in the US reported the case of a University of Tennessee graduate student who developed rhabdo 48 hours after taking her very first indoor spinning class. After the class she reported not being able to move her legs at all. Her liver and kidneys were also shutting down. Fortunately, after medical treatment, she recovered.
In a 2016 case report titled, Spinning Out of Control: A 19-Year-Old Female with Spinning-Related Exertional Thigh Compartment Syndrome, doctors made the report of a 19 year old woman who developed rhabdo – complete with swelling in her thighs and dark urine – after participating in a 45 minute spinning class.
This woman told doctors that while she exercised regularly, the intensity of this particular cycling class was more than what she usually did. She also told doctors that this was the first spinning class she ever did. Because of the thigh swelling, surgeons had to slice into her thighs to relieve the pressure that building up.
In 2016, Researchers in Korea reported a case of rhabdo in a healthy but unfit 21 year old college student. Two days before seeking medical treatment, she reported taking part in a 40 minute supervised cycling class. Her creatine kinase level was 16,000 u/L when admitted to the hospital. After 10 days of hospitalization, she was discharged and her creatine kinase level had decreased to 460 u/L.
In a 2016 paper titled Freebie Rhabdomyolysis: A Public Health Concern. Spin Class-Induced Rhabdomyolysis, researchers report on 3 “unusual cases” of rhabdo following spinning classes.
- In the first case, a 33 year old woman sought medical treatment 4 days after she took a 15 minutes of spinning. She had weakness and in pain in both thighs and reported vomiting and feeling light headed immediately after cycling. Her creatine kinase level was 60,000 u/L. The report does not say if this woman was in an actual indoor cycling class or was riding a stationary bike at home.
- The second case involved a 20 year old male who went to the hospital 3 days after a spinning class. He has weakness in both thighs, thigh swelling and was not able to lift his legs. This person also had a rare, genetic liver disorder called “Gilberts Syndrome.” His creatine kinase level was 14,493 u/l at the time of admission.
- In the 3rd case, a 33 year old woman was admitted to the hospital 2 days after taking a spinning class. Her symptoms included thigh pain, reduced urination, nausea and vomiting. She had a history of using non steroidal anti-inflammatory medications (NSAIDs). Her her creatine kinase levels were over 80,000 u/L and her symptoms were so severe as to require dialysis.
The case of a 35 year old woman admitted to the hospital with rhabdo, 3 days after taking a low intensity spinning class was outlined in this 2016 case report titled Rhabdomyolysis After Ankle Strain and Light Cycling. The woman had severe leg and back pain after the class that grew in intensity.
This woman also reported falling from the bike at the gym (due to a handle bar malfunction). After the fall, she contained to ride the bike for 45 minutes. She also reported using ibuprofen for the pain she was experiencing. While her injury was not seen as contributing to rhabdo, in theory, the injury and NSAID use may have played a role. We will never know. She had no risk factors for the condition.
This woman showed no leg swelling and no dark colored urine. Her creatine kinase level was 72,000 u/L at the time she arrived at the emergency room. She stayed in the hospital for 7 days, after which and was discharged.
Are these the only cases out there? I'm sure they are not. These are the case reports I've was able to locate. I'm quite sure many cases go unreported. I'm also sure there are those with “milder forms” of the disorder who never get medical treatment.
What Do These Cases Have In Common?
From the case reports above, there is one glaring aspect that most have in common:
- The people were not used to indoor cycling classes. Many said this was the first class they took.
From this, we can say that the most likely explanation for why indoor cycling is causing rhabdo is because people were not used to doing it and / or took part in a class that was more intense than they were used to.
This is the same reason as most other cases of exercise-induced rhabdo I've investigated over the years. It occurs because people increase the intensity of activities they are not used to doing, too quickly.
Tips For Reducing Rhabdo In Spinning Class
So you want to take an indoor cycling class. It's a great activity and can be performed safely. I asked Holly Hargrave who owns Athletic Genius, in Mountclair NJ to offer some ideas to help people get the most out of their first cycling class.
- If you can take a “beginner class” first, do it. If that's not possible, ride a stationary bike on your own for the first week or so. Start with a low intensity for just 5-10 minutes and increase the time slowly. This will help adapt your muscles to indoor-cycling classes.
- Tell the instructor you've never taken an indoor cycling class before. They will set you up properly and pay special attention to you in class.
- Bring water. If you run out of water during the class, go get some more. Water does not prevent rhabdo but it can help prevent
dehydration which can increase the risk. Proper fluid intake might also reduce kidney damage if rhabdo does occur.
- Don't over consume fluids. Encourage drinking when thirsty. Too many fluids can cause hyponatremia which might increase rhabdo. This is more proof that fluid intake does not prevent rhabdomyolysis from occurring.
- Exercising in hot class rooms can increase rhabdo especially in novices.
- Discourage fat burner supplement use. Fat burners (stimulants) have been implicated in rhabdo. See Supplement-Geek.com site for honest reviews on many weight loss supplements.
- Use RPE Scale (Borg Scale) instead of percent maximum heart rate. People of different fitness levels perceive intensity differently. 70% max heart rate might be harder to maintain in unfit people vs. fit people.
- Don't try to keep up with the class or instructor. When you are in the class, work at your own pace. If your tired, your tired. You will adapt. Just give it time.
Why Does Urine Change Color?
Many people with rhabdomyolysis report that their urine looks dark colored. It's often described as reddish-brown, like cola or ice tea. This is due to myoglobin (my-O-glow-bin) in the urine. Myoglobin is basically “muscle hemoglobin,” a very necessary compound. But, too much of it in the blood (which occurs when muscle cells die) is toxic to the kidneys. When myoglobin is in the urine, its called myoglobinuria.
Myoglobin has a reddish color to it and this is why the urine changes color.
It's important to remember that not everyone with rhabdomyolysis has dark colored urine. But when it's present, it's a sign of of the disorder.
Does Sodium Bicarbonate Help?
Some websites discuss taking sodium bicarbonate to help reduce kidney failure and other symptoms of rhabdo. Don't do that. According to this 2004 paper titled Preventing renal failure in patients with rhabdomyolysis: do bicarbonate and mannitol make a difference? the researchers point out that sodium bicarbonate will not help when creatine kinase levels are above 5000 u/L. You don't know what your CK levels are unless you go to the hospital.
Bottom line: Don't take advice from the internet. If you think you have rhabdo, don't wait. Turn your computer off and go to the hospital now.
How Likely Is This?
This is difficult to answer but given the millions of people who do indoor cycling each day, I think the overall risk is low. Still, that doesn't mean it cant happen to you.
Researchers, in a 2015 review paper on this issue, titled Spinning : an arising cause of rhabdomyolysis in young female, looked at spinning induced rhabdo in South Korea from 2011-2015. The group included 70 people (average age 48) suspected of having with rhabdo.
These researchers identified 13 cases (18.6%) that were attributed directly to spinning classes.
That doesn't mean people have an 18.6% chance of getting rhabdo from cycling. This review only looked at a small number in of people in Korea. One thing that was interesting though was that cycling-inducted rhabdo appeared to be more severe (people had longer hospital stays) than rhabdo occurring from other types of exercise.
These researchers also tracked the number of cases over time. They noted:
- 1 case in 2012
- 2 cases in 2013
- 7 cases in 2014
This provides some evidence that rhabdo from indoor spinning classes appears to be on the increase – at least in Korea during those years.
In a 2016 review, researchers in the US looked at cases from 2010 -2014. During this time, they identified 52 adults (16-55 years of age) who had rhabdomyolyis – 29 of which specifically stemmed from exercise.
Of those 29 people, 14 of the cases (48%) were attributed to spinning. Most of the people were healthy spinning was a brand new activity for them. The average creatine kinase level as admission to the hospital was 73,000 u/l. Like the report from Korea above, these doctors also report an increase in rhabdo following cycling classes.
At the end of the day, the best defense we have on reducing the odds of getting this is education. The more people know about this condition, the less likely it is to happen.
Is It Rhabdo Or DOMS?
Delayed Onset Muscle Soreness (DOMS) is refers to regular muscle soreness that pretty much everybody gets when they workout too much. Yes DOMS can be severe – and may occur alongside rhabdo but they are not the same thing.
One way to tell the differences is to remember that the pain from rhabdomyolysis can hurt even when you are not moving. Muscle pain from DOMS does not hurt when you are not moving. If you think you have rhabdo, stop what you're doing and don't move. Are you in pain now? If yes, its not DOMS. It's something more serious.
The PAR-Q And Group Exercise Classes
I believe group exercise instructors should pre-screen new attendees with PAR Q document. The letters PARQ stand for Physical Activity Readiness Questionnaire (click to download a PDF of the document). While the PARQ does not specifically screen for rhabdomyolysis, it can highlight other issues that may require a doctors permission before exercise. Pre-screening also gives cycling instructors the opportunity to get to know new attendees and educate them on issues relating to how to get the most out of the class.
I Think I have Rhabdo. What Should I do?
If you think you got rhabdomyolysis from a spinning class (or other activity), please do not sit there and hope it gets better. As you can see from the reports above, in many cases, the pain, swelling, inability to walk and other symptoms might only get worse. Even if you are reading these words in the middle of the night, I beg you to go to the hospital. Only then will you know for sure if it's rhabdo and get the treatment you need.
I truly hope these words have helped you.