What you should know before you clip into the pedals of an indoor bike.
By Laurie Yarnell
It’s easy to see the appeal of indoor cycling. It’s fun; it’s social; and you can enjoy riding a bike without worrying about traffic or inclement weather. And unlike running or weightlifting, it’s a low-impact exercise that still provides an intense workout. According to Spinning.com, participants can burn anywhere between 400 and 600 calories per average 45-minute class. No wonder spin studios are popping up all over the Hudson Valley. All in all, spinning can be a great form of exercise if you start out slowly, says Maureen Brogan, MD, a nephrologist at Westchester Medical Center, the flagship of the Westchester Medical Center Health Network (WMCHealth). But, according to a study Dr. Brogan recently conducted and had published in the American Journal of Medicine, it’s not without its risks, particularly for first-time participants who are not well-conditioned. Dr. Brogan found that high-intensity exercise associated with first-time spin classes can result in rhabdomyolysis, a condition in which proteins are released by damaged muscles that can send the spinner into kidney failure. “At the time we wrote the article, there were 46 cases in the literature of spin-class rhabdomyolysis, and the majority was after the first class.” says Dr. Brogan, who co-authored the study with Rudrick Ledesma, MD, Alan Coffino, MD, PhD, and Praveen Chander, MD. Here, Dr. Brogan shares her insights on this dangerous condition and tips on how to avoid it.
Why is this condition on the rise?
Spin class has become very popular — there are four spinning studios within a mile of my neighborhood — and most of them are handing out free passes for the first class. There are spin-class birthday parties, and some local PTAs are receiving group-class passes. And many studios intentionally keep the temperature high, to encourage participants to sweat more.
What galvanized your interest in this topic?
Over a two-year period, six of my patients presented with rhabdomyolysis right after their first spin-class experience. I reviewed the literature and saw that three of the cases were unusual, all occurring in younger patients. I was worried that if we didn’t inform the public and talk about how it could be prevented, we would continue to see more such cases.
Tell us about some of these patients.
They included a 20-year-old healthy male patient, a 32-year-old healthy female teacher who was on the bike for 15 minutes in the standing position, and another young patient, also a teacher, who developed kidney failure requiring hemodialysis three times a week as kidney-replacement therapy for one month.
What are the medical implications of rhabdomyolysis?
During this intense exercise, the muscles may not get enough oxygen, and inflammation and swelling may occur around the broken muscle cells later. The muscle-cell breakdown may cause electrolyte abnormalities, including high potassium and high phosphorus and low calcium, putting the patient at risk of cardiac arrhythmias and seizures. When the muscle cells break down, they also release a protein called myoglobin, which needs to be cleared by the kidney and can directly injure it.
Is the kidney damage suffered in these instances permanent?
No, I haven’t found a case of rhabdomyolysis due to spinning that caused permanent kidney damage, although one episode of acute kidney injury can increase one’s risk of another episode, even from another cause.
What are the signs that first-time spinners should seek medical help?
Go to the emergency department if you notice dark urine post-spinning, development of swelling and weakness in your thighs that cause difficulty walking or going up stairs, or just not feeling well for any reason. And note that some symptoms can take up to a few days to develop.
Want to Go for a Spin?
To make sure you are exercising safely your first time on an indoor bike, Dr. Brogan advises that you:
• Try to take a beginners’ class
• Inform the instructor that you are new to spinning
• Take a class when you are already well-hydrated
• Continue to drink water during and after the class
• Slow the cadence of the bike and use less resistance
• Avoid non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen, which are also harmful to the kidneys
• Refrain from taking a second class for several days, to make sure you are okay
• Seek medical help immediately for any symptoms like dark urine, swelling or thigh weakness