Every run comes with its own milestones, whether it is getting out of bed before sunrise, completing a first 10K, or gradually building the endurance to run alongside a community.
Somewhere between the encouragement of friends and the satisfaction of completing a workout, movement becomes a form of rest. Regular physical activity supports cardiovascular health, mental well-being, sleep, mobility and long-term quality of life.
But in a culture that increasingly celebrates endurance, personal records and the ability to “push through,” the physical consequences of overexertion can be easy to overlook. Have you heard of rhabdomyolysis?
What is rhabdomyolysis?
In a nutshell, rhabdomyolysis occurs when skeletal muscle tissue breaks down and releases substances into the bloodstream that can harm other organs, particularly the kidneys. In severe cases, changes in blood electrolytes can also affect the heart’s normal rhythm.
When muscle cells are damaged, they release substances such as myoglobin, creatine kinase (CK) and electrolytes. Myoglobin is a protein found inside muscle cells that can contribute to kidney injury when released in large amounts. CK, meanwhile, is an enzyme measured through blood tests to help assess muscle damage. Electrolyte disturbances, particularly elevated potassium, may become dangerous and affect the heart.
When muscle breakdown follows physical activity, it is called exertional rhabdomyolysis. It is typically associated with severe muscle pain, stiffness or weakness, alongside laboratory evidence of muscle injury. A commonly used clinical threshold is a CK level at least five times the upper limit of normal. However, an elevated CK level after exercise does not automatically mean a person has dangerous rhabdomyolysis or will develop kidney failure. Doctors interpret the result alongside symptoms, medical history and other test findings.
Exercise is only one possible cause. Severe injuries, prolonged immobilization, burns, infections, heat illness, certain medications and alcohol or drug use can also trigger the condition.
Think of it this way: our muscles normally keep certain substances contained within their cells. But when muscle tissue breaks down, these substances spill into the bloodstream, where they can affect organs that are not meant to handle them in large amounts.
Yet knowing the risks does not necessarily make it easy to recognize when we are pushing ourselves too far.
Muscle soreness vs. rhabdomyolysis
With the growing popularity of running clubs, fitness challenges and endurance events, it is understandable that people feel motivated to do more, run farther and test what their bodies can do.
But the same culture can quietly blur an important distinction: discomfort is not always evidence of growth.
Muscle soreness after a workout is common, especially when the body encounters unfamiliar movement or a higher workload. Delayed-onset muscle soreness, for example, often develops after exercise and gradually improves over the following days.
But severe pain, pronounced weakness, swelling or symptoms that feel disproportionate to the effort are different. They deserve attention, not another lap around the block.
Exertional rhabdomyolysis can occur when the physical demands placed on the body exceed what the muscles can safely tolerate. A person can be motivated, disciplined and physically active and still be vulnerable—particularly when increasing their workload too quickly, exercising in extreme heat or ignoring signs that something is wrong.
Discover: Rest as a Biological Requirement: The Role of Recovery in Long-Term Health Outcomes
Rhabdomyolysis symptoms after exercise
Rhabdomyolysis is different from the muscle soreness people normally experience after a workout. Its symptoms may appear hours or even days after the initial muscle injury.
Warning signs to watch out for include:
- Severe muscle pain, cramps or tenderness than expected
- Noticeable muscle swelling or weakness
- Unusual tiredness or difficulty doing activities that would normally feel manageable
- Dark urine that looks like tea or cola after exercise
- Urinating much less than usual
- Nausea, vomiting or feeling unusually unwell after intense exercise
One of the best-known warning signs is dark-colored urine. However, not everyone with rhabdomyolysis experiences this symptom. Myoglobin can also clear from the urine relatively quickly, so normal-looking urine does not rule out the condition.
If you experience symptoms that suggest rhabdomyolysis, stop exercising and seek medical attention promptly. Severe or worsening muscle pain, swelling, weakness, very little urine or feeling seriously unwell after strenuous activity should not be ignored.
Doctors may use blood tests to measure CK, assess kidney function and check electrolyte levels. Urine tests and other assessments may also be needed. Because CK levels can change over time, repeat blood tests may be recommended.
The goal is not to make anyone anxious after every difficult workout. It is to help people recognize when muscle pain goes beyond the usual soreness and may signal something more serious.
Understanding the risk factors
The concern is not simply distance, speed or sweat in isolation. It is the combination of what the body is asked to do and how much time it has had to prepare.
1. Exercise-related factors
Sudden increases in workout intensity, duration or frequency can place excessive demands on the muscles, particularly when the body has not had enough time to adapt.
Strenuous or repetitive exercise without proper conditioning, returning to intense workouts after a prolonged break, and inadequate recovery between sessions can also increase the risk of muscle damage.
Certain types of movement may place additional strain on the muscles. One example is eccentric muscle work, which occurs when muscles lengthen while generating force, such as when running downhill.
This does not mean runners need to avoid hills or challenging workouts. Rather, it highlights the importance of gradually increasing exercise intensity and allowing enough time for recovery between demanding sessions.
2. Heat, humidity and hydration
Heat and humidity deserve particular attention in a tropical climate. Exercising in hot conditions increases the body’s heat load, and high humidity can make it harder for sweat to evaporate and cool the body.
Exertional heat illness and rhabdomyolysis can occur together. A 2020 case report published by Filipino physicians described a young Filipino athlete who developed exertional heat stroke, multiorgan failure and rhabdomyolysis after running 6.8 kilometers in 34°C heat. He had no hydration support during training and was recovering from gastroenteritis. The case illustrates how serious heat-related complications can become, although a single report cannot tell us how common such outcomes are.
Dehydration is best understood as a contributing factor to complications rather than an automatic cause of rhabdomyolysis. A 2023 American College of Sports Medicine consensus statement explains that dehydration increases physiological strain during exercise in the heat, while emphasizing the importance of appropriate hydration, heat acclimatization and adjusting activity to environmental conditions.
Adequate fluid intake matters, but it is not a guarantee against overexertion or heat-related illness.
3. Individual health factors
Some people may be more vulnerable because of inherited muscle or metabolic conditions. Recent illness, fever, vomiting or diarrhea can also affect the body’s ability to tolerate strenuous activity.
Sickle cell trait is another consideration. In a large study of 47,944 Black U.S. Army soldiers, sickle cell trait was associated with a higher adjusted risk of exertional rhabdomyolysis, with a hazard ratio of 1.54. The study found no significant difference in overall mortality between soldiers with and without the trait.
While these findings cannot be directly applied to the Philippine population, they support the broader point that individual biology can influence risk.
4. Medications and substances
Certain medications, stimulants, recreational drugs, excessive alcohol consumption and some supplements have been associated with rhabdomyolysis or may increase the risk of complications.
This does not mean every medication or supplement is dangerous. Rather, what a person takes, alongside how they train and how they feel, can matter.
One medication group deserves particular attention: nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen.
A 2024 study published in JAMA Network Open examined 200 patients hospitalized with exertional rhabdomyolysis. Acute kidney injury occurred in 8.5% of the patients. Researchers found that NSAID use before hospitalization and dehydration were associated with a higher risk of kidney complications. Interestingly, CK levels alone were not associated with the development of acute kidney injury in this group.
This does not prove that NSAIDs directly cause kidney injury in every person with rhabdomyolysis. However, it highlights why using painkillers to mask unusual muscle pain and push through a strenuous workout may be unwise, particularly when dehydration or heat stress is also involved. Anyone taking prescribed medication should consult a healthcare professional before making changes.
How to prevent rhabdomyolysis: The strength in slowing down
There is a difference between pushing yourself to improve and pushing yourself beyond what your body can safely handle.
Progress does not have to mean adding more distance, increasing speed or setting a new record every time. It can mean recognizing when to rest, adjusting your pace, choosing a shorter route or allowing your muscles to recover before the next demanding session.
To reduce risk, build up your training gradually, allow recovery between intense workouts, avoid strenuous exercise when you are unwell, and take heat and humidity seriously. Stay hydrated, take breaks and pay attention to how your body responds.
Rest is not the opposite of commitment, and recovery is not the absence of progress.
Sometimes, the strongest thing an athlete can do is know when to stop.
*Photo by Alexander Krivitskiy on Unsplash
Editorial Note
Joyful Wellness provides general, science-informed health information to help readers make informed decisions about their well-being. Our content is intended for educational purposes and does not replace professional medical advice. For personal health concerns or symptoms, readers are encouraged to consult a licensed healthcare professional.
References
1. Sabouri, A. H., et al. (2024). “Acute Kidney Injury in Hospitalized Patients With Exertional Rhabdomyolysis.” JAMA Network Open, 7(8), e2427464. Read the full study. PubMed Central (PMC)+1
2. Ubaldo, O. G. V., et al. (2020). “The Fire from Within: Multiorgan Failure with Bimodal Rhabdomyolysis from Exertional Heat Stroke.” Case Reports in Hepatology. Read the Philippine case report. PubMed Central (PMC)
3. Roberts, W. O., et al. (2023). “ACSM Expert Consensus Statement on Exertional Heat Illness: Recognition, Management, and Return to Activity.” Current Sports Medicine Reports, 22(4), 134–149. Read the consensus statement. PubMed+1
4. Nelson, D. A., et al. (2016). “Sickle Cell Trait, Rhabdomyolysis, and Mortality among U.S. Army Soldiers.” The New England Journal of Medicine, 375, 435–442. Read the study. PubMed+1
5. Centers for Disease Control and Prevention (CDC/NIOSH). Signs and Symptoms of Rhabdomyolysis. CDC
6. Centers for Disease Control and Prevention (CDC/NIOSH). Reducing Risk for Rhabdomyolysis. CDC
7. Scalco, R. S., et al. (2016). “Exertional Rhabdomyolysis: Physiological Response or Manifestation of an Underlying Myopathy?” BMJ Open Sport & Exercise Medicine. Read the clinical review.
