If you're new to exercise or you've never felt a burning sensation in muscles during exercise, you might be wondering if what you're experiencing is abnormal. The good news is there are several explanations that point to why this feeling may be a normal response to exercise.
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Lactic acid is one of the reasons you experience a burning sensation in your muscles during exercise. Delayed-onset muscle soreness and exercise-related injuries may also be to blame.
Burning Sensation in Muscles
Your body responds to strenuous activity such as lifting weights, sprinting, cycling or other intense exercises in a variety of ways. Probably, the most common cause of a burning sensation in muscles during exercise is lactic acid, which is a natural byproduct of exertion that your body produces. The Cleveland Clinic calls this muscle pain a good pain and says it should end immediately after you stop the activity.
Why your body responds this way when working out often relates to the intensity of the exercise. "When you exercise very intense, your muscles can't get all the oxygen needed to break down glucose for energy quick enough, so lactic acid accumulates in muscles and spills over into the bloodstream," Dr. Allen Conrad, BS, DC, CSCS, a certified strength and conditioning specialist, tells LIVESTRONG.com.
Since lactic acid is produced from the body to help convert energy during your workout, Conrad explains that the faster and more intense the exercise is, the more burning you may feel as your body tries to break down food for energy. "The more strenuous the activity, the more lactic acid is spilled over into the bloodstream, which leads to more burning sensation during the exercise," he adds.
Delayed-Onset Muscle Soreness
Another reason you might experience a burning sensation in your muscles during exercise is a phenomenon called delayed-onset muscle soreness or DOMS. According to the American College of Sports Medicine, DOMS can happen after performing an activity that places new stress on a muscle or when a muscle is asked to do too much too soon, which causes small microtears in the muscle fiber.
Additionally, Conrad points out that the longer you stay in the burn during exercise and the greater the force on your muscles during exercise, the greater the muscle damage.
Even though DOMS happens after you've finished working out, it can stick around for a few days, which means if you exercise during that time, you might feel your muscles burn with little exertion. For the most part, DOMS symptoms typically last 12 to 24 hours after the causing exercise was performed, but it may continue up to 72 hours.
If you have burning pain longer than 24 hours after the workout, Conrad says it's helpful to perform low-intensity, low-repetition exercises of the same muscle group each day until the DOMS soreness goes away. However, if the pain lasts more than a few days, consult your doctor.
Read more: The Treatment for Delayed Onset Muscle Soreness
When to Worry
Most of the time, the burning sensation in muscles during exercise is caused by a normal reaction to working out, such as lactic acid buildup. That said, there are certain medical conditions you need to be aware of that can cause a burning sensation in the body, and may need further medical attention.
One issue you shouldn't ignore is chronic exertional compartment syndrome. According to the Mayo Clinic, chronic exertional compartment syndrome affects the muscles and nerves and happens as a result of exercise. It causes pain, swelling, aching, burning or cramping in a specific area of the limb, usually the lower leg. If these symptoms continue to occur or they get worse while engaging in physical activity, talk to your doctor so they can determine a correct diagnosis.
Another red flag to consider when muscles burn with little exertion while working out is an injury to the muscle or surrounding area. The American Academy of Orthopaedic Surgeons says that some of the more common soft-tissue injuries that can happen during exercise include sprains, strains and bruises.
If you believe the cause of your muscle burn has to do with a soft-tissue injury, stop exercising immediately and consult your doctor.
- Cleveland Clinic: "Is Your Exercise Causing Good or Bad Pain? How to Tell"
- America College of Sports Medicine: "Sore and More"
- Montgomery County Chiropractor Center: "Dr. Allen Conrad: Personal Interview"
- Mayo Clinic: "Chronic Exertional Compartment Syndrome"
- American Academy of Orthopaedic Surgeons: "Sprains, Strains and Other Soft-Tissue Injuries"