8 Reasons Your Muscles Are Sore That Have Nothing to Do With Working Out

Having sore muscles you can't trace to a workout might be your body reacting to stress.
Image Credit: milorad kravic/iStock/GettyImages

Sore, fatigued and achy muscles are often caused by exercising too hard, and generally feel better with time. But if you haven't worked out recently, muscles that hurt for "no reason" could be an indicator of an illness or other health condition.

Here, Gbolahan Okubadejo, MD, a New York City-based spinal and orthopedic surgeon, discusses reasons you might experience muscle soreness with no apparent cause and when it's time to see a doctor.

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Muscle soreness after exercise is to be expected. Delayed-onset muscle soreness — or DOMS — typically appears within about 24 to 72 hours after a workout. It can cause mild or very severe muscle pain that can make daily activities difficult.

However, if you haven't exercised recently, and you have sore muscles for no reason or pain lasting more than three days, it's time to visit the doctor to rule out underlying medical conditions.

1. You Have a Viral or Bacterial Infection

"Colds, viral and bacterial infections can cause body aches," Dr. Okubadejo says.

Here's why: "The immune system sends white blood cells to fight off the infection and inflammation can result, leaving the muscles feeling stiff and achy," he explains.

Fix it:​ To relieve sore muscles caused by an infection, Dr. Okubadejo recommends drinking a lot of water and broth and getting plenty of rest. You can also take Tylenol and use a heating pad to manage symptoms as your body recovers, he says.

2. You’re Stressed

If you experience back and shoulder pain, headaches and body aches, stress may be the source of your sore muscles.

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"If you're constantly under stress, your muscles may not get the chance to relax," Dr. Okubadejo says. That's because your muscles switch into self-preservation mode.

"​Your muscles have their own self-defense mechanism and tend to contract to ward off injury while under stress," Dr. Okubadejo says.

Fix it:​ “Once relaxed, the muscles will release again,” Dr. Okubadejo says. The best way to loosen tense muscles is through exercise and stretching. Any type of workout will help, but swimming and yoga are especially great options, he says.

3. You’re Not Getting Enough Sleep

Sleep is a stellar healing environment. It gives your body the time it needs to recover from the day's events, activities and stress, Dr. Okubadejo says.

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Without sufficient sleep, your body can't properly recuperate, which can lead to aches and pains.

Fix it:​ Trouble catching zzzs? Dr. Okubadejo suggests the following strategies for a sound slumber:

  • Avoid caffeine, alcohol and heavy meals close to bedtime.
  • Limit cell phone use before bed — the blue light disrupts sleep.
  • Listen to calming, meditative music.
  • Establish good sleep hygiene by going to bed at the same time each night and waking up at the same time each morning.

4. You’re Dehydrated

Believe it or not, muscle aches might be a sign that you're not drinking enough fluids. When you're dehydrated, it interferes with normal body processes, such as delivering oxygen to the right places and digesting food, Dr. Okubadejo says.

Essentially, muscle discomfort or pain is your body's way of alerting you to dehydration and telling you: ​drink more water, stat.

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Fix it:​ Aim to consume eight 8-ounce glasses of water per day (more if you work out or run for long durations) and drink Gatorade to quickly replenish lost electrolytes, Dr. Okubadejo says.

5. You Have a Deficiency

Certain vitamin deficiencies can also bring on body aches. For example, hypocalcemia — a condition where people have low amounts of calcium in their blood — can trigger tension in your muscles, Dr. Okubadejo says. That's because the muscles (and kidneys) depend on calcium to function optimally, he explains.

Surprisingly, sometimes the underlying cause of hypocalcemia is a vitamin D deficiency, because your body needs adequate vitamin D to absorb calcium, Dr. Okubadejo adds.

Similarly, if your body doesn't have sufficient red blood cells, you're most likely anemic, and this can also lead to body and muscle aches, he says.

Fix it:​ Consult with a doctor who can test you for these or other deficiencies and help you determine a proper course of treatment, Dr. Okubadejo says.

6. You Have Chronic Fatigue Syndrome

If you experience muscle pain and soreness in addition to unusual headaches, difficulty sleeping, trouble concentrating and severe exhaustion that lasts for six months or longer, chronic fatigue syndrome — also known as myalgic encephalomyelitis (ME/CFS) — could be to blame.

ME/CFS is a serious, chronic illness that affects different parts of the body (including your muscles and joints) and is not improved by bed rest, according to the U.S. Department of Health & Human Services.

Fix it:​ If you think you may have ME/CFS, see your doctor, who can perform an exam and diagnostic tests. While currently there is no cure or approved treatment, your medical provider can help you develop a plan to manage your symptoms.

7. You Have Lyme Disease

Muscle and joint aches can also be an indication of Lyme disease, a tick-borne illness caused by the bacterium Borrelia burgdorferi.

"With Lyme disease, musculoskeletal interference, particularly arthritis, is common," Dr. Okubadejo says.

"Early in the illness, patients may report 'traveling' musculoskeletal pain in muscles, bone, joints or tendons," he adds.

Fix it:​ Consult with your medical provider, who can assess you for Lyme disease through diagnostic tests and treat you with antibiotics. Your doctor may also recommend topical anesthetics such as lidocaine or anti-inflammatory agents to help relieve muscle pain, Dr. Okubadejo says.

8. You Have Fibromyalgia

"​Those who experience aches and pains for a long period of time with no known cause might suffer from fibromyalgia," Dr. Okubadejo says.

Fibromyalgia is a chronic nervous system condition that causes widespread pain and tenderness in muscles and joints, according to the American College of Rheumatology.

What's worse, the constant discomfort also makes it hard for people with fibromyalgia to get adequate rest, resulting in sleep deprivation, which we already know plays a part in sore, achy muscles, Dr. Okubadejo says.

Fix it:​ “Both the cause and the cure for fibromyalgia are unknown,” Dr. Okubadejo says. “If you think you have fibromyalgia, see a doctor for help in dealing with this condition.”

A medical professional may prescribe medication along with regular exercise, diet, a good sleep routine and cognitive behavioral therapy to help relieve symptoms, per the American College of Rheumatology.

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Is This an Emergency?

If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911. If you think you may have COVID-19, use the CDC’s Coronavirus Self-Checker.
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