Why do my muscles cramp during exercise (or at other times)?

Several of my clients and students have complained about muscle cramps during certain exercise,  at night while sleeping  or while doing day to day activities.   I am lucky in that I rarely get them but it sent me digging into how I might be able to help.

What causes a muscle cramp?
The best description of what causes a muscle cramp I found was from the Mayo Clinic website:
“Overuse of a muscle, dehydration, muscle strain or simply holding a position for a prolonged period of time may result in a muscle cramp. In many cases, however, the exact cause of a muscle cramp isn’t known.

Although most muscle cramps are harmless, some may be related to an underlying medical condition, such as:

  • Inadequate blood supply. Narrowing of the arteries that deliver blood to your legs (arteriosclerosis of the extremities) can produce cramp-like pain in your legs and feet while you’re exercising. These cramps usually go away soon after you stop exercising.
  • Nerve compression. Compression of nerves in your spine (lumbar stenosis) also can produce cramp-like pain in your legs. The pain usually worsens the longer you walk. Walking in a slightly flexed position — such as you would employ when pushing a shopping cart ahead of you — may improve or delay the onset of your symptoms.
  • Mineral depletion. Too little potassium, calcium or magnesium in your diet can contribute to leg cramps. Diuretics — medications often prescribed for high blood pressure — may also deplete these minerals.”

Once you have a cramp the best way to deal with it is:

  • Stretch the cramped muscle and gently rub it to help it relax.
  • Apply heat or cold. Use a warm towel or heating pad on tense or tight muscles. Taking a warm bath or directing the stream of a hot shower onto the cramped muscle also can help. Alternatively, massaging the cramped muscle with ice may relieve pain.

 The best way to help prevent minor cramps is:

  • Avoid dehydration. Drink plenty of water every day.   This is a tough one because everyone is different.   The amount you need depends on your age, what you eat/drink,  your activity level, the weather, your health and possibly medications.   My rule of thumb is to drink at least 8 cups a day.   You can experiment with this if you need to but that should do it.   Drink WATER before, during and after exercise.   In fact, sip water throughout the day.  NO DIET DRINKS, sports drinks or soda.   These either have too much sugar or hurt more than help.
  • Stretch your muscles.   The Mayo Clinic site recommends that you stretch before and after you use any muscle for an extended period. If you tend to have leg cramps at night, stretch before bedtime. Light exercise, such as riding a stationary bicycle for a few minutes before bedtime, also may help prevent cramps while you’re sleeping.
  • Experiment with getting more minerals into your diet such as potassium, calcium and magnesium.

The most common mineral deficiency is potassium.   From the WebMD website I found that “Experts suggest 4,700 milligrams of dietary potassium a day for adults as part of a balanced diet.   But the average intake is lower for U.S. adults. Men average 3,200 milligrams per day of potassium, and women average 2,400 milligrams.”

Why is this? We are eating way too many processed foods and not eating enough fruits and vegetables.   Eating things high in potassium is the best way to meet your needs.   Use supplements only if the doctor tells you to.

Top Potassium Food Sources  Source: U.S. Department of Agriculture (USDA)
•Winter squash, cubed, 1 cup, cooked: 896 mg
•Sweet potato, medium, baked with skin: 694 mg
•Potato, medium, baked with skin: 610 mg
•White beans, canned, drained, half cup: 595 mg
•Yogurt, fat-free, 1 cup: 579 mg
•Halibut, 3 ounces, cooked: 490 mg
•100% orange juice, 8 ounces: 496 mg
•Broccoli, 1 cup, cooked: 457 mg
•Cantaloupe, cubed, 1 cup: 431 mg
•Banana, 1 medium: 422 mg
•Pork tenderloin, 3 ounces, cooked: 382 mg
•Lentils, half cup, cooked: 366 mg
•Milk, 1% low fat, 8 ounces: 366 mg
•Salmon, farmed Atlantic, 3 ounces, cooked: 326 mg
•Pistachios, shelled, 1 ounce, dry roasted: 295 mg
•Raisins, quarter cup: 250 mg
•Chicken breast, 3 ounces, cooked: 218 mg
•Tuna, light, canned, drained, 3 ounces: 201 mg

Risk Factors and when you should consult your doctor.  From WebMD.com
“Potassium levels in your body are influenced by several factors, including kidney function, hormones, and prescription and over-the-counter medications.  “People who take thiazide diuretics, often used to treat high blood pressure, may need more potassium. That’s because thiazide diuretics promote potassium loss from the body. Steroids and laxatives also deplete potassium.

Other drugs used to lower blood pressure, including beta-blockers and ACE inhibitors, raise potassium levels in the body.

People with reduced kidney function may need to limit their daily potassium intake.

Ask your doctor or pharmacist about how all of the medications you take affect the potassium levels in your body, and if you need more, or less, of the mineral.”

As for calcium and magnesium, I could not find a lot of studies that showed a strong correlation to cramps and these minerals.

My recommendation
Start a journal.   Note when you get cramps and then start to increase your intake of potassium rich foods.   Keep a journal of the number of milligrams you are eating and see if you notice a correlation!    It might also be good to note and track your water intake as well as when you exercise and at what intensity (give it a 1-10 – my class might be an 8 if you are working hard)

I hope this helps.   

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