There's nothing like a muscle cramp — also known as a charley horse or a spasm — to capture your complete attention. You know the feeling ...

You're running across a tennis court and suddenly it feels like someone is jabbing a fork into your calf. Or you're swimming your laps in the pool, and your toes curl up and cramp so badly you have to quit kicking and head for dry land. Or you're asleep in bed — nighttime cramps are very common — and you're jolted awake with a shooting pain in your thigh. Ouch, ouch and ouch all around!

So much for the problem. Let's talk about a solution. Though it's still a bit of a mystery why certain people get cramps, there are lots of things you can do for prevention and relief. Let's begin with a little basic physiology, so you'll understand what's going on.

CRAMPS R US. Every movement you make involves the contraction and relaxation of a muscle. When your muscle contracts (gets shorter), there is a change in the concentration of sodium and potassium ions (minerals called electrolytes) inside the muscle. When your muscle relaxes, the concentration of sodium and potassium goes back to normal. At least, that's the ideal.

But if you work your muscles too hard or too long (overexertion) or if you don't drink enough fluid (dehydration), you may cause the ionic concentration to get so out of balance that your muscle contracts — and stays contracted. The result? A cramp! Sometimes the muscle will cramp right away, and sometimes it has a delayed reaction and cramps up later at night.

OTHER CAUSES. There are other causes of cramps, too. Women who wear high heels in spite of all the pain and pressure on the delicate architecture of the foot are begging for leg cramps. So are sedentary people in generally poor condition. Aging and circulation problems can cramp your active lifestyle and so might certain medications (diuretics, for instance). Sometimes the cause can be ill-fitting athletic shoes. Or a sudden change in body temperature. A change in terrain that puts more strain on your muscles — from walking the flats to climbing up hills — can also bring on leg cramps.

So this is where your own brain has to kick in. What might be causing your cramps? Most causes have simple solutions you can implement yourself. In some cases, the problem is vascular and involves a breach in your circulation system — and for that, you have to see a doctor. Sorry.

TIPS FOR RELIEF AND PREVENTION. Self-care is the best care when it comes to your health and wellness, so if you suffer from cramps, consider the following:

MASSAGE. There's a good chance you can relieve your cramp by calmly and gently massaging and stretching the cramping muscle. This is hard to manage when you're writhing around in pain, so try a few deep, relaxing breaths at the first sign of trouble.

Let's say it's your calf that's cramping. At the same time you're massaging the stricken area, flex your foot, so your toes are pointing back toward your knees. (This contracts the muscle in front of your shin and relaxes your calf.)

WARM UP. Warming up your muscles before you work out and stretching after can help prevent cramping. Proper stretching relieves muscle tension, keeps blood flowing to flush away waste products and slows neural impulses. If you're plagued by night cramps, try some gentle stretching before you go to bed.

SLEEP WITHOUT POINTING. Don't go to sleep with your toes pointed. Naturally, this is tough to monitor when you're in Dreamland, but it helps if you can sleep on your side. Also, don't restrict your toes with tight blankets or sheets. That can bend your toes down and trigger cramps. Sleeping with socks on can help, too.

STAY HYDRATED. This is a biggie. Many of us go around dehydrated, and that can contribute to cramping. Drink, drink, drink enough water to keep your urine clear. Dark and yellow urine is a sign you're not drinking enough.

THINK POTASSIUM. A small can of tomato juice gives you a quick jolt of potassium, and so can bananas and oranges.

ENERGY EXPRESS-O! THE UPSIDE OF CRAMPS.

"Every difficulty in life presents us with an opportunity to turn inward and to invoke our own inner resources. The trials we endure can and should introduce us to our strengths." — Epictetus, born about A.D. 55.

Marilynn Preston — fitness expert, personal trainer and speaker on healthy lifestyle issues — is the creator of Energy Express, the longest-running syndicated fitness column in the country. She welcomes reader questions, which can be sent to MyEnergyExpress@aol.com. To find out more about Preston and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.

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