Dear Doctor: Our family visits a lake in the mountains every summer where the water almost never gets above 60 degrees. I dislike swimming in cold water, but my husband and dad insist that it's good for you. It won't get me into the water, but I just want to know -- are they right?

Dear Reader: Some people find cold-water swimming invigorating. Others, like the groups who take part in those midwinter "polar bear plunges," love an even icier challenge. And then there are those of us who prefer not to suffer for our swim.

Swimming in and of itself is great exercise. Your heart, lungs and muscles all get a workout. The buoyancy of the water is kind to weight-bearing joints, and the concentration, isolation and repetition of swimming laps can be meditative. And while there are plenty of theories about how and why spending time in cold water is good for you -- it sure does feel fantastic once you get out -- when it comes to scientific evidence, things get a bit trickier.

Research into cold-water immersion tends to focus on its use as therapy for sports injuries. Some studies with individuals who do open-water ocean swimming cite a lower rate of respiratory illness, but that data is anecdotal. And while several studies have found an increase in white blood cells in individuals who take daily cold showers, whether the resulting boost in immune response translates into long-term better health remains an open question.

What's more apparent are the potential dangers of swimming in cold water. Water conducts heat far more efficiently than air. By some estimates, you lose heat 25 times more quickly in water than in air. That's why the body responds so differently to a walk in 60-degree weather and a swim in water at that same temperature. It's also why, when you get into water that's 60 degrees or colder, it causes a phenomenon known as "cold shock."

In cold shock, the body releases adrenaline and stress hormones, which can make you either feel exhilarated or panicky. In response to the sudden cold, you lose control of your breath. Your lungs contract and you gasp and breathe irregularly, a response that can last for up to a minute. To protect the vital organs, blood vessels contract, which raises blood pressure. As the body redirects blood flow away from the periphery and to your core, coordination can become impaired.

Because of this, experienced cold-water swimmers warn against jumping into icy water. Instead, they recommend that you dash water on your face, chest and shoulders to "warn" your nervous system of what's coming. Then wade in, steadily but slowly, until you're fully submerged. Monitor your breathing and heartbeat and, if all is well, off you go.

It's understandable that your dad and husband would want to make swimming an all-family affair. But whether to brave the chilly lake is a matter of personal preference.

If you -- or they -- have high blood pressure or any heart issues, don't do it. And if you are going to go the cold-water route (for just a few minutes or so the body will acclimate), have fun.

Just don't stay out too long. And never swim alone.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: Because of the potential risks of proton pump inhibitors, should I have an H. pylori breath or stool test to make sure I have this bacterium before committing to long-term treatment with a PPI?

Dear Reader: That's an excellent question, and it reflects our increasing knowledge about both the bacterium and PPIs. First identified in 1982, Helicobacter pylori is a bacterium that causes chronic inflammation of the stomach lining and stomach, as well as duodenal ulcers; it can also lead to gastric cancer and a slow-growing type of cancer known as MALT lymphoma. In fact, H. pylori is the most common chronic bacterial infection in humans. As for PPIs, they can cause deficiencies in some nutrients and increase the risk of infection with the bacterium C. difficile.

Because these PPIs (Nexium, Prilosec, Prevacid, Aciphex, Protonix, Dexilant) decrease the acidity in the stomach, allowing for healing of inflamed tissues, they're used to treat inflammation in the stomach; ulcers of the stomach or the duodenum; and acid reflux.

Whether you should take PPIs long-term depends on your condition. In most cases for which the medication is prescribed long-term, you would have an endoscopy to visualize the esophagus, stomach and the duodenum (first portion of the small intestine). If the endoscopy found a stomach or duodenal ulcer, your gastroenterologist would have tested for H. pylori with a rapid urease test or with a biopsy test. So if you had an endoscopy that found an ulcer, you likely already have your answer.

If you didn't have an endoscopy and have been diagnosed with gastritis, then I would recommend checking for H. pylori. If you're infected, you could be treated with antibiotics instead of a long-term PPI. The breath test for H. pylori evaluates the bacterial infection's ability to break down urea, a chemical compound excreted in urine, and produce carbon dioxide. This is a very good test with an 88 to 95 percent sensitivity in picking up the organism, but the sensitivity decreases substantially if you are already taking a PPI.

One study in those taking the PPI Prevacid found the sensitivity of the urea breath test decreased by 33 percent. The stool test for H. pylori has a sensitivity of 94 percent in picking up the organism. It is also more cost-effective than the breath test. But again, if you are already taking a PPI or even Pepto-Bismol, the sensitivity significantly decreases.

If you're considering taking a PPI long-term for acid reflux (heartburn), there has been no proof that treating an H. pylori infection would improve the acid reflux unless you had an ulcer in the duodenum. Again, this is something that would be seen on endoscopy. Regarding acid reflux, you should first look at stopping cigarette smoking, alcohol, caffeine and chocolate before considering long-term use of a PPI.

In summary, if your doctor diagnoses you with gastritis, an H. pylori stool test would be of benefit. If your doctor suspects an ulcer, then I would recommend getting an endoscopy, during which you would be tested for H. pylori.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: My brother, who is 65, was diagnosed with inclusion body myositis about five years ago, and the muscles in his arms, legs and hands are deteriorating rapidly. He's someone who loves life, so this is very hard to watch. His physician says there's no cure. What can you tell me about the disease? Is it being studied anywhere?

Dear Reader: We're very sorry to hear about your brother's struggles. We know from experience how difficult it is to see a loved one be unwell and be unable to help.

Inclusion body myositis, also known as IBM, is a progressive degenerative muscle disease, sometimes also referred to as a muscle wasting disease. The word "progressive" means that once the disease process begins, it will continue to advance.

As you already learned, there is no treatment or cure for IBM at this time. However, advances in the areas of precision medicine and immunotherapy will hopefully lead to new methods to manage, if not cure, the disease.

Let's start with what is known about inclusion body myositis.

There are two types of IBM. One, which is extremely rare, is inherited. It results from a genetic defect that is passed along from a parent's DNA. The other form, which has no genetic link and is slightly more common, is known as sporadic. Sporadic IBM, also referred to as s-IBM, is seen most often in people 50 years and older. It is more common in men than in women.

Although the exact cause of s-IBM is not yet known, it is believed to be the result of a malfunction in the immune system. In autoimmune disorders, the body's defense mechanisms mistakenly attack healthy tissue. In s-IBM, certain white blood cells attack muscle tissue and cause ongoing inflammation. There is also a second avenue of attack, which causes the muscle fibers to degenerate.

For many people, the first symptom of s-IBM is an increasing tendency to stumble, trip or fall. This is due to damage to the quadriceps, the large muscles of the thighs. The muscles of the wrists and fingers are also often affected.

Treatment at this time focuses on the use of corticosteroids to address inflammation, or drugs to suppress the immune system. However, several types of new drugs are now being studied in ongoing clinical trials. These are focused both on the inflammatory response in s-IBM, as well as stopping the progression of muscle destruction. Although some participants in the clinical trials have shown modest or even good response to the drugs, the benefits thus far have proven to be short-term.

If you are interested in learning more about clinical trials for s-IBM, visit clinicaltrials.gov, a government website that lists studies receiving federal funding, as well as some that are funded by private industry.

For information about clinical trials at the National Institutes of Health Clinical Center, located in Bethesda, Maryland, call the NIH Patient Recruitment Office at (800) 411-1222. Or you can email prpl@mail.cc.nih.gov.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)