THE WOMAN who asked, a while back, about new sources for her favorite "Sore Muscle Soak" opened the floodgates, for me at least, into the world of hydrotherapy. Other readers' suggestions (see page 8) started me wondering about the known effects of baths, salts and other soaking ingredients. That led me to Dr. Douglas Lewis, a naturopathic doctor and chairman of the department of physical medicine at Bastyr University, where he teaches a class on hydrotherapy.

One key aspect of hydrotherapy, Lewis says, is hydrostatic pressure. Because water is more dense than air, it exerts more pressure against a body. Such hydrostatic pressure pushes fluid that has leaked out into the space around cells back into circulation. "That immersion can actually increase the blood volume, decreasing edema (swelling) in some areas, therefore reducing stiffness and pain."

Hydrostatic pressure increases as water deepens, making a hot tub more effective than an average bathtub.

Water temperature is another vital factor. "Both heat and cold slow down the rate at which nerve impulses react, which allows muscles to relax," Lewis says. That's why, in some circumstances, health professionals recommend either heat or ice, whichever we prefer.

For most new injuries, however, heat isn't advisable. "Heat by itself is pro-inflammatory: It causes blood vessels to dilate and become more circulatory," Lewis says. Folks with active inflammation shouldn't attempt heat treatments for the first 72 hours, to avoid increasing swelling. (I witnessed this firsthand once when a man with a newly twanged wrist put his whole hand in a bucket of warm water, only to have it swell up like an inflated glove. The warm water quickly was replaced with ice water — yow! — and the swelling subsided.)

Fitness news you can use Low-carb, or not low-carb? Some energy bars may not contain what's claimed on their labels. ConsumerLab.com of White Plains, N.Y., tested 30 bars and said their tests did not agree with the listed ingredients for 18 of them. Fifteen bars had more carbohydrates than stated; apparently some manufacturers exclude glycerin, a sweetener and moisture additive, from carbohydrate totals, though the FDA requires that it be counted as such, says Dr. Tod Cooperman, president of ConsumerLab. For more details, go to www.fatwatch.net. Altruist Fitness If you're organizing a fitness event that also benefits others or want to take part in one, go to www.seattletimes.com/onfitness and click on the links to add an event or ongoing training program or see our Altruist Fitness calendar. Getting soaked Though no one so far has come up with a new source for the reader in search of the brand of "Sore Muscle Soak" sold at Amphora, a local chain now out of business, several folks shared their favorites: • www.hgtv.com/HGTV/project/ 0,1158,FOLI_project_21847,FF.html (a recipe for a "Men's Sore Muscle Soak"). • store.yahoo.com/bath-factory/. • Queen Helene Batherapy, available at Puget Consumers Coop, among other places. • "I recommend any bath salt with Dead Sea Salt in it," one reader wrote, "or just straight Epsom salts." • Or search for "Sore Muscle Soak" at www.google.com; a recent foray found 122 hits.

For older injuries or stiffness, however, a warm bath can relax muscles and improve blood flow. "When you improve blood flow, you improve everything," Lewis says.

"You do have to be careful with any hot water," he adds. For home baths, he recommends keeping the temperature around 104 degrees. Even then, blood vessels can dilate so much that when standing up afterward, you can get light-headed or even pass out from lack of blood flow to the brain. People with a tendency toward arrhythmia or tachycardia should avoid hot baths, although baths have been used to help reduce high blood pressure. Women who are or might be pregnant are advised to not bathe in water over 102 degrees for not more than 10 minutes.

Lewis is an enthusiastic proponent of contrast baths. Some, at least.

"There are some physiotherapy and sports facilities that use immersion in cold water. I've even seen immersion in ice. I'm not sure I approve.

"Short immersions on the other hand, the old idea of the Polar Bear Club, can be quite good: stimulating to the immune system, invigorating, also benefiting alertness. I always finish my hot shower with an absolutely cold rinse, for about two minutes. This time of year I hate it — but I love it."

For many ailments, Lewis recommends three minutes of hot (heating pad, gel pack or warm towel) followed by only 30 seconds of cold, repeated three to five times or up to half an hour. "You're not trying to chill anything — unless you're trying to chill tissues with an active inflammation — or to deaden nerve endings, you're looking for a reflex action."

Lewis also likes the use of jets in baths; moving water distributes the temperature and thus warms the body more evenly , and also massages tissue, improving circulation.

"Water is unbelievably powerful and we just take it for granted," he says.

As for adding ingredients to baths, "I tend to be fairly conservative in my view. The only thing I have found to be known to be effective is Epsom salts," or magnesium sulfate, which has anti-inflammatory effects. Though many people have used Epsom salts, they may be surprised to hear the amount Lewis has found people need to notice relief: 2 pounds for an average bath of 35 to 40 gallons of water. That's half of one of those milk-carton-size jugs.

What about aromatherapy? There's clearly not enough room to delve into its effects here. I've recently received an intriguing new book, "How Aromatherapy Works" by Michael Alexander ($85). I think I'll take that and a jug of Epsom salts — and go do some research.

Molly Martin is assistant editor of Pacific Northwest magazine. Paul Schmid is a Seattle Times news artist.

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