If, like me, you've ever taken yoga classes and waited fruitlessly to be infused with ancient wisdom, you'll love a documentary out on DVD today. "Enlighten Up!" traces the journey of Nick Rosen, a guinea pig handpicked by the documentary's maker, Kate Churchill, as he tries various styles of yoga and travels in the United States and India to explore its roots. The pair scores interviews with figures ranging from B. K. S. Iyengar, who created the popular eponymous style of yoga, to "Diamond" Dallas Page, a former pro wrestler who now teaches yoga to "regular guys."

The tension in the film comes from Churchill's Tracy Flick-esque determination (via her questioning of Rosen) to make him see the light when it comes to yoga's spiritual, transformative side, even as he remains skeptical. Rosen is a journalist with a pitch-perfect pedigree for this project: His father is a lawyer and his mother a shamanistic healer. While he appreciates yoga for what it contributes to his physical fitness, its deeper meaning is elusive. I won't ruin the end, but suffice it to say that while he isn't untouched by the experience, he doesn't achieve the result that Churchill probably wished for him at the outset of filming.

Alzheimer's disease is known for the knockout blow it delivers to memory and other cognitive functions. But this disease of the brain may also be linked to muscle weakness, according to a study published today in the Archives of Neurology. Among the 900 older adults in the study, those who were initially stronger had a smaller chance of getting Alzheimer's in the future. (The average follow-up time was 3.6 years.) Muscle strength was also tied to a lower risk of developing mild cognitive impairment, the precursor to Alzheimer's disease, the study found.

As tempting as it is to yell from the hilltops that hitting the gym prevents Alzheimer's, this study wasn't designed to tell if there's a causative effect, says Patricia Boyle, a neuropsychologist with the Rush Alzheimer's Disease Center in Chicago and an author of the study. It's looking like one degenerative process drives both conditions, and it shows up first as muscle weakness before manifesting itself as cognitive problems. That common danger may be damage to the mitochondria—the cells' energy factories—or central nervous system disorders like stroke, the study authors say. Or, the same accumulations of plaques and tangles in the brain that are characteristic of Alzheimer's disease may be responsible. "We know they cause cognitive problems, but there's increasing evidence that they cause motor dysfunction," says Boyle. That suggests that screening older folks for muscle strength may offer a way to identify who is most at risk of the disease, she says.

It's been a bad autumn for deaths during U.S. running races—at least six during half marathons and one during a marathon. Although the specific causes of death aren't known in all cases, heart ailments are at the top of the list of possible explanations whenever someone dies suddenly during an athletic event, be it a road race, triathlon, or a football or basketball game. As rare as these events are when compared with deaths from car accidents, homicide, or even the flu, doctors are debating whether lives could be saved by more carefully scrutinizing athletes before they compete. Sounds good, but is it possible?

First, let's understand what problems doctors are trying to ferret out, and in whom. When a middle-aged person experiences sudden cardiac death or a fatal heart attack during athletic exertion, he is more likely to have plain old heart disease (also called coronary artery disease) caused by a buildup of plaque inside the blood vessels leading to the heart, says Euan Ashley, an assistant professor of cardiology at the Stanford School of Medicine and director of the Stanford Hypertrophic Cardiomyopathy Center. But when a high school, college or younger elite athlete collapses and dies, he or she most likely had an undiagnosed inherited cardiovascular disease, most commonly hypertrophic cardiomyopathy, in which the heart muscle thickens and can throw off the rhythm of the heart. (Other electrical malfunctions in the heart are also a possibility.)

Why are these problems an issue during sporting events or strenuous exertion? While exercise can dramatically cut the chance of heart disease, during the minutes you actually are exercising, your risk of a heart attack or sudden death actually temporarily rises, says Ashley. The long-term benefits of exercise vastly outweigh any short-term risk, so there's no excuse for not exercising unless your doctor specifically orders it. (Even 2007 research on the body-stressing marathon suggests that it's riskier to drive the course than to run it.)

On Sunday, November 1, some 42,000 runners will share the experience of running the ING New York City Marathon. But marathon organizers are taking special measures to make sure they won’t also be sharing the flu—specifically, the H1N1 virus, aka swine flu.

For the first time, marathoners’ goody bags—customarily filled with things like minipacks of pain relievers and samples of energy bars—will include small hand sanitizer sprays printed with the logo of the New York Road Runners, the organization that puts on the race. The official marathon program also says hand sanitizer will be available at the prerace expo and the race's start.

Is a traffic light coming to U.S. food labels? It certainly sounds like a possibility. The Food and Drug Administration said today that it's concerned about the proliferation of front-of-package nutrition labeling programs like Smart Choices, which are supposed to offer quick and easy guidance to consumers on purchasing more healthful foods. Trouble is, as the FDA said in a letter to the food industry, the different programs have different criteria, which can be confusing for consumers. They may also be violating the law if they give false or misleading information or convey an overall impression of healthfulness even if the nutritional content shows otherwise. (Hello, Froot Loops, which FDA Commissioner Margaret Hamburg described but did not specifically name as a Smart Choices-approved cereal, even though it has more than 40 percent sugar. Smart Choices, meantime, said in a statement that it complies with all laws and regulations and looks forward to working with the FDA.)

The Institute of Medicine has new recommendations for the federal programs that provide breakfast and lunch in primary and secondary schools, and for the first time, it endorses calorie limits. The IOM report says lunches shouldn't be more than 650 calories in grades K through five, 700 for middle schoolers, and 850 for grades 9 through 12. Breakfasts, meantime, should range from 500 to 600 calories depending on the grade.

The report also advises that schools offer more—and more varied—fruits and vegetables, including one cup per day of fruit at breakfast and an additional cup for high schoolers at lunch. Juice should make up no more than half of the fruit provided. More veggies should also be offered, and at least a half cup should be from the "rainbow," meaning leafy greens or orange vegetables rather than starches, such as potatoes. If kids are buying food a la carte, they should be required to take at least one serving of fruits or veggies per meal. The IOM also said schools should move toward whole-grain products rather than the refined variety, and 1 percent or nonfat milk rather than whole or 2 percent.

How well do you move? It sounds like an easy question—or one that might be answered by your performance on the dance floor. But it's neither. Whether you can perform a deep squat or leg lift, for example, can indicate areas of the body that are tight or weak and show if you're compensating in a way that might be harmful even if you aren't consciously aware of it. That's the philosophy behind the Functional Movement Screen, a tool used to root out those weaknesses before they hamper your sports performance or become full-fledged injuries.

Gene Schafer, an athletic trainer, challenged—er, invited—me to take the screening test at the rehab and training facility he owns, ARC Athletics in New York. I was fairly confident I'd ace it. After all, this test doesn't aim to evaluate your athletic performance but "movement patterns that are key to normal function," according to the FMS website. If I run, swim, and strength-train several times a week, surely I've got those basic movement patterns down pat, I thought.

When faced with a sore knee or a back pain, the first inclination is to look to the bones and joints. And that's appropriate in some cases. But many times, the answer lies in how all of the elements of the musculoskeletal system work together, especially those often overlooked muscles, says sports chiropractor Rob DeStefano. By taking this more global perspective, you're more accurately able to treat (and prevent) nagging injuries and aches, according to Muscle Medicine (Fireside), a new book DeStefano wrote with orthopedic surgeon Bryan Kelly and health writer Joseph Hooper. It takes you on a tour of your body's trouble spots—including the lower back and the knee—and helps you tease out the roots of common problems and possibly even how to fix them yourself. I asked DeStefano about muscle medicine in a chat; here are some edited excerpts:

If you have pain in your back, knee, ankle, or other body part, whom should you turn to for help?
We're often taught to go to the top of the diagnostic chain, the orthopedist. But the truth is that most orthopedic surgeons, unless they [have some particular interest or specialty], don't want to see patients unless it's a surgical case. Otherwise, it's just evaluating and referring out. A good manual therapist who will refer out when it's necessary-whether a chiropractor, a physical therapist, or an internist who works with manual therapy—is a good port of entry.

Nutrition and diet associations have come under fire for their relationships with food companies; most recently, the American Society for Nutrition was criticized for its role in administering the controversial Smart Choices food labeling program. Today the American Academy of Family Physicians announced its own corporate partnership program, called the Consumer Alliance, and said that the Coca-Cola Co. will be its first partner.

Under the terms of the arrangement, Coke will provide a grant—which AAFP President-elect Lori Heim says is "in the strong six figures"—annually to the group, which will develop consumer education content on beverages and sweeteners for its consumer-oriented website, FamilyDoctor.org. The AAFP, emphasized Heim, "has total control over editorial materials," which for now is the extent of the arrangement. Coke won't be using an AAFP symbol in marketing its products, for example, though the company's financial assistance will be credited on the site.

The new season of The Biggest Loser means the popular TV show is once again a hot topic around the water cooler. Even as fans spend Wednesday morning rehashing the show, some in the fitness industry have recently criticized the show for its unrealistic depictions of weight loss. I recently caught up with Bob Harper, one of the show's trainers, to talk about what viewers should take away from the show—and what he thinks about carbs, colonics, and screaming trainers. Here are five take-aways from our chat:

• Nutrition is at least as important as exercise. People who begin a weight loss effort are often totally confused about the role of nutrition. Some think that if they work out, they can eat whatever they want. Not true! But Biggest Loser contestants often come in thinking the reverse, says Harper. "They think they'll work out a lot and won't eat at all," he says. Also not a good strategy. You need to hit the sweet spot: fueling your body enough with healthy foods to give you energy to get through the day (and your exercise routine), but not so much that you take in more than you're burning off.

[See what I wrote about diet and our 10-week workout routine.]