Friday, February 24, 2012

How Exercise Fuels the Brain



February 22, 2012, 12:01 am
How Exercise Fuels the Brain

By GRETCHEN REYNOLDS
New York Times

Does exercise keep your brain running?

Moving the body demands a lot from the brain. Exercise activates countless neurons, which generate, receive and interpret repeated, rapid-fire messages from the nervous system, coordinating muscle contractions, vision, balance, organ function and all of the complex interactions of bodily systems that allow you to take one step, then another.
This increase in brain activity naturally increases the brain’s need for nutrients, but until recently, scientists hadn’t fully understood how neurons fuel themselves during exercise. Now a series of animal studies from Japan suggest that the exercising brain has unique methods of keeping itself fueled. What’s more, the finely honed energy balance that occurs in the brain appears to have implications not only for how well the brain functions during exercise, but also for how well our thinking and memory work the rest of the time.
For many years, scientists had believed that the brain, which is a very hungry organ, subsisted only on glucose, or blood sugar, which it absorbed from the passing bloodstream. But about 10 years ago, some neuroscientists found that specialized cells in the brain, known as astrocytes, that act as support cells for neurons actually contained small stores of glycogen, or stored carbohydrates. And glycogen, as it turns out, is critical for the health of cells throughout the brain.
In petri dishes, when neurons, which do not have energy stores of their own, are starved of blood sugar, their neighboring astrocytes undergo a complex physiological process that results in those cells’ stores of glycogen being broken down into a form easily burned by neurons. This substance is released into the space between the cells and the neurons swallow it, maintaining their energy levels.
But while scientists knew that the brain had and could access these energy stores, they had been unable to study when the brain’s stored energy was being used in actual live conditions, outside of petri dishes, because brain glycogen is metabolized or burned away very rapidly after death; it’s gone before it can be measured.
That’s where the Japanese researchers came in. They had developed a new method of using high-powered microwave irradiation to instantly freeze glycogen levels at death, so that the scientists could accurately assess just how much brain glycogen remained in the astrocytes or had recently been used.
In the first of their new experiments,
published last year in The Journal of Physiology, scientists at the Laboratory of Biochemistry and Neuroscience at the University of Tsukuba gathered two groups of adult male rats and had one group start a treadmill running program, while the other group sat for the same period of time each day on unmoving treadmills. The researchers’ aim was to determine how much the level of brain glycogen changed during and after exercise.
Using their glycogen detection method, they discovered that prolonged exercise significantly lowered the brain’s stores of energy, and that the losses were especially noticeable in certain areas of the brain, like the frontal cortex and the hippocampus, that are involved in thinking and memory, as well as in the mechanics of moving.
The findings of their subsequent follow-up experiment, however, were even more intriguing and consequential. In that study, which
appears in this month’s issue of The Journal of Physiology, the researchers studied animals after a single bout of exercise and also after four weeks of regular, moderate-intensity running.
After the single session on the treadmill, the animals were allowed to rest and feed, and then their brain glycogen levels were studied. The food, it appeared, had gone directly to their heads; their brain levels of glycogen not only had been restored to what they had been before the workout, but had soared past that point, increasing by as much as a 60 percent in the frontal cortex and hippocampus and slightly less in other parts of the brain. The astrocytes had “overcompensated,” resulting in a kind of brain carbo-loading.
The levels, however, had dropped back to normal within about 24 hours.
That was not the case, though, if the animals continued to exercise. In those rats that ran for four weeks, the “supercompensation” became the new normal, with their baseline levels of glycogen showing substantial increases compared with the sedentary animals. The increases were especially notable in, again, those portions of the brain critical to learning and memory formation — the cortex and the hippocampus.
Which is why the findings are potentially so meaningful – and not just for rats.
While a brain with more fuel reserves is potentially a brain that can sustain and direct movement longer, it also “may be a key mechanism underlying exercise-enhanced cognitive function,” says Hideaki Soya, a professor of exercise biochemistry at the University of Tsukuba and senior author of the studies, since supercompensation occurs most strikingly in the parts of the brain that allow us better to think and to remember. As a result, Dr. Soya says, “it is tempting to suggest that increased storage and utility of brain glycogen in the cortex and hippocampus might be involved in the development” of a better, sharper brain.
Given the limits of current technologies, brain glycogen metabolism cannot be studied in people. But even so, the studies’ findings make D.I.Y. brain-fuel supercompensation efforts seem like an attractive possibility. And, according to unpublished data from Dr. Soya’s lab, the process may even be easy.
He and his colleagues have found that “glycogen supercompensation in some brain loci” is “enhanced in rats receiving carbohydrates immediately after exhaustive exercise.” So for people, that might mean that after a run or other exercise that is prolonged or strenuous enough to leave you tired, a bottle of chocolate milk or a banana might be just the thing your brain is needing.

Wednesday, February 1, 2012

91-year-old yoga teacher asks, 'Why should I quit?'




Bernice Bates, who at 91 is officially the world's oldest yoga instructor, teaches in front of a yoga class, as she's been doing since 1960.
By Lisa Flam TODAY.com contributor

Before her feet even touch the floor each morning, Bernice Bates is practicing yoga. While still in bed, she does her vinyasa, a series of seven or eight postures that gets her blood flowing. She puts her arms above her head for a stretch and a yawn, pulls her knees to her chest, “walks” the ceiling with her feet and stretches her shoulders and hands. “By the time you’re through — it takes about eight minutes — you’re ready to walk, instead of slopping around,” Bates said.
“You can walk to the kitchen, to the bathroom, whatever your procedure is and not sort of drag yourself and say, ‘I don’t want to do this. I don’t want to do that.’ You’re ready to go.” Yoga has been a way of life for Bates, 91, for more than half her life: She began practicing and teaching hatha yoga in about 1960. In a fitting tribute to her decades of helping others learn her passion, she recently won the distinction of the Guinness World Record holder of oldest yoga instructor. Guinness says she is the oldest yoga instructor to complete the complex verification process.
It’s an honor, the humble yogi feels, that isn’t hers alone. “I don’t have this reward by myself,” she said. “I share it with all the students I’ve taught through the years.” Bates credits yoga with keeping her flexible, fit and healthy. “I think yoga is the best exercise there is,” says Bates, who has always been active and still swims laps. “I’ve never had anything I had to go to the doctor for, except checkups,” says Bates, who tips the scale at 105 pounds and is about 5 foot, 2 inches tall. “That should say something.” Yoga involves the whole body — muscles, ligaments, organs, she says, and gives you energy without exhausting your body. “You’re not just standing on a treadmill and going, going, going and you get off and can hardly walk,” she says. “Yoga itself means yoke, that’s to join. We join our mind, our body and our spirit in everything we do.
“Yoga gives you flexibility like you’ve never had before, and it makes you healthy because you’re working on the whole body, inside and out,” she said. Bates, who has instructed children and adults, now leads a weekly one-hour class nine months a year at the Mainlands Retirement Community Center in Pinellas Park, Fla., where she lives. Most students are in their 60s and 70s, though she has two fellow nonagenarians and several students in their 80s. She leads her students through 10 to 12 poses and ends with relaxation. “We go over our whole body and tense each part, then we relax,” she said. Bernie, as her students call her, provides handouts so they can practice at home. And when they can finally do something they once couldn’t, like touch their toes, “it makes me feel like it’s worthwhile,” she says. Some students have been with her for the 15 years she’s taught at Mainlands, and they all adapt to the class as they grow on in years. Some participate while sitting on chairs. “It’s for everybody,” she says enthusiastically about yoga.
“There’s thousands of postures. You can pick and choose. You do what you can. “It’s non-competitive, which is the best thing about it,” she said. Bates is a widow of eight years and a mother of three, grandmother of seven and great-grandmother of three. Yoga has enhanced her full life. “It just encouraged me to keep going and it made my life better,” Bates said. “You’re active, so you don’t gain 100 pounds.” She lives alone and tends to her flower garden, does the housework and likes to rearrange her furniture, so she’s always moving it around.
“If I didn’t keep myself in shape, I wouldn’t be able to do it at 91,” she says. Her decades of physical activity have only added to her strong Methodist faith. “Anything you do for your body that’s good is going to enhance improvement in your religion too,” she said. “You get more faith that way.” With students seeking her guidance each week, the world’s oldest yoga teacher is going to keep on teaching.
“Why should I quit? she asks. “As long as I can do it and be a help to someone else, I’ll just stay as long as I can. I get a joy out of seeing someone learning.”