How Sugar Affects the Body in Motion By GRETCHEN REYNOLDS

Sugar is getting a bad reputation. A cover article in The New York Times Magazine several weeks ago persuasively reported that our national overindulgence in fructose and other sugars is driving the epidemics of obesity, diabetes and other illnesses. But that much-discussed article, by the writer Gary Taubes, focused on how sugars like fructose affect the body in general. It had little opportunity to examine the related issue of how sugar affects the body in motion. Do sweeteners like fructose — the sweetest of the simple sugars, found abundantly in fruits and honey — have the same effect on active people as on the slothful?
A cluster of new studies suggests that people who regularly work out don’t need to worry unduly about consuming fructose or other sugars. In certain circumstances, they may even find the sweet stuff beneficial.
The unique role that the various sugars play in exercise is well illustrated by a new study published in March in Medicine & Science in Sports & Exercise. It involved a group of highly trained cyclists and their livers. For the experiment, Swiss and British researchers directed the cyclists, all men, to ride to exhaustion on several different occasions. After each ride, they swallowed drinks sweetened with fructose or glucose, another simple sugar often identified as dextrose on ingredient labels. (Some also drank a milk-sugar sweetener.)
The liver is often overlooked when we consider organs integral to exercise, but it is an important reservoir of glycogen, the body’s stored form of glucose. All sugars, including sucrose, or table sugar, and high-fructose corn syrup, which usually consists of almost equal portions of glucose and fructose, are converted into glucose, and stored as glycogen, in the body. Strenuous exercise diminishes or exhausts this liver glycogen, and until those stores are replenished, the body isn’t fully ready for another exercise bout.
In this study, the scientists used magnetic resonance imaging to measure the size of each rider’s liver, before and after the rides. All of the cyclists lost liver volume during their workouts, a sign their livers were depleted of glycogen. But those who afterward drank fructose replaced the lost volume rapidly, showing a 9 percent gain in volume after six-and-a-half hours versus a 2 percent gain among the riders drinking glucose-sweetened drinks. Over all, the researchers concluded, fructose-sweetened drinks were twice as effective as the glucose-sweetened drinks in stimulating the liver to recover.
This finding concurs with a large body of earlier research suggesting that fructose is particularly useful for avid athletes. During long, hard workouts, they can burn through almost all of their stored glycogen and fade. But drink or eat something sugary, and the muscles can keep working.
Interestingly, absorption seems to be best if the sweetener contains both glucose and fructose. A 2008 study of cyclists found that if they downed a sports drink sweetened with glucose during a two-hour bout of moderate pedaling, they rode faster during a subsequent time trial than riders who had drunk only water. But if the sports drink contained both glucose and fructose (in a two-to-one ratio), the riders were 8 percent faster in the time trial than those drinking glucose-sweetened fluids alone. (Most bottled sports drinks on the American market are sweetened with high-fructose corn syrup, so contain glucose and fructose in a closer to one-to-one ratio.)
Does this suggest that those of us who regularly but moderately work out might want to consider sugar loading? Alas, the answer is no. Large amounts of sweetened sports drinks, gels and bars are recommended only for the “serious athlete” who works out for more than two hours at a time, Asker Jeukendrup, director of the human performance lab at the University of Birmingham in England and co-author of both studies, said in an e-mail. “If someone goes for a 30-minute walk, the duration and intensity will be too short” for sugar to make a difference in terms of performance, he said.
But that half-hour stroll could affect how your body responds to sugar, other new science suggests. You may not need Skittles to fuel the walk, but the walk will affect how your body metabolizes the candy, if you do indulge. Activity can “significantly reduce the health risks associated with fructose and other forms of sugar,” said Dr. Richard J. Johnson, a professor of medicine at the University of Colorado Anschutz Medical Campus in Denver, who has long studied fructose metabolism and was an author of a review article last year about fructose and exercise.
Consider, again, the liver. In sedentary people, ingesting large amounts of fructose, which is mostly metabolized in the liver, has been associated with the development of a disorder known as fatty liver. That condition can reduce the body’s ability to respond to insulin, the hormone that helps to control blood sugar. A person with a fatty liver often develops resistance to insulin, becomes less able to control levels of glucose in the blood, and drifts almost inexorably toward Type 2 diabetes.
But exercise can derail this process. A review of recent studies, published in December, concluded that beginning an exercise program could significantly lessen the amount of fat in someone’s liver, even if that person didn’t lose weight during the program.
Moderate exercise — about 30 minutes a day five times a week — also aids in the control of blood sugar levels if a person has developed Type 2 diabetes, according to a comprehensive review published this week in The Journal of the American Medical Association.
Over all, Dr. Johnson said, the “current science suggests that exercise exerts a positive physiological influence” on some of the same metabolic pathways that sugar harms. “Exercise may make you resistant to the undesirable effects of sugar,” he said.
Not that any of us should live on sweets. “Sugar is not all bad,” Dr. Johnson concluded, “but it’s hardly nutritionally good, either.” The best sweet option, he added, is fruit, which comes prepackaged with a small but satiating dose of all-natural fructose.

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How Sports May Focus the Brain by Gretchen Reynolds

Who can cross a busy road better, a varsity wrestler or a psychology major? That question, which seems to beg for a punch line, actually provided the motivation for an unusual and rather beguiling new experiment in which student athletes were pitted against regular collegians in a test of traffic-dodging skill. The results were revelatory.
For the study, published last week in The Journal of the American College of Sports Medicine, researchers at the Beckman Institute for Advanced Science and Technology at the University of Illinois at Urbana-Champaign recruited 36 male and female students, ages 18 to 22. Half were varsity athletes at the university, a Division I school, and they represented a wide variety of sports, including cross-country running, baseball, swimming, tennis, wrestling, soccer and gymnastics. Some possessed notable endurance; others, strength and power; and still others, precision and grace.
The rest of the volunteers were healthy young collegians but not athletes, from a variety of academic departments.
All showed up at various times to a specially appointed lab, where a manual treadmill was situated amid three 10-foot-square video screens. One screen stood in front of the treadmill, with the others at either side. Donning goggles that gave the video images on the screens depth and verisimilitude, the students were soon immersed in a busy virtual cityscape.
When the immersive video began, the students found themselves plopped into an alley between buildings. From there, they were instructed to walk toward a busy street and, once they’d arrived, gauge oncoming traffic. The virtual cars whizzed by in both directions at daunting speeds, between 40 and 55 miles per hour.
When it felt safe, the students were to cross the road. They were told to walk, not run, but had a limit of 30 seconds from the time they left the alley. In some attempts, they had no distractions. In others, they listened to music through headphones or, emulating a common campus practice, chatted on a cellphone with a friend. Each volunteer attempted 96 crossings.
Success varied. “Over all, there was an 85 percent completion rate,” in which students made it to the other side of the road without incident, said Laura Chaddock, a graduate student at the university and lead author of the study. Failure meant impact — thankfully virtual.
The student athletes completed more successful crossings than the nonathletes, by a significant margin, a result that might be expected of those in peak physical condition. But what was surprising — and thought-provoking — was that their success was not a result of their being quicker or more athletic. They walked no faster than the other students. They didn’t dash or weave gracefully between cars. What they did do was glance along the street a few more times than the nonathletes, each time gathering slightly more data and processing it more speedily and accurately than the other students.
“They didn’t move faster,” said Art Kramer, the director of the Beckman Institute and a leader in the study of exercise and cognition, who oversaw the research. “But it looks like they thought faster.”
René Marois, the director of the Human Information Processing Laboratory at Vanderbilt University, who was not involved with the experiment, said, “This is a very interesting study.” The fact that the athletes displayed no outsize physical coordination during the crossings “was surprising,” he wrote in an e-mail. Upon reflection, he added that the finding did have a certain intuitive logic. “To the extent that athletes, in their sport, must routinely make split-second decisions in often very complex environments (e.g., whether to pass or kick the incoming soccer ball), it would make sense to me that they would have superior skill sets in processing the fast-paced information to successfully cross the street.”
Interestingly, though, until this study, no experiment had looked at whether being adept at sports would translate into success at a real-world everyday task like crossing the street. Most studies have more narrowly examined whether and why expert athletes are good at athletic things. A study published last month by researchers in China, for instance, found that professional badminton players, when shown video clips of a match, could predict with uncanny accuracy where the shuttlecock would land. While watching the videos, they also displayed considerably more electrical activity in brain areas associated with attention and memory than recreational players did. Playing elite badminton had made them better able to anticipate what would happen during badminton play.
Would the badminton pros also be capable of navigating crowded city streets better than the amateurs? The new Beckman Institute study would suggest yes — and quite possibly because of similar brain responses. Although the Illinois researchers did not directly measure electrical activity in the volunteers’ brains, it seems likely, Ms. Chaddock says, that the constant multitasking and information processing demanded by athletics increases both the capacity of the athletes’ mental information processing systems and their speed.
Of course, it’s also possible that sports didn’t make the athletes better at information processing. Instead, they may have been blessed with naturally fine processing abilities and, as a result, became accomplished athletes. “I’d guess,” Dr. Kramer said, “that to some degree it’s both.” But, he added, the athletes handled the crossings better than the nonathletes, regardless of whether their sport required exquisite timing and tactical thinking — which strongly suggests, he said, that physical training does reshape the brain.
The researchers hope at some point to study that issue in more depth, but even now, the takeaway seems clear. Practicing a sport, whether it’s running, swimming, tennis or perfecting a back flip, may sharpen your concentration and increase your ability to dodge through a busy intersection without incident.
One caveat, though: keep cellphones pocketed. Listening to music didn’t increase the number of accidents, but chatting on a phone did, even for athletes. No amount of sports training, Ms. Chaddock said, seems likely to make walking and talking in traffic a wise move.

Brain Calisthenics for Abstract Ideas By BENEDICT CAREY Published: June 6, 2011

 For about a month now, Wynn, 17, has been practicing at home using an unusual online program that prompts him to match graphs to equations, dozens upon dozens of them, and fast, often before he has time to work out the correct answer. An equation appears on the screen, and below it three graphs (or vice versa, a graph with three equations). He clicks on one and the screen flashes to tell him whether he’s right or wrong and jumps to the next problem.
“I’m much better at it,” he said, in a phone interview from his school, New Roads in Santa Monica, Calif. “In the beginning it was difficult, having to work so quickly; but you sort of get used to it, and in the end it’s more intuitive. It becomes more effortless.”
For years school curriculums have emphasized top-down instruction, especially for topics like math and science. Learn the rules first — the theorems, the order of operations, Newton’s laws — then make a run at the problem list at the end of the chapter. Yet recent research has found that true experts have something at least as valuable as a mastery of the rules: gut instinct, an instantaneous grasp of the type of problem they’re up against. Like the ballplayer who can “read” pitches early, or the chess master who “sees” the best move, they’ve developed a great eye.
Now, a small group of cognitive scientists is arguing that schools and students could take far more advantage of this same bottom-up ability, called perceptual learning. The brain is a pattern-recognition machine, after all, and when focused properly, it can quickly deepen a person’s grasp of a principle, new studies suggest. Better yet, perceptual knowledge builds automatically: There’s no reason someone with a good eye for fashion or wordplay cannot develop an intuition for classifying rocks or mammals or algebraic equations, given a little interest or motivation.
“When facing problems in real-life situations, the first question is always, ‘What am I looking at? What kind of problem is this?’ ” said Philip J. Kellman, a psychologist at the University of California, Los Angeles. “Any theory of how we learn presupposes perceptual knowledge — that we know which facts are relevant, that we know what to look for.”
The challenge for education, Dr. Kellman added, “is what do we need to do to make this happen efficiently?”
Scientists have long known that the brain registers subtle patterns subconsciously, well before a person knows he or she is learning. In a landmark 1997 experiment, researchers at the University of Iowa found that people playing a simple gambling game with decks of cards reported “liking” some decks better than others long before they realized that those decks had cards that caused greater losses.. Some participants picked up the differences among decks after just 10 cards.
Experts develop such sensitive perceptual radar the old-fashioned way, of course, through years of study and practice. Yet there is growing evidence that a certain kind of training — visual, fast-paced, often focused on classifying problems rather then solving them — can build intuition quickly. In one recent experiment, for example, researchers found that people were better able to distinguish the painting styles of 12 unfamiliar artists after viewing mixed collections of works from all 12 than after viewing a dozen works from one artist, then moving on to the next painter. The participants’ brains began to pick up on differences before they could fully articulate them.
“Once the brain has a goal in mind, it tunes the perceptual system to search the environment” for relevant clues, said Steven Sloman, a cognitive scientist at Brown University. In time the eyes, ears and nose learn to isolate those signs and dismiss irrelevant information, in turn sharpening thinking.
Good teachers at all levels already have their own techniques to speed up this process — multiplication flash cards, tips to break down word problems, heuristic rhymes — but scientists are working to tune students’ eyes more systematically and to build understanding of very abstract concepts.