Body of Evidence

The research is in, and the conclusions are clear: Many of our old athletic habits are bad for us, and much of what we think we know about sports science is wrong. Here, a guide to rediscovering your body's pitfalls and potential.

BRAIN
It's well known that brains benefit from workouts. Exercise jump-starts the creation of new brain cells and increases cognitive ability. But what kind of exercise is best? In one of the first studies of its kind, published in April, students at the University of Illinois performed significantly better on memory and judgment tests immediately after 30 minutes of intense aerobic exercise than after either weight training or, for that matter, sitting quietly.

EYES
If your sport of choice often exposes your eyes to bright sunlight, haveanother espresso. In an experiment last year, scientists bombarded mouse eyeballs with UV light. The lenses predictably clouded with cataracts. But when they bathed the eyeballs with caffeine before exposing them to sunlight, the UV damage was almost completely eliminated. Researchers speculate that xanthinoid compounds found in coffee and tea protect against sun damage in the eyes.

MIND
Turns out distraction is a performance enhancer. In a study by the University of Chicago, athletes told to concentrate on a word unrelated to their sport performed well under pressure. Asked to think, instead, through the steps of what they were about to do, they flubbed up almost every time. Intellectualizing may overtax the mind's limited working memory.

TEETH
Sports drinks—good for hydration, not so much for teeth. Earlier this year, New York University dentists found that cows' teeth soaked for 90 minutes in sports drinks containing high levels of citric acid (as most sports drinks do) softened and started to dissolve. Often imbibe? Ask your dentist if you need acid-neutralizing toothpaste.

ROTATOR CUFFS
A first-of-its-kind study published in May by researchers at the University of Utah School of Medicine uncovered a strong familial link to rotator-cuff tears. Even one family member with the injury increases your risk. The researchers are now trying to pinpoint exactly which genes influence the joint's fragility. In the meantime, kayakers and rowers, whose shoulders are under especially high stress, might want to check their family history. If you've got weakrotator cuffs in your genes, ask an athletic trainer to set up a prophylactic regimen of shoulder-strengthening exercises.

STOMACH
Hunger might not always come from an empty tank. In a recent experiment out of Britain, groups of fit cyclists were given different drinks during an intense time trial. Some contained sugar, others maltodextrin (a tasteless carbohydrate), and others just plain water (all were flavored similarly). The cyclists were asked to swish the liquids in their mouths and spit them out. Those who swished the sugar- or carb-filled waters cycled much faster than those who received the plain water. Researchers speculate that fatigue may depend, in part, on signals taste buds send to the brain that say, "Energy is available," whether any calories reach the stomach or not. Fatigue, in other words, may be partly in the mind.

HIPS
Pain-racked knees? The culprit may be weak hips. Puny hip muscles have popped up in recent studies as the underlying cause of "runner's knee," or patello­femoral pain syndrome, the most common overuse injury in runners. Weak hips also have been linked to iliotibial-band tightness, another frequent knee complaint in runners and cyclists. The solution, according to a study published in Clinical Biomechanics, may be weight training target=ing the hips. After six weeks of hip work, the runners in the study had biomechanically improved strides and less knee wiggle, which should "reduce injury risk."

KNEES
The good news: Distance running might actually be good for your knees. In research published last year, runners in their sixties and seventies had less knee arthritis than age-matched sedentary types. The bad news: Past knee injuries, especially ligament tears, can forever alter gaitmechanics. A study published by Stanford in February concluded that even slight changes cause portions of the joint to rub together, wearing away cartilage, leading to arthritis, and leaving you hobbled.

COLLARBONES
Easy to crack, as Lance Armstrong recently learned. Doctors once let many broken clavicles heal without surgery. But recent studies have found lingering shoulder disabilities in some of those whose bones weren't pinned. If your clavicle fractures, consult an experienced sports orthopedist—surgery may get you back to pre-injury peak performance faster.

GUT
Distance runners and competitive cyclists, in particular, are prone to colds and upper-respiratory infections. Scientists are only beginning to untangle the complex interactions of exercise and immunity, but recent studies suggest that introducing goodgut bugs may right some of the damage.According to a 2008 British Journal of Sports Medicine report, elite distance runners who ingested large doses of the probiotic Lactobacillus fermentum fell sick only half as often as a group taking a placebo.

LOWER BACK
Creaky backs afflict even the fittest; maybe especially the fittest. One recent study found that Australian Olympians have "significantly more severe" spinal-disk degeneration than non-athletes of the same age, while another concluded that 65 percent of cross-country skiers complained of back pain. A comprehensive review of back pain published in February's Spine journal reported that stress management, shoe inserts, lumbar-support braces, and weight lifting weren't that effective. The only verifiable remedy? Carefully supervised back-exercise programs.

FINGERS
Long ring finger? Lucky you. In March, researchers at England's Southampton University reported that boys whose ring fingers stuck out past their index fingers were much faster in 50-meter sprints than the rest of the field. Other studies show a correlation between elongated ring fingers and distance-running ability. Scientists think testosterone levels in utero influence digit growth and, perhaps, athletic ability.

HAMSTRINGS
Tight hamstrings too often end in agonizing pulls among sprinters, soccer players, and marathon runners. Recent studies suggest that hamstring inflexibility contributes to knee problems, too. OK, so stretch your hamstrings. But a March study from the Rehabilitation Institute of Chicago found that some stretches are better than others. Proprioceptive neuromuscular facilitation?(PNF), in which you actively contract and relax the muscle, improves hamstring flexibility at first. But longer-term passive stretches, in which a partner raises and gently pulls and stretches your leg, result in the greatest increases in hamstring length and flexibility.

FEET
Must running shoes be expensive? Not according to a new, recession-smart study in the British Journal of Sports Medicine. Researchers from the University of Dundee purchased three different pairs of running shoes at three different price points, then had 52 runners put them through a series of comfort and function tests. The result? The expensive shoes performed nobetter than the cheapo shoes, especially in tests of "cushioning of plantar pressure," or forefoot cushioning, an important measure of running-shoe function.

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