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THE SCIENCE OF RUNNING

Get smart, run fast and get the latest on compression technology with Alex Hutchinson's Science of Running.

Brain training

Exercise makes you smarter – that’s been clear for many years. But what kind of exercise is best? Two studies published last year offer some good news to runners. First, researchers at the University of Illinois put a group of volunteers through a memory test, then repeated the test after they had either run, lifted weights, or rested for 30 minutes. The results were published in Medicine & Science in Sports & Exercise. The runners had faster reaction times to the memory tests after exercise, while the weightlifters and controls saw no change. The reason, researchers suspect, is that the growth factors stimulated by resistance training stay in the muscles, while the products of aerobic training circulate through the bloodstream to the brain.

Researchers in Taiwan added another twist by training two groups of mice. In one group, the mice were allowed to run on an exercise wheel at their own pace; the other group was trained more rigorously on mini-treadmills at a pace determined by the researchers. In a complex cognitive test, the harder-trained mice performed better, according to results that appeared in the Journal of Physiology last July. We can never be sure that results in mice will translate to humans, but for now, the evidence suggests that running makes you smarter, and the harder the better.

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Music to runners’ ears

For decades, researchers have been studying the effects of “distraction” on exercise, trying to find out ways of making us more comfortable while we sweat. The latest study, due to appear in a forthcoming issue of the Scandinavian Journal of Medicine & Science in Sports, offers some new insight into the differences between fast and slow music. This is a hard question to study, because the results tend to be affected more by whether the exercisers like the music you pick than by the tempo. So British researchers chose a program of six songs, then played them either at regular speed, 10 per cent faster, or 10 per cent slower, while subjects who were unaware of the speed changes rode exercise bikes. The results were clear: the subjects pedalled a few per cent further and faster when the music was fast, and slowed down when the music was slow. Interestingly, perceived exertion was also higher with the fast music, so it’s not simply that fast music numbed the pain – the subjects were actually willing to suffer more as long as the music was pushing them along.

Distraction isn’t always beneficial, though. Another upcoming study, by researchers at Elon University in North Carolina, compared the effects of music and video for distraction during exercise. They found that watching TV didn’t have the same performance boost as music. In fact, Elon professor Paul Miller noted, the opposite was true of the video-watchers: “They certainly were not working harder,” he said, “and in some cases, they were so distracted from the task that they may have actually been working less.”

Dynamic compression technology

We’ve written before about the possible benefits of compression socks, which help return blood from the legs toward the heart and are thought to speed up recovery after a hard workout or race. That technology, it seems, is no longer cutting-edge. Instead, elite runners like U.S. marathoner Ryan Hall are turning to “dynamic compression” from a gadget called the NormaTec MVP. The device involves donning giant inflatable leggings that squeeze the legs with a “peristaltic pulse” that moves rhythmically from the bottom of the legs to the top, pushing blood toward the heart.

Given that compression socks have an ever-growing following, this seems like a reasonable idea – a sort of cross between compression leggings and massage. Indeed, the company’s website features testimonials from a wide range of professional athletes and university trainers. That being said, you’d expect to see some research to back up the fairly bold claims of faster healing and reduced pain. So far, we haven’t turned up any relevant studies in research databases, and haven’t been able to obtain any studies from the company.

Drinking problems

A few years ago, there were a lot of headlines about hyponatremia, a state of dangerously low sodium in your blood that can result from drinking too much during exercise. At least five runners in the U.S. and Britain have died from the condition in the past decade, raising awareness about the risks of over-hydration. But the condition is still poorly understood, which led researchers at the University of London to study 88 volunteers taking part in the 2006 London Marathon, measuring their sodium levels before and after the race. The results appeared recently in the British Journal of Sports Medicine.

The major surprise was that 11 of the volunteers – more than expected – developed “asymptomatic hyponatremia,” meaning their sodium levels were significantly below normal without causing any problems. As expected, the runners who developed hyponatremia drank more frequently during the race (typically every 1.5K) compared to those who stayed healthy (typically every 3K). But there were some unexpected results, too. Four of the 11 hyponatremics lost weight during the race, which suggests that they weren’t actually drinking too much water. The researchers suggest instead that exercise stimulated the release of a hormone that caused these subjects to retain more fluid than normal.

On the surface, these results are reassuring, since none of the subjects suffered any ill effects. Still, the unexpectedly high prevalence of hyponatremia should remind us that too much liquid can be as damaging as too little. And the risks are real: the year after this study was conducted, a 22-year-old fitness instructor collapsed and died from hyponatremia during the London Marathon.

Pool-running muscles

For injured runners, deep-water pool running is the next best activity for maintaining aerobic activity while using most of the same muscles. You have to work harder than usual to get your heart rate to its usual levels, in part because the water acts like a giant compression suit helping to push blood from your legs back towards your heart. If you can handle the boredom, it’s a good aerobic workout.

Until now, though, no one has really investigated how much the leg muscles really benefit from mimicking the running stride. Researchers from the University of Nevada, Las Vegas took a group of seven runners, wired them up with electrodes on various parts of their legs, and then had them run at various intensities first on a treadmill, then in the pool (wearing drysuits to avoid zapping themselves). The results, which appeared recently in Medicine & Science in Sports & Exercise show that tibialis anterior (shin) and gastrocnemius (calf) muscle activation was much lower in the pool than on land. Rectus femoris (quad) and biceps femoris (hamstring) activation was a little more ambiguous: it tended to be a bit lower in the pool, but the different stride patterns meant there was some overlap.

This certainly doesn’t mean that pool running isn’t worthwhile – it was always just a temporary substitute for the real thing. But it may suggest that runners who have been in the pool for an extended period of time should be particularly careful about their lower legs as they begin running on land again.