The Science of Running

How a Break from Running Affects Your Brain; Gotta Be the Shoes; The Art of Descent; Age and Intervals

Grouchy? Check. Restless? Check. Runners often notice changes in their mood when they take a prolonged break, whether planned or unplanned, from their regular training routine. But is it possible that a few weeks off might even make you dumber? That’s what researchers at the University of Maryland investigated in a study published in the journal Frontiers in Aging. They recruited 12 longtime runners who were, on average, 61 years old, had been running for 29 years, and were logging 60k a week – and they asked them to stop running completely for 10 days.

mri scans taken before and after the break showed a pronounced decrease in blood f low to the hippocampus, which is crucial for learning and memory, as well as to several other regions in the brain. The change could ref lect structural adaptations like a decrease in the network of blood vessels feeding blood to the brain, though the study couldn’t confirm this hypothesis. Whatever the mechanism, decreased blood f low could affect the health of the brain in the long term.

What about the short term? The researchers also tested verbal f luency, asking the subjects to name as many animals or fruits as they could in 60 seconds. Before the break, they averaged 19.9 words; after 10 days off, they managed 17. 4. This difference isn’t statistically significant, so it would take a larger number of subjects to figure out if the break triggered a meaningful change. And it’s certainly not a reason to avoid taking much-needed breaks from training once or twice a year. But overall, the study offers a reminder that, just like physical fitness, mental fitness melts away if you stop training for too long.

Gotta be the shoes

It’s no secret that heavier shoes require more energy to run in. But can shoes really produce a measurable difference in race time? According to a new study from the University of Colorado’s Locomotion Lab, the answer is yes. Volunteers ran a series of 3,000 m time trials in what they thought were identical pairs of Nike Zoom Streak 5 racing f lat. Unbeknownst to them, tiny lead beads had been sewn into some of the shoes to make them 100 or 300 g heavier than the base weight of just over 200 g. Tests showed that the runners burned 1.11 per cent more energy for every added 100 g, and ran 0.78 per cent slower in the time trials.

At first glance, this may seem like a conclusive argument in favour of ditching your shoes entirely. But previous research from the same lab has shown that the cushioning in shoes can reduce the energy you burn by three to four per cent, since it absorbs energy that you would otherwise have to dissipate by clenching your leg muscles. So the ideal trade-off – for racing, at least – seems to be the lightest possible shoes that also provide some cushioning. In training, lead research Rodger Kram points out, these minor differences in energy cost are less important than finding a comfortable shoe that keeps you injury-free.

Age and intervals

The great chicken-and-egg question for aging runners is whether you train less because your body lets you down, or your body lets you down because you train less. Or to put it another way, does your fitness still respond to training as effectively it used to? In a recent study by researchers in Norway, published in Medicine & Science in Sports & Exercise, volunteers between the ages of 20 and 83 with typical fitness levels for their age completed an eight-week fitness program, involving three interval workouts per week. The results showed no age difference whatsoever in the percentage increase in fitness, which was just over 10 per cent. That doesn’t mean age is an illusion – but it does offer some reassurance that, however old you are, your body will respond to hard work and get fitter.