THE SCIENCE OF RUNNING

A weight off your mind

About 40 per cent of runners overpronate. Their feet rotate too far inward with each stride, and as a result they’re told to wear “motion control” shoes to limit their pronation. This isn’t always a popular diagnosis, since motion control shoes tend to look big and clunky, and they’re made of stiffer materials. If Olympic runners are wearing ultralight shoes that look like little more than socks with metal spikes on the bottom, we figure, then being confined to brick-like shoes must be a severe handicap to our running.

But that’s not necessarily true, according to a new study in the International Journal of Sports Medicine. Researchers had 14 subjects run at a comfortable training pace for 40 minutes in a pair of motion control shoes (New Balance 1122) and a softer, lighter pair of cushioning shoes (New Balance 1022), while measuring their oxygen consumption, heart rate and perceived exertion. There were no significant differences between the two shoe types in any of the parameters, even though the motion control shoes were 24 per cent heavier.

This doesn’t mean the laws of physics have been repealed: wearing heavier shoes certainly does require a bit more work, which is why elite runners race in the lightest shoes they can find. The key in this study was that it was performed at around 65 per cent of maximum effort – a fairly typical aerobic training pace, but much slower than racing. At this sub-maximal level, the difference in shoe weight and stiffness simply wasn’t significant. That’s why even Olympians don’t mind wearing chunkier motion control shoes in training, if that’s what their gait requires.

Pollution probes

You inhale about 10 times more air when you’re running than you would normally. As public health authorities like to remind us, this may be cause for concern if you’re running in polluted conditions. To investigate this, Australian researchers asked 10 runners to jog back and forth for 20 minutes along a 100-metre stretch of a busy four-lane highway in Tasmania, then measured the concentration of volatile organic compounds (pollutants commonly found in gasoline, among other places) in their blood. Not surprisingly, they found that levels of toluene, ethylbenzene and xylene increased – though it remains unclear what levels should be considered unsafe.

Before we leap to any conclusions, it’s worth recalling a series of earlier studies that measured pollution exposure for cyclists and drivers following identical routes along busy roads. Even though the cyclists were breathing harder and took longer to get there, the air inside cars was so much worse that drivers had twice as much exposure to volatile organic compounds than cyclists. Certainly, we heartily endorse the advice not to do your runs back and forth along a four-lane highway – but that’s as much about preserving sanity as avoiding pollution.

Finding the true maximum heart rate

If you want to use a heart rate monitor to help you train at the right effort level, it’s important to know your maximum heart rate. The old chestnut about “220 minus your age,” unfortunately, turns out not to be very accurate. Even a modified formula of 208 minus (0.7 times your age) will still over- or underestimate max heart rate by at least 10 beats per minute for about a third of the population. Experts usually recommend a progressive treadmill test in a laboratory to figure out your real maximum. But a study in the Journal of Sports Science and Medicine now suggests that even lab tests don’t cut it.

Researchers at the University of Nebraska at Kearney measured maximum heart rates for 20 collegiate runners under three conditions: on a treadmill in the laboratory; during a hard training session of 8 x 400m with one minute recovery; and during a cross-country race of 6K for the women and 10K for the men. The average maximum heart rates in training (207 beats per minute) and in competition (206) were much higher than the lab-measured value of 194. In some ways, that’s a relief, since most of us don’t have access to fancy treadmills in laboratories. If you really want to find out what your max is, strap on a heart rate monitor during your next road race. Just make sure you don’t start too fast then die badly at the end, since you won’t reach your max that way.

Core strength and running speed

A stronger core is supposed to offer all sorts of benefits, from flat abs to less lower back pain. But does it actually translate to improved running performance? It does, according to a Journal of Strength and Conditioning Research study by researchers at Barry University in Florida. In a study of 28 recreational runners, those doing a six-week core strengthening program improved their 5K time significantly compared to a control group. Strangely, the parameters that the researchers thought would explain any changes – lower leg stability and ground reaction force – remained unchanged in both groups. So they don’t know why core strengthening makes you faster – but it does.

Toe joints

We spend a lot of time celebrating the good things that running does for our bodies. But come sandal season, it’s hard not to notice that runners tend to beat their toes up pretty severely. Ill-fitting shoes and anatomical peculiarities mean that many runners end up with black toenails – often referred to as “runner’s toe” – from bleeding under the nail. Even losing a nail isn’t uncommon. Fortunately, these are mainly cosmetic issues. But the toes also house delicate joints lubricated by something called “synovial fluid” – and of all the joints in the body, these toe joints are the only ones to bear weight through the synovial membrane.

Some doctors have worried that running puts too much stress on the delicate toe joints, causing them to secrete excess synovial fluid. This could lead to inflammation, discomfort and possibly even joint degeneration. So a team of radiologists in the United Kingdom put this theory to the test. They asked nine runners to rest for 24 hours, took an MRI to measure how much fluid was in their toe joints, then had them run for 30 minutes and took another MRI. The results, published in Skeletal Radiology, were encouraging: while there was fluid in the joints, running had no apparent effect on the amount of fluid. This is still a young area of inquiry – no one is really sure exactly how much fluid is supposed to be there – but it looks like running doesn’t trigger any problems.