The Science of Running
Alex Hutchinson rounds up the latest in endurance research
Blood Donation
Sure, you want to do the right thing – but you also want to snag a new PB. So how should you handle blood donation when you’re in the midst of training for an upcoming race? A typical donation extracts 450 ml of blood, including the hemoglobin-rich red blood cells that carry oxygen from your lungs to your muscles. That represents about nine per cent of the total hemoglobin in your body – enough that you’ll notice a significant slow-down when you run hard. (In fact, that slow-down is precisely the opposite of the performance-boost cheating athletes get from injecting fresh blood into their veins.)
It takes about five weeks for your hemoglobin levels to return to normal, though it varies from person to person. In one study, volunteers took anywhere from 20 to 59 days to restore their pre-donation levels – the average was 36 days. But the effects are most noticeable in the first week: a new study from the University of North Texas, published in the journal Applied Physiology, Nutrition, and Metabolism, found that cycling performance was reduced by 19 per cent two hours after a blood donation, seven per cent two days later; and by just 3.7 per cent seven days later. This suggests that you won’t notice much difference in your performance after that first week.
Still, there is another option. The North Texas study also examined the effects of plasma donation, in which your blood is extracted and spun in a centrifuge to separate the different components of blood. The plasma is mostly water, rich in proteins that can help burn victims and patients with liver disease; the rest of the blood, including the oxygen-carrying red blood cells, is returned to your body. Instead of affecting aerobic endurance, plasma donation causes a temporary drop in anaerobic exercise capacity because of the loss of lactate-buffering substances, the researchers found. Performance was 10.5 per cent worse two hours after plasma donation, but the good news is that it had returned to normal after just two days, since plasma is replaced rapidly as long as you hydrate well.
Ultimately, whole-blood donation is more useful to more people than plasma donation, and the evidence suggests that if you donate during the recovery period after a goal race, it will hardly affect your training at all. The lesson is if you’re training hard and can’t spare the hemoglobin, consider plasma donation instead.
If you’re training hard and can’t spare the hemoglobin, consider plasma donation instead.
Endurance Booster
The vegetable drink of choice for endurance athletes these days is beet juice. Studies suggest that it boosts performance by raising levels of nitric oxide in the body, allowing muscles to use less oxygen as they contract. But beet juice also has some less desirable side-effects on the digestive system that can interfere with race performance, so researchers have been looking for alternate ways of boosting nitric oxide levels. One promising candidate is L-arginine, a supplement that in a 2010 experiment from the University of Exeter appeared to boost endurance.
Since then, though, other researchers have published conf licting results on arginine’s effectiveness. Now the same researchers that published the original study have revisited the topic – and in a new study, just published in the European Journal of Applied Physiology, they report that arginine doesn’t boost exercise performance or reduce the oxygen needed for muscle contraction after all. Instead, they believe the results of their original experiment were skewed by some of the other ingredients in the supplement they used – which included, among other things, beet juice as a colouring agent. The upshot: keep drinking beet juice, and make sure to line up early at the pre-race port-a-potty.
Brain Zap
Researchers in Brazil recruited 10 competitive cyclists, applied electrical current to a specific region of their brains for 20 minutes, and then asked them to complete an incremental cycle test to exhaustion. The results, published in the British Journal of Sports Medicine, showed that after the current was applied, the cyclists had lower heart rates, slower increase in perceived effort, and produced four per cent more power compared to a placebo ride where they received fake brain stimulation.
The results offer an impressive boost to the view that physical limits are ultimately determined by the brain, not the muscles or heart or lungs. The brain regions the researchers zapped were the insular cortex, which monitors distress signals from elsewhere in the body, and the temporal cortex, which is associated with feelings of pleasure, pain and exertion. Of course, there’s also the potential for abuse: worryingly, there’s currently no way to determine whether athletes have received brain stimulation, says lead researcher Alexandre Okano of the Federal University of Rio Grande do Norte.
Nuclear Tendons
From 1955 until they were banned in 1963, aboveground nuclear tests produced a huge spike in the levels of carbon-14 in the atmosphere – so huge that the isotope can still be detected in people who were alive then. Or rather, it can be found in certain body parts that don’t regenerate once you’re an adult. Teeth are one example. Another, researchers in Denmark recently reported, is the Achilles tendon. Using tendon samples taken during forensic autopsies, they showed that the levels of carbon-14 in the tissue correspond very closely to the cumulative exposure to atmospheric C-14 during the first 17 years of the subjects’ lives. In other words, it’s a high-tech demonstration of a truth all too many runners have encountered: damaged Achilles tendons regenerate very, very slowly, if at all. If you notice tendon pain, deal with it immediately and try not to let it worsen.