The future of endurance. By Marina Kalcina, featuring Rick Mirabella
As the story goes, Pheidippides ran 26 miles from the town of Marathon to Athens to announce a Greek victory and warn the Athenians of the incoming Persian fleet. This epic run had three notable consequences. The first two were relatively immediate: Pheidippides, who had run 280 miles in the 10 days prior to his marathon, dropped dead from exhaustion. The second: His message allowed the Athenian army to organise their defence, thus defeating the Persians a second time and making Europe as we know it possible.
The third consequence happened centuries later. The first marathon, inspired by Pheidippides' legendary runs, was introduced to the modern Olympic Games in 1896. Fittingly, a Greek man by the name of Spiridon Louis won the event.
Since then, interest in running has been on the rise. The first running boom occurred after the 1972 Munich Olympic Marathon, when a German student, who was not actually in the race, crossed the line ahead of American runner Frank Shorter. This dramatic event is said to have captured imaginations worldwide, and saw 25 million Americans take up some aspect of the sport thereafter. The current running boom has seen an estimated 200 million people worldwide take to the sport in the last five to ten years.
A marathon is certainly on the to-do list of many runners. Perhaps it’s due to the belief that people who have run 42.195km are part of an elite club, the opportunity it creates to make like-minded friends, or the nice pair of quads one acquires from this type of running. Whatever the reason, marathon running in particular has grown in popularity at an astounding rate. In the US alone, there was a reported 47% increase in the number of marathon finishers between 2000 and 2011.
Deciding to run a marathon is one thing; finishing it is quite another. What biological changes does it take to run the mother of all races?
According to Rick Mirabella, Head Coach and founder of Runnez, a research-based running app and online coaching platform, designed for all fitness levels, would-be marathoners should train their bodies in multiple ways. “A balanced program that factors in all training components including long runs, tempo, interval, and fartlek running, combined with regeneration days, will yield a vast increase in the body’s mitochondria and capillaries,” he says.
Mitochondria, the little energy factories inside our cells, consume oxygen to produce ATP, an energy molecule that allows muscle contraction, and subsequently locomotor activity, to occur. Capillaries deliver oxygen to the mitochondria. Over time, and with the right training, we become more efficient at using oxygen to make ATP rapidly. This occurs through mitochondrial biogenesis, which is triggered under certain physical stimuli – such as the various running types outlined by Mirabella.
Not only does endurance training stock up muscles with capillaries and mitochondria, the left ventricle of the heart also increases in size, meaning it can hold and pump more blood. In addition, endurance runners have more red blood cells, haemoglobin-packed blood and high blood volume compared to sedentary individuals.
What are we left with? In short, a high VO2 max, which is the maximum amount of oxygen that can be consumed and used in one minute. The more endurance training you do, the higher your VO2 max ‒ and the more economically you can run. So, in essence, you increase your pace, and therefore the distance you run, but your level of effort remains the same.
For a century, researchers have focussed on the role of the muscles to explain the limits of endurance, and training programs have been built on this knowledge. What the focus has not been on, until recently, is the brain.
“Mental fatigue plays a big role in every sport, notably endurance sports such as running," says Mirabella. "For optimum performance, you need the physical base, but if you have it and still don’t perform to expectation, then we must look to the mental."
In a 2009 study, Samuele Marcora and colleagues found that, just as muscle fatigue has an impact on physical performance, so too does mental work – and the impact is just as large. Subjects spent 90 minutes either passively watching a documentary about trains, or sitting at a computer completing the AX-CPT test, a ‘cognitively challenging task’ that involves responding repeatedly to a sequence of letters. Both groups then immediately completed a cycling test. Compared with the film watchers, participants in the task group found the exercise harder and reached exhaustion 15% earlier.
This means that it may not be physical shortcomings, like oxygen shortages in your muscles, that impact the way you race, but rather the way your brain perceives these signals.
Physiologists have long believed that marathoners run until their muscles are depleted of glycogen, or their legs fail. However, very few marathoners reach that breakdown point. One theory, espoused by sports scientist Tim Noakes at the University of Cape Town, is that the brain acts as a ‘central governor’ when racing, and, to ensure self-preservation, limits our ability to push beyond fatigue.
“Anyone who has ever exercised at all realises that a large portion of training physically is ‘above the shoulders’," says Mirabella. "Noakes’ idea about the brain preserving the body by putting a stop to ‘painful’ speeds goes a long way to explain why some people can be in ‘agony’ for a few kilometres, and then kick for the last 100m of a race.”
The 'central governor' theory suggests that we can improve our marathon performance simply by training the brain. It doesn’t seem so far-fetched – after all, we train muscles to increase capillary and mitochondrial density. We train the heart to increase the thickness of the left ventricle and improve oxygen transport. The brain is an organ like the heart – so can we train it, too?
In a 2015 study by the UK's Ministry of Defence overseen by Samuele Marcora, subjects trained on a stationary bike three times per week while engaging in the AX-CPT cognitive task. After 12 weeks, the group that had completed their training without the mental component showed a 42% improvement in their time-to-exhaustion test results. The group that combined physical and mental training improved by a huge 126%.
So according to Marcora, yes, you can train your brain. You train it to tolerate a harder perceived effort by fatiguing it with cognitively demanding tasks. When that mental stimulus is removed, the physical task being trained for seems easier. According to Mirabella, training your brain might be as easy as running after a one-hour drive or a stressful day at work.
Exerting yourself mentally – using either Marcora’s or Mirabella’s suggestions – and following up with a run is designed to simulate the point in a race or marathon when the brain starts to fatigue. Brain training gives the runner practice at pushing through this mental state. But what is actually happening in the brain when we train it, and how is it changing?
According to Marcora, focussing on a monotonous task for an extended period of time causes a build-up of the neurotransmitter adenosine. This is the same neurotransmitter that builds up when you are sleep-deprived. Inducing mental fatigue triggers a flood of adenosine, and, if you do this every training session, neurons and synapses may eventually adapt to keep adenosine levels lower. Over time, the brain’s contribution to your overall feeling of effort stays lower as a marathon progresses. This allows faster running with the same level of exertion.
So is the future of marathon training centred on the brain? That depends on whom you ask. Marcora believes there is nothing left to gain from the traditional physiological way of training, and that innovation in fitness must come from elsewhere. In Mirabella's fitness circle, many coaches consider brain training a gimmick, but he remains open to the idea.
“The bottom line is, we just don’t know enough about the brain, so we’d be crazy to ignore the results of these studies," says Mirabella. "But we do need more research and time. Personally, I’ve been embracing these findings and incorporating them into my coaching. I can’t wait to see how much of an influence brain training has on coaches and athletes 50 years from now.
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