In each of the six Aprils that we have been in Toronto, it has snowed. For some, this might not seem strange. For others, including myself, it is a reminder that though we live in the most populated city in the country, we enjoy an oddly extreme climate. It can be >40°C (104°F) with 90% humidity in the summer and -30°C (-22°F) in winter. And don’t even get me started on “wind chill” or the humidex. Large fluffy flakes are coming down now.
It was within this context that I would do my long Saturday run. Today, 40k, and it was snowing lightly. I have been slowly building my long runs – kind of the usual thing – but I was simultaneously testing the limits of running fasted: 12+ hours of not eating prior to the run.
In the weeks prior, longer and longer fasted runs have given me consistent experiences and benchmarks. I would reach a point, usually about 75% of the distance, where brain fog would set in and from that moment onward, I would experience steady increasing protestations from my muscular system. This is probably not the best strategy if you are trying to enjoy your runs, but it gave me some valuable information and raised interesting questions. If my body has enough fat to fuel it for hundreds of miles, and I am efficient at utilizing it, then why does it start to shut things down after only a couple of hours of easy running?
The major “symptoms” that start to manifest at this 75% point are the aforementioned brain fog and then muscle dysfunction. That is, the muscles involved in running start to feel stiffness and pain, and get harder and harder to move. It’s a feeling that is not entirely unlike strain: when you do a repeated high-exertion workout and your muscles start to fail. The big difference though, is post-workout. Where after a workout-to-failure muscles sustain damage that results in soreness for days, the long-run symptoms disappear after the run is over and I eat a good meal. So what’s causing the muscle shut-down if not actual muscle damage.
Without the benefit of being able to connect my body to a diagnostic computer, I can only guess, but my theory is that it is explained by the Central Governor Model as postulated by Tim Noakes.
To clumsily paraphrase, the Central Governor theory states that many of the bodily phenomena that we experience during exercise are actually controlled by the brain, not by a direct physiological response. The idea is that our bodies are much more tightly monitored and regulated than conventional exercise wisdom might dictate and our autonomic brains will act to protect us from harm, long before we reach the point of doing real damage. Simply put, our brains will slow us down or stop us if we are going too hard for our own good – and will do so early.
Muscle cramping is an acute example of a Central Governor control mechanism. Still not completely understood, cramping is now thought not to be due to an electrolyte imbalance, but a way that the brain/body will put the brakes on you to prevent you from harming yourself. Similarly, many of the physical manifestations that cause us to slow down may be the work of the central governor, not the actuality of muscles “running out of steam.”
Personally, I think this makes perfect sense. It’s no surprise that humans, possessors of self-consciousness and ego, would be drawn to some of the theories that have shaped conventional wisdom: that “we are in control”, that our conscious mind rules over all else. That, given adequate willpower, we could literally run ourselves to death. This line of thinking has led to the notion that we can go until our bodies are physically unable, at which point we DECIDE to slow down or stop. We drink because we ARE dehydrated. We eat because our bodies NEED the food energy. Evolutionarily speaking, though, this is nonsensical. It presumes that our only preemptive mechanisms are conscious. (Remember the popular notion that by the time you are thirsty, you are already dehydrated?)
The Central Governor model proposes that our body is in a constant state of regulation to achieve internal homeostasis and is governed by a control centre, the brain. And one of the ways the brain acts to achieve homeostasis is by creating of the conditions for behavioural change. In exercise, these manifest as hunger, thirst, fatigue, pain and “loss of will.”
When it comes to running, I think we can train more than just the physiological (making the body more able) and mental (improving willpower). I believe that we can learn to be more attuned to the subtle signals that come from the brain/body so that we can better act on them. If we consider fatigue and bonking as “gross” signals from the Central Governor, there are a multitude of earlier, gentler signals that present themselves if we pay attention.
For example, during my long fasted runs I would notice a mild hunger pang after about two hours. If I ignored this (I did) it would go away, to return stronger in another half hour. If I again ignored it, brain fog would begin to set in, along with a noticeable lack of desire to continue running. Further ignoring would result in an ever-increasing loss of desire to run, followed by muscle discomfort, occasional pain and what I can only describe as “resistance to moving” – it becomes physically difficult to generate power with my legs. The latter stages of my longest fasted run, 37k, were like running through mud and I decided that that was pretty much my fasted limit.
So today, I feasted. Well, not exactly – I had high-fat yoghurt with blueberries and chopped banana (about 300 calories). I also brought some snacks with me, the only portable food in the cupboard: Persian dates, about 150 calories worth. As I ran, I paid attention to the inevitable hunger pangs and responded by popping a date or two and even though my overall food intake was relatively modest, the difference was stark. The brain fog never arrived and instead of a slow steady decline in will and vigour, my energy levels ebbed and flowed, declining slowly then picking up again at around 30k. By the 40k mark I felt compelled to round it up to 42.2 even though, Pheidippides aside, it is just as arbitrary a distance. My point is that I had energy left.
Relating this all to the Central Governor, here is my theory: eating during a run has a more important role than simply providing calories and/or sugar. It sends a signal to your brain that appears to tell it that “everything is okay, we are not going to starve/die.” Eating a date or two (eight to be exact) during an almost 4-hour outing is not enough to replenish glycogen stores but it seems to be enough to tell your brain not to panic. I’ve had similar experiences years ago when I used to take gels on long runs. I would feel slightly depleted, take a gel and within a minute or two I would feel a surge of energy – far too soon for the sugar to have actually entered my bloodstream. This demonstrates to me the power of the brain’s control over the regulation of energy output and how it responds to certain types of stimuli.
So I’ll continue to train my body, focus my mind and have some long, healthy conversations with my Central Governor.
Next time I’m going to see how it responds to eating fat…