I remember reading a quote from one of running's iconic coaches, Lydiard, or someone of his stature, years ago. Paraphrasing, he said the long run does not start until seventeen miles. I thought it was a ridiculously elitist thing to say. But I came to understand why he said it. Runs of increasing length run moderately fast are about increasing connective tissue and muscle strength, greater mitochondrial density, capitalization, and increases in myoglobin, heart muscle strength, and running efficiency. But around seventeen or eighteen miles, if running fast enough, the runner will have consumed a substantial portion of her glycogen, the carbohydrate stored in muscle for immediate use while exercising. The body uses a mix of fat and glycogen for energy production. At rest, while walking or running slowly, the primary energy source is fat. As effort and speed increase, the body derives more energy from glycogen, which is more efficiently converted to power the muscles. An ultra-marathoner can run past 26.2 miles with no energy issues because she is running more slowly and getting more energy from her unlimited fat reserves. However, a marathon's point is to run for a time goal. At that pace, glycogen depletion becomes an issue, and the runner can hit the infamous Wall. The long run, which is longer than 17 miles, is crucial for the marathoner. During this training, the marathoner adapts her physiology to the demands of running 26.2 miles and her biochemical energy pathways to run faster while burning more fat proportionally.
I understand and respect what that number represents as someone who has run past 17 miles many times. That's why I cannot bring myself to call my seven miles a long run. "Long run" holds a special place in my mind as training, sometimes testing, oneself for the Wall. It is a training modality reserved for the marathoner.
While on a run, I thought of Candace Burt's recent post about running with her dogs. Current research suggests that dogs were domesticated from wolves multiple times in multiple places as humans spread across the Earth. This suggests that the mutual benefits were strong. It is easy to see how homo sapiens or even his predecessors derived advantage from this partnership. Proto dogs brought increased visual, aural, and olfactory acuity to the relationship. Wolves and humans are nearly unique in their ability to trot and run across vast distances to hunt or, in the case of humans, gather. Some paleoarcheologists believe that running may have been humans' killer advantage in competition for scarce food. But, as I run and think of dogs as running companions, have to wonder if the partnership between humans and dogs might have been the actual advantage that propelled humans to the position of apex predator. Dogs extend human hunting senses far beyond our natural limitations. It is easy to envision how this was a strong selective mechanism on both species; we both ate well thanks to the partnership. When the night came, humans must succumb to sleep in a world of night time predators. Any dog owner knows what good sentinels his partners can be. Likewise, with our relative lack of need to sleep, proto dogs may have gained increased protection by remaining near human encampments.
As Canis Lupus slowly became Canis lupus became Canis lupus familiaris, it became the only animal that could actually read human facial expressions, as research now suggests. This would be valuable feedback to man's best friend as not all humans and not all human emotions are beneficial to dogs. There is some preliminary research suggesting that dogs can even communicate back to humans with facial expressions of their own, increasing the richness of the inter-species communication. One can view the human-dog relationship, at least in hunter-gatherer societies, as a symbiotic one.
In light of this, we can understand the human love for dogs and their mindless, instinctive need for us, no matter how we often treat them. We can also think of those who abuse them as something proto-human, sub-human.