Have you ever thought about what it takes to run? I do not think most people realize how much of their body is designed just for running. We have a lot of muscles, tendons, and bones that are not needed for walking but are essential for running. Some of those are leg and foot tendons and ligaments that act like springs, foot and toe structure that allows efficient use of the feet to push off, shoulders that rotate independently of the head and neck to allow better balance, and skeletal and muscle features that make the human body stronger, more stable and able to run more efficiently without overheating. It was not until about two or three million years ago before we started developing those muscles, ligaments, bones and the body structure that makes us one of the best endurance species on the planet.
We have some key features that help us in running. We have a ligament that runs from the back of the skull and neck down to the thoracic vertebrae; this ligament acts as a shock absorber and helps the arms and shoulders counterbalance the head during running. The low and wide shoulders of modern humans are almost disconnected from our skulls. This allows us to run more efficiently, but has nothing to do with walking. Our short forearms make it easier for the upper body to counterbalance the lower body during running. They also reduce the amount of muscle power needed to keep the arms flexed when running.
Our vertebrae and disks are larger in diameter relative to body mass than those in other animals. So are the surfaces areas of our hips, knee and ankle joints. These larger bones allow for improved shock absorption during running by spreading out the force of when a runner makes contact with the ground.
The Achilles tendon acts like springs that stores and releases mechanical energy during running. These tough, strong bands of tissue anchor our calf muscles to the heel bone. We also have an enlarged heel bone for better shock absorption, as well as shorter toes and a big toe that is fully drawn in toward the other toes. This arrangement of bones in the foot creates a stable or stiff arch that makes the whole foot more rigid, so the runner can push off the ground more efficiently. During a run, all of these tendons and bones work together to contract then uncoil to help push a runner ahead.
When it comes to sprinting, compared to other species on the planet, we are horrible. So if we stretch out that distance a little bit then we do a lot better. Horses, for example, are a lot faster than humans in short distances, but in foot-to-hoof competitions, humans usually catch horses between the 20 and 25 mile mark, particularly in warm weather. Dogs are excellent distance runners when it’s cold, but run with Fido in July and he doesn’t do that well. Evan a chimp can out sprint us for a very short distance.
Our skull has features that help prevent overheating during running. As sweat evaporates from the scalp, forehead and face, the evaporation cools blood draining from the head. Veins carrying that cooled blood pass near the carotid arteries, thus helping cool blood flowing through the carotids to the brain. Our lengthy human body—with a narrow trunk, waist and pelvis—creates more skin surface for our size, permitting greater cooling during running. The fact we are not covered with a fur coat also helps in the summer heat.
All of these characteristics make it so when you shift from a modest walk to a modest run; you can double your speed with only a 40 percent increase in energy output. Even our brains release endorphins that make us feel good when we run, ‘runner’s high’. All this is just to remind you that you can run, you should run, millions of years of evolution has made that way.