Distance running has become one of the most popular, accessible and cost-efficient forms exercise. The health and fitness benefits of distance running fall under the broader category of endurance exercise and include adaptations like improved metabolism, reduction of cardiovascular risk, reduced all-cause and cardiovascular mortality, increased breakdown of fat stores and many more. What might be less evident is how well designed the human body is for running. The ability of the human body to adapt to its environment and survival needs is phenomenal. Throughout human history our bodies have changed according to the instinctual needs to evade predators and catch our food. Bramble and Leiberman (2004) suggest 4 specific reasons why we have evolved to become great distance runners:
The connective tissue in human beings has great elastic capacity, specifically we have springy tendons and ligaments in the legs such as the Achilles tendon and muscles of the arches underneath the feet that can reduce the metabolic cost of running by 50%. These structures function like a spring allowing us to store energy during each foot-strike which is then used to propel us forward as we push off of our toes.
Running exposes our bodies to much higher forces than walking, especially when the foot collides with the ground, producing a shock wave that passes up the body from the heel through the spine to the head. These forces are approximately twice as high during running than during walking and may approach 3–4 times body weight at higher speeds. One evolutionary adaptation has been to increase the surface area of our joints in order to dissipate these imposed forces. This can be seen in certain joints and bones through the knees, hips, pelvic and low back.
The shift from moving about on all 4’s to walking on our feet created an unstable situation which called for the development of special mechanisms to improve stability and balance during running.Some of these developments include expansions in joint surface area through our pelvic region, increased size of our bum muscles to help push us forward, and the ability to counteract the rotation through our hips by moving our trunk and arms in the opposite direction.We also have a very strong ligament connecting the back of our head to our spine which increases stability by reducing the amount of forward head movement that happens when we run.
Temperature Regulation & Breathing
As we all know movement generates heat. Early human evolution witnessed a decrease in body hair which heats us up more, and an increase in sweat glands which help to cool us off. We also developed an elaborate network of blood vessels carrying venous blood that plays a role in cooling hot arterial blood before it reaches the brain. Finally, we saw a change from nose to mouth breathing which allows us to unload excess heat, allow for higher air flow rates and reduces the amount of work that breathing muscles have to do.
The increase in technological advances has meant in part that we move less. Everything can be delivered to us. Just because we don’t need to catch our food and run away from predators doesn’t mean that we should stop running; an activity that is built into human history. Developments in civilisation have also meant that we now move about on hard, stable, unforgiving surfaces like concrete, and wear thick soled shoes which deprive the receptors in our feet of information related to changes in temperature, pressure and contours. This is very different to the barefoot running on land that we began on during our early days. But as always our versatile human body will work to adapt to our environment, and with a bit of help from a health and exercise practitioner along the way if needed, we can return to one of the most natural human activities and enjoy it.