Gravity & it’s effects on the HMS (Human Movement System).

August 20, 2015
August 20, 2015 nilebratcher

Gravity & it’s effects on the HMS (Human Movement System).

On earth there are gravitational forces that pull us downward. This constant compression affects every joint & system in the human body. Ranging from blood flow, to propulsion of the Gut and even the body’s inate need the need to stay balanced and upright. We will address these as they relate to Human Movement.

The Human body moves in two major ways; Pronation and Supination. These terms describe Collapsing (Pronation) & Propulsion (Supination). In other words Sit and Stand. They are synonymous with Human Movement. Why? They are the movements that give into or move against gravity. In space there is no Gravity or downward pull. To illustrate; Astronauts face daunting effects from life in space. They must spend hours daily performing resistance training to combat muscle atrophy & the decrease in bone density. These conditions result from zero gravity, defined as having no load bearing on the Human frame. Subsequently, leading to the decrease in Bone density & frailty. Similar processes occur for Muscles. With no sense of Posture or Gait lack of load leads to impotent muscles that begin to deteriorate in a short period of time. Conversely, on Earth when one is standing the bones and muscles are in effect pushing against gravity which  makes us under load.

Lack of gravity can also affect the body’s balance system. Human’s posses a complex integrated set of neural circuits that allows us to maintain balance, proprioceptive sensors in our joints and muscles that allow us to understand body orientation and interpret vision to remain upright and balanced. In space this complex system is dramatically altered because there is no center for orientation.


An influx of sedentary lifestyles globally has been unprecedented in the past two decades. We sit for an hour to commuting to work, sit another eight hours at work, sit around hour committing back home, exercise for forty five minutes, sit for dinner, then sit another three hours watching the game or our favorite television series. Being in this collapsed position for extended periods has been shown to cause gastrointestinal issues, cardiac arrest, deep vein thrombosis, chronic back pain and obesity. Why? Simply, Humans need movement. Movement is key to a healthy life & body.

My father-in-law, who was born in Cambodia, is eighty years old and has no Diabetes, Heart Disease or Cancer. As a young adult he spent his working days not in a chair, but moving to perform his daily routines. This lifetyle unbeknownst to him contributed to his healthy elder years. Supination & Locomotion or Gait can improve food propulsion, defecation, increased blood flow to the lower quadrants, subtract pressure on the spine, increase heart strength and Brain health. The American heart association’s guidelines for physical activity are thirty minutes per day of Aerobic (with oxygen) exercise such as walking. Just that little can have a long term effect on one’s health.

On the other hand, what happens when a person has some type of medical issue that requires hospitalization and they are immobilized as a result? The extended and abnormal time being sedentary and supine (On Back), can cause scores of health complications; Bed Sores, Pneumonia, atrophy of muscles and Pulmonary Embolisms. Taken to the extreme-the individual becomes completely unable to move on their own because their muscles have become impotent-much like astronauts who do not use resistance training; our bodies need to move in order to maintain the ability to move. Supine & sedentary, increases & Locomotion becomes absent. I see some so called “Elderly” using electronic mobile wheelchairs to get to their destinations, perhaps for seemingly good reasons for choosing this method of transportation. But do not these results of the various circumstances we have discussed in of Astronauts in space radiate in similarity?