Physical activity, food, and reproduction are some of the minimal requirements for life. They evolved not as choices, but as requirements for individual and species survival. Modern humans have been able to engineer most physical activity out of daily life.
Humans now have a choice not to be physically active. Conclusive and overwhelming scientific evidence, largely ignored and prioritized as low, exists for physical inactivity as a primary and actual cause of most chronic diseases. Thus, longer-term health was also engineered out with the successful removal of physical activity as a necessity for immediate survival.
The comprehensive evidence herein clearly establishes that lack of physical activity affects almost every cell, organ, and system in the body causing sedentary dysfunction and accelerated death. The massive multifactorial nature of dysfunction caused by sedentarism means that just as food and reproduction remain as requirements for long-term continued human existence, physical activity is also a requirement to maximize health span and lifespan.
The only valid scientific therapeutic approach to completely counter sedentary dysfunction is primary prevention with physical activity itself.
In summary, the body rapidly maladapts to insufficient physical activity, and if continued, results in substantial decreases in both total and quality years of life. Taken together, conclusive evidence exists that physical inactivity is one important cause of most chronic diseases. In addition, physical activity primarily prevents, or delays, chronic diseases, implying that chronic disease need not be an inevitable outcome during life.
Check out the full review which contains 579 references! >> http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4241367/