A recent comprehensive article in the New England Journal of Medicine (NEJM) further reported  that habitual physical activity minimizes vulnerability to future disease and maximizes an individual’s health and lifespan.  Sadly, many people today do not engage in the lowest amount of physical activity since the origin of our species.

Inadequate exercise now emerges as a global public health crisis with grave consequences. Thus, successfully promoting lifelong physical activity represents an unparalleled opportunity to improve health and wellness.  

I have written about exercise before and mentioned that it helps prevent weight gain and obesity.  In addition, it lowers blood pressure and reduces the risk of heart disease, heart attacks and strokes. Exercise decreases the odds of contracting diabetes and certain cancers including breast and colon.  The other benefit includes the fact that exercise strengthens muscles and bones and helps prevent debilitating falls.

Exercise is a powerful tool to protect the brain against the detrimental effects of aging. Exercise rushes oxygenated blood to help nourish brain cells and fosters the growth of new blood vessels to critical areas of the brain.  By exercising, you can improve a variety of cognitive functions that tend to increase with age and the onset of dementia.  A number of studies have shown that people who exercise have a lower risk of Alzheimer’s and other forms of dementia.

Historical Evidence

The journal article illustrates how and why lifelong physical activity reduces mortality and morbidity.  According to authors, humans were selected to be considerably more active than other primates including our closest relatives, the great apes (e.g. chimpanzees).   

Evidence from the three oldest genera of hominins (extinct relatives of the human lineage) suggests that during the course of human evolution there was selection for considerable increases in physical activity. Initially, this increase began with the evolution of bipedal walking about 7 million years ago. After bipedal walking physical activity levels increased further with the emergence of the hunting and gathering way of life some 2 to 3 million years ago.

To obtain sufficient food, hunter-gatherers had to walk about 9 to 15 km (5-½ to 9 miles) a day and engage in other forms of physical activity including digging and endurance running that together amount to approximately two to four hours per day of moderate to vigorous activity. This high level in hunter gatherers comes with the beneficial cardiovascular risk profiles across the lifespan. Hypertension among hunter gatherers was rare and they possessed favorable low density lipoprotein cholesterol values and low triglyceride cholesterol levels compared to Western societies.

Hunter gatherers who survived childhood lived on average 68 to 78 years in the absence of modern medical care, and they remained physically active well into old age.

Following the Agricultural Revolution and for much of the Industrial Revolution, human physical activity levels remained high.  However, such activity levels have plummeted globally in industrialized populations over the past few generations. This decrease is explained by the widespread availability of cars and public transportation, a shift toward jobs involving little or no manual labor, the growth of labor-saving machines like washers and elevators, and the development of computers, television and other forms of passive entertainment that discourage leisure time physical activity.  

According to one analysis, total physical activity in the United States declined by 32% from 1965 to 2009. As a result, the majority of the population in high income countries reached adequate levels of activity only by choosing to exercise. (Exercise is defined as discretionary physical activity undertaken for the sake of health and fitness.)

Benefits

Not surprisingly,  there have been no sufficiently powered, prospective, randomized trials (the gold standard for evidence) demonstrating the favorable impact of exercise on either incident cardiovascular events or all cause mortality.  Such a study would be challenging, long term, costly and potentially unethical given the known risks of a sedentary lifestyle.

Longevity studies would be further compromised by medical intervention that may be needed to control groups and unethical to withhold. However, intervention studies (assigning patients to various methods) have shown a benefit of exercise for diabetes prevention, glycemic control, weight and fat loss and obesity.  

There are strong associations between physical activity and both cardiovascular disease and mortality. One such experiment dates back to the 1950s, in which data from the London Bus study revealed that sedentary bus drivers (who sat approximately 90% of their shifts) and conductors (who climbed nearly 600 steps per day) had vastly different cardiovascular outcomes and mortality. Despite similar demographic backgrounds, the conductors enjoyed a 30% reduction in coronary artery disease and a 55% reduction in sudden death. This was one of first systematic data linking physical activity with favorable outcomes on heart disease and longevity. A number of other subsequent studies came to the same conclusions.

Final Thoughts

The NEJM article cited the need for clinicians to become more involved in promoting exercise and to consider exercise as medicine.  Exercise should not be viewed as an optional activity for those fortunate enough to the have the means, time and motivation. Instead, view it as a powerful method to decrease vulnerability to many diseases and to extend life expectancy. The Harvard Health Letter claims you can walk your way to better health in less than 30 minutes a day.

Max Sherman is a medical writer and pharmacist retired from the medical device industry.  His new book “Science Snippets” is available from Amazon and other book sellers. It contains a number of previously published columns.  He can be reached by email at  maxsherman339@gmail.com.