• To reduce the risk of chronic diseases in adulthood, increase physical activity to 30 minutes at moderate-intensity — most days of the week. 
• Former U.S. Surgeon General C. Everett Koop highlighted the health risks and costs of overweight and obesity and issued a call in 1994 to Americans to take action and founded “Shape Up America!”
• Research shows that walking 10,000 steps a day will significantly improve your health, endurance, burn calories, lower BP and give you a healthier heart; being physically active and walking and light jogging are almost uniformly beneficial for health and do increase life span.

The evidence

A 2013 review of more than 50,000 American adults evaluated at the Cooper Institute’s Aerobics Center Longitudinal Study found a 19%  lower risk of dying from any cause than non-runners. Increased physical activity does not need to include jogging—even less exercise has important health promoting benefits. Examples of such moderate-intensity activities are brisk walking, bicycling, raking leaves, and gardening. When compared to a sedentary lifestyle, any degree of activity can actually improve health so consider some simple ways to move more:

• park your car further away at stores
• get off the bus or
 subway a few stops earlier
• dance more
• take the batteries out of the remote control
• use a stationary bike while watching TV
• ride bikes
• play outside
• go to a park
• walk the neighborhood
• walk the stairs instead of the elevator
• get a dog

Even as little 15 minutes of daily exercise or about half of the minimum level found in current recommendations can be associated with a significant lower risk of death (Wen et al Lancet 2011;378:1244-1253). A recent May, 2016 report of more than 1.4 million participants in the National Cancer Institute’s Cohort Consortium found that the benefits of routine leisure-time activity extend to a reduced incidence of 13 cancers (75% of cancers in the US).

Leisure-time exercise (defined as 3-5 METS of exercise is equivalent to walking about 150 minutes per week). Those at the higher end of activity, or greater than 5 METS compared to lowest level showed the greatest benefits in decreased risk of cancer. These findings support promoting physical activity as a key component of population-wide cancer prevention and control efforts (JAMA Intern Med.2016.1548 published online May 16, 2016).

METS for life

Exercise is truly medicine. Exercise physiologists define 1 metabolic equivalent (or 1 MET) as 3.5cc of oxygen uptake per kilogram per min, which is the resting oxygen uptake in a sitting position. In other words, 1 MET = the energy (oxygen) used by the body at rest, while sitting quietly or reading a book, for example. The harder your body works during any activity, the more oxygen is consumed and the higher the MET level. The metabolic benefits such as improved blood sugar (and improved insulin sensitivity), blood pressure, lipids and weight with a moderate exercise program are well known.

A recent 2013 study that included mostly men who presented for stress-testing found that those who could achieve a 10 METS or more level had an excellent prognosis and a statistically important lower risk of cardiovascular events compared to those who could not reach this level. (Fine NM et al Mayo Clin Proc. 2013;88(12):1408-1419).

Activity that burns 3 to 6 METs is considered moderate-intensity physical activity and activity that burns >6 METs is considered vigorous-intensity physical activity. Common everyday chores considered as moderate-level exercise (3-6 METS):         

• Washing and waxing a car for 45-60 minutes
• Washing windows or floors for 45-60 minutes
• Gardening for 30-45 minutes
• Wheeling self in wheelchair for 30-40 minutes
• Pushing a stroller 1½ miles in 30 minutes
• Raking leaves for 30 minutes
• Shoveling snow for 15 minutes
• Stair walking for 15 minutes

Common sport activities considered as at moderate-level exercise level (3-6 METS):

• Playing touch football for 45 minutes
• Walking 2 miles in 30 minutes (1 mile in 15 minutes)
• Shooting baskets (basketball) for 30 minutes
• Dancing fast (social) for 30 minutes
• Performing water aerobics for 30 minutes
• Swimming laps for 20 minutes
• Playing basketball for 15-20 minutes
• Jumping rope for 15 minutes
• Playing volleyball for 45-60 minutes

Exercise pearls: simply adding more walking into daily life whether in increments of 10 to 15 minutes or 30 minutes all at
 once can really improve your metabolism and even add more quality and years to your life. Beware of sitting too much -even if you think you are reasonably active. The minimum amount of activity to be effective at improving health benefits, believe it or not, is standing. Standing >2h/day is associated with a 10% reduction of death from all-cause. (Prev Med. 2014;69:187-91)

• A pedometer is a great way to start and track progress with a goal of getting
 10,000 steps in daily. The simple idea of more moderate walking has proven results and is a recommendation virtually for all Americans and is health metric of “healthy” lifestyle. Most middle-aged Americans can achieve an health-promoting level exercise at the important 10 METS level of aerobic activity. Women in general have a lower maximal aerobic capacity than men and 10 METS in men is equivalent to 8 METS for women.

A better understanding how exercise works

The identification of the body’s natural energy sensor has led researchers to an important muscle enzyme called adenosine monophosphate-activated kinase (AMPK). This molecule can be turned-on by muscle contraction and exercise. It is thought of as the body’s regulator of energy production, storage, and expenditure. AMPK activity is important in the control of blood sugar and decreasing insulin resistance -the condition related to prediabetes and diabetes. In addition, this molecule increases the burning of fat (called fatty acid oxidation), and the lowering of cholesterol and triglycerides. The major weight control hormones called leptin and adiponectin are closely connected to AMPK activity and is hoped will help researchers better understand how exercise may enhance weight control.

Summary

For all of us who wish to enjoy healthy aging, a quote from Dr. Kenneth Cooper, who has inspired millions to exercise for good health with the release of his first best-seller Aerobics, “We do not stop exercising because we grow old — we grow old because we stop exercising.”

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