What’s Your Dose of Exercise?

The benefits of exercise are indisputable.

Exercise has been recognized to have a positive impact on almost every health and vision condition – everything from heart disease to glaucoma, from diabetes to macular degeneration, from depression to cataracts.  For those concerned with weight loss getting adequate exercise is more important than diet.

People who are active are less likely to develop certain malignancies including colon and prostate cancer, osteoporosis and dementia, and extend their average life expectancy by three to seven years without doing anything else.¹  Even low levels of exercise confer great benefit.

Exercise Extends the Biological Clock

Exercise appears to prevent cell deterioration.  Researchers have found that it prevents shorting of DNA at the ends (telomeres) of chromosomes.  Such shortening limits cell division, creating a ticking biological clock.  When the telomeres get too short the cell dies.  In addition, exercise does more than protect telomeres.  It protects the cell from deterioration in other ways preventing programmed cell death.²

The current common sedentary lifestyle with insufficient exercise is a problem for more than half of Americans who don’t get enough moderate exercise each day.  Physical inactivity is now considered a world-wide pandemic as rates of cardiovascular disease, cancer, dementia and other conditions increase.  These and other conditions would be improved with increased exercise.

At the same time ‘dosage’ of exercise is important.  The amount of exercise needed by a 20-something and a retiree are different.  It doesn’t follow that more exercise is better in the case of high-level activity. Some doctors foresee a period in the future when doctors will be able to prescribe effective amounts of exercise for their patients.

Minimum Effective Dose of Exercise

The 2008 AMA standard  recommends 30 minutes of moderate exercise daily (e.g. brisk walk) for good health.  But recent studies have found that even less is beneficial.

A large study in Taiwan evaluated the amount of exercise taken by almost 200,000 men and almost 220,000 women.  The subjects were placed in one of five categories depending on how vigorous the exercise: inactive, low, medium, high or very high and life expectancy was calculated for each group.³

• The low activity group exercised for an average of 15 minutes a day and had a 14% lower risk of mortality with a 3-year longer life expectancy compared to the inactive group.

The researchers’ conclusion was that a minimum of only 15 minutes a day, or 90 minutes a week of moderate exercise  benefits  health, even for patients with cardiovascular disease.⁴

A study of runners’ habits over a 15 year period found that running only 5-10 minutes a day still produced a lower rate or death from cardiovascular and all other causes.⁵ In the National Walkers’ and Runners Health studies’, monitored over 10 1/2 years, heart attack survivors who exercised only 8 to 24 minutes a day experienced mortality rate reductions.

Moderate to Highest Safe Dosage Levels

Extending moderate exercise such as walking briskly  to 30 minutes a day is connected to even better health results. From the Taiwan study:⁶

• The medium activity group exercised for an average of 30  minutes a day, had an 18% lower mortality risk, a 1% lower cancer risk.
• The high activity group exercised an average of 45 minutes a day with an 22% lower mortality risk.
• The very high group exercised an average of an hour a day with a 26% lower mortality risk.

The benefits were independent of age, gender or history of heart disease.  Every extra 15 minutes resulted in an extra 4% decrease in mortality risk – the highest levels being 63-88 minutes of exercise every day.  The more vigorous the exercise, the greater the reduction.  Similarly in European studies more exercise was associated with a lower death rate from all causes.⁷

• The subjects of the National Walkers’ and Runners’ studies  who exercised moderately 38 to 96 minutes a day experienced the largest reduction in death rates compared to those who got only 8 to 24 minutes of exercise.
• Cardiovascular patients who exercised 7 minutes a day with high levels of activity (eg, running) had the best reduced mortality over 15 years.
• However, running 51 to 176 minutes or more a week was not connected with more benefits.

In summary, a greater amount of moderate exercise or small amounts of high-level exercise are beneficial for health, but large amounts of very vigorous exercise do not increase the benefits.

Next: Prevention protocol