Intensity and Duration of Exercise Is One more Important than the Other?

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This article was edited and updated on November 8, 2015.

Three recent studies confirm for us, once more, that exercise is important for our physical and mental health. These studies also suggest that exercise should be at least of moderate intensity, and we should do it often.

More Minutes exercised translates into More Benefits

A growing body of research shows that physical activity encourages cognitive health as well as physical function. But how much exercise is needed to see those results? A research team at Kansas University Medical Centre explored that question.

For 26 weeks, four groups of people 65 years and older were assigned to do moderate-intensity exercise for different lengths of time: one group did no exercise at all; others did 75, 150, or 225 minutes per week. These individuals were underfit or sedentary but had no symptoms of cognitive decline. The cognitive function of each participant, regardless of the group, was assessed both before and after the research period.

The notable results of this study are:

“For improved brain function, the results suggest that it's not enough just to exercise more,” said lead author Eric Vidoni, PT, PhD, research associate professor of neurology at Kansas University Medical Center. “You have to do it in a way that bumps up your overall fitness level.” 2 An acceptable overall fitness level is usually gained by sustained physical activity — week in and week out.

SOURCE: PLOS ONE, doi:10.1371/journal.pone.0131647 (July 9, 2015) For the abstract and full text, click here.

More Minutes Exercised Helps to Lose Body Fat

After experiencing menopause, women tend to gain body fat. This extra weight can contribute to other problems, including breast cancer which is the second most common form of cancer among women. 3 This study tried to determine if exercise would reduce body fat, which might reduce one of the risks of breast cancer.

Researchers chose 384 women who were inactive, postmenopausal and had a body mass index of 22 (normal) to 40 (obese). They were assigned to 30-or-60-minute exercise sessions of moderate-to-high intensity for five days a week. They were asked to achieve 65%-75% of heart rate reserve for at least half of each exercise session.

The results were quite conclusive: Women who exercised for 300 minutes per week lost more body fat, about 2.2 pounds (one kilogram), when compared to women who exercised 150 minutes per week.

“Exercise can cause body fat to drop which is especially important for cancer of the breast since fatty tissue is the primary source of hormones that can drive breast cancer after menopause,” explained Christine Friedenreich, PhD, of the Alberta Health Services.

SOURCE: JAMA Oncology, online (July 16, 2015) doi:10.1001/jamaoncol.2015.2239 For the abstract and link to the full text, click here.

How fast do you walk? It may reveal how long you will live.

A third study seems to indicate that we can learn much about a person's health based on how fast they walk. In this study, researchers learned that those who walk 1 meter per second (about 2.25 mph) or faster consistently live longer than others of their age and sex who walk more slowly.

These findings were based on the analysis of nine previous studies that examined the walking speed, sex, age, body mass index, medical history and survival rate of almost 34,500 people. By the end of the study, the researchers could reliably predict the 10-year survival rate of a group of people based on how fast they walked along a 4-meter track.

Walking speed was a more accurate predictor of life expectancy than age or sex.

"The numbers were especially accurate for those older than 75. This suggests that for older people, walking speed could be a sort of "vital sign," like blood pressure and heart rate," the researchers commented.

The researchers also emphasized that the purpose of this study wasn't to get people to walk faster in hopes of living longer. "Your body chooses the walking speed that is best for you, and that is your speed, your health indicator," Studenski (one of the researchers) said. "And that's what it really is: an indicator. Going out and walking faster does not necessarily mean you will suddenly live longer. You still need to address the underlying health issues."

"The way we walk and how quickly we can walk depends on our energy, movement control and coordination, which, in turn, requires the proper functioning of multiple body systems, including the cardiovascular, nervous and musculoskeletal systems," Studenski said.

Researchers believe that this finding will have many practical applications. It is a quick and easy way for seniors and their doctors to gauge their own health. Walking speed, and in turn, mobility, will be a useful way to measure whether someone is still maintaining a healthy, active and independent lifestyle.

For the full article about this research, go here.

Conclusion

These three studies reveal that moderate-intensity exercise for a minimum of 300 minutes a week will maintain or improve your health, possibly prevent breast cancer, and perhaps increase your walking speed (an indicator of good health).

Some other articles that may interest you are:

I am a BCRPA-certified fitness instructor in Vancouver, BC. I teach four classes at the West End Community Centre in Vancouver, BC, mostly designed for the older adult. The Inevitable Disclaimer: Everything published here expresses only my opinion, based on my training and research. What you do with the information is entirely your own responsibility. I am not liable for any injury you suffer that seems to be related to anything you read here. Always consult your doctor before beginning an exercise program. For other articles, return to the table of contents.


  1. These three dots behave exactly like a footnote. Click on them and you will get more information about the topic. 

  2. Cardiovascular fitness is the ability of the heart and lungs to supply oxygen-rich blood to the working muscle tissues and the ability of the muscles to use oxygen to produce energy for movement. This type of fitness is a health-related component of physical fitness that is brought about by sustained physical activity. 

  3. Older age and obesity are two other risk factors.