Physical Activity and Cancer: Fact Sheet

Key Points

* Physical activity is any bodily movement produced by skeletal muscles; such movement results in an expenditure of energy.

* Physical activity is a critical component of energy balance, the term researchers use to describe how weight, diet, and physical activity influence health.

* There is strong evidence that physical activity is associated with a reduced risk of cancers of the colon and breast.

* Several studies also have reported links between physical activity and a reduced risk of prostate, lung, and endometrial (lining of the uterus) cancers.

* Current NCI-funded studies are exploring the role of physical activity in survivorship and quality of life, cancer risk, and the needs of populations at increased risk.

What is physical activity?

Physical activity is any bodily movement produced by skeletal muscles; such movement results in an expenditure of energy. Physical activity is a critical component of energy balance, a term used to describe how weight, diet, and physical activity influence health, including cancer risk.

How is physical activity related to health?

Researchers have established that regular physical activity can improve health by:
helping to control weight, maintaining healthy bones, muscles and joints, reducing the risk of developing high blood pressure and diabetes, promoting psychological well-being, reducing the risk of death from heart disease, and reducing the risk of premature death.

In addition to these health benefits, researchers are learning that physical activity can also affect the risk of cancer. There is convincing evidence that physical activity is associated with a reduced risk of cancers of the colon and breast (see IARC report under related topics). Several studies also have reported links between physical activity and a reduced risk of cancers of the prostate, lung and lining of the uterus (endometrial cancer). Despite these health benefits, recent studies have shown that more than 60 percent of Americans do not engage in enough regular physical activity.

How much physical activity do adults need?

The Centers for Disease Control and Prevention (CDC) recommend that adults: " engage in moderate-intensity physical activity for at least 30 minutes on five or more days of the week, or " engage in vigorous-intensity physical activity for at least 20 minutes on three or more days of the week (1). Examples of moderate-intensity and vigorous-intensity physical activities can be found on the CDC Physical Activity Page.

What is the relationship between physical activity and colon cancer risk?

Individuals who are physically active can reduce their risk of developing colon cancer by 40 percent to 50 percent, with the greatest reduction in risk among those who are most active. A decreased risk of colon cancer has been consistently reported for physically active men. Many studies have reported a reduction in colon cancer risk for physically active women. The relationship between physical activity and risk in women, however, has been less consistent.

Physical activity most likely influences the development of colon cancer through multiple, perhaps overlapping, biological pathways. Many researchers believe physical activity aids in regular bowel movements, which may decrease the time the colon is exposed to potential carcinogens. Increased physical activity also causes changes in insulin resistance, metabolism, and hormone levels, which may help prevent tumor development. Physical activity has also been found to alter a number of inflammatory and immune factors, some of which may influence colon cancer risk.

How can physical activity reduce breast cancer risk?

Physically active women have up to a 40 percent reduced risk of developing breast cancer. Most evidence suggests that physical activity reduces breast cancer risk in both premenopausal and postmenopausal women. Although a lifetime of regular, vigorous activity is thought to be of greatest benefit, women who occasionally engage in physical activity also experience a reduced risk compared to inactive women. A number of studies also suggest that the effect of physical activity may be different across levels of BMI, with the greatest benefit seen in women in the normal weight range (generally a BMI under 25 kg/m-squared). For example, a recent major report from the Women's Health Initiative found that among postmenopausal women, walking 30 minutes per day was associated with a 20 percent reduction in breast cancer risk. The health benefits of physical activity were greatest among women who were of normal weight; they experienced a 37 percent decrease in risk. The protective effect of physical activity was not found among overweight or obese women. Researchers have proposed several biological mechanisms that may explain the relationship between physical activity and breast cancer development. Physical activity causes changes in hormone metabolism, body mass, and immune function, which may prevent tumor development.

How might physical activity reduce prostate cancer risk?

Physical activity probably reduces men's risk for prostate cancer by 10 percent to 30 percent. The likely association between physical activity and prostate cancer is based on a small number of studies that evaluated the role of physical activity in men who developed prostate cancer. Most of these studies indicate that inactive men have higher rates of prostate cancer compared to men who are very physically active. While it is probable that men who are physically active experience a reduction in risk for prostate cancer, the potential biological mechanisms that may explain this association are unknown .

How might physical activity reduce endometrial cancer risk?

Studies also suggest that women who are physically active have a 30 percent to 40 percent reduced risk of endometrial cancer, with the greatest reduction in risk among those who are most active. The possible association between physical activity and endometrial cancer is based on a limited number of studies, some of which indicate that inactive women have higher rates of endometrial cancer compared to physically active women. Changes in body mass and alterations in level and metabolism of sex hormones, such as estrogen, are the major biological mechanisms thought to explain the association between physical activity and endometrial cancer. A few studies have examined whether the effect of physical activity varies according to the weight of the woman, but the results have been inconsistent.

How might physical activity reduce lung cancer risk?

It is possible that individuals who are physically active have a 30 percent to 40 percent reduced risk of developing lung cancer. The possible link between physical activity and lung cancer is based on a limited number of studies that have found higher rates of lung cancer among those who are physically inactive compared to those who are active, after accounting for smoking status. The relationship between physical activity and lung cancer risk is less clear for women than it is for men.

However, the results of many of these studies are difficult to interpret because smokers who are able to engage in physical activity may have much better lung function. Investigators hypothesize that improvements in pulmonary function and ventilation in active, compared to inactive individuals, may explain the possible association between lung cancer and reduced physical activity.

Is NCI exploring the role of physical activity in the quality of life and prognosis of cancer patients?

NCI-funded studies are exploring the ways in which physical activity may improve the quality of life of cancer patients and survivors. One study is examining the feasibility and benefits of a home-based moderate exercise program among breast cancer survivors (home-based). Another is testing the effectiveness of a nurse-directed walking exercise program to mitigate fatigue and maintain physical functioning during treatment for prostate, breast, or colorectal cancer.
For more information on these and related studies, go to: NCI Cancer Research Portfolio

What are some examples of NCI studies investigating the role of physical activity in cancer risk?

A number of NCI-funded studies are answering questions about the relationship between physical activity and the risk of developing cancer. For example, one study is investigating whether women who engage in moderate and strenuous physical activity have a reduced risk of endometrial and ovarian cancer, and if strenuous physical activity reduces this risk more than moderate physical activity. Another is examining the effect of one year of moderate aerobic and strength training exercise among patients with colorectal polyps.

Do any of these studies focus on special populations who are at increased risk of cancer?

NCI funds a number of research projects and interventions aimed at helping vulnerable populations reduce their risk for cancer by becoming more active, changing their nutritional behavior, and/or maintaining an optimal weight. Populations included in these projects include multiethnic working poor populations, African-American women, African-American church communities, rural church communities, overweight women, overweight men, and adolescents.

For example, one study involving rural churches is exploring methods of helping participants to change their nutrition, activity, and exercise patterns to meet cancer risk reduction guidelines.
NCI is supporting national and regional surveys to gain more accurate information on physical activity across all age groups and diverse populations as defined by race, ethnicity, income and other factors known to influence levels of physical activity. This information will help identify groups who may benefit from programs to increase physical activity.

http://www.cancer.gov/newscenter/pressreleases/PhysicalActivity

Exercise for Your Bone Health

Vital at every age for healthy bones, exercise is important for treating and preventing osteoporosis. Not only does exercise improve your bone health, it also increases muscle strength, coordination, and balance, and leads to better overall health.

Why Exercise?

Like muscle, bone is living tissue that responds to exercise by becoming stronger. Young women and men who exercise regularly generally achieve greater peak bone mass (maximum bone density and strength) than those who do not. For most people, bone mass peaks during the third decade of life. After that time, we can begin to lose bone. Women and men older than age 20 can help prevent bone loss with regular exercise. Exercising allows us to maintain muscle strength, coordination, and balance, which in turn help to prevent falls and related fractures. This is especially important for older adults and people who have been diagnosed with osteoporosis.

The Best Bone Building Exercise

The best exercise for your bones is the weight-bearing kind, which forces you to work against gravity. Some examples of weight-bearing exercises include lifting weights, walking, hiking, jogging, climbing stairs, tennis, and dancing. Examples of exercises that are not weight-bearing include swimming and bicycling. While these activities help build and maintain strong muscles and have excellent cardiovascular benefits, they are not the best way to exercise your bones.

Exercise Tips

If you have health problems - such as heart trouble, high blood pressure, diabetes, or obesity - or if you are over age 40, check with your doctor before you begin a regular exercise program.

According to the Surgeon General, the optimal goal is at least 30 minutes of physical activity on most days, preferably daily.

Listen to your body. When starting an exercise routine, you may have some muscle soreness and discomfort at the beginning, but this should not be painful or last more than 48 hours. If it does, you may be working too hard and need to ease up. STOP exercising if you have any chest pain or discomfort, and see your doctor before your next exercise session.

If you have osteoporosis, ask your doctor which activities are safe for you. If you have low bone mass, experts recommend that you protect your spine by avoiding exercises or activities that flex, bend, or twist it. Furthermore, you should avoid high-impact exercise in order to lower the risk of breaking a bone. You also might want to consult with an exercise specialist to learn the proper progression of activity, how to stretch and strengthen muscles safely, and how to correct poor posture habits. An exercise specialist should have a degree in exercise physiology, physical education, physical therapy, or a similar specialty. Be sure to ask if he or she is familiar with the special needs of people with osteoporosis.

A Complete Osteoporosis Program

Remember, exercise is only one part of an osteoporosis prevention or treatment program. Like a diet rich in calcium and vitamin D, exercise helps strengthen bones at any age. But proper exercise and diet may not be enough to stop bone loss caused by medical conditions, menopause, or lifestyle choices such as tobacco use and excessive alcohol consumption. It is important to speak with your doctor about your bone health. Discuss when you might be a candidate for a bone mineral density test. If you are diagnosed with low bone mass, ask what medications might help keep your bones strong.

For Your Information

For updates and for any questions about any medications you are taking, please contact the U.S. Food and Drug Administration at:
U.S. Food and Drug Administration
Toll Free: 888-INFO-FDA (888-463-6332)Website: http://www.fda.gov/

Fitness Predicts Longevity in Older Adults

Being physically fit after age 60 helps you live longer, regardless of your body’s fat content, according to a new study.

Although earlier research had suggested that obesity and low physical fitness each can increase the risk of dying during middle age, it was unclear whether this was also true in later years. In a new report from an ongoing study, Dr. Xuemei Sui of the University of South Carolina and her colleagues examined the links between fitness, fatness and mortality in older adults.

The scientists looked at more than 2,600 men and women, age 60 or older, who were participating in the Aerobics Center Longitudinal Study, funded by NIH’s National Institute on Aging (NIA) and National Heart, Lung and Blood Institute (NHLBI). Participants walked on a treadmill to determine their fitness levels. Their fat levels, or adiposity, were assessed by measuring their waist circumference, percent body fat and body mass index (a ratio of weight to height). The results were reported in the December 5, 2007, issue of the Journal of the American Medical Association.

During an average follow-up period of 12 years, 450 of the participants died. They were generally older, had lower fitness levels and had more cardiovascular risk factors, such as high blood pressure, high cholesterol and diabetes, than survivors. The percent of body fat did not appear to be related to the risk of dying. However, greater fitness, lower body mass index and lower waist circumference each reduced the risk of death.

The researchers grouped the participants into 5 categories based on their fitness levels. The least-fit group had a death rate 4 times higher than the fittest. Even those in the low-fitness group fared much better than the least-fit; the least-fit participants were twice as likely to die as those in the low-fitness group. In most cases, the death rates for those with higher fitness levels were less than half of the rates for those who were least fit but weighed similar amounts.

The researchers say their findings suggest that you don’t need to be thin to benefit from regular physical activity. Regular activity—like brisk walking for at least 30 minutes most days of the week—will keep most older adults out of the lowest fitness category and possibly help prolong their lives. A key to healthy aging is being physically active, regardless of your weight.—by Vicki Contie

http://www.nih.gov/news/research_matters/december2007/12172007fitness.htm

Bike update ...

Brought the bike into the local bike shop for a final tune-up today. Could not quite get the brakes adjusted, and I couldn't tighten down the headset.

In retrospect, since I'm not a bike mechanic, I should have bought the bike form a local bike shop. In the end the costs would have been the same, and I wouldn't have had all the frustration with shipping and delivery. 

Lesson learned!

New personal best for me today ...

Got up this morning and decided to combine a couple of my walk itineraries into one. So I did a 5-6 miler today (need to validate with car odometer), in an hour and 15 minutes.

On the last mile, I had thoughts of doing the loop again, but wisely thought that I had pushed enough today, and would leave the 10-12 mile fantasy for another day!

Competitive Walks

A question has surfaced as to why there are literally no competitive walks ... not race walking ... just regular fast walking competitions that most of us can do.

It seems that the walk (and run)  promoters have ignored the masses, the great number of people who might just take a turn at being competitive if it were possible for fast walkers.

The only walk/races that I could find are those sponsored by the Tidewater Walkers, in VA.

Any others? Am I missing something?

My bike finally arrived ...

My bike arrived, to my honest surprise, on 7:15PM, last Friday evening.

UPS must have figured out that since the bike arrived at the Deerfield Beach depot at 6AM on Friday, they could get it to me on Friday rather then on Monday. Good for UPS ... certainly the customer came first, and here the old addage applies ... under promise and over deliver.

Target customer service also got back to me, the delay was probably related to international time zone differences (I think they outsource their support to India). I got a very nice, and very well written, email of apology, and they waived my original shipping fee of $16.99 ... which was a nice gesture.

The lessons learned here (hopefully by both Target and UPS) is that it's not about the mistake, it's about how elegantly you recover from the mistake.

My bike story just got a lot uglier ....

So I ordered this great Forge bike on Target.com on 1/6 ... since this was the only reseller of Forge that I could find. I really liked the bike, and the price, expecially since I would be doing light fitness riding, to break up my walking routine.

So Target ships me the wrong bike, and I then ship the bike back to Target.com. Bye the way all of this shipping requires me to take off time from work. The least Target could have done was let me take it back to my local Target store, but no that would be over the top customer service.

So Target ships the correct bike (I assume that ... I still do not have the bike delivered ... read on) via UPS. UPS does not contact me on the day of delivery, and they leave a little note stuck in the door, that they will try a second attempt on 1/17 between 2PM and 5PM. So my wife arranges to be off from work and waits all afternoon for UPS to deliver the bike.

No bike delivery for me!

I call UPS customer support, and find out that they accidentally shipped my bike to Jacsonville, FL, and would deliver it on 1/18, but someone had to accept delivery, and sign for the bike.

Well we can't take more time off from work for these two stupid companies. So I suggested that they could deliver the bike to my office on 1/18. Not UPS ... they have to ship the bike to another UPS depot that services the area where my office is located. Result ... now they say they will deliver the bike on 1/21!

Duh!

Bye the way ... not once has anyone I've talked to at Target, or UPS ... said they were sorry for this incredilbly poor level of service.

I actually think I will cancel the order, and needless to say will never shop Target.com!

Fed-X rules!

Wake up and smell the roses ...

Did a relaxed 2.5 miles today thru Parkland Isles. Didn't look at the watch (oh maybe a couple of times), and decided that I would just have fun looking around and seeing what's in front of my face. It's really interesting when you really focus on your surroundings what you really can see.

Next walk I'm going to take my digital camera, and record the walk photographically, so when I can no longer do the walk I will be able to 'walk visually'!

My best time yet ...

I just did my measured 3.5 mile walk in 49 minutes this morning ... which for me is my personal best pace. The last mile was a real push, but at the end it was worth it ... thank god for 'Lucy in the Sky With Diamonds' ... and a couple of Led Zepplin tunes!

Doing the job correctly the first time ...

Well my bike arrived in almost record time ... ordered on Sunday and delivered on Friday. The only problem is that they delivered the wrong bike. It's really amazing how poor our services are getting.

The technology of online ordering is almost flawless in many cases, but when it comes to pick, pack, and ship ... it's all about the people. The bike they delivered to me was one digit off with regards to the one they were supposed to ship.

Now the company has to ship me a new bike, recondition the packaging of the wrong bike, and eat two additional shipping costs.

That will eat into their margin ... just because someone didn't take the time to do his/her job correctly!

More 2 legged exercise!

Well I did it ... finally got a really good bike for some alternative fitness. I found this great company ... Forge Bikes ... not a recognized brand ... yet! They have built a really nice bike with an aluminum frame and high quality components. Check them out at http://www.forgebikes.com

10K Today!

OK ... I reached the 10,000 steps per day level today, and I'll take this as a good omen for 2008.

I did a 2.5 mile brisk walk this AM, and then was just movin thru space over the course of the day got me to 10,001 ... OK so the last 50 steps were forced, and had me walking around outside until the pedometer clicked 10K!

Hi five me!

Holiday walking ...

Well, with all the holiday time off, I've really been putting in the miles. Found a terrific 2.5 mile walk through Parkland Isles, and down Holmberg road. Lots of water, birds, and nice houses.

Did my 2.5'er today in 37 minutes ... going to start tracking my miles as soon as I find a calendar widget for this blog.

Any ideas out there?

btw .... HAPPY NEW YEAR!