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“Resistance training is moving ‘front and center’ as a major behavioral lifestyle activity for improving health, preventing disease, and even reducing the risk for premature death. Rather than being an ‘adjunct’ to other components in a lifestyle, it now appears that resistance training is central to a healthy lifestyle.” Richard Winett, PhD, Master Trainer, August 2009
“Strength and fitness are likely partly protective through some overlapping mechanisms, but also operate more powerfully through independent mechanisms. Therefore, continuing to perform both resistance and aerobic training makes sense.” Richard Winett, PhD, Master Trainer, August 2009
Strength and Fitness Fight Cancer Independently
Resistance Training Aids Breast Cancer Rehab
We are learning more and more about the health benefits of exercise. We have three new studies on different forms of exercise and cancer. One study deals with leisure-time physical activity and cancer mortality. Another evaluates the benefits of weight training after treatment for breast-cancer. Finally, we have a comprehensive study which examines muscular strength, body fat, and aerobic fitness as cancer predictors.
Let’s look at the studies separately, and then together.
Physical Activity—Effort Counts
A study from Finland, first published in the British Journal of Sports Medicine on July 28, 2009, found that at least 30 minutes a day of moderate to high intensity physical activity cut cancer deaths in half.
Some have proposed that the volume of physical activity—burning 1,000 calories a week, for example—is as or more important than the type, frequency, or intensity of the activity. The aim of his study was to assess the role of intensity in the reduction of cancer mortality. Is picking berries or fishing as effective as running, skiing, or lifting weights?
To find out, 2,560 men, aged 42 to 60, with no history of cancer, were questioned about their leisure-time physical activities (frequency, duration, and intensity) over a period of one year, and then followed for an average of 16.7 years. During the follow-up period, there were 181 cancer-related deaths, mainly gastrointestinal (57) and lung cancer (48).
Exercise intensity was measured in metabolic equivalents of oxygen consumption (METs). One MET is defined as the oxygen uptake when a person is at rest. In this study, the average oxygen uptake of running was 10.1 MET, skiing was 9.6 MET, ball games was 6.7 MET, biking to work was 5.8 MET, dancing and weight lifting were 5 MET, brisk walking was 4.2 MET, picking berries was 3.6 MET, and fishing was 2.4 MET. (MET ratings, of course, vary based on the effort put into the activity. Running, for example, uses more oxygen than jogging.)
Here’s what they found.
Men with leisure-time physical activity averaging more than 5.2 MET (highest quartile) were found to have half the risk of dying from cancer compared to men with an average intensity level of 3.7 MET (lowest quartile). The fitness of the participants was also measured using a maximum exercise tolerance test on a cycle ergometer. “An increase of 1 MET of physical fitness amounted to a 12% reduced risk in cancer death,” the researchers reported. (Results were after adjustment for age, smoking, alcohol consumption, body mass index, and total intake of calories, fat, and fiber.)
So, intensity level does indeed make a difference, a big difference. (That stands to reason, because high-intensity exercise triggers positive adaptations. That's what overload is about.)
“Mean intensity of leisure-time physical activity is inversely associated with the risk of premature death from cancer in men,” the report concluded.
“Intensity should be at least moderate so that the beneficial effect of physical activity for reducing overall cancer mortality can be achieved,” the researchers wrote. “Anything above an average of 4 MET can be considered moderate-intensity exercise,” said Sudhir Kurl, MD, the lead researcher.
Little research has been done on the mechanisms by which moderate to high intensity physical exercise prevents cancer development, but the researchers speculated that they include “beneficial effects on energy balance and body mass, intestinal transit time, hormonal concentrations (e.g., reduced testosterone), prostaglandin levels and antioxidant enzyme activities….It is also possible that exercise training can improve the non-specific immune systems…which are thought to be the primary line of defense against the development of malignancies.”
Asked if he practices what he preaches, Dr. Kurl replied: “Of course!” He jogs 3 times a week and works out in the gym twice a week.
I interpret that to mean that he lifts weights, which brings us to an important--and liberating--new study of weight training for breast-cancer survivors.
Lifting after Breast-Cancer Treatment
“For many years, we told [breast-cancer survivors] not to lift anything heavier than a handbag,” said Anna Schwartz, an affiliate professor of nursing and author of Cancer Fitness, who was not involved in the new study. “This is the first really well-designed study that demonstrates that women can do a lot more than we thought.”
The impediment is lymphedema, one of the most troubling complications that can develop after treatment for breast cancer; up to 70% of beast-cancer survivors experience some symptoms of lymphedema. This unceasing condition adds to the physical and emotional strain of dealing with breast cancer.
The underlying problem is damage to the lymphatic system in the area of the breast. The lymphatic system drains the body's tissues and organs into a series of tubes or ducts. Lymph fluid contains mostly protein and white blood cells (the blood cells that fight infection). The fluid is filtered through lymph nodes (glands) and eventually drains into the bloodstream. Lymphedema is swelling caused by build up of lymph fluid after the patient’s lymph nodes are removed or interrupted during surgery or radiation. The swelling causes discomfort and pain in the arms and hands.
Doctors have typically told lymphedema sufferers to avoid lifting anything over 10-15 pounds--2 pounds with the affected limb--because of the potential for flare up and infection. Women are advised to ask for help with shopping bags, avoid picking up children, and to stick with milder forms of exercise, such as walking, swimming and light aerobics. Weight lifting is a definite “no-no.”
A new study by Kathryn H. Schmitz, PhD, MPH, University of Pennsylvania School of Medicine, and colleagues, published August 13, 2009 in the New England Journal of Medicine, shows that the dangers of resistance training may have been overblown—that strength training may actually be a substantial help to women struggling with lymphedema.
The study randomly assigned 141 breast-cancer survivors with stable lymphedema (average age mid-50s) to a twice weekly 90-minute progressive weight lifting program or a control group that did no lifting. The carefully monitored sessions included gentle stretching, cardiovascular warm-up, abdominal and back exercises, and standard weight-lifting exercises for the upper and lower body. The lifting started with “little-to-no resistance.” As long as no signs of flare-up were noted, resistance was progressively increased by “the smallest possible increments.” No upper limits were placed on the weight to which women could progress in any exercise. “During lymphedema exacerbations,” upper body exercises were stopped until a “lymphedema therapist” gave approval to resume training “with resistance reset to the lowest possible level and then increased again” as before. Lower body training continued. In short, they tried hard to do no harm.
The careful year-long program was well rewarded.
Importantly, there were “no serious adverse events related to the intervention.” At the end of the study, the women who lifted were significantly stronger than the controls. Some of the women could bench press as much as 85 pounds, with an average of 53 pounds—a 29% improvement. The proportion of women who experienced swelling was 11-12% in both groups, but the lifters were more likely to report that their symptoms had improved, with half as many (14%) reporting flare-ups as the controls (29%). This is consistent with previous findings that exercise “enhances the flow of lymph and improves protein resorption and that the increased pulmonary work associated with exercise assists lymph flow,” the report explained.
“Slowly progressive weight lifting had no significant effect on limb swelling and resulted in a decreased incidence of exacerbation of lymphedema, reduced symptoms, and increased strength,” the report concluded.
Lead author Kathryn Schmitz, an exercise physiologist, is optimistic that the study will change doctors’ advice on weight training to lymphedema-sufferers. “Hopefully this will be the last nail in the coffin for that kind of misguided advice,” she told reporters.
The third and last study looks at multiple factors as cancer predictors. It extends previous analysis by the same researchers showing that “muscular strength…is inversely and independently associated with all-cause cancer mortality, even after adjusting for cardiovascular fitness.” The aim of the new study was to examine the “independent and joint associations” of muscular strength, fatness, and cardiovascular fitness with cancer mortality.
Spot-light on Muscular Strength
We already have good evidence that aerobic fitness lessens cancer risk; see the Miracle of Movement http://www.cbass.com/MiracleMovement.htm . We also know the overweight kills: http://www.cbass.com/Overweightkills.htm . This study and the earlier analysis by the same researchers cast a new light on muscular strength as a major predictor of cancer mortality. Both studies, led by Jonatan R. Ruiz of the Department of Biosciences and Nutrition at the Karolinska Institute in Hudding, Sweden, utilized data collected at the Cooper Clinic in Dallas, Texas, and incorporated into the Aerobic Center Longitudinal Study (ACLS). The new study by Ruiz and colleagues is reported in Cancer Epidemiology, Biomarkers & Prevention (May 2009).
The study involved 8,677 men (age 20 to 80) who received comprehensive medical exams, including muscular strength and aerobic fitness testing, at the Cooper Clinic between 1980 and 1989. Body composition was also measured as part of the exam. During an average follow-up period of 18.9 years (ending December 31, 2003), 503 of the men died, 199 from cancer and 145 from cardiovascular disease. (Dr. Cooper has told me that I am enrolled in the ongoing ACLS.)
Muscular strength in the upper and lower body was tested using one-rep maximum in the bench press and leg press. Cardiovascular fitness was measured with a maximal treadmill test. In both categories, the men were divided into three equal groups based on age-specific performance. Men with the best performance were placed in the top third, the men with the poorest performance in the bottom third, with those in between in the middle third.
The stated purpose of the study was to examine the associations between muscular strength, overall and waistline fatness, and cancer deaths.
Here is the primary conclusion: “Higher levels of muscular strength are associated with lower cancer mortality risk in men, independent of...overall and central adiposity, and other potential confounders.” There’s more to it than that, however.
The details are quite enlightening for anyone interested in living a long and healthy life. The particulars are a bit mind-numbing, but the end result is clear as a bell.
There were three main findings on strength, fatness and cancer mortality.
First, muscular strength was significantly and inversely associated with cancer mortality; men in the moderate and high strength category had about 37% fewer cancer deaths than those in the lowest strength category. This association remained after adjustment for overall and waistline fatness, and for cardiovascular fitness.
Secondly, percent body fat was positively associated with rates of cancer mortality; higher body fat was associated with higher rates of cancer deaths. This association, however, did not persist after adjustment for muscular strength or cardiovascular fitness. In other words, higher strength and fitness appear to substantially override higher body fat.
Third, a combination of muscular strength and fatness is powerfully associated with cancer death; men in the lowest third for muscular strength with high levels of fatness have a 40% to 50% higher rate of cancer death than obese men with at least moderate (middle third) muscular strength. In short, a moderate level of muscular strength helps a lot if you are obese.
“Taken together, these findings indicate that having at least moderate age-adjusted levels of muscular strength may counteract the deleterious consequences attributed to adiposity,” the report stated. “Efforts should then focus not only on reducing levels of adiposity but also on increasing the muscular strength level.” (Emphasis mine)
Now we shift focus to cardiovascular fitness. Listen to what Ruiz and his colleagues say about the importance of aerobic fitness: “Higher levels of cardiorespiratory fitness are strongly associated with lower risk of cancer mortality in men and women, young or older people, and in diabetic or nondiabetic persons, independently of their weight status and tobacco use.” Clearly, aerobic fitness has a powerful effect on cancer risk.
The Ruiz report says men who were strong but unfit were at appreciably higher risk than men who were strong and fit.
(This is important!) The study found that muscular strength and cardiorespiratory fitness were only “moderately correlated.” This suggests that the associations between the two forms of fitness and cancer risk involve “different mechanisms.” Both strength and aerobic fitness appear to have profound and independent effects on cancer risk. A combination of the two forms of fitness, working together, would appear to be most protective—and that’s what the study found.
Age-adjusted death rate in men with high levels of both muscular strength and cardiovascular fitness was 60% lower than the death rate in unfit men with the lowest level of muscular strength. Unquestionably, it pays to be both strong and fit.
The Ruiz report lists a number of “plausible mechanisms” that may explain the independent protective benefits of higher levels of muscular strength. They include: “regulation in the metabolism of insulin, and insulin-like growth factors…, reduced exposure to systemic inflammation, sex hormones, improved antioxidant defense and immune function, and reduced overall and central adiposity.”
The take-home message from Ruiz and his colleagues is loud and clear: “Maintaining a healthy weight should continue to be a cornerstone in the prevention of chronic disease and premature death….It is equally important to maintain healthy muscular strength levels, and, most importantly, to prevent falling into the lower strength categories.”
They suggest regular resistance training involving the major muscle groups of the upper and lower body at least two days per week. “Resistance and aerobic exercise should complement each other.” (My emphasis)
My friend Dr. Richard Winett, who made me aware of the Ruiz study, summed up the new status of strength/resistance training in the August, 2009 issue of his Master Trainer: “Resistance training is moving ‘front and center’ as a major behavioral lifestyle activity for improving health, preventing disease, and even reducing the risk for premature death. Rather than being an ‘adjunct’ to other components in a lifestyle, it now appears that resistance training is central to a healthy lifestyle.”
Referring to the findings of the Ruiz study, he added: “Strength and fitness are likely partly protective through some overlapping mechanisms, but also operate more powerfully through independent mechanisms. Therefore, continuing to perform both resistance and aerobic training makes sense.”
The simple regimen of Sudhir Kurl, MD, the lead researcher in the study from Finland on leisure-time physical activity, embodies the new science-based prescription for fitness and health. He jogs and lifts.
Yes, I know; that’s the old formula. The difference is that we now have a much better understanding of why it works so well.
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