Issue 91 June 19, 2006

Scientists keep piling on the reasons why exercise can save your life. It’s a good thing, too, because in our busy world, we need lots of support for our exercise habits. It’s easy to let a workout slip when we are inundated by other pressures. But, especially during the summer months, exercise is an ally in the fight against skin cancer.

A study reported in the May 13 issue of the medical journal Carcinogenesis found that mice exposed to ultraviolet B light (UVB) who were also provided continual access to running wheels took longer to develop skin tumors and developed fewer and smaller tumors than a group of similarly exposed mice that didn't have a gym handy. This is the first time the relationship between skin carcinogenesis and increased activity by voluntary running wheel exercise has been studied in a laboratory. In both groups, the number of tumors per mouse increased with time, but animals with access to running wheels had approximately 32 percent fewer tumors than animals without running wheels.

Tumor size per mouse in the non-exercising group was, on average, more than three times greater than that of the group with the running wheels. As one might expect, the exercising mice ate and drank more but had less body fat than their more sedentary associates. The number of tumors also decreased among mice with lower amounts of body fat.

"This relationship between body fat and tumors may also play an important role in carcinogenesis and warrants further investigation, particularly with obesity on the increase in the Western world," says Allan H. Conney, Professor of Chemical Biology at Rutgers University.

In another first, the researchers also detected what could be the mechanism responsible for this effect. Follow-up work suggests that exercise enhances UVB-induced apoptosis (programmed cell death) both in the skin - a normal, protective process that removes sun-damaged cells - and in UVB-induced tumors.

"While UVB is triggering the development of tumors, exercise is counteracting the effect by stimulating the death of the developing cancer cells," says Conney, who is also the director of the Susan Lehman Cullman Laboratory for Cancer Research at Rutgers' Ernest Mario School of Pharmacy.

Conney noted that all these conclusions are based on laboratory studies on mice, and it is not yet known whether exercise decreases the risk of sunlight-induced skin cancer in humans. Clinical trials are needed to further investigate these findings.

But since there is no downside to exercise, be like Mighty Mouse and hit the running wheel, er, treadmill!

Obesity Linked to All Types of Breast Cancer
According to a new study, women who gain weight in adulthood face a higher lifetime risk of all types of breast cancer. Published in the July 1, 2006 issue of CANCER, a journal of the American Cancer Society, the study reveals that the greater the weight gain as an adult, the greater the risk for all types, tumor stages, and grades of breast cancer, particularly advanced malignancies. The most obese women were up to three times more likely to have regional or distant metastases than women with less weight gain. Fat tissue increases circulating estrogen, thereby adding to the risk. Interestingly, current weight as defined by body mass index was not as important as a woman's weight gain from the age of 18. Led by Heather Spencer Feigelson of the American Cancer Society, researchers investigated the risk between weight gain and type of invasive breast cancer among 44,161 postmenopausal women who were not taking hormone therapy. The researchers found that the greater the weight gain, the greater the risk for all types, stages, and grades of breast cancer. Compared to women who gained 20 pounds or less during adulthood, women who gained more than 60 pounds were almost twice as likely to have ductal-type tumors and more than 1.5 times more likely to have lobular-type cancers. The risk for metastatic disease increased for all women who gained weight, with the risk greater than three-fold for women who gained more than 60 pounds. Dr. Feigelson and her colleagues conclude that "these data further illustrate the relationship between adult weight gain and breast cancer, and the importance of maintaining a healthy body weight throughout adulthood."

Exercise Unlikely to Cause Sudden Cardiac Death in Women
Sudden cardiac death during exertion is an extremely rare occurrence in women, and regular moderate to vigorous exercise may significantly lower the long-term risk, according to a study in the March 22/29, 2006 issue of the Journal of the American Medical Association, an issue devoted to women's health. Despite the known benefits of exercise, studies have also documented associations between incidents of exertion and sudden cardiac death. Dr. Christine Albert and colleagues used data from the Nurses' Health Study to determine the risk of sudden cardiac death in women during moderate to vigorous exertion. There were 288 cases of sudden cardiac death among the 84,888 women who completed the 1980 questionnaire. The researchers found that only nine of these deaths actually took place during moderate to vigorous exertion, and that only three of these happened while the women were exercising. Of 69,693 women without a history of CHD, stroke, or cancer at the study's beginning, 32 percent (22,172) reported no regular moderate to vigorous exercise, and 15 percent (10,680) reported exercising for four or more hours per week. The absolute risk of sudden cardiac death associated with moderate to vigorous exertion was "exceedingly low," the researchers found, at 1 per 36.5 million hours of exertion. Risk of sudden cardiac death was temporarily elevated during moderate to vigorous exertion, compared to the risk during lesser or no exertion. Regular moderate to vigorous activity lessened this temporary risk, and was also associated with a lower long-term risk of sudden cardiac death.

Athlete's Corner
Consider incorporating the following dynamic exercises pre-race or before any high intensity workout. These exercises stretch muscles more effectively than static stretches. Begin with a light five- to 10-minute jog. Always maintain good posture.
Straight leg march: Begin by standing with your arms at your sides. Swing your straight right leg and left arm forward, and touch your left hand to your right knee or shin, whichever you can reach. Switch as you "walk" forward.
Walking knee to elbow: While standing on your toes, start with the arms in front of you, a little lower than shoulder height and slightly bent. Raise your right knee to your left elbow and repeat on alternate side. Move slowly back from the spot where you ended after the first exercise.
Shuffle/Crab: Turn sideways and assume a crouch with wide legs. Begin by moving your right leg away from the left, and then bring the left to meet the right, all while moving sideways in a shuffling motion. This exercise activates the musculature of the hip, increasing range of motion and movement efficiency. Try to keep the toes pointing forward (the direction you're facing) instead of the way you're moving. Repeat with the left leg leading.
Back pedal: Simply run backwards over the 10 to 12 yards while over-exaggerating your stride. Pace is slightly faster than moderate for this movement. Be light on your feet.
Strides: Sprint at 50 percent of your max speed for 10 to 12 yards, moving forward with a slight over-stride. With this circuit, allow 10 to 15 seconds walking rest between each movement, and repeat the entire circuit two or three times.
(Modified from advice appearing on acefitness.com)

Want more information? Please contact Laura Jones at: (434)978-3800