It's that time of year again--days filled with friends, family, and, of course, lots of food. We remember the fun times we shared, the presents we gave and received, and now the long list of well-intentioned New Year's resolutions. It's inevitable not to fulfill every goal on your list, but if there's one to conquer in the coming year, more exercise is definitely the one. It does more good than you think.
Everybody knows that aerobic exercise builds endurance and strengthens the heart, and strength training builds muscles. But did you know that exercise creates new brain cells? Or that it can help ward off cancer and diabetes? Or that it can keep you from accumulating the wrong kind of body fat?
My colleague David Schardt, senior nutritionist at the Center for Science in the Public Interest, examines the many health benefits of exercise in depth in the current issue of Nutrition Action Healthletter. Here is some of what he found:
1. Exercise curbs your risk of cancer. Researchers at the Washington University School of Medicine in St. Louis, who recently reviewed 52 studies of exercise and colon cancer, found that the most active people were 21 percent less likely to be diagnosed with this cancer than their least active counterparts. Brisk walking or other moderate activities may lower the risk of colon cancer, but studies show moderate-to-vigorous exercise is needed to reduce the risk of breast cancer.
The good news is that it may never be too late to start exercising. In the NIH-AARP Diet and Health Study, researchers tracked 119,000 women in their 50s and 60s for seven years. Those who reported more than an hour a day of moderate-to-vigorous activity--even if they hadn't exercised earlier in life--were 16 percent less likely to be diagnosed with breast cancer than those who rarely exercised. The American Cancer Society now recommends at least 30 minutes of moderate-to-vigorous exercise five days a week, but 45 to 60 minutes is preferable.
2. Exercise Creates New Brain Cells. On average, older adults perform more slowly and less accurately on cognitive tests than do younger people. But older adults who are more fit perform better and are sometimes no different from young adults, according to Charles Hillman, director of the Neurocognitive Kinesiology Laboratory at the University of Illinois at Urbana-Champaign. A 2006 study by University of Illinois researchers put 30 healthy, but sedentary, men and women aged 60 to 79 on an aerobic exercise training program. After six months, their brain volume had increased--meaning more grey and white matter--and more connections formed between brain cells. Aerobic exercise increases the supply of a protein called BDNF (brain-derived neurotrophic factor), which protects brain neurons and promotes the growth of new nerve cells and synapses that are related to learning and memory.
3. Exercise Boosts Insulin Sensitivity. As we age or put on weight, our bodies don't respond as well to insulin, a hormone that allows blood sugar to enter cells, where it is stored or used as fuel. Aerobic and strength-training exercises improve insulin sensitivity by increasing the number of protein molecules called glucose transporters, which allow your cells to better respond to insulin. Insulin resistance increases the risk of heart disease and, if blood sugar levels continue to rise, type two diabetes.
4. Creatine Helps Build Muscle. Creatine makes energy available to muscles during times of high demand, so if you have more creatine in your muscles, you can lift heavier weights for a longer period of time. For men and women, the compound turns on muscle-building genes--which direct muscle proteins to grow--and stimulates satellite cells that form new muscle fibers after they've been damaged by injury, disease, or weightlifting. It is naturally produced by the liver and kidneys or can be purchased in a powder and pill form over the counter.
5. Sitting Can Kill You. According to Peter Katzmarzyk, an epidemiologist at the Pennington Biomedical Research Center in Baton Rouge, Louisiana, people who spend most of the day sitting down have much higher mortality rates than those who don't, even if they are physically active during another part of the day. The inactivity of muscles while sitting may change the way they metabolize compounds and may affect the regulation of insulin and glucose. Instead of sitting for long periods of time, try standing up periodically, walking around, or engaging in similar activities to encourage blood flow and increase muscle activity in your legs.
6. You're Never Too Old to Build Muscle. Dozens of studies show that you can build up your muscles and increase your strength with resistance or weight training no matter how old you are. Ben Hurley, an exercise physiologist at the University of Maryland, says the oldest person he's known of to do this was 103 years old. Hurley suggests building muscle three times per week, which can become more noticeable in as little as four weeks. Your strength--the maximum force you can produce--improves in as little as one workout.
7. Exercise Prevents Visceral Fat Gain. Visceral fat, which accumulates around the organs deep inside the belly, is linked to insulin resistance, heart disease, and diabetes. In 2005, Cris Slentz, an exercise physiologist at the Duke University Medical Center, and his colleagues reported that sedentary overweight men and women who followed an exercise program equivalent to a 30-minute walks six times a week for eight months stopped gaining visceral fat. If they increased their exercise routine to the equivalent of jogging 20 miles a week, they lost seven percent of their abdominal fat as well. Surprisingly though, people in the control group, who was not told to step up their exercise, saw their visceral fat increase by nine percent after six months.
Excess weight can cause serious health problems and raise health care costs. Americans spend approximately $150 billion a year on medical expenditures related to obesity. It's never too late to start a regular exercise routine, so lace up those sneakers and hit the gym or take your workout outside. Grab a buddy if you need some encouragement, but do yourself a favor and get moving!
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