Posts tagged "Exercise"
Exercise fuels the brain's stress buffers
The article below is excerpted from the American Psychological Association help center. I thought you might find it interesting to learn directly what the psychology profession believes about the positive impact of exercise on stress.
Exercise fuels the brain's stress buffers
Exercise may improve mental health by helping the brain cope better with stress, according to research into the effect of exercise on neurochemicals involved in the body's stress response.
Preliminary evidence suggests that physically active people have lower rates of anxiety and depression than sedentary people. But little work has focused on why that should be. So to determine how exercise might bring about its mental health benefits, some researchers are looking at possible links between exercise and brain chemicals associated with stress, anxiety, and depression.
So far there's little evidence for the popular theory that exercise causes a rush of endorphins. Rather, one line of research points to the less familiar neuromodulator norepinephrine, which may help the brain deal with stress more efficiently.
Work in animals since the late 1980s has found that exercise increases brain concentrations of norepinephrine in brain regions involved in the body's stress response.
Norepinephrine is particularly interesting to researchers because 50 percent of the brain's supply is produced in the locus coeruleus, a brain area that connects most of the brain regions involved in emotional and stress responses. The chemical is thought to play a major role in modulating the action of other, more prevalent neurotransmitters that play a direct role in the stress response. And although researchers are unsure of exactly how most antidepressants work, they know that some increase brain concentrations of norepinephrine.
But some psychologists don't think it's a simple matter of more norepinephrine equals less stress and anxiety and therefore less depression. Instead, they think exercise thwarts depression and anxiety by enhancing the body's ability to respond to stress.
Biologically, exercise seems to give the body a chance to practice dealing with stress. It forces the body's physiological systems - all of which are involved in the stress response - to communicate much more closely than usual: The cardiovascular system communicates with the renal system, which communicates with the muscular system. And all of these are controlled by the central and sympathetic nervous systems, which also must communicate with each other. This workout of the body's communication system may be the true value of exercise; the more sedentary we get, the less efficient our bodies in responding to stress.
Thanks to Rod K. Dishman, PhD, of the University of Georgia, and Mark Sothmann, PhD, of Indiana University's School of Medicine and School of Allied Health Sciences.
The Best Exercise for Healthy Bones
Healthy Bones?
A special section of Medicine & Science in Sports & Exercise, the journal of the American College of Sports Medicine detailed a continuing controversy in the field of sports science about exactly how exercise works on bone and why sometimes, it doesn’t. “There was a time, not so long ago,” when most researchers assumed “that any and all activity would be beneficial for bone health,” says Dr. Daniel W. Barry, an assistant professor of medicine at the University of Colorado, at Denver, who has studied the bones of athletes and the elderly.
Recent Research
Recent findings are showing that competitive swimmers had lower-than-anticipated bone density, and that competitive cyclists sometimes had fragile bones and, finally, some studies suggest, that weight lifting did not necessarily strengthen bones much. Too much endurance exercise may actually reduce bone density. In a study by Dr. D.W. Barry, competitive cyclists lost bone density during a long training season. Dr. Barry says that it’s possible that exercise that is too prolonged or intense may lead to too much calcium loss through sweat. The endocrine system may interpret this loss of calcium as serious enough to start leaching the mineral from bone.
The Best Exercise
The current message about exercise and bone building may be that the best exercise is to simply jump up and down. "Jumping is great, if your bones are strong enough to begin with,” Dr. Barry says. “You probably don’t need to do a lot either.” (If you have a family history of osteoporosis, check with a doctor.) 
Hopping also aids in balance, which may be as important as bone strength in keeping fractures at bay. Dr. Barry says, “fragile bones don’t matter, from a clinical standpoint, if you don’t fall down.
Why Exercise Makes You Less Anxious
Exercise Creates new Brain Cells
Researchers at Princeton University recently made a remarkable discovery about how neurons respond differently to stress than to inactivity. Scientists have known for some time that exercise stimulates the creation of new brain cells (neurons) but not how, precisely, these neurons might be functionally different from other brain cells.
Exercise creates a Calm Brain
Preliminary results presented at the annual meeting of the Society for Neuroscience in Chicago, showed that experimental rats had created, through running, a brain that seemed biochemically, molecularly, calm when presented with stressful situations.
How Exercise Remodels the Brain
For years, it has been a given that exercise enhances mood. But how exercise might directly affect mood and anxiety — psychological states — was unclear. Now, thanks to improved research techniques scientists are beginning to tease out how exercise remodels the brain, making it more resistant to stress. At the University of Colorado, Boulder, scientists have examined the role of the neurotransmitter serotonin, considered to be the “happy” brain chemical. The view of serotonin has been undermined by this and other research. In those experiments, rats exposed to a laboratory stressor, showed increased serotonin activity in their brains. But those rats, that had run for several weeks before being stressed, showed less serotonin activity and were less anxious and helpless despite the stress.
Moderate Exercise reduces Effects of Oxidative Stress
Researchers have looked at how exercise alters the activity of the dopamine neurotransmitter in the brain, and on the antioxidant powers of moderate exercise. Anxiety in people has been linked with excessive oxidative stress, which can lead to cell death, including in the brain. Moderate exercise, appears to reduce the effects of oxidative stress. In an experiment at the University of Houston, rats whose oxidative-stress levels had been artificially increased were extremely anxious when faced with unfamiliar terrain during laboratory testing. But rats that had exercised, even if they had received the oxidizing chemical, were relatively calm under stress. When placed in unfamiliar circumstances, they didn’t run and hide, like the unexercised rats. They casually explored.
Positive Stress of Exercise
“It looks more and more like the positive stress of exercise prepares cells and structures and pathways within the brain so that they’re more equipped to handle stress in other forms,” says Michael Hopkins, affiliated with the Neurobiology of Learning and Memory Laboratory at Dartmouth, who has been studying how exercise differently affects thinking and emotion. “It’s pretty amazing, really, that you can get this translation from the realm of purely physical stresses to the realm of psychological stressors.”
Don’t Quit, Keep Exercising
The stress-reducing changes evoked by exercise on the brain don’t happen overnight. In the University of Colorado experiments, rats that ran for only three weeks did not show much reduction in stress anxiety, but those that ran for six weeks did. “Something happened between three and six weeks,” says Benjamin Greenwood, a researcher in the Department of Integrative Physiology at the University of Colorado. Dr. Greenwood added that it was “not clear how that translates” into exercise advice for humans. We do not know how intense the exercise needs to be. Dr. Greenwood says, the lesson is “don’t quit.” Keep running or cycling or swimming or doing Yoga. You may not feel a magical reduction of stress after your class, if you haven’t been exercising. But the molecular biochemical changes will begin, Dr. Greenwood says. And eventually, he says, they become “profound.”
See the New York Times
