Semua Ada Chasya

8.03.2010

New Straits Times

Exercise to stay calm
By Gretchen Reynolds

RESEARCHERS at Princeton University recently made a remarkable discovery about the brains of rats that exercise. Some of their neurons respond differently to stress than the neurons of slothful rats.
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. In the experiment, preliminary results of which were presented last month at the annual meeting of the Society for Neuroscience in Chicago, scientists allowed one group of rats to run.

Another set of rodents was not allowed to exercise.

Then all of the rats swam in cold water, which they don't like to do.

Afterward, the scientists examined the animals' brains.

They found that the stress of the swimming activated neurons in all of the brains.

(The researchers could tell which neurons were activated because the cells expressed specific genes in response to the stress.) But the youngest brain cells in the running rats, the cells that the scientists assumed were created by running, were less likely to express the genes.

They generally remained quiet.

The "cells born from running," the researchers concluded, appeared to have been "specifically buffered from exposure to a stressful experience." The rats had created, through running, a brain that seemed biochemically, molecularly, calm. For years, both in popular imagination and in scientific circles, it has been a given that exercise enhances mood.

But how exercise, a physiological activity, might directly affect mood and anxiety-psychological states was unclear.

Now, thanks in no small part to improved research techniques and a growing understanding of the biochemistry and the genetics of thought itself, scientists are beginning to tease out how exercise remodels the brain, making it more resistant to stress.

In work undertaken at the University of Colorado, Boulder, for instance, scientists have examined the role of serotonin, a neurotransmitter often considered to be the "happy" brain chemical.

That simplistic view of serotonin has been undermined by other researchers, and the University of Colorado work further dilutes the idea.

In those experiments, rats taught to feel helpless and anxious, by being exposed to a laboratory stressor, showed increased serotonin activity in their brains.

But 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, though, appears to dampen the effects of oxidative stress.

In an experiment led by researchers at the University of Houston and reported at the Society for Neuroscience meeting, rats whose oxidative-stress levels had been artificially increased with injections of certain chemicals were extremely anxious when faced with unfamiliar terrain during laboratory testing.

But rats that had exercised, even if they had received the oxidising chemical, were relatively non-chalant under stress.

When placed in the unfamiliar space, they didn't run for dark corners and hide, like the unexercised rats. "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, a graduate student 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." The stress-reducing changes wrought by exercise on the brain don't happen overnight, however, as virtually every researcher agrees.

In the University of Colorado experiments, for instance, rats that ran for only three weeks did not show much reduction in stress-induced anxiety, but those that ran for at least six weeks did.

Research associate Benjamin Greenwood said that it was "not clear how that translates" into an exercise prescription for humans.

We may require more weeks of working out, or maybe less.

And no one has yet studied how intense the exercise needs to be.

But the lesson, he says, is "don't quit." Keep running or cycling or swimming.

(Animal experiments have focused exclusively on aerobic, endurance-type activities.) You may not feel a magical reduction of stress after your first jog, if you haven't been exercising.

But the molecular biochemical changes will begin, he says.

And eventually, he says, they become "profound."

7.26.2010

Human Resources Management

Human Resources Management The HRM function and HRD profession have undergone tremendous change over the past 20-30 years. Many years ago, large organizations looked to the "Personnel Department," mostly to manage the paperwork around hiring and paying people. More recently, organizations consider the "HR Department" as playing a major role in staffing, training and helping to manage people so that people and the organization are performing at maximum capability in a highly fulfilling manner. Recently, the phrase "talent management" is being used to refer the activities to attract, develop and retain employees. Some people and organizations use the phrase to refer especially to talented and/or high-potential employees.