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.
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Body Shape, Fat Distribution May Be Best Predictor of Health Risks
Excess body fat is a health hazard, but the distribution of that fat may be the best predictor of future health risks. The results of a new study published in the September issue of the American Journal of Clinical Nutrition indicate that how much fat a person has is less important than the location of fat when it comes to determining risk for cardiovascular disease.
For the study, researchers at Wake Forest University Baptist Medical Center evaluated body fat distribution in nearly 400 adults between the ages of 47 and 86. They found that the amount of non-subcutaneous fat — the fat deposited around organs and between muscles — was directly correlated to the amount of hard, calcified plaque present in the body.
Calcified plaque is associated with the development of atherosclerosis, or hardening of the arteries, a condition that increases the risk of developing heart disease. Among American men and women, heart disease is the leading cause of death.
Over the past decade, dozens of studies have demonstrated the importance of body shape and body fat distribution in determining a number of health risks. Individuals who tend to store body fat around their waists are considered to be apple-shaped because, like the fruit, they're largest around the middle.
Pear-shaped individuals, on the other hand, store more of their excess body fat around their hips, buttocks and thighs.
How do you know which fruit you most resemble? The answer lies in a measurement called the waist to hip ratio (WHR). To determine your WHR, all you need is a tape measure and a calculator.
Start by standing erect, and measuring your waist at a point about one inch above your navel. Next, measure your hips by placing the tape measure around your buttocks. To determine your WHR, divide your waist measurement by your hip measurement.
If your WHR is 0.8 or less, your body can be classified as pear-shaped. If your WHR is higher than 0.8, your body shape falls into the apple category. To a large degree, the shape of your body determines which type of fat you'll accumulate most when you gain weight.
Body fat comes in two main varieties: subcutaneous fat, which lies just under the skin, and non-subcutaneous fat, which is stored deep in the torso and the muscles of the body.
The most clinically significant type of non-subcutaneous fat appears to be visceral fat, which surrounds the organs, including the heart and liver.
While pear-shaped individuals tend to have more subcutaneous fat, people who are apple-shaped tend to have more visceral fat.
Subcutaneous fat is close to the surface of the body. It's the visible fat you can pinch with your fingers. While this type of fat may be cosmetically unappealing, it typically doesn't represent a significant health hazard.
Excessive visceral fat is considered far more dangerous. Packed away in the abdomen, it isn't always visible from the outside, but this type of fat is far more metabolically active than subcutaneous fat, and most of its actions are harmful to the body.
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