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Yoga: the secret to a great body...and better test scores?? (Lymphatic System/Blood Pressure).

X CHROMOSOME: GENETICS/ REPRODUCTION

The X chromosome is one of two sex chromosomes--gene-containing chemical structures--that determine whether you're born male or female. In humans, females possess two X chromosomes; males have one X and one Y. The X chromosome is much longer than the Y, and also contains many more genes; the Y carries just enough genes to ensure that a fetus (unborn baby) develops male features, such as testicles to produce sperm. Until recently, researchers assumed sperm production was solely the role of the Y. But scientists at the Whitehead Institute Center for Genome Research in Cambridge, Mass., have found that nearly half of all genes related to the earliest stages of sperm production reside on the X--universally thought of as the female sex chromosome.

What do Christy Turlington, Angelina Jolie, and Melissa Joan Hart have in common? They're among 18 million Americans devoted to a 5,000-year-old system of breathing and stretching--yoga. For some, says Turlington, it's about attaining a strong, toned body. But many devotees roll out their yoga mats to gain less visible rewards. "Yoga feels so good," says Justine Grissin-Churchill, 13, at Hunter College High School in New York City. She started yoga last year to attain calm and focus before class tests. Now medical research may validate Grissin-Churchill's goals--and yoga's healthful benefits.

Yoga began in India as a philosophic system combining postures, breathing exercises, and meditation. Some recent studies indicate yoga actually induces physiological changes to combat stress and strengthen the immune system's ability to fight illness. For example, a pose called "downward-facing dog," in which you stand in an upside-down V, could stimulate the body's lymphatic system, helping ward off infections.

The lymphatic system is a network of vessels and nodes, or tissue clusters, which among other functions fights infection by draining and recirculating a fluid called lymph in all body tissues. Within lymph nodes located under the arms and in the groin and neck, disease-fighting white blood cells ingest foreign bacteria and other substances, and reroute purified lymph back to the bloodstream and body tissues (see diagram, below).

HEALING POWER?

Many Western doctors say they need more scientific proof to confirm yoga's beneficial effects. But studies by Dr. Herbert Benson of the Mind Body Medical Institute at Harvard University suggest that in addition to boosting lymphatic activity, yoga slows brain activity and decreases heart rate and blood pressure (the force with which the heart pumps blood to the rest of the body). Benson also discovered that by focusing on something repetitive--the traditional yoga chant of ohm, your breath, or a body movement--and attempting to let go of all other thoughts, you create a relaxation response. The response spurs the opposite effect on the body of the fight-or-flight response produced by fear (see p. 14).

Studies at hospitals around the country suggest the relaxation response reverses negative stress effects in part by lowering the body's oxygen consumption by up to 17 percent in just three minutes (see p. 25). Today, hospitals such as the Presbyterian Medical Center in New York City are offering yoga classes to recovering heart-disease patients.

Some experts think yoga can be a boon for teens, too. "They're often stressed out," says Baron Baptiste, founder of Baptiste Power Vinyasa Yoga in Boston. "They have to deal with academic and peer pressure, along with dramatic changes in their growing bodies." Baptiste's studios recently launched special youth workshops.

"Teens suffer from stress-related problems like trouble sleeping, migraine headaches, and panic attacks,' says Dr. Gloria Deckro, director of research and training at the Mind Body Medical Institute. Deckro helps schools around the country develop classes like yoga to teach students the relaxation response. To illustrate her message, she places bio-dots--sensors measuring blood pressure and temperature--in students' hands while they perform yoga exercises or meditation. Her point? To show teens they can manage stress. "We give them tools to help them realize their day isn't ruined because they find a zit on their nose or don't get the highest grade," she says.

"Some kids think yoga is a bit wacky," says New York eighth-grader Justine Grissin-Churchill. "I love it--if only I had a lot more time to practice."
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Publication:Science World
Date:Feb 7, 2003
Words:694
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