Sunday, August 15, 2010

Are you sitting down? It's slowly killing you

Regular workouts don't decrease death risk if you're also a couch potato

Hitting the gym every day might do little to decrease your risk of death if you spend the rest of your time sitting down, a new study suggests.

The results show the time people spend on their derrieres is associated with an increased risk of mortality, regardless of their physical activity level.

The findings suggest public health messages should promote both physical activity and less time on the couch, the researchers say.

The current obesity epidemic in the United States has been attributed in part to reduced overall physical activity.

While several studies support a link between sitting time and obesity, type 2 diabetes, risk factors for cardiovascular disease risk and unhealthy dietary patterns in children and adults, very few studies have examined time spent sitting in relation to total mortality. Thus, public health guidelines focus largely on increasing physical activity with little or no reference to butt-on-the-chair time.

Alpa Patel, a researcher at the American Cancer Society (ACS), and his colleagues analyzed survey responses from 123,216 individuals (53,440 men and 69,776 women) who had no history of cancer, heart attack, stroke or emphysema that were enrolled in the ACS's Cancer Prevention II study in 1992. Participants were followed from 1993 to 2006.

The researchers examined the participants' amount of time spent sitting and physical activity in relation to mortality over the 13-year period.

Women more affected by sitting More leisure time spent sitting was associated with higher risk of mortality, particularly in women.

Women who reported more than six hours per day of sitting (outside of work) were 37 percent more likely to die during the time period studied than those who sat fewer

than three hours a day. Men who sat more than six hours a day (also outside of work) were 18 percent more likely to die than those who sat fewer than three hours per day. The association remained virtually unchanged after adjusting for physical activity level. Associations were stronger for cardiovascular disease mortality than for cancer mortality.

When combined with a lack of physical activity, the association was even stronger. Women and men who both sat more and were less physically active were 94 percent and 48 percent more likely to die during the study period, respectively, compared with those who reported sitting the least and being most active.

"Several factors could explain the positive association between time spent sitting and higher all-cause death rates," Patel said. "Prolonged time spent sitting, independent of physical activity, has been shown to have important metabolic consequences, and may influence things like triglycerides, high density lipoprotein, cholesterol, fasting plasma glucose, resting blood pressure, and leptin, which are biomarkers of obesity and cardiovascular and other chronic diseases."

(High density lipoprotein is considered the "good" kind of cholesterol.)

The results are published in an early online edition of the American Journal of Epidemiology.

Tuesday, August 3, 2010

The Red Planet is about to be spectacular

This month and next, Earth is catching up with Mars in an encounter that will culminate in the closest approach between the two planets in recorded history.

The next time Mars may come this close is in 2287.  

We will never see this again in our lifetime  ...nor will the people of the next 50-to-1,000 Life Times!

Due to the way Jupiter's gravity tugs on Mars and perturbs its orbit, astronomers can only be certain that Mars has not come this close to Earth in the Last 5,000 years, but it may be as long as 60,000 years before it happens again. The encounter will culminate on August 27th when Mars comes to within 34,649,589 miles of Earth and will be (next to the moon) the brightest object in the night sky. It will attain a magnitude of -2.9 and will appear 25.11 arc seconds wide.
At a modest 75-power magnification
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Mars will look as large as the full moon to the naked eye.  
Mars will be easy to spot. At the beginning of August it will rise in the east at 10p.m. and reach its azimuth at about 3 a.m.
By the end of August when the two planets are closest, Mars will rise at nightfall and reach its highest point in the sky at 12:30a.m. That's pretty convenient to see something that no human being has seen in recorded history. So, mark your calendar at the beginning of August to see Mars grow progressively brighter and brighter throughout the month.

Check it out, guess no one will get much sleep in August.

A little bit of facts about Mars
Text courtesy NASA/JPL

The Red Planet
Mars is a small rocky body once thought to be very Earthlike. Like the other terrestrial planets—Mercury, Venus, and Earth—its surface has been changed by volcanism, impacts from other bodies, movements of its crust, and atmospheric effects such as dust storms. It has polar ice caps that grow and recede with the change of seasons; areas of layered soils near the Martian poles suggest that the planet's climate has changed more than once, perhaps caused by a regular change in the planet's orbit.
Martian tectonism, the formation and change of a planet's crust, differs from Earth's. Where Earth tectonics involve sliding plates that grind against each other or spread apart in the seafloors, Martian tectonics seem to be vertical, with hot lava pushing upwards through the crust to the surface.
Periodically, great dust storms engulf the entire planet. The effects of these storms are dramatic, including giant dunes, wind streaks, and wind-carved features.

Water on Mars?
Scientists believe that 3.5 billion years ago, Mars experienced the largest known floods in the solar system. This water may even have pooled into lakes or shallow oceans. But where did the ancient floodwater come from, how long did it last, and where did it go?
At present, Mars is too cold and its atmosphere is too thin to allow liquid water to exist at the surface for long. There's water ice close to the surface and more water frozen in the polar ice caps, but the quantity of water required to carve Mars's great channels and flood plains is not evident on—or near—the surface today. Images from NASA's Mars Global Surveyor spacecraft suggest that underground reserves of water may break through the surface as springs. The answers may lie deep beneath Mars's red soil.
Unraveling the story of water on Mars is important to unlocking its past climate history, which will help us understand the evolution of all planets, including our own. Water is also believed to be a central ingredient for the initiation of life; the evidence of past or present water on Mars is expected to hold clues about past or present life on Mars, as well as the potential for life elsewhere in the universe. And, before humans can safely go to Mars, we need to know much more about the planet's environment, including the availability of resources such as water.

Mountains, Moons, and More
Mars has some remarkable geological characteristics, including the largest volcanic mountain in the solar system, Olympus Mons; volcanoes in the northern Tharsis region that are so huge they deform the planet's roundness; and a gigantic equatorial rift valley, the Valles Marineris. This canyon system stretches a distance equivalent to the distance from New York to Los Angeles; Arizona's Grand Canyon could easily fit into one of the side canyons of this great chasm.

Mars also has two small moons, Phobos and Deimos. Although no one knows how they formed, they may be asteroids snared by Mars's gravity.