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Scientists Say Walking Burns More Calories Than Previously Thought

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Step-counters, rejoice: physiologists have found that the equations used for calculating energy expenditure are inaccurate, and say we’re likely burning more calories walking than we realized. They published their report in the Journal of Applied Physiology. 

Today, most programs use one of two methods to estimate calories burned by walkers: the ACSM (for the American College of Sports Medicine) and the Pandolf, which was invented by the military. These equations are about 40 years old, which is reason enough to test them again. They were also developed using just a few adult men of average height, and if we’ve learned anything in the last few years, it’s that a small group of adult men cannot be used as a stand-in for the entire population.

So Southern Methodist University (SMU) physiologists Lindsay Ludlow and Peter Weyand decided it was time to put these formulas to the test. "Burning calories is of major importance to health, fitness and the body's physiological status," Weyand said in a press statement. "But it hasn't been really clear just how accurate the existing standards are under level conditions because previous assessments by other researchers were more limited in scope." 

The researchers built a database of existing data in the scientific literature. With this data, they could compare the ACSM, Pandolf, and other standard equations. They found that for people walking on firm, level ground, both the ACSM and Pandolf underestimated calories burned in 97 percent of the cases examined by researchers. Clearly, a new equation was in order. 

Ludlow and Weyand set out to create an algorithm that would work for anyone. "The SMU approach improves upon the existing standards by including different-sized individuals and drawing on a larger database for equation formulation," Weyand said. 

Dr. Ludlow monitors a colleague during a treadmill test. Image Credit: Hillsman Jackson, SMU

If you want to play along at home (in your ... home physiology lab), here’s what they came up with:

(VO2 is oxygen consumption and Ht is height measured in meters.)

Ludlow said their equation should apply “…regardless of the height, weight, and speed of the walker. And it’s appreciably more accurate.”  

A lot more accurate, in fact (not that that’s a high bar). The new equation is four times more accurate when used to calculate energy expenditure of a mixed group of adults and kids. For adults alone, it’s still two to three times more accurate than the old formulas. 

Accurate accounting of energy expenditure is important for more than just casual walkers. Once a person’s estimated calorie-burn rate has been established, the formula can be used to predict how much energy that person will use—and therefore how much they will need—for a certain task. Such an algorithm could be useful for athletes in training, but also for military operations, in which the need for physiological efficiency is at a premium.

"These soldiers carry incredible loadsup to 150 pounds, but they often need to be mobile to successfully carry out their missions," Weyand said. In other words, they've got to be taking in enough calories to get the job done.

As yet, the formula has only been tested for walkers on solid, flat ground. The researchers’ next step is to expand the algorithm to calculate calorie burning on hills. 

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Courtesy Murdoch University
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Animals
Australian Scientists Discover First New Species of Sunfish in 125 Years
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Courtesy Murdoch University

Scientists have pinpointed a whole new species of the largest bony fish in the world, the massive sunfish, as we learned from Smithsonian magazine. It's the first new species of sunfish proposed in more than 125 years.

As the researchers report in the Zoological Journal of the Linnean Society, the genetic differences between the newly named hoodwinker sunfish (Mola tecta) and its other sunfish brethren was confirmed by data on 27 different samples of the species collected over the course of three years. Since sunfish are so massive—the biggest can weigh as much as 5000 pounds—they pose a challenge to preserve and store, even for museums with large research collections. Lead author Marianne Nyegaard of Murdoch University in Australia traveled thousands of miles to find and collected genetic data on sunfish stranded on beaches. At one point, she was asked if she would be bringing her own crane to collect one.

Nyegaard also went back through scientific literature dating back to the 1500s, sorting through descriptions of sea monsters and mermen to see if any of the documentation sounded like observations of the hoodwinker. "We retraced the steps of early naturalists and taxonomists to understand how such a large fish could have evaded discovery all this time," she said in a press statement. "Overall, we felt science had been repeatedly tricked by this cheeky species, which is why we named it the 'hoodwinker.'"

Japanese researchers first detected genetic differences between previously known sunfish and a new, unknown species 10 years ago, and this confirms the existence of a whole different type from species like the Mola mola or Mola ramsayi.

Mola tecta looks a little different from other sunfish, with a more slender body. As it grows, it doesn't develop the protruding snout or bumps that other sunfish exhibit. Similarly to the others, though, it can reach a length of 8 feet or more. 

Based on the stomach contents of some of the specimens studied, the hoodwinker likely feeds on salps, a jellyfish-like creature that it probably chomps on (yes, sunfish have teeth) during deep dives. The species has been found near New Zealand, Australia, South Africa, and southern Chile.

[h/t Smithsonian]

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Gregory H. Revera, Wikimedia Commons // CC BY-SA 3.0
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Space
Study Suggests There's Water Beneath the Moon's Surface
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Gregory H. Revera, Wikimedia Commons // CC BY-SA 3.0

Astronauts may not need to go far to find water outside Earth. As CNN reports, Brown University scientists Ralph E. Milliken and Shuai Li suspect there are significant amounts of water churning within the Moon’s interior.

Their findings, published in the journal Nature Geoscience, lean on the discovery of glass beads encased in the Moon’s volcanic rock deposits. As recently as 100 million years ago, the Earth’s moon was a hotbed of volcanic activity. Evidence of that volatile time can still be found in the ancient ash and volcanic rock that’s scattered across the surface.

Using satellite imagery, the researchers identified tiny water droplets preserved inside glass beads that formed in the volcanic deposits. While water makes up a small fraction of each bead, its presence suggests there’s significantly more of it making up the Moon’s mantle.

Milliken and Li aren't the first scientists to notice water in lunar rocks. In 2008, volcanic materials collected from the Moon during the Apollo missions of 1971 and 1972 were revealed to contain the same water-flecked glass beads that the Brown scientists made the basis of their recent study. They took their research further by analyzing images captured across the face of the Moon and quickly saw the Apollo rocks represented a larger trend. "The distribution of these water-rich deposits is the key thing," Milliken said in a press statement. "They're spread across the surface, which tells us that the water found in the Apollo samples isn't a one-off. Lunar pyroclastics seem to be universally water-rich, which suggests the same may be true of the mantle."

The study challenges what we know about the Moon's formation, which scientists think occurred when a planet-sized object slammed into the Earth 4.5 billion years ago. "The growing evidence for water inside the Moon suggests that water did somehow survive, or that it was brought in shortly after the impact by asteroids or comets before the Moon had completely solidified," Li said. "The exact origin of water in the lunar interior is still a big question."

The findings also hold exciting possibilities for the future of space travel. NASA scientists have already considered turning the Moon into a water station for astronauts on their way to Mars. If water on the celestial body is really as abundant as the evidence may suggest, figuring out how to access that resource will definitely be on NASA's agenda.

[h/t CNN]

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