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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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Space
SpaceX's Landing Blooper Reel Shows That Even Rocket Scientists Make Mistakes
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SpaceX's Falcon 9 rocket launches.
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On March 30, 2017, SpaceX did something no space program had done before: They relaunched an orbital class rocket from Earth that had successfully achieved lift-off just a year earlier. It wasn't the first time Elon Musk's company broke new ground: In December 2015, it nailed the landing on a reusable rocket—the first time that had been done—and five months later landed a rocket on a droneship in the middle of the ocean, which was also unprecedented. These feats marked significant moments in the history of space travel, but they were just a few of the steps in the long, messy journey to achieve them. In SpaceX's new blooper reel, spotted by Ars Technica, you can see just some of the many failures the company has had along the way.

The video demonstrates that failure is an important part of the scientific process. Of course when the science you're working in deals with launching and landing rockets, failure can be a lot more dramatic than it is in a lab. SpaceX has filmed their rockets blowing up in the air, disintegrating in the ocean, and smashing against landing pads, often because of something small like a radar glitch or lack of propellant.

While explosions—or "rapid unscheduled disassemblies," as the video calls them—are never ideal, some are preferable to others. The Falcon 9 explosion that shook buildings for miles last year, for instance, ended up destroying the $200 million Facebook satellite onboard. But even costly hiccups such as that one are important to future successes. As Musk once said, "If things are not failing, you are not innovating enough."

You can watch the fiery compilation below.

[h/t Ars Technica]

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Health
8 Potential Signs of a Panic Attack
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It's not just fear or worry. In fact, many panic attacks don’t look like panic at all. Panic attacks come on rapidly, and often at times that don't seem to make sense. The symptoms of panic disorder vary from person to person and even from attack to attack for the same person. The problems listed below are not unique to panic attacks, but if you're experiencing more than one, it's a good idea to talk to your doctor either way.

1. YOU'RE DIZZY.

Doctors sometimes call the autonomic nervous system (ANS) the "automatic nervous system" because it regulates many vital bodily functions like pumping blood all on its own, without our having to think about it. Panic attacks often manifest through the ANS, leading to increased heart rate or decreased blood pressure, which can in turn lead to feeling lightheaded or faint.

2. YOU'RE LOSING YOURSELF.

Feeling detached from yourself is called depersonalization. Feeling detached from the world, or like it's fake or somehow unreal, is called derealization. Both forms of dissociation are unsettling but common signs that a panic attack has begun.

3. YOU'RE QUEASY.

Our digestive system is often the first body part to realize that something is wrong. Panic sends stress hormones and tension to the gut and disrupts digestion, causing nausea, upset stomach, or heartburn.

4. YOU FEEL NUMB OR TINGLY.

Panic attacks can manifest in truly surprising ways, including pins and needles or numbness in a person's hands or face.

5. YOU'RE SWEATY OR SHIVERING.

The symptoms of a panic attack can look a lot like the flu. But if you don't have a fever and no one else has chattering teeth, it might be your ANS in distress.

6. YOU KNOW THE WORST IS COMING.

While it may sound prophetic or at least bizarre, a sense of impending doom is a very common symptom of panic attacks (and several other conditions). 

7. BREATHING IS DIFFICULT.

The ANS strikes again. In addition to the well-known problems of hyperventilation or shortness of breath, panic attacks can also cause dyspnea, in which a person feels like they can't fill their lungs, and feelings of choking or being smothered.

8. YOU'RE AFRAID OF HAVING A PANIC ATTACK. 

Oddly enough, anxiety about anxiety is itself a symptom of anxiety and panic attacks. Fear of losing control or getting upset can cause people to avoid situations that could be triggering, which can in turn limit their lives. 

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