Athletes training for endurance competitions tend to eat a lot, especially carbohydrates, which produce glucose to fuel the muscles. Olympic swimmer Michael Phelps took in 12,000 calories a day during the 2008 Summer Olympics, for example. Regimented nutrition diets are also popular among athletes. The top Mixed Martial Arts fighters employ full-time nutritionists who prepare each meal for them.
More bodybuilders, professional cyclists and other athletes are turning up their nose at food. Some of them fast two days a week by eating about 600 calories a day (not a fast proper, but enough to achieve its metabolic effects) and then eating regularly the other five days. In shoptalk, this is called the 5:2 diet. Meanwhile, these athletes are doing aerobics and strengthening exercises – in other words, full training.
At first this sounds odd. Exercise uses energy that needs to be replenished by food. How could fasting work into the equation? And yet an animal study released this week offers evidence that fasting and exercise work well together, even increasing endurance.
Mark Mattson, a neuroscientist at Johns Hopkins University and head of the neurosciences lab at the National Institute on Aging in Baltimore, Md., says that, from an evolutionary perspective, it makes sense that fasting and exercise might have a synergistic effect. Our pre-historic ancestors likely went without food for long stretches and hunted on an empty stomach, Mattson says. To catch prey, their survival depended on peak mental and physical performance.
“Individuals whose brains and bodies function well in the fasting state had a survival advantage,” says Mattson, who coauthored the study that appeared Tuesday on the website for the Federation of American Societies for Experimental Biology (FASEB).
In the study, mice were placed in groups: One group ate as much as it wanted and exercised 45 minutes each day on a treadmill; a second group fasted every other day and exercised 45 minutes on a treadmill; and a third group also fasted every other day but did not exercise. A control group of mice ate whatever it wanted and did not exercise. The diet was standard high carb. The study lasted two months.
The mice who fasted and exercised had better wheel endurance, in some cases up to 30 percent, than mice in all four groups. This was despite the fact that the exercising mice were taking in 10 to 15 percent fewer calories than the sedentary mice. “The key finding is that intermittent fasting during a period of daily running results in enhanced endurance,” Mattson says.
The paper mentions that a group of professional cyclists who fasted overnight (no breakfast) had better race times the following day than on the days when they didn’t fast. The paper also discusses a study of men who fasted for 16 hours a day while performing strengthening exercises regularly. The men lost body fat and gained muscle mass despite the caloric restriction. For people who regularly fast or are on a diet, strengthening exercises can prevent loss of muscle mass by increasing fatty acid oxidation in muscle cells, the paper says.
The authors of the mice study claim that during a 12- to 16-hour fast, the body depletes its energy source of glucose, or sugar, in the liver. The body switches to fatty acids for fuel. Instead of burning sugars, the body burns fat, a more efficient source of energy. This mobilizes ketone bodies.
Ketones have almost magical affects on the body and, according to some scientists, on the mind, as well. The metabolic change from glucose to ketones has been associated in human and other animal studies with better health and greater resistance to chronic diseases. Cognitive studies suggest the brain becomes sharper when ketones are activated — think ancient hunter with an empty belly chasing and outwitting quarry.
In the mice study, the exercising and fasting animals “used fats (as energy) much more than those not on intermittent fasting,” Mattson says. “Their ketones were way up. The exercise enhances the effects of intermittent fasting.”
In recent years, ketone chatter has made its way into popular culture. Many celebrities — such as socialite Kim Kardashian, actress Halle Berry and country musician Tim McGraw — are on the keto diet, which consists of low carbs and high fats. Basketball stars Lebron James and Kobe Bryant have also gone keto.
The diet is thought to simulate the benefits of intermittent fasting by forcing the body to use fat as a fuel source. A low-carb diet such as the keto diet can lower glucose levels and activate ketone bodies, scientists say. Dieters get the healthful effects of fasting without actually doing it.
But studies are mixed on whether the keto diet improves endurance, and a lot of dietitians are skeptical of its nutritional profile.
Michelle Harvie, a research dietician in Manchester, England, who co-developed the 5:2 diet, says people lose weight on the keto diet, but the diet lacks fiber and has a lot of saturated fats, which put people at risk for cardiovascular diseases.
“And there is increasing evidence that its effect on the gut microbiome is pretty adverse,” she says. “The gut microbiome is a poorly understood but potentially important part of our metabolic health.”
As for intermittent fasting, Harvie says human studies show it’s an effective way to lose weight. Mattson goes further. Besides increasing endurance, fasting for 12 to 16 hours can “increase activity in neuronal networks involved in learning and memory,” he says.
Harvie hopes for a fasting revolution. “At the end of the day, [in the U.K.] and in the U.S., there is no fast,” Harvie says. “There is just a constant graze from dusk to dawn and even in the middle of the night. So I think we need to get back to some sort of pattern or spells of not eating.”
What Magnetic Fields Do to Your Brain and Body
There’s no escaping magnetic fields—they’re all around us. For starters, the Earth itself is like a giant magnet. A spinning ball of liquid iron in our planet’s core generates the vast magnetic field that moves our compass needles around and directs the internal compasses of migrating birds, bats, and other animals. On top of that, ever-industrious humans have produced artificial magnetic fields with power lines, transport systems, electrical appliances, and medical equipment.
We may not be able to see, hear, feel, or taste the magnetic fields that surround us, but some may wonder whether they can still exert effects on our bodies and brains. This question becomes more pertinent, and the answers more tantalizing, as the strength of the magnetic field in question gets cranked up.
A magnetic field arises whenever a charged particle, like an electron or proton, moves around. Since the electric currents running through blenders, hairdryers, and wires in the walls of our homes consist of flowing electrons, they all generate magnetic fields. Through these sources, the average person is exposed to magnetic fields reaching 0.1 microtesla in strength on a daily basis. By comparison, the Earth’s magnetic field, which we are always exposed to (as long as we remain on the planet’s surface), is about 500 times stronger. That means the magnetic force penetrating your body as you lounge around your home or spend a day at the office is decidedly insignificant.
From time to time, a scientific study finds a link between living near high-voltage power lines and illness. Heightened risk of childhood leukemia is the most commonly cited potential health consequence, but whether or not the risk is real has been hard to pin down. One glaring issue is that scientists have yet to figure out the mechanism by which such weak magnetic fields—which are still in the microtesla range for homes next to power lines—could adversely affect the human body. In 2010, the International Commission on Non-Ionizing Radiation Protection concluded that the evidence that living near power lines increases the risk of the deadly blood cancer “is too weak to form the basis for exposure guidelines.”
An MRI machine. (Credit: VILevi/Shutterstock)
What’s the Threshold?
Meanwhile, a team of scientists at the Utilities Threshold Initiative Consortium (UTIC) has been busy working to figure out the threshold at which the human body shows a physiological response to a magnetic field. According to Alexandre Legros, a medical biophysicist at the Lawson Health Research Institute and Western University in London, Ontario and a UTIC scientist, the smallest magnetic field that has reliably been shown to trigger a response in humans is around 10,000 to 20,000 microtesla. But crucially, to produce the effect, the field cannot be static like Earth’s magnetic field; rather, it must change directions over time. When these strong, direction-shifting magnetic fields get directed at a human, small electrical currents begin to pulse through the body. Above that threshold, the currents can stimulate super-sensitive cells in the retina, known as graded potential neurons, giving the illusion of a white light flickering even when the affected person is in darkness; these visual manifestations are known as magnetophosphenes.
The 10,000-microtesla threshold is well above the strength of any magnetic field encountered in everyday life. So in what situations might magnetophosphenes occur?
“There’s only one circumstance in which you may perceive magnetophosphenes,” says Legros: “If you’re in an MRI [magnetic resonance imaging] machine and moving your head fast.” An MRI scanner is essentially a big magnet that produces a powerful magnetic field of around 3 tesla (or 3 million microtesla) — millions of times larger than the fields we’re normally exposed to. But because it’s a static magnetic field, MRI scanners don’t exert any noticeable effect on the body. That would change, however, if the patient inside the scanner were to rapidly move his or her head back and forth. “Moving quickly induces a time-varying field, so by doing that you are inducing currents in different structures of your brain,” says Legros. Those currents may lead to nausea, loss of balance, a metallic taste in your mouth, or in some cases, magnetophosphenes.
On par with the magnetic field of an MRI is the one produced by a medical procedure known as transcranial magnetic stimulation (TMS). But unlike MRI, which makes detailed pictures of the inside of the body, the purpose of TMS is to stimulate the brain. That task requires an electric current, which is why TMS relies on a magnetic pulse rather than a static magnetic field. When this pulse is delivered via an electromagnetic coil placed against the scalp, the resulting current jolts a particular part of the brain with the aim of treating neurological diseases like depression.
Out-of-this-World Magnetic Fields
The magnetic fields associated with MRI and TMS are the strongest that a human might realistically be exposed to. Still, they are “hilariously puny” compared to those found beyond our planet, says Paul Sutter, an astrophysicist at Ohio State University and chief scientist at the COSI Science Center in Columbus, Ohio. At the extreme lies the aptly-named magnetar, which is a rare type of neutron star with a magnetic field one thousand trillion times stronger than Earth’s.
An artist’s impression of a magnetar. (Credit: ESO/L. Calçada/Wikipedia (CC BY 4.0))
If any human ever got close to a magnetar, they would quickly find themselves in dire straits. “Strong magnetic fields can start to do surprising things,” says Sutter. At the atomic level, the strong magnetic field would move all of the positive charges in your body in one direction and the negative charges the other way, he explains; spherical atoms would stretch out into ellipses and soon they would start to resemble thin pencils. That drastic change in shape would interfere with basic chemistry, causing the normal forces and interactions between atoms and molecules in the body to break down. “The first thing you would notice is your entire nervous system, which is based on electrical charges moving throughout your body, is going to stop working,” says Sutter. “And then you basically dissolve.”
Sutter guarantees that our local neighborhood — which he defines as a radius of a few hundred light-years around Earth — has been surveyed and certified magnetar-free. None of these exotic objects are approaching us, and none of the massive stars nearby are likely to turn into magnetars when they die. The nearest magnetar is a safe distance of tens of thousands of light-years away. So, at least for the time being, we can rest easy and take comfort in our planet’s own meager magnetic field.
The Aftermath of Michael Jackson’s Antigravity Lean
The infamous lean.
In Michael Jackson’s 1987 music video “Smooth Criminal,” the legendary performer leans forward 45 degrees from a straight-up position — and comes back. It’s a feat that seemingly defies both physics and physiology, and the move has become another element of MJ’s aura of mystery.
Some type of cinematic or mechanical trick must be responsible, since most people can manage only a 20-degree forward tilt before toppling headlong. Yet Jackson performed the move live on tours around the world for years.
In a study published this week in the Journal of Neurosurgery, three scientists examine the so-called Antigravity Lean, not from a physics but from a physiological perspective. The three neurosurgeons, all at the Postgraduate Institute of Medical Education and Research in Chandigarh, India, combine in the article their knowledge of Jackson with data on spine biomechanics.
It’s been known for years how Jackson defied gravity. His shoes had a slot that slid onto a bolt in the floor, allowing him to perform the dramatic lean.
Bending forward is limited by the erector spinae muscles, which act like cables to support forward bends up to 20 degrees, though some dancers can achieve 30 degrees, the paper says. When near the max of a bend, you can feel the strain on the Achilles’ heel as the ankles become the fulcrum for balance. People soon return to vertical or catch themselves from falling headlong.
Though Jackson’s 45-degree bend is not physically possible without trickery, the King of Pop still needed incredible core strength and leg muscles to pull it off, the authors write. Not just anyone can lock their shoes into the floor and become Michael Jackson, it seems.
“Several MJ fans, including the authors, have tried to copy this move and failed, often injuring themselves in their endeavors,” the researchers write.
Figure A shows the Antigravity Tilt (a 45-degree forward bend) and the normal limit that most people can bend forward. Jackson used shoes with a slot that slid onto a bolt in the floor. Figure B shows the shift when the body’s fulcrum is the hip and when it’s the Achilles’ tendon. (Illustration courtesy of Manjul Tripathi)
Tough Act to Follow
Jackson’s sleight of foot inspired generations of dancers who push the limits physically. This has resulted in spinal stresses not previously seen by neurosurgeons.
This is not to point the finger at Jackson. But it does suggest the reality that injuries can occur that might require implant spinal surgery, the article says, something potentially devastating to a dancer.
But it’s not all bad news — neurosurgeons have gained a lot of new information on how to treat spinal cord injuries in recent years, something that could be in part thanks to MJ’s envelope-pushing dance moves.
“The King of Pop has not only been an inspiration but a challenge to the medical fraternity,” Tripathi says.
Your Emergency Contact Does More Than You Think
You know when you’re filling out your medical paperwork and it asks for your emergency contact? Sure, the process might be annoying, but that emergency contact could actually be put to good use by researchers.
Since many of us use a family member, those contacts can help scientists create family trees. And they can also be used for genetics and disease research, according to a study released Thursday in Cell. Discovering what diseases are inheritable can be a laborious and expensive process — patients must be recruited and researchers must clearly determine patients’ phenotypes (physical traits that include eye color, height, and overall health and are often influenced by your genes).
To make that process easier researchers from three major New York medical centers generated family trees from millions of electronic medical records to create a database.This is the first time electronic health records have been used to trace ancestry and it’s the largest study of heritability using such records.
The More You Know
The researchers identified 7.4 million relatives with an algorithm that matched names, addresses and phone numbers from three medical centers. They found 500 inheritable phenotypes in the data just by looking at test results and observations in health records. The traits included diseases affecting skin, blood and mental health.
The data can help determine the heritability level of many common diseases. For example, researchers found that having an increase of HDL (good) cholesterol is 50 percent heritable, while LDL (bad) cholesterol is only 25 percent heritable. The study’s findings were consistent across the participating medical centers and published studies.
Previous heritability research primarily documented Caucasians of northern European descent, according to the study’s first author Fernanda Polubriaginof, but this research is much broader.
“This dataset will allow us for the first time to compute whether there are differences in other races and ethnicities,” said Polubriaginof in a news release.
Future studies could look at medical records for the hereditary contribution of any trait. Due to privacy issues, patient identifiers were removed for the data, which can only be used for research at the moment. Though, with patient consent, emergency contacts could be put to important use in the future.
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