【推荐1】What do extreme marathoners, mountain hikers and professional bicycle racers all have in common? They push their bodies to unsustainable (不可持续的) extremes of physical stress.

We tend to think there’s no limit to human physical achievements. But a new study, published in Science Advances, says there is a definite limit to human endurance (耐力). Beyond that, our bodies begin to break down.

To find the limit, a US research team tracked marathon runners over a five-month period, measuring competitors’ initial basal metabolic rates (BMR, 基础新陈代谢率) – the amount of energy they expend when they rest. Then they looked at how many calories(卡路里) each runner burned per day.

The team found that the maximum amount of energy a human can expend is 2.5 times of BMR. It equals 4,000 calories of energy per day. These calories can help a trained athlete to run about 42 kilometers in a day.

But people can’t keep using this amount of calories all the time. “You can do really intense stuff for a couple of days, but if you want to last longer then you have to dial it back,” US evolutionary anthropologist Herman Pontzer told the BBC.

Pontzer explained that the problem is our guts (消化道). “There’s … a limit to how many calories our guts can effectively absorb per day,” he said in the Daily Mail. At that point, the body is burning calories more quickly than it can absorb food and convert (转化) it into energy.

These new findings could help athletes to best work underneath this ceiling. For example, they could manage their daily exercise time based on their BMR, to get enough calories and keep going.

However, Pontzer’s team can’t rule out the possibility of someone breaking this limit. “So I guess it’s a challenge to elite endurance athletes,” said Pontzer. “Science works when you’re proven wrong. Maybe someone will break through that ceiling some day and show us what we’re missing.”

【推荐2】Essentially, everyone has two ages: a chronological(按时间计算的) age, how old the calendar says you are, and a biological age, basically the age at which your body functions as it compares to average fitness or health levels.

“Chronological age isn’t how old we really are. It’s merely a number,” said Professor David Sinclair at Harvard University. “It is biological age that determines our health and ultimately our lifespan(寿命). We all age biologically at different rates according to our genes, what we eat, how much we exercise, and what environment we live in. Biological age is the number of candles we really should be blowing out. In the future, with advances in our ability to control biological age, we may have even fewer candles on our birthday cake than the previous one.”

To calculate biological age, Professor Levine at Yale University identified nine bio-markers that seemed to be the most influential on lifespan by a simple blood test. The numbers of those markers, such as blood sugar and immune measures, can be put into the computer, and the algorithm(算法) does the rest.

Perhaps what’s most important here is that these measures can be changed. Doctors can take this information and help patients make changes to lifestyle, and hopefully take steps to improve their biological conditions. “I think the most exciting thing about this research is that these things aren’t set in stone,” Levine said. “People can be given the information earlier and take steps to improve their health before it’s too late.”

Levine even entered her own numbers into the algorithm. She was surprised by the results. “I always considered myself a very healthy person. I’m physically active; I eat what I consider a fairly healthy diet. But I did not find my results to be as good as I had hoped they would be. It was a wake-up call,” she said.

Levine is working with a group to provide access to the algorithm online so that anyone can calculate their biological age, identify potential risks and take steps to improve their own health in the long run. “No one wants to live an extremely long life with a lot of chronic diseases,” Levine said. “By delaying the development of mental and physical functioning problems, people can still be engaged in society in their senior years. That is the ideal we should be pursuing.”

【推荐1】If you plan to learn a foreign language, you might think it’s going to be really challenging. You’ve probably heard a lot of talks about how it’s easier to learn languages as a young child, and that learning as an adult can be difficult. You might even know friends or family members who have tried to learn a foreign tongue and failed. That’s because they are surrounded by the failure. We’re here to cheer you up with some good news and inspire you to get started.

The amazing adult brain: whether you can learn languages at any age? Scientists are always learning about the human brain. Decades ago, experts believed that the brain developed during childhood and then retained that way for life. However, modern studies have shown us that the brain has the ability to continually form new neural (神经的) connections throughout adulthood. A 2010 Swedish study tested two groups of people, one in the range of age 21 through 30 and another between 65 and 80. Remarkably, they found no significant differences in Neuroplasticity (神经可塑性). In other words, this suggests that it’s possible for you to learn new things at any age.

Besides being possible to learn languages, research also suggests that it improves the adult brain in general. In a 2012 Chinese study, experts looked at a group of adults who were learning Mandarin (普通话) over a nine-month period. They found that these adults showed improved integrity in their white matter, the part of the brain that allows neural cells to communicate. The better your neural cells communicate, the easier it will be for you to learn new things.

Why may adults have an easier time learning? Children might be blessed with a naturally high degree of neuroplasticity, but that doesn’t mean learning is necessarily easier for them. In fact, adult brains have a number of great qualities that might actually make learning easier, especially if you take advantage of free language learning apps like Mondly.

【推荐3】It turns out that overworking your brain with either physical or mental exercise may lower your ability to delay self-satisfaction. And that may set you up for poor choices in your self-care and finances.

A new study published in the journal Current Biology asked excellent endurance athletes to overtrain for three out of 9 weeks, and compared them to a group who did a normal 9-week training program.

Not only did those overworked athletes perform worse on a cycling test at the end of the overtraining, MRIs of their brains during behavioral tasks showed more exhaustion in the cognitive control part of the brain system. "Cognitive control in this situation is the capacity to maintain exercise despite things like muscle pain," said study author Bastien Blain, a research associate at University College London. “And what we found is that there is an intelligence factor involved in exercising and it has a limited capacity. You cannot use it forever.''

In other words, your brain will burn out and affect your body's ability to exercise. But that's not all. Overworking that part of the brain also reduced the athletes' abilities to resist temptation of an immediate reward."For example, they were asked whether they preferred $10 now or $50 in six months," Blain said. “And those who overtrained were more likely to choose the immediate reward, which is interesting. It could provide a mechanism to explain why some athletes are using drugs to improve their performance."

One caution about the exercise study is that it only looked at endurance athletes, said. Dr. Mare-Andre Cornier, who is associate director of Colorado University's Anschutz Health and Wellness Center. "This is potentially very important for the higher end athlete who is overdoing it," he said.“But does this have anything to do with the average Joe going to the gym? You can't conclude that from this study."