1 . The rate of childhood obesity in the U.S. has tripled over the past 50 years. But what this trend means for children’s long-term health, and what to do about it (if anything), is not so clear.

The American Academy of Pediatrics (AAP) made waves this year by recommending that doctors put obese kids as young as two years old on intensive, family-oriented lifestyle and behavior plans.     1     This advice marks a shift from the organization’s previous stance of “watch and wait,” and it reflects the AAP’s belief that obesity is a disease and the group’s adoption of a more proactive position on childhood obesity.

Yet the lifestyle programs the AAP recommends are expensive, inaccessible to most children and hard to maintain — and the guidelines acknowledge these barriers. Few weight-loss drugs have been approved for older children, although many are used off-label.     2     And surgery, while becoming more common, has inherent risks and few long-term safety data — it could, for instance, cause nutritional deficits in growing children. Furthermore, it’s not clear whether interventions in youngsters help to improve health or merely add to the stigma overweight kids face from a fat-phobic society. This stigma can lead to mental health problems and eating disorders.

Rather than fixating on numbers on a scale, the U.S. and countries with similar trends should focus on an underlying truth: we need to invest in more and safer places for children to play where they can move and run around, climb and jump, ride and skate.

    3    In 2020 the Centers for Disease Control and Prevention found, unsurprisingly, that kids’ sports participation increases with their parents’ incomes: about 70 percent of kids whose families earn more than $105,000 a year participate in sports, but only 51 percent of middle-class kids and 31 percent of children at or below the poverty line do. This disparity hurts people of color the most. More than 60 percent of white children, for instance, participate in athletics, but only 42 percent of Black children and 47 percent of Hispanic children do. Experts blame these problems on the privatization of sports — as public investment in school-based athletics dwindles, expensive private leagues have grown, leaving many kids out.

According to the U.S. Department of Health and Human Services’ Physical Activity Guidelines for Americans, children between ages six and 17 should get at least an hour of moderate to intense physical activity every day. Yet only 21 to 28 percent of U.S. kids meet this target, two government-sponsored surveys found. The nonprofit Active Healthy Kids Global Alliance evaluates physical activity in American children, and in 2022 the group gave the U.S. a grade of D–.

Why is it so hard to get kids moving? In addition to fewer opportunities at school, researchers cite increased screen time, changing norms around letting kids play outdoors unsupervised, and a lack of safe places for them to play outside the home.

New York City, for example, had 2,067 public playgrounds as of 2019 — a “meager” amount for its large population, according to a report from the city comptroller — and inspectors found hazardous equipment at one quarter of them. In Los Angeles in 2015, only 33 percent of youths lived within walking distance of a park, according to the L.A. Neighborhood Land Trust. Lower-income neighborhoods tend to have the fewest public play spaces, despite often having a high population density.     4    

Kids everywhere need more places to play: trails, skate parks and climbing walls, gardens and ball fields, bike paths and basketball courts. Vigorous public funding to build and keep up these areas is crucial, but other options such as shared-use agreements can make unused spaces available to the public.

3 . Sportsmen in the running races of the Olympics are great athletes, but even the slow runners of the running world — joggers in the park — have good health. A study out this week in the Journal of the American College of Cardiology finds that even 5 to 10 minutes a day of slow running is enough to extend life by several years, compared with not running at all.

The new study focused on a group of more than 55, 000 men and women aged 18 to 100. About a quarter of them were runners. Over 15 years, those who ran just 50 minutes a week or fewer at a slow speed were less likely to die from either cardiovascular (心血管的) disease or other causes, compared with those who didn’t run at all.

The study suggests relatively low efforts are necessary to benefit from jogging, but it can be better to exercise more often. “A little bit is good but a little more is probably better,” says Dr. Aaron Baggish. A 2013 study in Denmark suggested that the secret of maximum longevity is up to 2. 5 hours of running a week.

Although running can make you less likely to have cardiovascular disease, it doesn’t entirely take the risk away from you. “There is no question that the healthier you are and the more exercise you do, the longer you’ll live and the better your quality of life will be,” Dr. Baggish says. “But it doesn’t mean you’ll never get sick.”

“Many long-term runners do not run because they want to live longer,” Dr. Baggish notes. “They run because it makes them feel better every day.”

For these runners, the cost of feeling good can be injuries, so Dr. Baggish supports the value of what he calls “active rest.” His belief, not supported by any recent research, is that it’s a good idea to spend 25% of exercise time over the course of a year running at a slow speed or doing other activities like swimming or biking.

5 . Online training is one of the fastest growing parts of the fitness industry. If you’re considering joining the online fitness community, consider these benefits and drawbacks.

One of the most popular reasons for working out following an online video is that it offers ultimate convenience. No need to roll out of bed at 5 a. m. to attend that 6 a. m. boot camp class, which may end up being full when you arrive.    1    And what if you’re on the road? No problem. You can access your workout video through your phone.

    2    Most online fitness programs are much less expensive than similar offline programs—most range in cost from $ 10 to $ 20 per month. Some are even free. For example, the online Les Mills+program offers a free 30-day trial of its 1,500-plus workouts.

Online training also has broad offerings. When you head online, you have instructors from around the globe, all ready and willing to help you master your favorite moves.    3    Just because there isn’t a Krav Maga class in your area doesn’t mean you can’t go online to find one led by qualified instructors.

All these are undoubtedly positive-online training provides fitness resources to general consumers wherever they are, without requiring access to a gym or fitness studio.    4    

Very few online fitness programs enable the instructor to see you, check your form, and offer corrections based on your performance.    5    This is particularly concerning for beginners, as they’re more likely to do incorrectly. Besides, if you struggle with self-motivation and prefer a social workout environment, online fitness may not be for you.

6 . Some people prefer to have a bite to eat before hitting the gym, known as a fed workout. Others would like to wait until after exercising to refuel their bodies, called a fasted workout.    1     Many experts say there’s no easy answer because it depends on the person.

If you want energy and strength for an ideal workout, you need fuel. A fed workout will provide your body with power. Eating before exercise may help you sustain longer sessions and lift heavier weights.     2     Muscle preservation is also an essential component of strengthening your body. Nitrogen (氮) is critical for processing protein that builds healthy muscles. People tend to lose less nitrogen during a fed workout than a fasted one.

Many fitness enthusiasts are not on board with this idea. They report feeling sick and inactive while trying to exercise after eating. With a fasted workout, you may not get the usual indigestion. Experts for fasted workouts further claim that eating afterwards makes your body use its fat reserves for energy, meaning you will burn more fat.     3     It can cause a sudden drop in your blood glucose (葡萄糖) levels, and you may feel dizzy. You may even be more likely to overeat.

    4     Not all foods are created equal. For example, if you choose a fed workout, you’ll probably lose a lot of water during an intense training, so you should consider drinking some beforehand. With a fasted workout, it would help if you had some nutrition right after your session is complete. Drink some water. Then, have a light meal or nutritional snack.

Deciding when to eat for an ideal workout is a personal choice. Both fasted workouts and fed activities have their benefits and shortcomings.     5    

7 . As race season approaches, many runners have the same goal: go faster. But in a study published in the journal Current Biology, researchers show that speeding up might require us to resist our natural biology. By combining data from runners monitored in a lab along with 37,000 runs recorded on wearable fitness trackers, scientists have found that humans’ natural tendency is to run at a speed that conserves caloric loss—something that racers seeking to shave time off their miles will have to get over.

The research group have been studying the mechanics of running in labs for 15 years but hadn’t gotten a chance to study running in the wild before. “We joined the two datasets to gain new insights and combine the more messy wearable data with the gold standard lab experiments to learn about how people run out,” says co-author Jennifer Hicks.

What surprised the team was the consistency they found across the combined datasets. “We had assumed earlier that people ran faster for shorter distances and then would slow their pace for longer distances,” says first author Jessica Selinger. But this wasn’t the case. Most of the runners analyzed stuck with the same speed, whether they were going for a short run or a long one over ten kilometers.

From an evolutionary (进化) standpoint, it makes sense that people would run at the speed that uses the least amount of energy. This caloric conservation is something that has been observed across the animal kingdom. But humans’ reasons for running have changed, and if the goal is speed, there are some tricks runners can use.

Listening to music with a faster pace has been shown to help speed up stride (步伐) frequency, which increases running speed. In addition, picking faster running partners can give you a boost.

Hicks hopes that having large pools of fitness data from wearables will help researchers gain insights about populations. “You can look at connections with the built environment and access to leisure resources and start to layer all of that data to really understand how to improve physical activity and health more broadly,” says Hicks.

8 . Even light activity such as housework might help to keep the brain young, researchers say, adding to a growing body of evidence that, when it comes to exercise, every little helps.

Writing in the journal Jama Network Open, the international team of researchers report how they came to their findings by studying at least three days of activity-tracker data from 2,354 middle-aged adults from the US, together with the participants' brain scans.

From the latter, the researchers worked out individuals' brain volume, a measure linked to ageing: about 0.2% of the volume of the brain is lost every year after the age of 60. Loss or shrinkage (萎缩) of brain tissue is linked to dementia (痴呆), Spartano noted.

After taking into account factors including sex, smoking status and age, the team found that every extra hour of light physical activity per day was linked to 0.22% greater brain volume, equal to just over a year's less brain ageing. What's more, those who took at least 10,000 steps a day had a 0.35% greater brain volume than those who took, on average, fewer than 5,000 steps a day—equivalent to 1.75 years' less brain ageing.

However, the study has limitations. It used mainly white participants, and cannot prove cause and effect. The authors add that not all time spent sedentary is necessarily "bad" for the brain—particularly if people are engaged in a task that takes a lot of thinking.

Dr James Pickett, head of research at Alzheimer's Society, said, "Don't worry if you're not hill-running, but find something you enjoy and do it regularly, because we know that what's good for the heart is good for the head."

10 . What is the best sport for your body type?

Just because someone has dreamt of playing football from childhood does not mean it is the best sport for him or her. Finding the sport your body is best suited to can make a big difference to how much you enjoy it and how good at it you are.

A person with an ectomorph body type is tall and slim with little fat or muscle. This person has narrow shoulders and hips, and thin arms and legs. Ectomorphs have difficulty putting on weight because of a fast metabolism (新陈代谢).     1     . What suits ectomorphs is endurance sports. Marathon running, swimming, and football are excellent choices for them.     2     , basketball may also be a great option.

Mesomorph body types are the typical image of an athlete. Their arms and legs are muscular and they have broad shoulders and narrow hips. Mesomorphs can put on or lose weight easily and build muscle quickly.     3     . Possibilities range from weightlifting and boxing to cycling for shorter distances.

A person who is an endomorph naturally carries more body fat. They are often short, with a high waist, and well developed upper arms and thighs.     4     , they can be very good at power sports because of their larger mass. This body type is not suited for agility (敏捷) and speed, but strength activities like wresting or powerlifting can be a great fit.

It is important to note that the three body types are extremes. No one is 100% ectomorph or completely endomorph.     5     . Another key point is that diet and environment also contribute to athletic ability and genetics plays a large part. And the most important thing is to choose a sport you enjoy.