2 . Scientists are now digging into precisely why exercise holds so many benefits for our mental health and memory. The answer, studies say, lies in our brain chemistry.

Each time you work up a sweat, your body releases feel-good happy hormones (荷尔蒙), including endorphins, dopamine and endocannabinoids, the latter being responsible for the so-called runner’s high. Now researchers are also pointing to myokines (肌肉因子) as an important contributor to the mental health benefits of exercise. When our muscles contract, myokines are released into the bloodstream, helping your muscles and organs communicate. They think this communication increases resilience to stress, reduces symptoms of mental suffering and anxiety and has a direct effect on depression.

A 2021 scientific report published in Neuropharmacology showed evidence that myokines boost brain function, like improving memory and mood. “Myokines reduce systemic inflammation (炎症), which is especially beneficial for people with drug-resistant depression whose low mood is linked to high inflammation,” explains Dr Jennifer Heisz, an expert in brain health and associate professor in the department of kinesiology at McMaster University in Canada.

A recent study published in the British Journal of Sports Medicine showed that treatment for depression can be much more effective when physical activity is added to the usual care. Participants found benefits after 12 weeks of exercising for 30 to 60 minutes a day. “While exercise is not a replacement for professional mental health treatment, physical activity can complement and enhance the effects of the treatment,” says lead researcher Ben Singh, a research fellow at the University of South Australia.

“It is amazing to consider how moving our bodies can heal our minds,” says Heisz. Whether you’re cycling, walking around your neighbourhood or doing yoga, getting sweaty is good for your body and mind. To get the biggest overall health boost, the key is to zero in on sports and activities you enjoy, so you’ll keep going back to them.

3 . Tai chi, a traditional, slow-moving form of Chinese physical exercise, is known to increase flexibility and improve balance. New research has been conducted to determine whether tai chi has an influence on lowering blood pressure in people with prehypertension (高血压前期).

In the study, Chinese scientists put 342 adults with prehypertension into two groups. The average age of people taking part in the study was 49. About half the participants (参与者) took part in aerobic exercise, including jogging, climbing stairs and cycling. The other half was trained to practice tai chi. Both groups got hour-long exercises four times a week.

Nearly 22% of the people who practiced tai chi saw their blood pressure fall to be normal, compared with nearly 16% of people in the aerobic exercise group. And fewer patients in the tai chi group went on to develop high blood pressure than patients in the aerobic exercise group.

So what is it about tai chi that helps lower blood pressure? “The practice tends to get more of a response from the parasympathetic (副交感的) nervous system, which is the network of nerves that relaxes your body after periods of stress or danger,” says Ruth Taylor-Piliae, a professor at the University of Arizona’s College of Nursing.

“I think the beauty of tai chi is that you don’t have to have a special gym membership, you don’t have to have special clothing,” Taylor-Piliae says. “Once you learn tai chi, you can do it anytime and anyplace. And it does provide a calming and relaxing effect.”

Evidence suggests it can also help protect against cognitive fall and even improve memory. But you have to practice it continually to get the most benefit.

4 . Starting a daily running routine needs determination. Looking back on my old running routine, it wasn’t so much the passion that affected my sticking to a regular schedule — but it was the environment. There had to be no rain pouring down, there had to be not many people on the basketball court and the ambient (周围的) temperature had to be just right. Or maybe I was just making an excuse for myself not to get up at 5 in the morning?

I was quite successful at doing so when I was 15 and when it was summer. When I was overweight, I ate more snacks than the actual full meals in a day, and I hardly got off the sofa. One summer day, I decided that it was time to put a stop to the idea that I was just the fat kid. I didn’t want to put in that box anymore. There was a tipping point (临界点) where inspiration happened, and discipline (自律) just took over from there. I needed to make sure that I ran 10 laps of the park a day — this was the contract (契约) I made with myself that summer. And if I achieved that, I knew I’d be closer to my goal of being just a kid with normal weight.

Ten laps, six days a week — sometimes no breakfast, hardly a bite at dinner, one snack a day—this lasted two months. I’d lost over 30 pounds that summer, which was roughly a quarter of my body weight. Some days, I didn’t have the motivation. But the contract I made with myself kept reminding me — if I’d break it, would I even bother making future self-contracts anymore? There were sleepy days, and there were days when I should have rested my trembling knees, but discipline won over them all.

9 . 听下面一段独白，回答以下小题。

10 . 听下面一段较长对话，回答以下小题。