Some people put their bicycles away once they learn how to drive a car, while some others don’t. 【小题1】 Serious cyclists often arrange to take part in races.

One kind of race is the time trial. Each racer leaves the starting line at a different time and heads hard for the finish line. The cyclist who covers the distance in the shortest amount of time wins the race. A time trial is a very safe race for beginners. 【小题2】

Another kind of race is more difficult. A few city blocks are closed to traffic. Then all the racers line up in a tight pack and begin racing at the same time. They cover many laps (一圈) going around and around the city blocks. 【小题3】 It also requires skillful handling of the bicycle as it runs at full speed around other bicycles. The racer who completes all the laps first is the winner.

【小题4】 Racers have to cover anywhere from 35 miles to almost 3,000 miles. The racecourse may be a straight stretch of road or a long series of roads across the country. The prize goes to the first person who crosses the finish line.

Between races cyclists stay in good condition by doing exercise that builds up their strength so that they can keep riding for long periods of time. As cyclists become more experienced, they often join bicycling groups and become licensed racers. 【小题5】 If you’re a cyclist, keep practicing. You could become a star.

We already know that exercise is good for our bodies. Daily exercise fights the loss of muscle tone and flexibility that tends to increase slowly with age. And it turns out that it has the same fountain-of-youth effects on our brains.

Studies show that over time our minds also become less flexible and nimble. We lose the ability to process new information or switch between mental tasks quickly — and now we know why.

A recent study examined nearly 100 individual studies on exercise and brain function and discovered exercising an average of 52 hours over six months is "associated with improved cognitive(认知的)performance in older adults with and without cognitive damage." The type of exercises that are beneficial include aerobic, strength-training and mind-body.

In previous studies, researchers from Japan's University of Tsukuba wanted to explore this idea by looking at the effect of exercise on this weakening of the brain. They tested the oxygen ability of 60 Japanese men between the ages of 64 and 75 who did not show any signs of dementia or other mental symptoms. Next, they looked at the brain activity of each man as he completed a mental task. They found that the fitter a participant was, the less brain activity he used to complete the tasks when compared with his out-of-shape peers(同龄人).

Although much research is focused on how exercise may benefit an aging brain, exercise offers brain health benefits at almost any age, and this includes children. A review of 14 studies showed that more physically active schoolchildren do better academically. Exercise actually causes your brain to grow in size. So get moving and keep moving for best results.

Every teenager wants to look good. In fact, any type of regular, physical activity can improve your fitness(健壮). The most important thing is that you keep moving!

Exercise should be a regular part of your day. It can be in gym class, joining a sports team, or working out on your own. Keep the following tips in mind to keep fit.

Stay positive and have fun. A good attitude is important. Find an activity that you think is interesting. You are more likely to keep with it if you choose something you like. A lot of people find it’s more fun to exercise with someone else, so see if you can find a friend or family member to be active with you.

Take one step at a time. Small changes can add up to better fitness. For example, walk or ride your bike to school or to a friend’s house instead of getting a ride. Get on or off the bus several blocks away and walk the rest of the way. Use the stairs instead of taking the elevator.

Get your heart pumping. Whatever you choose make sure it includes aerobic activity that makes you breathe harder and increases your heart rate. This is the best type of exercise because it increases your fitness level and makes your heart and lungs work better. It also burns off body fat. Examples of aerobic activity are basketball, running, and swimming.

Don’t forget to warm up with some easy exercise before you do any physical activity. This warms your muscles up and may help protect against injury. Stretching(伸展) make your muscles and joints more flexible too.

Your goal should be to do some type of exercise every day. It is best to do some kind of aerobic activity without stopping for at least 20 to 30 minutes each time. Do the exercise as often as possible, but exercise to the point of pain. If you keep moving, you will stay fit!