or decades, health professionals have proclaimed that exercise is important for sound physical health. Exercise promotes healthy bones, muscles, and joints. It also reduces people’s risk for obesity and many diseases. Nevertheless, to cut budgets and devote more time to academics, schools across the United States have reduced, or even eliminated, physical education classes. A 2006 study reported that only 14 percent of elementary schools, 15 percent of middle schools, and 3 percent of high schools in the United States offered the equivalent of three class periods of physical education per week. In addition, many elementary schools have eliminated recess. And outside of school, many students lead a sedentary lifestyle. Given these facts, has the reduction of physical education in schools been a wise decision?

Several recent scientific studies have found that exercise has a benefit not previously realized: It improves children’s brain function. One study took place at the Champaign-Urbana campus of the University of Illinois. There, researchers had nine- and ten-year-olds run on a treadmill to determine their fitness levels. Previous studies with animals had shown that baby rodents that had access to running wheels enlarged certain areas of their brains. They also performed better on rodent intelligence tests than did less active baby rodents. The study of nine- and ten-year-olds yielded similar results. First, the children were asked to respond to arrows on a computer screen. The fit children were better at paying attention to relevant cues and ignoring unnecessary information. Then magnetic resonance imaging (MRI) technology was used to scan the children’s brains and measure specific areas. The MRIs showed that the fit children had significantly larger basal ganglia. (This part of the brain helps to maintain attention and coordinate thoughts and actions.) The children in the fit and unfit groups had similar socioeconomic backgrounds, body mass index, and other variables. Therefore, researchers concluded that physical fitness was responsible for the enlargement of the basal ganglia.

In a second study, also at the University of Illinois, a different group of nine- and ten-year-olds was also categorized according to fitness levels. These children were given tests of their complex memory. This activity takes place in the part of the brain called the hippocampus. MRI scans showed that the fit children had a heavier hippocampus than did the children who were less fit. The basal ganglia and the hippocampus interact in many brain functions needed for intricate thinking. Researchers concluded that if exercise strengthens the size of these regions and strengthens the connection between them, being fit might contribute to better thinking.

Even a small amount of aerobic activity can have a positive impact. An earlier study at the University of Illinois found that just twenty minutes of walking before a test raised children’s test scores. This result occurred even if the children were overweight or otherwise unfit.

Question1. Which sentence best expresses the main idea of the passage?
a. Exercise is important for good health.

b. Recent studies have shown that exercise improves children’s brain function.

c. Schools across the United States have greatly reduced their physical education programs.

d. Several scientific studies about the effect of exercise on the brain have been conducted at the University of Illinois.