VOA标准英语2010年-Frequent Aerobic Exercisers Get Fewer

There's been lots of research over the years concluding that physically¹ active people are less likely to have serious conditions, such as heart disease. Now, a new study indicates that those who engage in frequent aerobic² exercise are also less likely to catch cold or have other respiratory symptoms. Some 1,000 participants in the study filled out a daily diary of their exercise, and then the numbers were crunched³ by researchers led by David Nieman of Appalachian State University in North Carolina.
"We found that the most important lifestyle factor in predicting the number of sick days during the winter and fall was the amount of physical activity," he said in a telephone interview.
Specifically, aerobic physical activity, bouts⁴ of 20 minutes or more, enough to increase the heart rate and break a sweat. "People [who] put in those bouts, five days a week during the 12-week period, had more than a 40-percent reduction in sick days."The reduction factored in other data, such as study participants' diet, weight, education, and gender⁵. Five weekly aerobic sessions of about 20 minutes each seemed to produce the best results. Those who exercised less frequently were more likely to catch cold. Nieman says the explanation comes from what happens to certain white blood cells [Neutrophils and natural killer⁶ cells] when the body kicks into exercise mode: these immune cells start roaming the blood stream, looking for invaders⁷, such as the viruses that cause colds and other respiratory infections.
"Most immunologists interpret this as what they call improved immunosurveillance, or the ability of the immune system to detect and then engage pathogens and destroy them," Nieman explained.
The so-called common cold is one of the most frequent illnesses in many parts of the world. According to one study, the economic burden is estimated at $40 billion a year in the U.S. alone.
David Nieman's study is reported in the British Journal of Sports Medicine.

1 physically   

adj.物质上，体格上，身体上，按自然规律

参考例句：

• He was out of sorts physically,as well as disordered mentally.他浑身不舒服，心绪也很乱。
• Every time I think about it I feel physically sick.一想起那件事我就感到极恶心。

2 aerobic   

adj.需氧的，增氧健身法的，有氧的

参考例句：

• Aerobic exercise helps to build up stamina.有氧健身操有助于增强耐力。
• Aerobic dance is conductive to the health.有氧舞蹈有助于健康。

3 crunched   

v.嘎吱嘎吱地咬嚼( crunch的过去式和过去分词 )；嘎吱作响；（快速大量地）处理信息；数字捣弄

参考例句：

• Our feet crunched on the frozen snow. 我们的脚嘎吱嘎吱地踩在冻雪上。 来自《简明英汉词典》
• He closed his jaws on the bones and crunched. 他咬紧骨头，使劲地嚼。 来自英汉文学 - 热爱生命

4 bouts   

n.拳击（或摔跤）比赛( bout的名词复数 )；一段（工作）；（尤指坏事的）一通；（疾病的）发作

参考例句：

• For much of his life he suffered from recurrent bouts of depression. 他的大半辈子反复发作抑郁症。 来自《简明英汉词典》
• It was one of fistiana's most famous championship bouts. 这是拳击界最有名的冠军赛之一。 来自《现代英汉综合大词典》

5 gender   

n.（生理上的）性，（名词、代词等的）性

参考例句：

• French differs from English in having gender for all nouns.法语不同于英语，所有的名词都有性。
• Women are sometimes denied opportunities solely because of their gender.妇女有时仅仅因为性别而无法获得种种机会。

6 killer   

n.杀人者，杀人犯，杀手，屠杀者

参考例句：

• Heart attacks have become Britain's No.1 killer disease.心脏病已成为英国的头号致命疾病。
• The bulk of the evidence points to him as her killer.大量证据证明是他杀死她的。

7 invaders   

入侵者，侵略者，侵入物( invader的名词复数 )

参考例句：

• They prepared to repel the invaders. 他们准备赶走侵略军。
• The family has traced its ancestry to the Norman invaders. 这个家族将自己的世系追溯到诺曼征服者。