这里是美国之音慢速英语健康和生活方式报道。
In winter, people might lessen their outdoor exercise. The days get dark earlier, and it can be very cold! These conditions can make it harder for some of us to get outdoors for exercise.
在冬天里，人们可能会减少户外运动。每天天黑得越来越早，而且天气都很冷。这种情况会让我们中的一些人更难到户外锻炼。
However, cold days can be perfect for outdoor workouts!
然而，冷天可能对户外锻炼来说是个极佳的选择。
There are at least three important health benefits to cold-weather workouts.
寒冷天气锻炼至少有3个重要的健康益处。
1. The body works harder in cold weather.
1. 寒冷天气身体会更加卖力工作
Health experts at the Medical University of South Carolina say the body must make extra energy to keep warm in low temperatures. This means the body is burning more calories and fat.
南卡罗来纳医科大学的健康专家们表示，人体在低温条件下需要制造额外能量以保持体温。这意味着身体会燃烧更多的卡路里和脂肪。
Your lungs also may work better in cold weather. Researchers at Northern Arizona University in Flagstaff found some interesting results in a study of goats.
肺在寒冷天气里也会工作更加良好。位于弗拉格斯塔夫市的北亚利桑那大学的研究人员在对山羊的研究中发现了一些有趣的结果。
Yes, I said "goats."
没错，我说的是山羊。
But still, their results were pretty interesting.
但是，他们的研究结果还是很有趣。
The scientists looked at how cold-weather activity affected goats. They found that "during the three coldest months, the sedentary but cold-exposed goats experienced a 34% increase in maximal oxygen uptake ... and a 29% increase in running speed." When temperatures increased in the spring both oxygen uptake and running speed of the goats decreased.
科学家们研究了寒冷天气的活动对山羊的影响。他们发现，“在最寒冷的三个月里，久坐不动但是暴露在寒冷中的山羊的最大摄氧量增加了34%，奔跑速度提高了29%。”当春季气温上升时，山羊的摄氧量和奔跑速度都会降低。
2. Regular cold-weather exercising may help the immune system.
2. 定期在寒冷天气锻炼可能对免疫系统有益
The winter season is also cold and flu season. Making outdoor exercise a usual part of your workout may help you avoid both colds and the flu. It may strengthen your body's defense system.
冬季也是感冒和流感高发季节。让户外运动成为锻炼的一部分可以帮助人们避免感冒和流感。它可以强化人体的防御系统。
The Mayo Foundation for Medical Education and Research found that winter workouts can cut your risk of getting the flu by 20 to 30 percent.
梅奥医学教育和研究基金会发现，冬季锻炼可以把流感患病风险降低20%到30%。
3. Exercising outdoors in cold weather may help your mental health.
3. 寒冷天气锻炼身体可能对心理健康有益
Some people who suffer from "winter blues" or Seasonal Affective Disorder, may benefit from going outside to exercise in the fresh air and sunshine.
一些“冬季忧郁症”或是季节性情感障碍的患者可能会受益于外出在阳光和新鲜空气中锻炼身体。
An outdoor workout increases exposure to sunlight. Sunlight helps the body produce vitamin D. And vitamin D produces hormones that brighten your mood.
户外锻炼可以多晒太阳。阳光有助于身体产生维生素D，而维生素D会产生让你心情愉快的激素。
Dangers of a cold-weather workout
寒冷天气锻炼的危险
So, there are several health benefits of exercising outdoors in very cold weather. But there are also dangers.
因此寒冷天气到户外运动有多项健康益处，但是它也有危险。
Frostbite is one of the most common.
冻伤就是最常见的危险之一。
Edward Ward is a doctor at Rush University Medical Center. He explains how frostbite happens.
爱德华·沃德（Edward Ward）是拉什大学医学中心的医生。他解释了冻伤是如何发生的。
"When the air temperature drops below zero especially factoring wind chill, things freeze. And that includes the fluids that's within your fingers or your toes, nose, ears, anything that's exposed to that wind chill can be affected by frostbite."
他说：“当气温下降到零度以下，尤其是加上风寒，万物就会冻住，其中就包括人们的手指、脚趾、鼻子、耳朵里的液体。任何暴露在风寒中的物体都可能会受到冻伤影响。”
Protecting your fingers, toes, ears and nose is very important. Cold winds affect these parts of the body more quickly than other parts.
保护你的手指、脚趾、耳朵和鼻子是非常重要的。寒风对人体这些部位的影响比其它部位更快。
Christopher Sampson is a doctor with University of Missouri Health Care. He explains that frostbite can happen rapidly -- in less than 30 minutes.
克里斯托弗·桑普森（Christopher Sampson）是密苏里州大学卫生保健部门的一位医生。他解释说，冻伤可能会在30分钟内迅速发生。
"With frostbite people can start experiencing symptoms pretty rapidly, on average with mild winds and cold temperatures it can occur in as less than 30 minutes, with extreme cases. When it's very, very cold and winds are very, very strong, sometimes frostbite can develop in as little as 5 minutes."
他说：“人们冻伤后很快会开始出现症状。一般在微风和寒冷气温下，它会在不到30分钟内发生。在极端情况下，当天气很冷风很大时，有时候短短五分钟内就会冻伤。”
The beginning of frostbite is called "frostnip."
冻伤的初步症状被称之为“亚冻伤。”
Experts at the Mayo Clinic explain that "with this mild form of frostbite, your skin pales or turns red and feels very cold. Continued exposure leads to prickling and numbness in the affected area. As your skin warms, you may feel pain and tingling. Frostnip doesn't permanently damage the skin."
梅奥诊所的专家解释说，“这种轻微冻伤会使你的皮肤发红，并且感觉非常寒冷。持续暴露会导致受创部位的刺痛和麻木。当皮肤变暖时，你可能会感到疼痛和刺痛。亚冻伤不会给皮肤造成永久性伤害。”
But, frostbite can. It can even lead to loss of tissue and limbs.
但是冻伤会。它能造成失去组织和四肢。
Hypothermia
失温
The most serious danger is hypothermia. Hypothermia is when the body temperature has fallen below 35 degrees Celsius or about 95 degrees Fahrenheit. This happens when your body can not produce enough energy to keep the body warm enough.
最严重的威胁是失温。失温是指体温降到35摄氏度或95华氏度以下。当身体无法产生足够能量维持体温时就会发生这种情况。
Hypothermia can kill you. There are several signs to watch for before it is too late.
失温会让你丢命。在为时已晚前可以关注以下迹象：
difficulty in movement
运动障碍
difficulty in thinking
思维障碍
slowed reactions
反应迟缓
unclear speech
口齿不清
cold feet and hands
手脚发冷
shivering
身体发抖
sleepiness
嗜睡
Falling on ice
冰上滑倒
However, Dr. Sampson says it is ice that creates the biggest risk for workouts outside when it is very cold. People don't see the ice, step on it and fall.
然而，桑普森博士表示，当天气寒冷时，户外锻炼最大的风险是冰。人们没看到冰，踩上去滑倒。
Dress properly
正确着装
But if you are dressed right, you can exercise safely in low temperatures.
但是如果你着装正确，就能在低温下安全地锻炼。
Experts on several health websites say it is important to dress in layers.
几家健康网站的专家表示，分层穿衣很重要。
The layer closest to the body should be made of a material that takes moisture away from the body. The next layer should be a material that traps heat, such as wool. And finally, the outer layer should be water resistant.
最贴近身体的衣物应该用排汗材料制成。下一层衣物应该用保暖材料，例如羊毛。最后，外层衣物应该是防水的。
Of course, don't forget gloves, hat, good socks and shoes. When it is really cold, a scarf or face mask will protect your skin and lungs.
当然，不要忘记手套、帽子、合适的袜子和鞋子。当天气非常冷的时候，戴上围巾和口罩可以保护你的皮肤和肺。
Check the weather forecast
关注天气预报
Temperature is not the only things that will affect your outdoor workout. It is also important to consider wind and water.
温度并非影响户外锻炼的唯一因素。关注风和雨也很重要。
Wind can go through your clothing and steal the layer of warm air that surrounds your body. If you get wet, you may not be able to keep your body temperature high enough.
风能穿过衣物，带走你身体周围的热气。如果身上弄湿了，你可能无法维持足够高的体温。
So, if you are a generally healthy person, do not think you must move your workouts indoors in winter. As long as you dress properly, drink enough water and exercise safely, you can get a lot out of a cold-weather workout.
所以，如果你身体基本健康，不要认为冬天必须把锻炼放在室内。只要你穿着得当，喝足够多水，并安全地锻炼，你就能从寒冷天气的锻炼中受益良多。
And that's the Health & Lifestyle Report.
以上就是本期健康和生活方式报道的全部内容。
I'm Anna Matteo.
我是安娜·马特奥。(51VOA.COM原创翻译，禁止转载，违者必究！)