很多人以为拉伸运动是在拉伸肌肉，但实际上，拉伸的真正目的是拉长和调动肌肉周围的结缔组织。

Science shows that stretching isn't actually literal—you're not even "stretching" your muscles at all. In fact, the true purpose of stretching is to lengthen and mobilize the connective tissue around your muscle, which does wonders for both your joints and your muscles. What's more, stretching helps your blood flow, reduces your risk of injury, helps you lose weight, and even relieves your stress.
科学告诉我们，拉伸运动并不是字面意思那样，你甚至根本没有“拉伸”到你的肌肉。事实上，拉伸的真正目的是拉长和调动肌肉周围的结缔组织，这对关节和肌肉都有好处。更重要的是，拉伸运动可以帮助血液流动，降低受伤的风险，有助于减肥，甚至可以缓解压力。

运动后不拉伸会怎样？

1.You Could Feel Sick
可能会感到身体不适

You won't be surprised to know that when you exercise, you raise your heart rate for a period of time. While it's great to get that blood flowing, experts will tell you that it's just as important to "get your heart rate back to a normal level after the workout is over." This is also known in the fitness world as "cooling down."
我们都知道运动时心率会升高。虽然这会加速血液流动，但专家表示，“锻炼结束后让心率恢复到正常水平”同样重要，这在健身界也被称为“降温”。

"After physical activity, your heart is still beating faster than normal, your body temperature is higher and your blood vessels are dilated," write the health experts at the American Heart Association. "This means if you stop too fast, you could pass out or feel sick. A cool-down after physical activity allows a gradual decrease at the end of the episode."
美国心脏协会健康专家称：“在体育活动之后，心脏仍然比正常情况下跳动得更快，体温更高，血管扩张。这意味着，如果你太快停下来，你可能会昏倒或感到恶心。运动后的‘降温’会让你在运动快结束时逐渐平静下来。”

2.Your Muscles Will Likely Become Stiffer and More Sore
肌肉更加僵硬酸痛

When you exercise your muscles, it produces an inflammatory response in the form of lactic acid, which is actually what causes your muscles to become sore. When you rest—or "recover"—in the time between bouts of exercise, your body naturally breaks down and gets rid of that lactic acid. One thing that helps your body dispose of that lactic acid? You guessed it: Stretching. Stretching helps your distribute oxygen throughout your body and muscles, which, according the Healthline, "can reduce lactic acid production and rid your muscles of any accumulation of lactic acid."
当你锻炼肌肉时，肌肉会产生炎症反应释放乳酸，这是导致肌肉酸痛的原因。当你在两次锻炼之间休息“恢复”时，你的身体会自然分解并代谢掉这些乳酸。有没有方法可以帮助身体排出乳酸？你猜对了，答案是：拉伸运动。拉伸有助于将氧气分配到全身和肌肉，据Healthline网站称，拉伸“可以减少乳酸的产生，消除肌肉中积累的乳酸。”

At the same time, stretching right after exercise will also relax what are guaranteed to be stiffer muscles that are far more likely to cramp.
同时，运动后立即拉伸也会放松那些更僵硬、更容易抽筋的肌肉。

3.You'll Be at Risk of Injury
存在受伤风险

According to the experts in the sports medicine department at UC Davis Health, inflexibility will cause you to have muscles that tire quicker and joints that are more prone injury, it will lead to "abnormal stress on structures and distant from the initial site of inflexibility" , and your weakened range of motion will lead to less blood and nutrients to your joints. In the case of the latter, it's why people often feel stiffness and pain in their "weight bearing" joints, such as the knees and hips.
加州大学戴维斯分校医学中心运动医学系专家称，僵硬会导致肌肉更易疲劳，关节更易损伤，这将导致“结构上的异常应力，柔韧性会变得更差”，运动范围的缩小会导致关节的血液和营养供应减少。这就是为什么人们的“负重”关节（如膝盖和髋关节）经常感到僵硬和疼痛的原因。

Put simply: "Stretching after you exercise helps optimize the range of motion about your joints and boosts circulation," write the leading health experts at The Mayo Clinic.
梅奥诊所首席健康专家表示，简单来说，“运动后拉伸有助于扩大关节的活动范围，促进血液循环”。

如何进行拉伸

专家建议，运动结束后先待心跳平复至每分钟120次以下，然后进行适当拉伸。

Step one: "Walk for about 5 minutes, or until your heart rate gets below 120 beats per minute."
第一步：“走动约5分钟，或者待心率降到每分钟120次以下。”

Step two, moving to stretching: "Hold each stretch 10 to 30 seconds. The stretch should be strong, but not painful. Breathe while you're stretching. Exhale as you stretch, inhale while holding the stretch."
第二步，开始拉伸：“每次拉伸10到30秒。拉伸应该很有力，但不会疼痛。拉伸时保持呼吸。做动作时呼气，保持拉伸动作时吸气。”

下面来学习几个简单实用的拉伸动作：

1. 单腿简式腘绳肌拉伸

要点：站立，一只脚在前，背部挺直。双手放在髋部，从髋部开始向前折叠，另一条腿重复。

2. 跪姿股四头肌拉伸

要点：左腿在前屈膝90度。抓住右脚向腰部，换另一只脚重复。

3. 婴儿式臀大肌拉伸

要点：坐在地板上，挺直背部，慢慢地将一条腿拉到胸前，把大腿转出来，另一条腿重复。

4. 下犬式背阔肌拉伸

要点：靠墙一定距离站立，身体平行于地板。保持背部平坦，然后从胸部开始慢慢弯曲。

5. 体侧屈腹斜肌拉伸

要点：把手放在站立腿的前面，背部挺直，抬起对侧手臂，让髋部从前向后打开。

6. 三角肌拉伸

要点：站立，手臂伸直，轻轻按压以增加肌肉的伸展， 另一只手重复练习。

切记做拉伸时也要量力而行，如果你以前从来不做拉伸，不可能达成完全的伸展。但是随着时间推移，这种情况将会改善。

来源：Eat This，新华网