很多瑜伽练习者会惊讶地发现，关节也会变得过度灵活。但是在很多关节中，韧带和肌腱对防止关节过度活动起了很重要的作用，如果它们变得过度松弛后，那关节就有可能受伤或者为以后的损伤起了铺垫。这种有过度灵活性的关节称之为超伸的关节，其中，膝关节是最容易产生这个问题的。事实上，这种关节或多或少都是一根长的骨头（股骨，或大腿骨）堆叠在另一根长的骨头（胫骨，或小腿骨）上。这个部位的韧带和肌腱都是用来把这些骨头连接到一起的。

Most people are all too aware of how easily and dramatically the knee's connective tissues can be injured by twisting. But fewer people are aware that knee hyperextension--too much opening at the back of the knee--also creates misalignment and bad movement habits that can pave the way for arthritis and more serious knee injuries.

大部分人都知道膝盖的连接组织很容易在扭转中受到严重的伤害。但是很少的人意识到膝关节的过度伸展—膝盖后部的过度打开—也会产生错位，由此而形成的运动习惯会容易造成关节炎以及更为严重的膝关节损伤。

Do You Hyperextend?
你是膝关节超伸吗？
Wearing minimal or tight-fitting clothes so you can clearly discern the alignment of your legs, stand sideways in front of a full-length mirror, far enough away that you can see your whole body. In normal standing alignment, the leg forms a straight line from ankle to hip, with knee over ankle and hip over knee. If your knee is hyperextended, however, the leg will appear to curve back, with the knee behind an imaginary straight line drawn from ankle to hip.

穿一条窄的或紧身的裤子，以便清晰地看到自己腿的轮廓，侧身站在一面全身镜前面，站远一点，以足够看到整个身体。在正常的站姿中，从脚踝到髋部会形成一条直线，脚踝、膝盖、髋部在同一条直线上。然而，如果你的膝盖是超伸的，腿看上去会向后反弯，如果从脚踝到髋部画一条直线的话，膝盖会在这条直线的后方。

Since hyper-extended knees are basically a problem of too-loose ligaments and tendons around the knee, you can cause or exacerbate such looseness through poor alignment in yoga poses. The soft tissues at risk of being overstretched include the cruciate ligaments deep inside the knee, the medial and lateral collateral ligaments on the inner and outer surfaces of the knee, and the popliteal ligaments, which cross the back of the knee. There are also several large tendons that cross the back of the knee and normally help prevent hyperextension: the hamstring tendons coming down from the back of the thigh and the gastrocnemius tendons coming up from the calf.
超伸的膝盖基本上都是来自于膝盖附近过度松弛的韧带和肌腱，而不正确的瑜伽体式可以引起或加剧这种松弛。这类容易过度松弛的软组织包括膝盖深部的十字韧带、位于膝盖内、外表面的中间和侧部的间接韧带，以及膝盖后侧韧带，后侧韧带正好穿过膝关节的后面。还有一些穿越膝关节后部的大肌腱，它们也会帮助防止膝盖超伸，包括从大腿后侧向下的腘绳肌肌腱和小腿向上的腓肠肌肌腱。
If you look at the hyperextended knee pictured at left, you can see that these tendons are overstretched. The overstretched knee ligaments and tendons are also usually accompanied by changes in adjacent muscle groups, including the soleus muscle, which is deep in the calf. The soleus originates on the upper tibia and fibula, then runs down the calf to attach to the heel. If it is short and tight, it will pull the upper ends of the tibia and fibula backward, contributing to hyperextension. So if you have hyperextended knees, it's important to regularly practice bent-knee calf stretches, like Malasana (Garland Pose) and simple squats.
如果你从左侧观察超伸的膝盖的图片，你可以发现这些肌腱被过度拉伸了。过度伸展的膝关节韧带和肌腱通常也伴随着相邻肌群的变化，比如小腿深层的比目鱼肌。比目鱼肌起自胫骨和腓骨的上部，然后沿着小腿一直到脚后跟。如果这块肌肉肌纤维短并且僵紧，它会把胫骨和腓骨的上部向后拉，造成超伸。所以如果你有超伸的膝盖，你应该规律的联系弯曲膝盖的小腿伸展体式，比如花环式以及简单的蹲姿。
Though yoga probably will not shorten overstretched knee ligaments, it can help stabilize your knees by strengthening the surrounding muscles.
虽然瑜伽不能缩短你已经被过度拉伸的膝关节韧带，但是它可以通过加强附近的肌肉来稳定膝关节。
Protecting Your Knees
保护你的膝盖
Of course, you want to practice your poses in a way that won't increase hyperextension and knee instability. If you tend to hyperextend, typical calf and hamstring stretches done with a straight knee can aggravate the problem unless you take care to engage your quadriceps (front thigh muscles). People with hyperextended knees usually have weak quadriceps, or do not tend to engage them fully in straight-legged poses like Tadasana (Mountain Pose) and Trikonasana (Triangle Pose). Instead of engaging the quads to stabilize and protect the knees, people who hyperextend usually just push their knee joints back. To overcome this habit, they need to strengthen the quads in bent-knee postures such as Virabhadrasana I and II (Warrior Poses I and II) and Parsvakonasana (Side Angle Pose) and train the quads to be active and strong in straight-knee poses.

当然，你不想因为练习体式加剧膝盖超伸和膝盖不稳定的情况。如果你已经有超伸的情况，那伸直膝盖做小腿和腘绳肌的拉伸会加剧超伸的情况，除非你同时收紧你的股四头肌（大腿前侧肌肉）。有超伸膝盖的人往往股四头肌比较弱，或者是在伸直膝盖的体式中没有完全收紧它们，比如山式和三角式。有超伸的人如果没有收紧股四头肌去稳定和保护膝盖的话，那他们通常就是将膝关节向后推。为了改掉这种习惯，他们需要在弯曲膝盖的体式中加强股四头肌的力量，如战士一式和二式，以及侧角式，以训练收紧股四头肌并能运用在伸直膝盖的体式中。

One of the best ways to start training the quads to work in the straight-knee position is by sitting on the floor with your legs stretched out straight in front of you. Contract your quads by gently pressing your thighbones down into the floor. If you have hyperextended knees, your heels will lift off the floor; if you watch carefully, you will observe that the part of your shinbone nearest each knee shifts back toward the floor. If that happens, your challenge is to learn to contract your quads without letting your knees hyperextend. To do this, gradually press your thighs down while keeping your heels on the floor; you will notice that now the upper shinbones do not drop toward the floor. Since you need to challenge a muscle regularly for it to build and keep strength, it's a good idea to practice this action a few times a week. Not only will you start building strength in your quads, but you'll also learn how to straighten the legs without hyperextending them.
训练运用股四头肌来伸直腿的最好的方法之一是腿伸直坐在地板上。通过轻轻地将大腿骨压向地面来收缩股四头肌。如果你的膝盖超伸，那你的脚跟会离开地面。仔细观察，你会发现最靠近膝关节的小腿上部想地板方向运动。如果这个发生了，那你的任务就是如何学会收缩你的小腿而不让关节超伸。慢慢地将大腿向下压，但同时让你的脚跟在地面上。你会发现，小腿的上部不会向地面移动了。因为你要训练一块肌肉，让它塑形和加强力量，你应该一周做几次这样的练习。这不仅仅是加强了股四头肌的力量，更让你学会不用超伸膝盖来伸直双腿。
Straighten Up
直起来
Now, let us apply this awareness to some yoga poses. Hyperextended knees are often a problem in Trikonasana, for several reasons. If you are doing the pose to the right, your right leg is at an angle to the floor that makes it easy for gravity to pull the leg into hyperextension. If your right hand is pressing down on your right shin firmly, you're pushing the tibia back. (Especially if your hamstrings are quite flexible and their tendons overstretched, they won't offer much resistance to the movement of the tibia.) And finally, if your quads are untrained and/or weak (unfortunately true for many students new to yoga), these muscles will not contract enough to prevent hyperextension and help protect the knee.
现在让我们把这种意识带到一些瑜伽体式中。因为某些原因，超伸的膝盖一直是练习三角式中的一个问题。如果你向右侧做三角式，你的右腿与地面呈一个角度，这样由于重力的作用，就会很容易将右腿的膝盖拉到超伸的状态。如果你的右手用力压在小腿上，那就会将胫骨向后压。（特别是如果你的腘绳肌非常灵活而且肌腱过度拉伸，那它们不会对胫骨的运动形成比较大的阻碍。）最终，如果你的股四头肌没用受过训练和/或比较弱（很不幸的是很多瑜伽的新练习者往往都是这种情况），那股四头肌不会足够地收缩以防止超伸和帮助保护膝关节。
If you do hyperextend your knees in Trikonasana, however, all is not lost. With careful practice, you can learn to do the pose with a strong, straight front knee. As you are learning this new alignment, it's helpful to watch yourself in a mirror or get feedback from a teacher with a good eye for structure; you want to make sure to correct your alignment enough to remove the hyperextension but not so much that you bend your knee.
然而，如果你在三角式中三角式中膝关节超伸了，也不是什么都没有。如果你仔细地练习，那你可以学习在体式中保持一个强健的、直的前部膝盖。当你学习这种新方法时，不妨在镜子前观察自己或者接收来自一个具有对身体构造有良好洞察力的老师的反馈。你应该通过纠正的练习来改掉超伸，同时也不过分地弯曲膝盖。
If you usually place your hand on your shin in Trikonasana, the first step in correcting hyperextension should be placing your hand on a block instead. Then move the part of the shinbone nearest the knee away from the floor. You can get a good feel for this movement if you try to press the upper shinbone into a finger (either your own or someone else's).
如果你在三角式中通常把手放在小腿上，那纠正超伸的第一步是把手放在瑜伽砖上。然后将接近膝盖的小腿部分远离地面。如果你能将上部的小腿骨向上压向一个手指（不管是你自己的或别人的），你都会感觉很好。
As an alternate strategy, you can place a block or some other firm object 6 to 7 inches high under your calf, and make sure you do not let your calf press into the block as you move into the pose. Whichever approach you take, move the shinbone just enough to straighten the knee so that it no longer curves back, but not so much that the knee bends forward.
另一种方式，你可以在小腿下放一块瑜伽砖或者其它一些高6-7英寸的物体，而且注意在做进入体式时不会将小腿压在这个物体上。不管你用哪种方式，移动小腿骨恰到好处地伸直膝盖，不再让膝关节往后弯，但也不要太高以免膝关节向前弯。
As you move the shinbone, you may notice that a little more weight shifts onto the ball of the foot and that there is less weight on your heel. Because many people prone to hyperextension lean too heavily on the heel, this is a good correction; remember that a goal in standing poses is to have your weight evenly balanced on the four corners of each foot (the inner and outer edges of the heel, and the inner and outer edges of the ball of the foot). If you press those four corners into the floor, your quads will contract, helping to stabilize your knee in its new, straight alignment.

当你在移动小腿时，你可能会注意到，更多一点的重量分配到脚掌，而在脚跟的重量却减少了。因为许多有膝盖超伸的人会倾斜并将重量太多的压在脚跟上，所以这是一种很好的纠正方式。记住，在站姿中你的目标是将重量平均分配在脚底的的四个角上（脚跟的内、外侧，脚掌的内、外侧）。如果你把这四个点压在地上，你的股四头肌将会收缩，帮助你将膝盖稳定在这种新的、直的方式上。

To accompany your Trikonasana work, also practice your new knee alignment in Tadasana or at any other time you find yourself standing for a moment--in line at the store, waiting for the teakettle to boil, taking a shower. Whether in Trikonasana or any of these standing moments, move the upper tibia forward slightly. For most people, about a half inch is enough.
为了练好三角式，你可以将这种膝盖的纠正运用在山式以及其他任何时间你可以站立的时候—在商店里排队、等水烧开、冲淋。无论是在三角式还是任何这些站立的运动中，你可以轻轻地将上部的胫骨向前移。对大多数人来说，半英寸就足够了。
As you begin to correct your knee alignment, you may become aware that your hyperextended knees are part of a bigger posture problem. As the knees curve back, there's a tendency for the pelvis to push forward, the chest to collapse back, and the head to jut forward. These forward-and-back shifts form a system of compensation that can contribute not only to knee problems but also to lower back and neck pain. So as you work on moving your upper tibia forward, you may also want to move your pelvis slightly back and your chest up and forward. Your efforts to protect your knees will then coincide with important physical goals of your yoga practice: to create strong, healthy joints and a spacious, vertical posture.
当你开始纠正你的膝盖时，你可能会意识到你的超伸的膝盖成为了一个更大的身体姿态问题的一部分。当膝盖向后弯时，骨盆就会有向前弯的趋势，胸部向后塌陷，头向前伸。这种前-后的移动会造成不仅是膝盖的问题，而且会造成下背部和脖子的疼痛。所以当你在把胫骨稍微往前移时，你可能也会把你的骨盆稍向后移，胸部展开并向前。你对于保护膝盖所做的努力将于练习瑜伽体式的一个重要目标相一致：建立强健的关节并且保持一个挺拔的身姿。
A licensed physical therapist and certified Iyengar Yoga teacher, Julie Gudmestad runs a private physical therapy practice and yoga studio in Portland, Oregon. She regrets that she cannot respond to inquiries requesting personal health advice.