Lorin at The Vegan Asana recently wrote about yoga sometimes hurting. In it she says, pain is okay
as long as the pain is not extreme, is not unusual, is not unbearable, does not produce dizziness or nausea, and is not in areas of the body that are very easily injured (e.g. knees) or where injuries could be quite dangerous (e.g. neck).
Great things to keep in mind with any physical activity. At the beginning of my class and throughout class, I remind students that though they should feel challenged within the poses, they should not feel any sharp pain and if they do, then they need to slowly and carefully come out of the pose. Additionally, I emphasize modified versions of poses by demonstrating that first then showing the more advanced positions before returning to the other version to encourage students not to push beyond what they are capable of at the present. (Yes, more often than not, I can tell when a student is not ready for a pose).
Despite all of that I still see plenty of students who push harder than they should at the risk of getting hurt.
But I encourage them to come back because I want them to learn that a great thing about yoga is that it provides an opportunity to tune in to your body while it is in action. Whether you are moving into the warrior poses, holding them or coming out, you are mindfully going slowly enough to listen to your body. You can ask: what felt good? What didn’t? Did adjusting one way make it better or worse? You will learn so much about your body during a yoga practice.
That is, if you are listening…
The key to avoiding getting hurt inside and outside of yoga is knowing where your edges are. Your physical edge is that line in your body right before the benefit of exertion becomes harmful and injury is likely. Like a cliff, you approach your edge slowly and carefully so that you don’t fall over. Knowing where solid ground ends and free fall begins is important to preventing injury.
For example, in a seated forward fold, a student with tight hamstrings shouldn’t grab his feet, jerk his torso towards his legs and pull as hard as he can to get his chest as close to his thighs as possible. This can cause a serious tear and take him out of commission for weeks. The fold should be approached slowly, bending from the hip creases while using the breath to gradually lower the chest towards the legs to deepen the stretch. Done carelessly, it’s not just your legs that you can hurt but your back as well.
The mentality of pushing past pain does more harm than good. Pain, after all, is your body telling you that it is not okay. Ignoring pain comes with a price that can easily be avoided if we spent just a little more time listening to our bodies and being kinder to ourselves. There is, of course, a difference between pain and intensity. In a stretch, it changes from intensity to pain when you are no longer enjoying the movement. At that point, pulling back is recommended.
It is up to us to define our own edges – physically and psychologically. It is the only sure-fire way to stay safe. If you have any wisdom to share about your experience with injury, please leave them here!
Yogitastic 
I always say, listen to your body and please don’t wait until it is screaming at you (i.e. sharp pain) to pay attention. I tend to think that works. What do you gain from doing something for 3 seconds that with proper care and preparation, you could do for 30 years to come?
Exactly. In a lot of instances, when you experience sharp pain it’s probably too late! Which is why I use a blanket under my knees as much as possible. I like my knees and I’d like to keep using them for a really long time to come. And when someone tells me to take a break, I definitely do.
Have you ever run into stubborn students? What did you do?
Yes – there’s occasionally someone who no matter what you say just has to try the super fancy version right this second and doesn’t listen when you talk to them individually. If it gets to the point where I can see that safety is compromised then I shut everyone down and move on to the next thing. Not sure that’s the most effective way, but my liability insurance provider probably appreciates it. In the end, though, if someone does something that busts their hamstring or whatever despite being given a gentler option, that’s on them.
I’d probably do the same, Annie! Some folks are just stubborn!