After that many years teaching I found out that these are the most common injuries related to bad practice/habits in yoga:

Very flexible people are drawn to yoga, because it is easy for them to attain a complicated posture and of course this always feels great to be good at something, who doesn´t enjoy that feeling. But these are the people that tend to injure themselves the most. Flexibility often comes alongside instability. So this flexible student with insufficient core support bends forward from the hip, without lifting the hip points, using the lower abdomen for support and eccentrically contracting the top of the hamstring (engage it as it stretches) the result is a huge strain to the top of the hamstring tendon, resulting in a tear that takes months, if not years to repair and can be very painful. ​

 The shoulder is called the shoulder complex for a reason, it is complicated. Yet we ask our students to jump back into chaturanga over and over during class, without any correct alignment. When the elbows bend and the shoulders go below the elbows the shoulders move into a position called protraction, where the shoulder blades move around the sides of the spine and also (elevation) where they also hike up around the ears compressing the neck. This position not only creates neck pain, but puts the shoulder in a very instable position, putting pressure on the bicep tendon at the front of the shoulder, resulting in fraying (partial tear) and sometimes complete tears. This is a very painful and very common injury from bad posture practice in yoga.
We also ask students to take a bind around their leg in poses such as Parvakanasana, the overzealous student wants to of course bind, but without an educated yoga teacher to advise them well, they lean forward stick their bottom back, putting strain on the semitendinosus and semimembranosus (inner hamstring) resulting not only in a hamstring tear, but also the shoulder pushes forward into the bicep tendon and the poor little rotator cuff in the back stands no chance in holding on and snaps, again a very painful injury that can happen in breath of a second.

This one is so crazy to me, you can die from doing these poses incorrectly. Yet I see it again and again in classes, students jumping on their head at the wall, with no shoulder blade support. If you cannot lift up using your core, without jumping you are not ready for this pose. The shoulder blades need to be retracted (together on the back) using the rhomboids, mid and lower trapezes muscles to stabilize. The neck spine (cervical spine) also needs to be extended in its neutral position, plus the arms need to press down so the weight is not all in the head until the neck is strong enough to support the whole weight of the body. The same with shoulder stand, this I would say is the most dangerous pose practiced in yoga without any thought of alignment. The neck is placed in the flexion position (rounded position, chin to chest) the inexperienced teacher does not know how to teach the students to put the weight in the shoulders and the top of the arms, keeping the weight out of the neck, which you can imagine a whole load of complications could arise from this.

Yoga is great healer for the body, but it can also be extremely harmful if the postures are done incorrectly. Ahimsa, is Sanskrit word for "nonharming" or "nonviolence," it is the first Yama or moral injunction in Patanjali's Yoga Sutra.
 
As yoga teachers it is our duty to look after our students and to keep them out of harm’s way, and this means informing ourselves correctly before we take the lead and start putting our students into these very deep complicated postures.
 
It is important that we study body mechanics and keep our students healthy and help those who come to us with trust to regain their health.
 
I have been teaching for over 18 years around the world and during that time, I was fortunate to work alongside leading experts in anatomy such as Leslie Kaminoff the writer of the book “Yoga Anatomy” that is used in many YTT across the world, also Tom Myers who developed the concept of Anatomy Trains, the myofascial meridians of the body, who has shaken up the fields of bodywork, medicine and yoga as we originally knew it, and many other leading experts.
 
The growing clientele who have developed injuries from practicing yoga with inexperienced teachers and overzealous students is on the rise. So far here in Europe there are no standards to become a yoga teacher. You can do a yoga teacher training online, or in a few weeks on a yoga retreat and come out of the course a “fully qualified yoga teacher”. I am shocked when I have teachers pass through my classes and they do not even know what the psoas muscle is, or that the knee has to be aligned over the ankle. They do not have enough experience to see when their students are misaligned and yet the growing number of students seeking help from yoga as a recommendation from their doctor to help cure their back, hip and knee problems is rising here in Spain.