Pros/Use – Stretches quadriceps and hip flexors. The above is not a traditional yoga pose. In my opinion is that westerners dreamed this one up for fitness class. Again no yogi trained by the various styles from India has this pose, at least not in Ashtanga yoga.
Cons – Places high stress on kneecap and other tissues in front of knee joint. Those with a history of knee problems should refrain from this stretch. Most health-care professionals also discourage use of this stretch.
Above is last of dangerous poses listed in NASM text book.
Ashtanga yoga has pose similar as follows, but is in the Advanced Series, which most never master until after years of practice.
Many western yoga studios include this pose depicted above, and I have not yet encountered in my Ashtanga Yoga practice, for after 15 years, I am not ready for this one. Takes years of practice.
Kapotasana from Ashtanga yoga advanced series
Note the difference of pose from Ashtanga yoga and the western version. Hips are up, not descending toward the ankles.
Again NASM publicizes its criticisms of yoga, without researching nor providing reliable information.