Triangle, while a simple pose, can be confusing. In part, because each of the best-known yoga gurus has their own style.
My preferred triangle is quite different from the Ashtanga, Bikram, or Iyengar ways. I imagine the head, spine, and hips flat against a wall — or literally, against the wall. Then, I lift my top hand to the ceiling to stretch my shoulders, arm, and spine. Almost pretending my top wrist is being suspended from the ceiling, I let the bottom arm hang, wherever it wants. The knee, shin, ankle, it doesn’t matter where it lands. For a slight modification that yields more core strengthening, try the Sivananda style. Sivananda teaches to extend the top arm horizontally, parallel to the floor.
For a strong triangle, the foundation needs to be solid, with feet positioned at right angles to each other. Craig Perkins is the founder of my alma mater, Yandara Institute. He says, “I see many of my students hyperextending their knees in various standing poses, especially triangle pose. When this happens I tell them to remember – thighs back, shins forward. This action creates a little microbend in the knee, something we want to maintain during asana practice.”
Dr. Loren Fishman, who specializes in the health and well-being of the spine, studied the benefits of yoga on the bones and posture for many years. In one two-year study, of which triangle pose was part of the Rx, everyone improved bone density significantly, without any negative side effects that bone-density drugs bring. Rather, side effects among the participants were positive: reduced back pain, less anxiety, and improvement for those with arthritis. All with just ten minutes of yoga, daily.
For parivrtta trikonasana (revolved triangle), the legs are in the same position with knees straight, but you twist the torso deeply. For example, reach the right arm to the left leg as the left arm lifts to the sky. To maximize the stretch, try to place your right-hand fingers on the outside of your left calf. As Dr. Fishman suggests in my book, "From the Boxing Ring to the Ashram," this is a particularly good pose for those with piriformis syndrome, provided there are no other spinal injuries.
Just like with any other new diet or workout plan, consult a yoga therapist to determine what is best suited for your particular physical and emotional well-being.