EXTENDED TRIANGLE POSE
The primary focus of triangle pose is the stretch of the front-leg hamstrings. Contributing subplots, or secondary regions that stretch, include the upper side of the trunk and the back-leg hamstring and gastrocnemius muscles. The front of the pelvis also opens as the back hip externally rotates. Be aware of the feet in Trikonasana, spreading the body weight evenly across the soles. Activate the gluteal muscles and the quadriceps of the back leg by attempting to scrub the back foot away from the front. Because the foot remains fixed on the mat and cannot move, the force of this action is transmitted to the back of the knee on the rear leg, opening this region. Notice how straightening the curve of the upper-side back increases the stretch of the front-leg hamstrings. This is because engaging the upper-side quadratus lumborum muscle tilts the pelvis slightly forward, lifting the ischial tuberosities. Look at the arrow showing the rotation of the trunk upward, and see the connection of this movement to the hamstring muscles. The tendency is for the front knee to turn in as the body turns up. Counter this tendency by externally rotating the hip to keep the knee facing forward. Press the ball of the foot into the floor to create a helical force up the leg. This illustrates the principle of co-activating muscles to create stability.
BASIC JOINT POSITIONS
Begin by turning the back foot in thirty degrees and the front foot out ninety degrees, so that a line drawn from the heel of the front foot transects the arch of the back foot. Activate the quadriceps to straighten the knees; contract the buttocks to open the front of the pelvis.
Next, bend the front knee and press the elbow onto the thigh by attempting to flex the trunk. This isolates and awakens the psoas muscle. You can also attempt to lift the leg up against the elbow (that is, attempt to flex the hip). Remember that the psoas flexes the trunk over the leg or flexes the leg toward the trunk. Recreating these movements against the resistance of the elbow awakens this muscle. When you activate the psoas, the pelvis tilts forward and the ischial tuberosities (the sitting bones) move backward. Feel how moving the origin of the hamstrings in this way increases the stretch. Straighten the front knee to stretch the hamstrings in the region of their insertions, and lower the trunk to deepen the pose.
STEP 1 Activate the psoas and its synergist (the pectineus) to flex the trunk over the thigh. Use the quadriceps to straighten the knee. Then refine the position of the kneecap, using the sartorius to adjust for external rotation and the tensor fascia lata for internal rotation.
STEP 2 Turn the back foot inward and dorsiflex it by contracting the tibialis anterior. Activate the quadriceps to straighten the knee and the tensor fascia lata to internally rotate the thigh. This counterbalances external rotation of the thigh—an action of the back-leg gluteus maximus. Engage the gluteus medius by fixing the back foot on the mat, and attempt to drag it away from the front foot. The force of this action opens the back of the knee, creating a unique stretch of the hamstrings and other structures in this region.
STEP 3 Engage the lower-side erector spinae muscles and oblique abdominals to laterally flex the trunk. Notice the effect of the erector spinae pulling on the pelvis and how this draws the sitting bones upward.
STEP 4 You can accentuate all of these actions by using the shoulders and arms to turn the trunk. Abduct the shoulders by contracting the lateral deltoids, and straighten both elbows by engaging the triceps. Reach toward the ground with the lower-side arm, pressing into the floor, a block, or the shin by abducting the shoulder blade away from the spine. This engages the lower-side serratus anterior. Then use the upper-side rhomboids to turn the trunk by drawing the scapula toward the midline. Externally rotate both shoulders with the infraspinatus and teres minor muscles. Draw the shoulders away from the neck by engaging the lower third of the trapezius.
SUMMARY Note how the antagonists of the muscles you have been activating are stretching. The front-leg hamstrings and gluteus maximus are the focal point of the stretch in Utthita Trikonasana, with the upper-side back and abdominals also stretching. The back-leg gastrocnemius and soleus muscles are stretched by dorsiflexion and internal rotation of the foot. Reaching down with the lower-side arm lengthens the rhomboids on this side, and drawing the upper-side scapula toward the midline lengthens the corresponding serratus anterior.
