A variety of Hatha Yoga poses provide a wealth of strengthening and endurance conditioning. Many Standing Yoga Poses like Virabhadrasana (Warrior Pose) or lunging Yoga poses like Hanurasana require proper knee alignment to allow for complete flow of energy and to maintain strength, safety, and stability in your Yoga class.
Two main alignment issues should always be addressed when attempting Yoga poses that place the forward leg into a deep knee bend over the foot:
1) Hyper flexion of the Knee Joint
*Our muscle fibers contain microfilaments that crossover and generate contraction or shortening of the muscle. To help visual these microfilaments, think of Velcro! When you completely line up a section of Velcro, it is very strong in maintaining its’ grip. If you line up only half of the Velcro, it starts to lose its’ ability to hold together. Lining up only a small fraction of the two pieces of Velcro leaves the Velcro very weak. Our microfilaments act in a similar way. As a muscle is stretched longer and longer, the microfilament crossover becomes less and less, and they have reduced ability to contract or sustain the endurance when the muscle is loaded. This is quite evident for the knee joint. When going into Warrior poses, the knee is place over the heel and knee bends to about 95 degrees. The quadriceps (thigh) muscle is elongated while also contracting (this can be considered an eccentric contraction). The microfilaments are still at a sufficient crossover placement to allow one to hold the pose with ample endurance. When one bends the knee below 90 degrees (thigh bone is moving below the level of the knee), the microfilaments have very little crossover and the muscle begins to loose its’ ability to sustain the contraction.
Since the muscle cannot sustain the contraction sufficiently, stressing energies move down the thigh into the quadricep tendons and into the knee joint. The pose moves from control into struggle and negative feedback signals are transmitted back to the nervous system. A similar alignment error in lunging Yoga poses is to have the knee traveling far forward over the toes as the knee bends. From a side view, one can clearly see that the knee is over flexed (hyper flexed) well below the 90 degree point. Even though kneeling lunging poses do not have the same energetic loading as Warrior Poses, the quadricep muscle is still required to contract to maintain knee stability. With the knee traveling too far forward and hyper flexing, stressing energies also move into the quadricep tendons and knee structures. Therefore, always observe that the knee is placed directly over the knee in these Yoga poses and avoid placing the thigh/hips lower than the knee level in Virabhadrasana.
2) Lateral Tracking of the Knee
*Very common in Warrior Yoga poses is to see participants have the forward knee slightly or excessively falling inwards in relation to the forward heel. This places an imbalanced energy in the quadricep muscles and can send chronic or acute injury into the knee. We have 4 muscles making up the quadriceps – an interior line (Vastus Medialis), an exterior line (Vastus Lateralis), a superficial middle line (Rectus Fermorus), and a deep middle line (Vastus Intermedius). These muscles join together into one tendon that inserts into the top of the knee cap (Patella). This connective line continues from the bottom of the knee cap into the patellar ligament to the top of the leg bone (Tibial tuberosity).
Think of these muscles like 4 ropes pulling on the knee cap when contracting. If you pull harder on one rope than the others, the knee cap will be pulled more in that direction. This brings us to Warrior Pose. When the knee is slightly falling inwards, the outer quadricep line (Vastus Lateralis) acts more energetically than the inner line (Vastus Medialis). The biomechanical line of this imbalanced energy creates an outwards pulling motion on the knee cap. Some individuals can be prone to having the knee completely shift or dislocate outwards (Lateral or Patellar Tracking). To avoid this imbalance and type of injury to the knee, insure that the knee does not fall inwards or towards the big toe in Warrior Pose. When you look briefly down to check your alignment, a good guide for knee placement is that you are able to see the big toe and inner edge of the foot.
As you maintain the pose, accessory muscles help maintain this knee line: outer shine muscles (Peroneal muscles) help ground the outer edge of the forward foot and draw the shine bone (Tibia) outwards / outer hip muscles (Abductors and Lateral Rotators) help move the thigh bone outwards as well. The benefit of this knee placement is the quadricep muscles maintain balanced support and energy on the knee cap and knee joint, and the outwards motion of the thigh bone places a more effective stretch into the groin muscles (in particular for Warrior 2 and Side Angle Pose).
Knee placement and integrity is just a small portion of alignment aspects for Warrior Pose.
Observe and study the whole body as you attempt these poses and move into a place where the body feels light, balanced, and confident.