Though often overlooked in yoga circles, the latissimus dorsi is celebrated poolside and in gyms everywhere as the muscle that gives the back body its attractive v-taper. The fan-shaped latissimus muscles (the “lats”) are the broadest muscles in the body (assuming their connective tissue is included) and they are hands-down the most powerful muscles of the back. Capable of lifting the body off the ground (as in a chin-up), they are used extensively when swimming, rowing and throwing a baseball. As important as they are, overly developed, tight lats may pose an issue for your yoga practice as they can wreak havoc with your downward dog, handstand and urdhva danurasana.
Tight lats can prohibit shoulder range of motion for those deeper poses. The lats span the distance from the lower back to the armpits. They cover the entire surface of the lower back, a large portion of the middle back and side body. You can easily feel their upper-middle portion at the outer edge of the armpit by sticking your thumb into the opposite armpit and squeezing the outer wall with the fingers. The lats originate on the posterior iliac crest; sacrum; thoraco-lumbar fascia; the spinous processes of sacral vertebrae 1-5, lumbar vertebrae 1-5, thoracic vertebrae 7-12; the lower three ribs; and the inferior angle of scapula. They insert on the inside of the upper humerus (the floor of the bicipital groove to be exact) but not before they do a fancy 180-degree twist.
The lats are sometimes called handcuff muscles because they extend, adduct and internally rotate the shoulder—hence the 180 degree twist, which adds torque to this action. If you were “reaching for the sky,” the lats would draw the arms down and inwards towards the centerline of the body before spinning them towards each other to take the backs of the hands into the small of your back. When the humerus is fixed, as in upward dog, the lats blossom the chest forward through the arms. They also work with one of their synergists (pectoralis major) to move the body from downward dog to plank. Because they raise the lower ribs on the inhale, the lats are considered breathing muscles too.
Tight lats prevent both the necessary external rotation and shoulder flexion necessary for poses such as urdhva hastasana and warrior 1 and, as such, distortions in the spine become evident, along with a less than 180-degree armpit-chest angle. Bear weight on the arms in poses such as downward dog, headstand, pincha mayurasana, and urdhva danurasana and the issue becomes more pronounced with splaying elbows (read: internally rotating shoulders). Poses requiring extreme shoulder flexion and external rotation, such as ekapada rajakapotasana will be all but inaccessible to those with tight lats. Raising the arms with tight lats can result in rotator cuff impingement.
This article originally appeared on the Yoga Tune-Up Blog.