To paraphrase the poet William Blake, you can see the world in a grain of sand. Similarly, you can learn a great deal about all asanas by carefully studying one. For this blog post, I focus on Hanumasana, or front splits. I use this pose in workshops to illustrate such factors as pose analysis, agonist/antagonist muscle pairs (and their synergists), physiological reflex arcs, and stretching biomechanics.
First, let’s look at the muscle-tendon unit—the muscle and its tendon—to see what lengthens in the pose. The muscle-tendon (MTU) unit is composed of several elements. These include the contractile structures (sarcomeres) and the fascial elements that surround the muscle fibers and tendons. Although these elements are often presented separately in articles on the science of stretching, in reality they are inextricably linked to one another. All of these elements contribute to muscle contraction and stretching. In addition, many factors contribute to the way a muscle lengthens, including the viscoelastic properties, creep (a type of deformation that has been postulated for fascial elements), neurological/psychological factors (such as muscle memory and tolerance), and extramuscular links to synergists. Individual muscle architecture or shape also plays a role. Below, I include several references from the scientific literature that discuss these factors in greater detail.
|Cross-section of muscle illustrating the contractile sarcomeres with fascial elements such as the perimysium|
Next, there is the timing of the stretch or how long to hold it.