Few yoga teachers would disagree that tadasana or samasthiti is the structural blueprint of asana practice. The names tadasana and samasthiti are used interchangeably, with the former being used more in the Iyengar tradition as a formal posture that is taught and held, and the latter being used in the Ashtanga tradition as a call to attention, and as the starting position for practice. Both traditions use the shape as a way to reset, rest, and find balance between asanas. Of the two terms, I prefer samasthiti; “sama” meaning “equal” or “the same” and “sthiti” meaning “stand upright.” When translated, this “equal standing” imparts more meaning to the shape than the common translation of tadasana, “mountain pose.”
This seemingly simple -- yet extremely difficult -- act of standing straight and still, body equal right to left, front to back, neither too firm nor too soft, sets the stage for every asana that follows. The ability to find the symmetry and tone of samasthiti in increasingly difficult postures and planes is what is often referred to as "alignment" in asana practice. It is not uncommon to hear yoga teachers ask students to find tadasana in triangle pose, or to create samasthiti in downward facing dog.
But does this mean samasthiti is the most important asana? Is the beginning position of yoga practice the most important aspect of that practice? Is creating symmetry in anatomical position therapeutic? Does it train the mind-body connection in all the ways our yoga practice is intended to? On which other criteria can we base the most important yoga pose? Is the pose we repeat the greatest number of times in a sequence the most important? How about the pose we stay in for the longest amount of time?
In Ashtanga yoga, there is a strong emphasis on repetition: the repetition of vinyasas within a given sequence, and the repetition of said sequence over days, weeks, months and years. With repetition being such an integral part of the Ashtanga system, it is useful to look at the postures that are repeated the greatest number of times. Within any Ashtanga sequence, adho mukha svanasana, urdhva mukha svanasana, chaturanga dandasana, and lolasana (down dog, up dog, plank, and swing) are the postures repeated more than any others.
Could this sequence of postures, simply referred to as a vinyasa, actually constitute the most important yoga poses? Adho mukha svanasana is clearly an integral asana. It teaches the yoga practitioner how to work with both the upper and lower body, is the foundation of inverted asanas, and is an easy place to begin exploration of the bandhas. Chaturanga dandasana plays an integral role in strengthening the upper body and core, and can also be considered the foundation of the arm balancing postures. Lolasana is clearly a very significant part of the vinyasa system, as it forms the foundation for the jumping vinyasas, and awakens the musculature related to mula and uddiyana bandha. Urdhva mukha svanasana is a bit trickier for me decipher. As far as backbends go it’s not terribly difficult, but I wouldn’t call it foundational in the way that salabhasana or chatush padasana (locust and bridge) are. It is, however, one of the few backbends with both the hands and feet in contact with the floor.
My feeling is that to fully understand the above postures’ role we have to look at what they have in common, and the sequence in which they’re performed. Adho mukha svanasana, urdhva mukha svanasana and chaturanga dandasana are unique in that they are all weight-bearing on both the hands and the feet. When performed correctly, this means they create connection and communication between the upper and lower body by recruiting them simultaneously. Done sequentially in a vinyasa, lolasana hyperflexes the spine, chaturanga extends the spine, urdhva mukha hyperextends the spine and adho mukha tractions the spine back towards neutral. This strong combination of movement and countermovement, going from hyperflexion, to extension, to hyperextension, back to neutral, over and over is the musculoskeletal essence of vinyasa practice.
But, again, does this repetition of fairly foundational and symmetrical asanas make them the most important? In Iyengar yoga, which is not a vinyasa system, repetition plays a small and sometimes nonexistent role. What the system lacks in repetition, however, it more than makes up for in duration of time spent in each asana. If timing is an essential part of Iyengar practice, it would make sense to look at what postures are held the longest to determine which are the most important. This leads us to inverted postures, a type of movement rarely seen outside of yoga, but thought to be where the true therapeutic benefits of asana practice lie.
B.K.S. Iyengar’s love, refinement, and practice of inversions is well known, especially sirsasana, which is essentially a inverted samasthiti. In his prime, reports of Iyengar spending an hour or more in headstand were common, and as he got older he continued to invert daily with props and restorative variations. Iyengar’s love of inversions is reflected in his teachings. Nearly all Iyengar sequences heavily feature inverted postures, and they’re often held for an extended period of time. An intermediate Iyengar practitioner is expected to be able to hold a ten-minute headstand, and less physically adept practitioners work with props to create physiological analogs of the classic inversions.
Pattabhi Jois was also a proponent of inversions and encouraged his early students to stay upside down for long periods of time. However, this trend seems to be mostly lost in Ashtanga yoga. Although inversions are practiced daily, most Ashtanga practitioners spend just a couple of minutes in sirsasana, and an even shorter amount of time in sarvangasana. Many variations of the inverted postures are also not included in the Ashtanga system, specifically the twisting and lateral variations of sirsasana and sarvangasana, as well as backbends in sarvangasana. The absence of these inverted poses and the de-emphasis on long holds is, in my view, a flaw in the Ashtanga approach.
So, ultimately, what are the most important asanas? In Zen Buddhism, when a student asks a master a question the master thinks is flawed, unanswerable, or should be un-asked, the master will reply “mu.” Mu literally translates as “nonexistence,” “nothingness,” or “un-.” Perhaps mu is the only reasonable answer to the most important asana. The question is fundamentally flawed and unknowable. Un-ask the question.