Hey.
I found this text of the in my opinion greatest living Yoga master (I know of), Dharma Mittra. He expresses what I believe much better than I could, here’s the link:
http://www.ecomall.com/greenshopping/asanas.htm
Please note particularly this passage:
Students often ask me how they can go deeper into a posture. In a way they are asking the wrong question. Form, breath, and focus are much more important than range of motion. As long as you’re aligned and breathing, don’t worry about how far you can go. That said, you must learn to relax in the pose in order to master it. The first few times you cross your legs in Lotus Pose, say, it’s extremely painful. After a few weeks of practice, you’ll be able to spend some minutes in it. Eventually you will feel comfortable.
As I understand it, he says that at first you will experience pain and then, with practice, you will eventually feel comfortable. So feeling comfortable and being relaxed in an Asana is the goal of the practice and to get there (which is wanted), the student has to go through pain and effort and they have to use force - because if they didn’t use force, where would the pain come from?
I also looked up the Sutras mentioned by Willem; last time I read them was more than a decade ago. Here are some translations of them:
Mukunda Stiles, Structural Yoga Therapy, pg. 13
46
Yoga pose
is a steady
and comfortable position.
47
Yoga pose is mastered
by relaxation of effort,
to create a lessening
of natural tendency
for restlessness,
and identification
of oneself as living
within
the infinite stream of life.
48
From that
perfection of yoga posture,
duality,
such as praise and criticism,
ceases
to be a disturbance.
49
When this is acquired
then naturally follows
a cessation
of the movements
of inspiration and expiration;
this is called
regulation of breath.
Hartranft, Chip - The Yoga-Sutra of Patanjali, pg. 37
46
The postures of meditation should embody steadiness and ease.
47
This occurs as all effort relaxes and coalescence arises, revealing that the body and the infinite universe are indivisible.
48
Then one is no longer disturbed by the play of opposites.
49
With effort relaxing, the flow of inhalation and exhalation can be brought to a standstill; this is called breath regulation.
Hartranft comments: “Posture, or asana, is the bodily aspect of Patanjali’s holistic system. Here the term refers only to those postures suitable for prolonged immobility.”
James Haughton Woods, The Yoga Sutras of Patanjali, pgs. 192 - 193
46
Stable-and-easy-posture.
47
By relaxation of effort or by a [mental] state-of-balance with reference to Ananta -
48
Thereafter he is unassailed by extremes.
49
When there is [stability of posture], the restraint of breath cutting off the flow of inspiration and expiration [follows].
Trevor Leggett, Sankara on the Yoga Sutras, excerpt online: http://www.leggett.co.uk/books/sys.htm
46
Posture is to be firm and pleasant
47
By relaxing effort and by samadhi (samapatti) on infinity
48
From that, he becomes immune to the opposites
49
Pranayama is to sit in the posture and cut off the flow of in breath and out-breath
B.K.S. Iyengar, Light on the Yoga Sutras of Patanjali, excerpt online: http://www.iyengar-yoga.com/articles/integratedscience/class15.html
46
"Sthira sukham asanam." - “Asana is perfect firmness of body, steadiness of intelligence and benevolence of spirit.”
47
"Prayatna saithilya ananta samapattibhyam." - “Perfection in an asana is achieved when the effort to perform it becomes effortless and the infinite being within is reached.”
48
"Tatah dvandvah anabhighatah." - “From then on, the saddhaka is undisturbed by dualities.”
BonGiovanni, The Yoga Sutras of Patanjali, online: http://www.sacred-texts.com/hin/yogasutr.htm
46
The posture should be steady and comfortable.
47
In effortless relaxation, dwell mentally on the Endless with utter attention.
48
From that there is no disturbance from the dualities.
49
When that exists, control of incoming and outgoing energies is next.
Charles Johnston, The Yoga Sutras of Patanjali, online: http://www.gutenberg.org/cache/epub/2526/pg2526.html
46
Right poise must be firm and without strain.
47
Right poise is to be gained by steady and temperate effort, and by setting the heart upon the everlasting.
48
The fruit of right poise is the strength to resist the shocks of infatuation or sorrow.
49
When this is gained, there follows the right guidance of the life-currents, the control of the incoming and outgoing breath.
I think:
The term “Asana” is, as noted by Hartranft, only referring to the sitting posture that is used to do the following steps of Ashtanga Yoga, beginning with Pranayama (as it is written in Sutra II 49) and continued with the other stages. These require a pose that allows immobility over a long period. The lotus-seat is probably the perfect example of what the Sutras are talking about. Here one can sit truly without any effort for hours and be focused on Pranayama, Pratyahara, Dharana and Dyana. But the Sutra is not saying anything about what’s going on in today’s Asana-classes in today’s “Yoga”-studios.
The interpretation of Sutra II 48 by Iyengar is in line with my viewpoint:
“Perfection in an asana is achieved when the effort to perform it becomes effortless and the infinite being within is reached.”
Effort becomes effortless. This is a process, effortlessness is the goal, and not the starting point. Without effort, this goal cannot be reached.
And the “amount” of effort (= amount of force) is depending on the physical capacity of the student and there is no general answer possible. Just don’t overrate and through that hurt yourself.