In all of my classes I try to include some sideways stretching of the body. In our normal everyday activities the muscles on the sides of the body do not get a lot of stretching and strengthening yet they are very important in maintaining good posture.
The muscles we are talking about here in particular are the obliques, serratus anterior and the lattisimus dorsi. Twisting practices are excellent for stretching these muscles as are practices which require you to lengthen each side of the body whilst contracting the muscles in the opposite side. A great practice to awaken and work with these muscles is Tiriyaka Tadasana or swaying palm tree pose. In this standing posture the hips remain facing the front whilst the torso moves from side to side with arms above the head.
It is important to make sure that the body does not lean forward or back whilst practising. I like to visualise the body between two panes of glass…unable to move forward or back only side to side.
“The tendency in bending sideways is always to twist the pelvis or the shoulders. We can help prevent this by flattening the lower back and tucking the tailbone under before doing postures like Trikonasana variation 3 (triangle sliding the hand down the side of the leg).
Another way to fix the pelvis so that it cannot rotate is either by squatting against the wall, or by beginning in Shashankasana (child pose) and bending to the side.” (Swami Bhaktipoornananda Saraswati 2000 Yoga Magazine)
Stronger sideways stretching is achieved in Trikonasana or triangle pose.
In Trikonasana the aim is to eventually straighten the legs whilst leaning to the side and taking the hand to the foot…however for most people this is not achieved without leaning forward which diminishes the effect of the sideways stretch. Initially you should practice with the knee bent and only take the hand as far as it will comfortably go whilst keeping the pelvis fixed. Again a good way to practice this is by practicing against a wall …you will soon discover if you are leaning forward!
Aside from stretching the muscles in the sides of the body Trikonasana strengthens the legs , knees, ankles arms and chest and helps open the hips groin and hamstrings. There is also a benefit to internal organs with the gentle massage of the digestive system that occurs.