Chair pose, utkatasana, is one of my favourite yoga poses to prep for the ski season. Chair pose is more of a convenience translation since the Sanskrit word utkata (उत्कट) actually means powerful, wild, intense, or fierce -- I love the focus on feeling rather than form here!
If you want to feel just that - POWERFUL, WILD and FIERCE - this is the pose for you.
♥ Inhale and reach your arms up (without lifting your shoulders to your ears), your palms either facing each other or joined above your head.
♥ Exhale, bend your knees and lower your seat down as if you were to sit down in a chair, ground through your heels.
♥ Turn your inner thighs back and apart (squeeze a block between your thighs to practice this action), extend your tailbone towards the floor and, in exactly the opposite direction, lengthen through the crown of your head without lifting your chin up or tucking it in. Avoid overarching in your lower back and/or sticking your front ribs out.
♥ Stay here for up to 30 seconds breathing deeply in and out through your nose, then either return to tadasana or follow up with a forward bend, uttanasana.
The main anatomical focus here is on the thighs but, as most yoga poses, utkatasana is actually a great all rounder. Aside from creating 'thighs of steel' (hence the great ski prep), utkatasana can help you strengthen pretty much everything else too: ankles, calves, core, back, shoulders and arms.
By working all the leg muscles, the pose will help strengthen and stabilise your ankles and knees and, therefore, help prevent injury in sports. Feet are the foundation here and need to remain strong and engaged for you to stay balanced -- which makes utkatasana a great therapeutic exercise for flat feet.
As the core and the diaphragm lift up, the organs of the abdominal cavity as well as the heart receive a nice stimulating massage.
Avoid this pose if you suffer from insomnia, low blood pressure, or have a headache.