Navasana

Navasana resembles a boat floating in the water. The arms form the gunwales, and the legs and torso form the hull. This pose flexes the trunk in an “open chain” fashion, strengthening the psoas and quadriceps muscles at the front of the hip, thighs, and abdomen.

Anatomy

I place navasana in the forward-folding section because it flexes the trunk. This is a forward bend that requires constant muscular effort to maintain. For this reason, the main story in the pose is an isolated strengthening of the core abdominal muscles and not so much a focused stretch, as with the other forward bends. Moving outward from the abdominals, several steps can be taken to stabilize the pose. For example, squeezing the knees together isolates and engages the adductor muscles of the thighs. Contracting the quadriceps straightens the knees and engaging the pelvic muscles flexes the hips. Similar subplots exist in the arms and shoulders. This type of co-activation produces the phenomenon of recruitment. For example, note that if you squeeze the knees together, you can more forcefully engage the abdominals. 

BASIC JOINT POSITIONS  

• The hips flex. 
• The knees extend. 
• The ankles plantar flex. 
• The feet evert. 
• The trunk flexes. 
• The shoulders flex, adduct, and externally rotate. 
• The forearms are neutral.