A comparison of EMG output of four lower extremity muscles during selected yoga postures.

The purpose of this study was to use surface electromyography (EMG) analysis to examine the muscle activation of the anterior tibialis (TA), gastrocnemius (GA), rectus femoris (RF) and biceps femoris (BF) muscles during several yoga poses: tree pose (Vrksashana), half moon pose (Ardha Chandrasana) and warrior III (Virabadrasana) when compared to a rest pose (mountain pose). Ten healthy females with more than 3 months of continuous yoga experience who practiced at least 1.5 h per week were recruited. EMG activity was recorded from the aforementioned muscles during mountain pose ("rest") for 30 s, three times. Subjects then performed the following yoga poses in a randomized sequence while surface EMG activity was recorded: tree pose, half-moon, and warrior III. Each pose was held for 20s to 30 s and performed three times. EMG data were band pass filtered and the root mean square (RMS) was obtained. The peak RMS of each of the resting trials was obtained and averaged to produce an average peak resting RMS value. The study revealed significantly greater EMG activity in TA and GA in all three poses when compared to BF and RF. BF produced greater EMG activity than RF in warrior III. In conclusion, single limb yoga poses require increased use of the ankle musculature when compared to thigh musculature.