Objective: The purpose of this study was to use surface electromyography (EMG) to examine the muscle activation of the tibialis anterior (TA), gastrocnemius (GA), rectus femoris (RF) and biceps femoris (BF) muscles during various yoga poses (asana). Muscle activation was then compared between poses and between males and females. Design: The study was a single occasion descriptive design. Subjects: Twenty healthy yoga practitioners (10 males, 10 females) with less than five years of experience were recruited. Setting: Subjects participated in a one time only visit for data collection at the Motion Analysis Laboratory at Quinnipiac University. Interventions: EMG activity was recorded during maximum voluntary isometric contractions (MVIC) of the TA, GA, RF, and BF using the Biodex Multi-joint System®. Subjects then performed the following yoga asanas while EMG activity was recorded: downward facing dog, chair pose, half-moon pose, and tree pose. Each asana was held for fifteen seconds and performed three times. Outcome measures: Raw EMG data were collected using a 4th order Butterworth filter with cutoff frequencies of 20 and 500Hz and the root mean square was obtained. Asana data were then normalized with the subjects’ individual MVIC. Integrated EMG was calculated for RF, TA, HS, GS, in each asana. A factorial linear mixed models regression analysis was performed. Compared to males, females had higher RF mean peak integrated EMG across all poses (p=.02), and higher GA and BF mean peak during the HM pose only (p’s <=.01). Significant differences between poses were also noted in the TA and BF for selected comparisons. Results: There were significant main effects by pose, primarily in CH, HM and TR poses. Gender appears to affect RF, GA and HM output in specific poses only. Conclusion: The study revealed differences in males v. females for some, but not all muscles. The actual pose (asana) appears to impact EMG output more than gender, however, further study is warranted.
Four in ten (38%) Americans use some form of complementary or alternative medicine to alleviate pain, stress or anxiety in their lives. Of the types of complementary and alternative medicine available, 6.1% use yoga. Research has shown that a regular yoga practice can decrease stress and anxiety, decrease symptoms of post traumatic stress disorder in veterans, decrease symptoms of depression, improve quality of life and reduce the risk of falling in older adults. Recently, researchers have added the study of muscle work during yoga asana to the growing body of yoga research. Electromyography (EMG) “is the study of muscle function through the inquiry of the electrical signal the muscles emanate”. Surface EMG, where electrodes are placed on the skin overlying a muscle, has been used to study many types of rehabilitative exercises. Zeller et al studied 9 women and 9 men performing various squatting activities. The authors found that women produced significantly more EMG when compared to men, during a single leg squat in the rectus femoris muscle only. No other significant differences based upon gender were found. Dwyer et al examined five lower extremity muscles during three exercises. The authors found that women generated greater EMG activity in the gluteus maximus and rectus femoris in all three exercises when compared to men. In contrast, Bouillon et al found no differences in EMG output based upon gender. Although some of the exercises studied resemble asana, none of the previously reviewed studies assessed EMG output during yoga asana. Only recently have researches used surface EMG techniques to study yoga asana.