Open Access Highly Accessed Research article

The biomechanical demands of standing yoga poses in seniors: The Yoga empowers seniors study (YESS)

Man-Ying Wang1, Sean S-Y Yu1, Rami Hashish1, Sachithra D Samarawickrame1, Leslie Kazadi1, Gail A Greendale2 and George Salem1*

Author Affiliations

1 Division of Biokinesiology and Physical Therapy, University of Southern California, 1540 Alcazar St, Los Angeles, CA 90033, USA

2 Division of Geriatrics, Geffen School of Medicine, University of California, Los Angeles, CA, USA

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BMC Complementary and Alternative Medicine 2013, 13:8  doi:10.1186/1472-6882-13-8

Published: 9 January 2013



The number of older adults participating in yoga has increased dramatically in recent years; yet, the physical demands associated with yoga performance have not been reported. The primary aim of the Yoga Empowers Seniors Study (YESS) was to use biomechanical methods to quantify the physical demands associated with the performance of 7 commonly-practiced standing yoga poses in older adults.


20 ambulatory older adults (70.7 + − 3.8 yrs) attended 2 weekly 60-minute Hatha yoga classes for 32 weeks. The lower-extremity net joint moments of force (JMOFs), were obtained during the performance of the following poses: Chair, Wall Plank, Tree, Warrior II, Side Stretch, Crescent, and One-Legged Balance. Repeated-measure ANOVA and Tukey’s post-hoc tests were used to identify differences in JMOFs among the poses. Electromyographic analysis was used to support the JMOF findings.


There was a significant main effect for pose, at the ankle, knee and hip, in the frontal and sagittal planes (p = 0.00 – 0.03). The Crescent, Chair, Warrior II, and One-legged Balance poses generated the greatest average support moments. Side Stretch generated the greatest average hip extensor and knee flexor JMOFs. Crescent placed the highest demands on the hip flexors and knee extensors. All of the poses produced ankle plantar-flexor JMOFs. In the frontal plane, the Tree generated the greatest average hip and knee abductor JMOFs; whereas Warrior II generated the greatest average hip and knee adductor JMOFs. Warrior II and One-legged Balance induced the largest average ankle evertor and invertor JMOFs, respectively. The electromyographic findings were consistent with the JMOF results.


Musculoskeletal demand varied significantly across the different poses. These findings may be used to guide the design of evidence-based yoga interventions that address individual-specific training and rehabilitation goals in seniors.

Clinical trial registration

This study is registered with NIH #NCT 01411059

Intervention; Lower-extremity; Biomechanics; Moment; EMG; Older adult