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Evidence-Based Complementary and Alternative Medicine
Volume 2012, Article ID 971896, 11 pages
Research Article

The Physical Demands of the Tree (Vriksasana) and One-Leg Balance (Utthita Hasta Padangusthasana) Poses Performed by Seniors: A Biomechanical Examination

1Division of Biokinesiology and Physical Therapy, University of Southern California (USC), 1540 E. Alcazar Street, Los Angeles, CA 90033, USA
2Division of Geriatrics, Geffen School of Medicine at the University of California, Los Angeles (UCLA), 924 Westwood Boulevard, Suite 200, Los Angeles, CA 90024, USA

Received 3 May 2012; Accepted 23 July 2012

Academic Editor: Andreas Michalsen

Copyright © 2012 Sean S.-Y. Yu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Yoga is considered especially suitable for seniors because poses can be modified to accommodate practitioners’ capabilities and limitations. In this study, biomechanical assessments on healthy seniors ( 𝑛 = 2 0 ; 7 0 . 1 ± 3 . 8  yr) were used to quantify the physical demands, (net joint moments of force [JMOFs] and muscular activation in the lower extremities) associated with the performance of 3 variations (introductory, intermediate, advanced) of 2 classical Hatha yoga poses – Tree and One-Leg Balance (OLB). ANOVA and Cohen's-d were used to contrast the postural variations statistically. The advanced (single-limb, without additional support) versions were hypothesized to generate the greatest demands, followed by the intermediate (single-limb [Tree] and bilateral-limb [OLB] with support) and introductory (bilateral-limb) versions. Our findings, however, suggest that common, long-held conceptions about pose modifications can be counter-intuitive. There was no difference between the intermediate and advanced Tree variations regarding hip and knee JMOFs in both the sagittal and frontal planes ( 𝑃 = 0 . 1 3 –0.98). Similarly, OLB introductory and intermediate variations induced sagittal JMOFs that were in the opposite direction of the classic advanced pose version at the hip and knee ( 𝑃 < . 0 0 1 ; 𝑑 = 0 . 9 8 –2.36). These biomechanical insights provide evidence that may be used by instructors, clinicians and therapists when selecting pose modifications for their yoga participants.