title: The biomechanical demands of standing yoga poses in seniors: The Yoga empowers seniors study (YESS).
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
  
  
  BACKGROUND
  This study is registered with NIH Clinicaltrials.gov #NCT 01411059.
authors.affiliation: Division of Biokinesiology and Physical Therapy, University of Southern California, 1540 Alcazar St, Los Angeles, CA 90033, USA.
authors.forename: Man-Ying
authors.initials: MY
authors.lastname: Wang
authors.forename: Sean S-Y
authors.initials: SS
authors.lastname: Yu
authors.forename: Rami
authors.initials: R
authors.lastname: Hashish
authors.forename: Sachithra D
authors.initials: SD
authors.lastname: Samarawickrame
authors.forename: Leslie
authors.initials: L
authors.lastname: Kazadi
authors.forename: Gail A
authors.initials: GA
authors.lastname: Greendale
authors.forename: George
authors.initials: G
authors.lastname: Salem
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D004576:Electromyography; D015444:Exercise; D005260:Female; D006801:Humans; D007596:Joints; D035002:Lower Extremity; D008297:Male; D018482:Muscle, Skeletal; D004856:Postural Balance; D011187:Posture; D015013:Yoga