title: Sirsasana (headstand) technique alters head/neck loading: Considerations for safety.
abstract: BACKGROUND
  This study examined the weight-bearing responsibility of the head and neck at moments of peak force during three headstand techniques.
  
  
  METHODS
  Three matched groups of 15 each (18-60 years old) were formed based upon lower limb entry/exit technique: symmetrical extended, symmetrical flexed, and asymmetrical flexed. All 45 practitioners performed 3 headstands. Kinematics and kinetics were analyzed to locate peak forces acting on the head, loading rate, center of pressure (COP) and cervical alignment.
  
  
  RESULTS
  During entry, symmetrical extended leg position trended towards the lowest loads as compared to asymmetrical or symmetrical flexed legs (Cohen's d = 0.53 and 0.39 respectively). Also, symmetrical extended condition produced slower loading rates and more neutral cervical conditions during loading.
  
  
  CONCLUSIONS
  Subjects loaded the head with maximums of 40-48% of total body weight. The data support the conclusion that entering the posture with straight legs together may reduce the load and the rate of change of that load.
authors.affiliation: Department of Kinesiology & Health Education, University of Texas at Austin, 2109 San Jacinto Blvd D3700, UT Mail Code: D3700, Austin, TX 78712-1415, USA. Electronic address: rachelhector@utexas.edu.
authors.forename: Rachel
authors.initials: R
authors.lastname: Hector
authors.affiliation: Department of Kinesiology & Health Education, University of Texas at Austin, 2109 San Jacinto Blvd D3700, UT Mail Code: D3700, Austin, TX 78712-1415, USA. Electronic address: jljensen@austin.utexas.edu.
authors.forename: Jody L
authors.initials: JL
authors.lastname: Jensen
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D006257:Head; D006801:Humans; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D009333:Neck / Q000502:physiology*; D009334:Neck Muscles; D011187:Posture / Q000502:physiology*; D012449:Safety; D015013:Yoga; D055815:Young Adult
keywords: Cervical loading; Headstand; Headstand forces; Inversion; Sirsasana; Yoga