title: Physical performance tasks: what are the underlying constructs?
abstract: OBJECTIVE
  To investigate the structural validity of a battery of physical performance tasks and to investigate the construct validity of the resulting factors.
  
  
  METHODS
  A measurement study.
  
  
  METHODS
  A large, private orthopedic clinic and a physical therapy clinic in an urban area.
  
  
  METHODS
  One hundred three consecutive adult patients with low back pain who were referred for physical therapy assessment.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  The physical performance battery was composed of the 50-foot speed walk, 5-minute walk, repeated trunk flexion, sit to stand, loaded reach, rollover tasks, and Sorensen upper-body lift. Participants also completed 5 self-report measures.
  
  
  RESULTS
  Two correlated (.74) factors, speed and coordination and endurance and strength, were derived from the physical performance tasks. The Sorenson upper-body lift task was the only indicator that was not useful in defining the factors. Both factors had statistically significant correlations with measures of physical disability, lack of self-efficacy, and negative affect. Both factors had a trivial correlation with a numeric rating of pain intensity.
  
  
  CONCLUSIONS
  There is support for 2 meaningful empiric groupings (ie, the derived factors) of the performance tasks. Pain intensity had a trivial overlap with speed-coordination and endurance-strength factors.
authors.affiliation: Department of Anesthesiology, University of Texas-Houston Health Science Center, Houston, TX 77030, USA. diane.novy@uth.tmc.edu
authors.forename: Diane M
authors.initials: DM
authors.lastname: Novy
authors.forename: Maureen J
authors.initials: MJ
authors.lastname: Simmonds
authors.forename: C Ellen
authors.initials: CE
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004185:Disability Evaluation; D016002:Discriminant Analysis; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010807:Physical Endurance; D015203:Reproducibility of Results