Physical performance tasks: what are the underlying constructs?
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.
Novy
Diane M
DM
Department of Anesthesiology, University of Texas-Houston Health Science Center, Houston, TX 77030, USA. diane.novy@uth.tmc.edu
Simmonds
Maureen J
MJ
Lee
C Ellen
CE
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