Use of a treadmill, lift, and carry battery as a composite functional performance test: analysis of data from a pragmatic randomized controlled trial in a military population participating in a functional restoration program.

Background: The treadmill, lift, and carry (TLC) battery is a composite functional performance test created to measure the effectiveness of a functional restoration (FR) program in a military population.

Purpose: To determine the validity, reliability, and minimal clinically important differences (MCIDs) of the individual tests and the composite TLC battery.

Methods: We assessed the validity by mean differences, effect sizes, and standardized response means pre- and post-FR; and by correlations between the TLC battery and other established measures. We assessed reliability by correlating pre- and post-FR scores. We used principal component analysis (PCA) to create a composite measure. We determined MCIDs via distribution methods and receiver operator curve analysis.

Results: There were significant (p < .001) mean changes and large effect sizes (0.6-0.8) pre- to post-FR. Pre- and posttest Spearman's correlations ranged from 0.5 to 0.6. Spearman's correlations between TLC battery scores and other measures were small (± 0.3-0.4) and significant (p < .001). PCA supported use of a single-component composite. MCIDs were treadmill time: 3 minutes; metabolic equivalent of task: 1.5 units; floor-to-waist lift: 15 lbs; waist-to-shoulder lift: 10 lbs; 40-foot carry: 10 lbs; and composite score: 6 units.

Conclusion: This secondary data analysis provides preliminary support for the validity and reliability of the TLC battery for use in military populations.