Background and purpose: The reliability and responsiveness of 2 physical performance measures were assessed in this nonrandomized, controlled pilot exercise intervention.
Subjects: Forty-five older individuals with mobility impairment (mean age=77.9 years, SD=5.9, range=70-92) were sequentially assigned to participate in an exercise program (intervention group) or to a control group.
Methods: The intervention group performed exercise 3 times a week for 12 weeks that targeted muscle force, endurance, balance, and flexibility. Outcome measures were the 8-item Physical Performance Test (PPT-8) and the 6-minute walk test. Test-retest reliability and responsiveness indexes were determined for both tests; interrater reliability was measured for the PPT-8.
Results: The intraclass correlation coefficient for interrater reliability for the PPT-8 was. 96. Intraclass correlation coefficients for test-retest reliability were.88 for the PPT-8 and.93 for the 6-minute walk test. The intervention group improved 2.4 points and the control group improved 0.7 point on the PPT-8, as compared with baseline measurements. There was no change in 6-minute walk test distance in the intervention group when compared with the control group. The responsiveness index was.8 for the PPT-8 and.6 for the 6-minute walk test.
Conclusion and discussion: Measurements for both the PPT-8 and the 6-minute walk test appeared to be highly reliable. The PPT-8 was more responsive than the 6-minute walk test to change in performance expected with this functional training intervention.