Performance-based measures of physical function for high-function populations

OBJECTIVES:: To improve and broaden the applicability of performance-based measures of function for use in clinical and research settings. DESIGN: Cross-sectional repeated-measures study. SETTING: Research clinic. PARTICIPANTS: Population-based sample of Japanese Americans without significant functional impairments aged 35 to 55 and 56 to 71 (N = 203). MEASUREMENTS: Performance-based measures of physical function, including range of standard tests, newer automated measures of balance and strength and data on cognitive function, lifestyle, medical history, and physical activity. RESULTS: Of the nonplatform balance measures, only the one-leg stand was reliable (reliability coefficient (rc) = 0.69) and able to discriminate between functional levels. Combining the Fourth National Health and Nutrition Examination Survey protocol of folded arm position while standing on a foam pad with the more-sophisticated balance platform test had the highest reliability and discrimination. With the strength chair, high rcs (0.88-0.96) were found for upper and lower extremity tests. Timed chair stands, a test of lower extremity and central strength were reliable. The 6-minute walk had a high rc (0.90). CONCLUSION: Many performance tests used today are not reliable. Only a few discriminate between the most highly functioning individuals and individuals with good function. Thus, a new recommended battery includes unassisted single-leg stand, balance platform "foam pad, eyes closed," elbow flexion and knee extension strength (strength chair), grip strength, timed chair stands, and the 6-minute walk. These simple performance-based tests have good reliability and discrimination across the range of function and can be used in most clinical and research settings to quickly assess global functional level.