Validation of Functional Fitness Tests as Surrogates for Strength Measurement in Frail, Older Adults with Chronic Obstructive Pulmonary Disease

Objective: This study evaluated the relationship of functional field tests to traditional laboratory strength tests In 40 frail, older adults with chronic obstructive pulmonary disease. Design: Participants completed two trials of upper (chest press) and lower (leg press) body maximal strength (maximal weight lifted one time) testing and one trial of functional fitness testing (Arm Curl, Lift and Reach, Chair Stand, Up and Go). The maximal weight lifted one-time values from both trials were compared with functional fitness test values to identify valid surrogates. Results: Among upper-body functional fitness tests, the Arm Curl had a moderately strong relationship to chest press (trial 1 : r = 0.55, P = 0.01; trial 2: r = 0.56, P = 0.01) whereas the Lift and Reach did not. Among lower-body functional fitness tests, the Chair Stand had a fairly strong relationship to leg press (trial 1 : r = 0.46, P = 0.01 trial 2: r = 0.38, P = 0.05), but the Up and Go did not. Conclusions: Only the Arm Curl and Chair Stand tests were valid surrogates. Although multiple field tests to measure strength in a clinical setting may be desirable, these data support limiting functional testing to the Arm Curl for upper-body and the Chair Stand for lower-body strength assessment.