Does the functional reach test reflect stability limits in elderly people?

Objective: To explore how the Functional Reach test correlates with the displacement of the centre of pressure and whether the test is a measure of the stability limits in healthy elderly people. Also to explore the performance parameters during the Functional Reach test. Design: Method comparison study. Subjects: Twenty-seven healthy elderly subjects. Methods: Whole body kinematics (ELITE systems), ground reaction forces (AMTI) and muscle activity (EMG) parallel with clinical yardstick measure while performing the Functional Reach test. Results: This study showed a low correlation (r=0.38) between reach distance and displacement of centre of pressure and a moderate correlation (r=0.68) between forward rotation of the trunk and reach distance. The movement during the Functional Reach test was characterized by a large forward rotation of the trunk and a small extension in the ankle. The latter constraining centre of pressure forward displacement. Conclusions: The results suggest that the Functional Reach test is a weak measure of the stability limits. Movement of the trunk seems to influence the test more than the displacement of the centre of pressure. When using the Functional Reach test for assessing balance, compensatory mechanisms should be taken into account.