Reproducibility of the jumping mechanography as a test of mechanical power output in physically competent adult and elderly subjects

OBJECTIVES: To compare the reproducibility of the newly developed jumping mechanography with other physical tests. DESIGN: Study 1: Repeated testing with an interval of 2 weeks to assess the short-term repetition error. Study 2: Testing on 5 successive days to assess learning effects. SETTING: Geriatric clinic, Esslingen, Germany. PARTICIPANTS: Study 1 had 36 subjects aged 24 to 88; Study 2 had 22 subjects aged 19 to 86. Locomotor competence in all subjects was assessed using the ability to walk unaided and to perform a tandem stand and tandem walk. MEASUREMENTS: The test battery consisted of timed up and go, freely chosen gait speed, maximum gait speed, chair-rising test, and maximum power in jumping mechanography. RESULTS: All subjects performed the jumping mechanography without major problems. Study 1: Of all tests, maximum power in jumping mechanography depicted the smallest intrasubject short-term error (3.6%), the largest intersubject coefficient of variation (45.4%), and the greatest test-retest correlation coefficient (r=0.99). Study 2: The only tests for which the learning effects were confined to the 1% range were the maximum gait speed test and the maximum power in jumping mechanography. CONCLUSION: Assessment of maximum power in jumping mechanography appears to have good test-retest reliability with negligible learning effects. Moreover, it results in a comparatively large intersubject variability, which makes it an interesting method in the assessment of aging effects in middle-aged to older subjects and patients.