Mechanographic analysis of the timed 4 stair climb test - methodology and reference data of healthy children and adolescents.

Objectives: The timed 4 stair climb test (4SC) is an accepted and widely used tool to assess motor function of patients with neuromuscular diseases. We aimed to establish reference data for the 4SC, and for mechanographic analysis of ascent (4SC-Up) and descent (4SC-Dn) in healthy children and adolescents.

Methods: We used a custom-made staircase measuring device to assess force, power and velocity during the ascent of 4 stairs in healthy subjects. Secondary outcome measures included mechanographic analyses such as the Chair-Rising-test and the myometric Grip Force-test.

Results: Data of 288 participants aged 4 to 16 years (144 males, 144 females) were analyzed. A simple algorithm integrating the minimal applied force was used to compensate for different movement strategies. Percentiles for average power, force and horizontal velocity were calculated. While results of the 4SC-Up test showed no age or gender dependency, we found 4SC-Dn results to be age dependent. Mean device measured times were significantly shorter than manually measured times (mean difference -0.19 s; p<0.001).

Conclusions: Mechanographic analysis of the 4SC appears to be a promising tool for evaluation of muscle strength and function of the lower extremities as it enables physically exact measurements of a highly relevant activity of daily living.