Reliability and Minimum Detectable Difference of Tibial Acceleration during Running

Abstract

Tibial acceleration is often measured in runners and may be related to injury risk. To evaluate differences between conditions, reliability and minimum detectable difference of common variables are needed. PURPOSE: To determine the test-retest reliability and minimum detectable difference of peak axial and peak resultant tibial acceleration during running in the laboratory and on a treadmill. METHODS: We recruited 19 runners (31 ± 6 years; 1.70 ± 0.08 m; 68.6 ± 11.6 kg; 10 women) who provided written informed consent. Tibial acceleration was collected at 1000Hz in the laboratory and 1023Hz on the treadmill via a research grade tri-axial accelerometer firmly attached to the anteromedial distal tibia during running at 3.0m/s. In the laboratory, foot contact was made on a synchronized force platform in 2 sessions for 5 trials each. Participants also ran on a treadmill for one minute following a self-directed warm up. Peak axial and peak resultant acceleration during stance were determined for 2 sets of: 5 steps in the laboratory, and both 5 and 10 steps on the treadmill. Interclass correlations (ICC(3,5) and ICC (3,10)) indicated reliability and minimum detectable differences were calculated. RESULTS: Test-retest reliability was excellent for both peak axial and peak resultant acceleration during laboratory and treadmill running. Minimum detectable differences were less than 2g. Averaging over 10 trials instead of 5 did not improve reliability.Table 1: Reliability and minimum detectable difference for peak axial and peak resultant tibial accelerations during laboratory and treadmill runningCONCLUSION: A difference of at least 1.5g for peak resultant acceleration and 2g for peak axial acceleration is needed to be sure that the difference exceeds measurement error. Smaller differences may simply be due to measurement error and may not reflect meaningful change. Study funded by College of Nursing and Health Professions Research Award.