The between-day repeatability, standard error of measurement and minimal detectable change for discrete kinematic parameters during treadmill running

Background: Kinematic parameters of the trunk, pelvis and lower limbs are frequently associated with both running injuries and performance, and the target of clinical interventions. Currently there is limited evidence reporting the between-day repeatability of discrete kinematic parameters of the trunk, pelvis and lower limbs during treadmill running. Research question: What is the between-day repeatability, standard error of measurement and minimal detectable change of discrete kinematic parameters of the trunk, pelvis and lower limbs during treadmill running? Methods: 16 healthy participants attended two kinematic data collection sessions two weeks apart. Three-dimensional kinematic data were collected while participants ran on a motorised treadmill at 3.2m/s. The interclass correlation coefficient, standard error of measurement and minimal detectable change were calculated for discrete kinematic parameters at initial contact, toe off, peak angles and joint excursions during the stance phase of running. Results: Good to excellent repeatability with low standard error of measurement and minimal detectable change values were observed for sagittal and frontal plane kinematics at initial contact (Range: ICC, 0.829 - 0.941; SEM, 0.6⁰- 2.6⁰; MDC, 1.5⁰- 7.2) and peak angles during stance (Range: ICC, 0.799 – 0.946; SEM, 0.6⁰- 2.6⁰; MDC, 1.7⁰- 7.1⁰). Peak transverse plane kinematics of the hip (ICC, 0.783; SEM, 3.2⁰; MDC, 8.7⁰) and knee (ICC, 0.739; SEM, 3⁰; MDC, 8.4⁰) demonstrated moderate between-day repeatability with large SEM and MDC values. Kinematics at toe off demonstrated the lowest ICC values and largest measurement errors of all parameters (Range: ICC, 0.109 – 0.900; SEM, 0.8⁰- 5.7⁰; MDC, 2.5⁰- 15.7⁰). Significance: This is the first study detailing the measurement error and minimal detectable change for discrete kinematic parameters of the trunk and pelvis during treadmill running. The reported values may provide a useful reference point for future studies investigating between-day differences in running kinematics