Excessive fluctuations in knee joint moments during early stance in sprinting are caused by digital filtering procedures

Abstract

Abstract:Inverse dynamics analyses are commonly used to understand movement patterns in all forms of gait. The aim of this study was to determine the effect of digital filtering procedures on the knee joint moments calculated during sprinting as an example of the possible influence of data analysis processes on interpretation of movement patterns. Data were obtained from three highly trained sprinters who completed a series of 30 m sprints.Ten different combinations of cut-off frequency were applied to the two-dimensional kinematic and kinetic input data with the kinetic cut-off frequency set equal to or higher than the kinematic cut-off frequency. When using the commonly adopted practice of filtering the kinetic data with a higher cut-off frequency than the kinematic data, exaggerated fluctuations in the knee joint moment existed soon after contact. In extreme cases, the knee moved between flexor, extensor and flexor dominance in less than 33 ms and through ranges exceeding 500 Nm. During an inverse dynamics analysis of locomotion, mismatched cut-off frequencies will likely affect the calculated joint moments if the cut-off frequency applied to the kinematic data is less than the true frequency content, particularly during impact phases. In the example of sprinting, exaggerated fluctuations in the knee joint moment appear to be data processing artefact rather than genuine characteristics of the joint kinetics. When the cut-off frequencies, and thus the frequency content of all input data, are matched, the fluctuations after contact are minimal, and such a procedure is suggested for inverse dynamics analyses of gait.

Lower limb joint kinetics during the first stance phase in athletics sprinting: three elite athlete case studies

“…Quantifying average horizontal external power during just the first stance phase therefore provides a performance measure that is directly relevant to the analysed technique. For the kinetic inputs to the inverse dynamics analysis, the force platform data were downsampled to the sampling rate of the kinematic data (200 Hz), and filtered with a cut-off frequency of 24 Hz to prevent the generation of artefacts soon after impact (Bezodis et al, 2013;Bisseling & Hof, 2006;Kristianslund, Krosshaug, & van den Bogert, 2012). Using these filtered kinematic and kinetic data in combination with the individual-specific segmental inertia data, a 2D inverse dynamics analysis was undertaken (Elftman, 1939;Winter, 2005).…”

Late swing or early stance? A narrative review of hamstring injury mechanisms during high‐speed running

“…During the beginning of the stance phase, the hip exhibits extensor dominance, reaching peak extension torque at approximately 4.1 N·m·kg, before changing to a flexion moment toward the latter half of stance . The reported knee moments during stance vary much more between studies, which may be attributed to different filtering techniques utilized . Schache et al described an extension moment for the first half of stance, with a peak torque of 3.6 N·m·kg, before a flexion moment is produced toward late stance.…”

“…17,31,32 The reported knee moments during stance vary much more between studies, which may be attributed to different filtering techniques utilized. 33,34 Schache et al 17,28 described an extension moment for the first half of stance, with a peak torque of 3.6 N·m·kg, before a flexion moment is produced toward late stance. However, other studies have reported a much more variable knee moment, sometimes switching several times from extension to flexion dominance throughout stance, although some researchers have argued that this may be an artifact of data processing.…”

Modulation of work and power by the human lower-limb joints with increasing steady-state locomotion speed

“…Force signals were sampled at 1500 Hz, and were digitally filtered using a zero-lag fourth-order Butterworth filter (Winter, 2009). The chosen cut-off frequency was 10 Hz so as to match that applied to the kinematic data, a procedure that is consistent with published recommendations (Bisseling and Hof, 2006;Kristianslund et al, 2012;Bezodis et al, 2013).…”