Relevance of Frequency-Domain Analyses to Relate Shoe Cushioning, Ground Impact Forces and Running Injury Risk: A Secondary Analysis of a Randomized Trial With 800+ Recreational Runners

Abstract

Cushioning systems in running shoes are used assuming that ground impact forces relate to injury risk and that cushioning materials reduce these impact forces. In our recent trial, the more cushioned shoe version was associated with lower injury risk. However, vertical impact peak force was higher in participants with the Soft shoe version. The primary objective of this study was to investigate the effect of shoe cushioning on the time, magnitude and frequency characteristics of peak forces using frequency-domain analysis by comparing the two study groups from our recent trial (Hard and Soft shoe group, respectively). The secondary objective was to investigate if force characteristics are prospectively associated with the risk of running-related injury. This is a secondary analysis of a double-blinded randomized trial on shoe cushioning with a biomechanical running analysis at baseline and a 6-month follow-up on running exposure and injury. Participants (n = 848) were tested on an instrumented treadmill at their preferred running speed in their randomly allocated shoe condition. The vertical ground reaction force signal for each stance phase was decomposed into the frequency domain using the discrete Fourier transform. Both components were recomposed into the time domain using the inverse Fourier transform. An analysis of variance was used to compare force characteristics between the two study groups. Cox regression analysis was used to investigate the association between force characteristics and injury risk. Participants using the Soft shoes displayed lower impact peak force (p < 0.001, d = 0.23), longer time to peak force (p < 0.001, d = 0.25), and lower average loading rate (p < 0.001, d = 0.18) of the high frequency signal compared to those using the Hard shoes. Participants with low average and instantaneous loading rate of the high frequency signal had lower injury risk [Sub hazard rate ratio (SHR) = 0.49 and 0.55; 95% Confidence Interval (CI) = 0.25–0.97 and 0.30–0.99, respectively], and those with early occurrence of impact peak force (high frequency signal) had greater injury risk (SHR = 1.60; 95% CI = 1.05–2.53). Our findings may explain the protective effect of the Soft shoe version previously observed. The present study also demonstrates that frequency-domain analyses may provide clinically relevant impact force characteristics.Clinical Trial Registration:https://clinicaltrials.gov/, identifier: 9NCT03115437.

Gait asymmetry in spatiotemporal and kinetic variables does not increase running-related injury risk in lower limbs: a secondary analysis of a randomised trial including 800+ recreational runners

“…This is the largest (and one of the few) prospective studies on the association between asymmetry in spatiotemporal and kinetic variables and injury risk in recreational runners. Furthermore, the reliability of the measurements is strengthened by the large number of steps analysed per participant’s leg (158±25 steps) and the use of frequency-domain analyses to assess impact loading 20 21. However, this study also has some limitations.…”

“…Previous work has demonstrated the relevance of frequency-domain analysis in investigating the relationship between impact forces and injury risk 20 21. Thus, we decomposed the vertical GRF signal for each stance phase into the frequency domain and separated the high-frequency and low-frequency components of the signal using 10 Hz as the cut-off value 20 22 23.…”

“…Thus, we decomposed the vertical GRF signal for each stance phase into the frequency domain and separated the high-frequency and low-frequency components of the signal using 10 Hz as the cut-off value 20 22 23. The high-frequency component was then recomposed into the time domain using the inverse Fourier transform to form the new signal and compute the variables of interest 21. Impact peak force was defined as the maximal value of the high-frequency signal, and time to impact peak force was defined as the time between initial contact and impact peak force.…”

“… 20 22 23 The high-frequency component was then recomposed into the time domain using the inverse Fourier transform to form the new signal and compute the variables of interest. 21 Impact peak force was defined as the maximal value of the high-frequency signal, and time to impact peak force was defined as the time between initial contact and impact peak force. Vertical instantaneous loading rate was the maximal slope of the high-frequency signal during the same period.…”

Particular Dimensions of the Social Impact of Leisure Running: Study of Poland

“…The hardness and weight of the shoes are analyzed in terms of injuries risk [56,57]. Exoskeletons are constructed to improve running performance [58][59][60]. All of these solutions may have the potential to reduce the risk of injuries and improve the quality of running, which could ultimately lead to an increase in the number of regular runners and, as a result, increase the health and life expectancy of the population.…”