Shock Attenuation Wavelet Transform Of Dominant Leg During A Fatiguing Run

Robbert P. van Middelaar, Marit A. Zandbergen, Allison H. Gruber, Jasper Reenalda

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Abstract

Running is associated with a high incidence of knee injuries. Neuromuscular fatigue is considered as main risk factor, suggesting that the body in a fatigued state is less able to attenuate impact forces sufficiently. This could lead to overloading and eventually injuries.

PURPOSE: Analyse vertical accelerations frequencies at the tibia (vTA) and sternum (vSA) with a Wavelet Transform to get insight in shock attenuation (SA) strategy of the body during a fatiguing run.

METHODS: 6 recreational runners (3F/3M, age 29.2 ± 12.8 years, height 182.8 ± 8.0 cm, weight 74.5 ± 7.5 kg , running >10 km per week for >1 year; uninjured in last 6 months; heel strikers) ran until exhaustion on a treadmill at 103% of their average 8 km race speed. Data were obtained overground on a 10-meter runway before and after the fatigue protocol with IMUs and an embedded 3D force plate. vTA and vSA were analyzed during stance with a Wavelet Transform (fig. 1), focusing on lower (0-9 Hz) - mid (10-25 Hz) - high (26-50 Hz) pseudo-frequency ranges, and impact (initial contact to first vTA peak instant times two) and active phase in time domain. SA was calculated in decibels (dB) from the vTA and vSA coefficient magnitudes.

RESULTS: Mean SA significantly decreased between non-fatigued and fatigued state in the lower pseudo-frequency range for both impact phase (-3.58 ± 0.89 to -2.52 ± 1.17 dB, p = 0.009) and active phase (-3.75 ± 0.93 to -2.73 ± 1.18 dB, p = 0.007). Other pseudo-frequency ranges showed no significant change (p > 0.05).

CONCLUSIONS: The body seems less able to attenuate low frequencies in fatigued state in both impact and active phase, indicating less attenuation by active attenuation mechanisms (joint motion with eccentric muscular contraction). This may be caused by a smaller range of motion or greater knee stiffness in fatigued state, possibly leading to future injuries. High frequencies are still well attenuated, SA by passive structures seem minimally affected by fatigue.
Original languageEnglish
Pages (from-to)147-148
JournalMedicine and science in sports and exercise
Volume53
Issue number8S
DOIs
Publication statusPublished - Aug 2021
EventACSM 68th Annual Meeting 2021 - Virtual Event
Duration: 1 Jun 20215 Jun 2021
Conference number: 68

Keywords

  • 2023 OA procedure

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