The effect of the walking speed on the stability of the anterior cruciate ligament deficient knee

Stergiou, Nicholas; Moraiti, Constantina; Giakas, Giannis; Ristanis, Stavros; Georgoulis, Anastasios D.

doi:10.1016/j.clinbiomech.2004.06.008

Cited by 126 publications

(150 citation statements)

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“…It is possible that our athletes had greater CV values at low speed because of more effort of neuromuscular system for more adaptation in low speed, as well. It may be suggested that skilled athletes with efficient agility have greater challenge in controlling their movements at low walking speed (26).…”

Section: Discussionmentioning

confidence: 99%

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Reliability of Zebris Motion Analysis System in Healthy Athletes and Athletes with Anterior Cruciate Ligament Reconstruction

et al. 2017

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Background: Reconstruction surgery is one of the treatment methods after an anterior cruciate ligament (ACL) injury especially in athletes. Reconstructed ACL is associated with altered joint biomechanics, abnormal muscle strength, gait disorder and decreased athletic performance. Abnormal walking pattern has been shown to be one of the functional consequences of ACL reconstruction. Objectives: The aim of this study was to investigate the reliability of kinematic and spatiotemporal gait parameters after ACL reconstruction using Zebris ultrasound movement analysis system. Methods: A sample of convenience including 20 healthy athletes and 20 athletes 4 to 6 months after ACL reconstruction participated. Subjects walked on a treadmill for one minute at preferred, high and low speeds and kinematic and spatio -temporal parameters including stride time, stride length, maximum knee flexion, maximum knee flexion velocity and maximum knee extension velocity are calculated. Results: In the patient group, relative reliability measures for almost all parameters were high at low (ICC: 0.7 -0.97), preferred and high speeds (ICC: 0.75 -0.97). This was also true for the control group, were reliability for all parameters was high at low, preferred (ICC: 0.74 -0.99) and high (ICC: 0.83 -0.99) speeds, except for stride time of the left leg which showed moderate reliability. Additionally, at high speed, all parameters revealed very high reliability. Conclusions: Zebris movement analysis system is a highly reliable instrument for the measurement of gait parameters at different speeds in healthy athletes and those after ACL reconstruction surgery. This implies its use in the assessment and treatment process of gait deficits in such a clinically important population.

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Section: Discussionmentioning

confidence: 99%

“…The subject reached the preferred speed once from higher speeds and once from lower speeds. After determining each subject's preferred speed, high and low speeds were defined as 20% above and 20% below the preferred speed, respectively (26). The time for familiarity with walking on the treadmill was 6 minutes for all participants (27).…”

Section: Walking Activitymentioning

confidence: 99%

Reliability of Zebris Motion Analysis System in Healthy Athletes and Athletes with Anterior Cruciate Ligament Reconstruction

et al. 2017

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“…Stergiou et al (2004) found higher values of entropy, Lyapunov exponent, and correlation dimension in elderly fallers when compared with non-fallers. The authors suggest higher random instability and noise (i.e.…”

Section: Introductionmentioning

confidence: 92%

“…LyE ranges between 0 (corresponding to periodic signals) and 0.5 (corresponding to random signals). Chaos is expected when LyE gives values between 0 and 0.5 (Stergiou et al, 2004).…”

Section: Coefficient Of Variation (Cov)mentioning

confidence: 99%

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Análisis biomecánico y perceptivo de la movilidad peatonal para fijar límites de seguridad y confort en la fricción de pavimentos urbanos

Alvarez¹

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Lyapunov Exponents

Dingwell¹

2006

Wiley Encyclopedia of Biomedical Engineering

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The analysis of potentially chaotic behavior in biological and biomedical phenomena has attracted increased attention in recent years. Chaotic systems exhibit a trademark “sensitive dependence on initial conditions” (SDIC), meaning that very small perturbations will cause the resulting trajectories to separate exponentially fast. Lyapunov exponents directly measure SDIC by quantifying the exponential rates at which neighboring orbits on an attractor diverge (or converge) as the system evolves in time. Dissipative deterministic systems that exhibit at least one positive Lyapunov exponent are by definition “chaotic.” Hence, Lyapunov exponents are considered one of the most useful diagnostic tools available for analyzing potentially chaotic dynamical systems. However, Lyapunov exponents are also notoriously difficult to estimate reliably from experimental data and one should always be very skeptical about accepting any claims of “chaos” based solely on findings of positive Lyapunov exponents alone. This article reviews the basic definitions of Lyapunov exponents and outlines several of the more widely disseminated algorithms available to estimate them from experimental time series data. Critical issues related to finding spurious exponents, analyzing noisy signals, and validating against surrogate data are reviewed. A brief discussion of how Lyapunov exponents have been applied to study a wide variety of biomedical and biological phenomena is also presented. Finally, some thoughts on appropriate interpretations of such findings and the future directions for using Lyapunov exponents to study potentially chaotic systems are presented.

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The effect of the walking speed on the stability of the anterior cruciate ligament deficient knee

Cited by 126 publications

References 45 publications

Reliability of Zebris Motion Analysis System in Healthy Athletes and Athletes with Anterior Cruciate Ligament Reconstruction

Reliability of Zebris Motion Analysis System in Healthy Athletes and Athletes with Anterior Cruciate Ligament Reconstruction

Análisis biomecánico y perceptivo de la movilidad peatonal para fijar límites de seguridad y confort en la fricción de pavimentos urbanos

Lyapunov Exponents

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