Elsevier

Gait & Posture

Volume 29, Issue 1, January 2009, Pages 143-145
Gait & Posture

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Wearing the F-Scan mobile in-shoe pressure measurement system alters gait characteristics during running

https://doi.org/10.1016/j.gaitpost.2008.05.018Get rights and content

Abstract

This study investigated the influence of wearing an F-Scan mobile in-shoe pressure measurement system on running characteristics. Six subjects ran on a treadmill at three speeds (3.5 m s−1, 4.5 m s−1 and 5.4 m s−1) with and without wearing the F-Scan system while kinematic data were collected at 240 Hz using a motion capture system. Six gait cycles were selected for analysis, with touchdown and toe-off visually identified based on foot markers displacement. Spatio-temporal gait parameters including stride frequency, stride length, stride length relative to height, and stance time were determined. A 2 × 3 ANOVA with repeated measures (α = 0.05) was performed to identify differences in each gait parameter between running with and without the F-Scan system at different speeds. Wearing the F-Scan system did not affect the stance time but lead to an increase in stride frequency (P < 0.05) and a decrease in stride length (P < 0.05) and relative stride length (P < 0.05). As speed increased, stance time decreased while stride frequency, stride length and relative stride length increased (all P < 0.001). These results imply that wearing the F-Scan system alters gait characteristics and therefore data obtained may not represent those in a real life setting, at least in the case of running. One should take into account the potential risk of the movement of interest being altered when interpreting data obtained while subjects were wearing the F-Scan system. Future instrumentation should minimize the potential influence a measurement device may have on natural movement.

Introduction

In-shoe pressure measurement systems are useful tools to obtain plantar pressure and force data during dynamic movements. Such systems are widely used in locomotion [1], sports [2] and footwear [3] research, and have led to success in clinical applications [4]. The repeatability [5], [6], [7], [8] and accuracy [5], [8], [9] of data measured using various commercial in-shoe pressure measurement systems have been addressed in the literature. Recording plantar pressure data using these systems requires external devices attached to the subjects. However, it has not been documented whether wearing these external devices will influence human movement. If these devices hinder natural movement patterns, data obtained while wearing these devices may not represent those during natural, unrestricted movements.

The F-Scan mobile system (Tekscan Inc., Boston, USA) is one of the most commonly used in-shoe pressure measurement system for gait analysis. This system utilized relatively low-cost and thin in-shoe sensors which can be easily trimmed to fit the size and shape of a shoe. Another advantage of this system is that pressure data are stored in a data-logger so that the subject can move freely and that field tests are made possible. However, this system has been criticized for its poor accuracy and repeatability [8]. While the F-Scan system is less superior in comparison to another commercial product – the Pedar system, its accuracy and precision can be greatly improved by using appropriate pressure for calibration [9].

The total mass of all external devices of the F-Scan system to be attached to the subject was approximately 1.8 kg, including two in-shoe sensors, two receiver units attached to the subject's lower leg, one data-logger unit attached at the waist level, several connecting cables and straps. Before using this system in running research, it was of interest to the investigators to examine the effect of wearing the F-Scan devices on the natural running pattern. It was believed that the F-Scan devices may affect running movement due to the following three reasons:

  • (1)

    Additional mass of the system

    It is well addressed that shoes of heavier mass negatively affect running economy [10], [11]. An increase in mass attached to the foot has also been shown to cause a decrease in running economy and stride frequency [12]. Thus, it was believed that the additional mass of the F-Scan system, in particular the ankle unit, may alter normal running pattern.

  • (2)

    Reduced friction at the foot/shoe interface

    The friction at the foot/shoe interface affects the shear force acting on the foot [13]. By altering sensory input at the plantar surface of the foot, one alters gait kinetics and muscular activation patterns [14]. The low friction of the F-Scan sensor may therefore lead to a change in gait characteristics.

  • (3)

    Obstruction from external units, cables and straps

    The external devices may hinder natural arm-swing and leg-swing movements, causing runners to alter running style.

The purpose of the present study, therefore, was to compare the gait characteristics during running with and without wearing the F-Scan mobile in-shoe pressure measurement system.

Section snippets

Methods

Six elite male runners (age = 22.0 ± 1.8 y, mass = 63.0 ± 7.3 kg, height = 1.77 ± 0.06 m) participated in the study. These runners were collegiate athletes competing at the National Collegiate Athletic Association Division 1 level at the time of the study. All experimental procedures were approved by the Institutional Review Board and informed consents were obtained prior to data collection. In order to identify touchdown and toe-off, reflective markers were placed on the heel and second metatarsal head over

Results

Table 1 presents the stride frequency, stride length, relative stride length and stance time when running with and without wearing the F-Scan system at three different speeds. Wearing the F-Scan system did not affect the stance time but lead to an increase in stride frequency (P < 0.05) and a decrease in stride length (P < 0.05) and relative stride length (P < 0.05). Under both conditions as speed increased, stance time decreased while stride frequency, stride length and relative stride length

Discussion

This study demonstrates that running while wearing the F-Scan mobile in-shoe measurement system leads to a higher stride frequency and shorter stride length compared with normal running on a treadmill. These results support our hypothesis that wearing external devices can alter gait characteristics during running. This implies that plantar pressure, ground reaction force and centre of pressure data obtained from the F-Scan system may not represent those in a real life setting without the

Conflict of interest statement

No personal relationship or financial support from any organizations would inappropriately influence this study.

Acknowledgements

The authors would like to thank Jason van Haselen for his help in analyzing the gait data, Dr Stephen Burns and Dr Mansoo Ko for their contribution in revising this manuscript, and Frans de Heer and Frank Remkes for their support in the development phase of the project.

References (18)

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