Biomechanical analysis of gait waveform data: exploring differences between shod and barefoot running in habitually shod runners

Highlights

• Differences between barefoot and shod gait also occur in swing phase.

• Lower limb joint co-ordination appears to differ between barefoot and shod gait.

• Habitual shod runners exhibit earlier movement initiation when barefoot than shod.

• Neuromuscular control in response to differing footwear requires further research.

• Statistical parametric mapping may provide important insight into gait where previously ignored.

Abstract

The aim of this study was to utilise one-dimensional statistical parametric mapping to compare differences between biomechanical and electromyographical waveforms in runners when running in barefoot or shod conditions.

Fifty habitually shod runners were assessed during overground running at their current 10-km race running speed. Electromyography, kinematics and ground reaction forces were collected during these running trials. Joint kinetics were calculated using inverse dynamics. One-dimensional statistical parametric mapping one sample t-test was conducted to assess differences over an entire gait cycle on the variables of interest when barefoot or shod (p < 0.05).

Only sagittal plane differences were found between barefoot and shod conditions at the knee during late stance (18–23% of the gait cycle) and swing phase (74–90%); at the ankle early stance (0–6%), mid-stance (28–38%) and swing phase (81–100%). Differences in sagittal plane moments were also found at the ankle during early stance (2, 4–5%) and knee during early stance (5–11%). Condition differences were also found in vertical ground reaction force during early stance between (3–10%).

An acute bout of barefoot running in habitual shod runners invokes temporal differences throughout the gait cycle. Specifically, a co-ordinative responses between the knee and ankle joint in the sagittal plane with a delay in the impact transient peak; onset of the knee extension and ankle plantarflexion moment in the shod compared to barefoot condition was found. This appears to affect the delay in knee extension and ankle plantarflexion during late stance. This study provides a glimpse into the co-ordination of the lower limb when running in differing footwear.

Introduction

The statistical analysis of running gait is often restricted to the definition and extraction of discrete parameters of the gait pattern such as peaks, ranges and instances considered meaningful. Various methods have previously been employed such as principal component analysis and support vector machine, but both are pattern recognition techniques used to extract important data from large datasets [1], [2]. These techniques are complex and often require large datasets to identify small changes. Recently, the use of one-dimensional statistical parametric mapping has been proposed to assess biomechanical waveform data considering the temporal nature of these data sets [3], [4].

In the case of describing barefoot running gait the variables of interest largely focus on discrete loci, such as the joint kinematics at initial ground contact, which include foot strike pattern and the initial loading rate [5], [6], [7]. In addition, data often are expressed and summarized over certain periods of the running gait, for example range of motion or weight transfer during the stance phase.

Based on the assumption that risk factors are most strongly correlated to the ground contact phase, most running injury research has focused on parameters measured between initial ground contact and the peak vertical ground reaction force [8]. Differences in footstrike pattern at initial ground contact when running in running shoes or barefoot have been of a special interest for many researchers especially with regards to its relationship with initial loading rate [9], [10]. However, recent studies have reported conflicting differences in the initial loading rate of the vertical ground reaction forced between barefoot and shod runners [5], [7], [11].

Although the reasoning for researching biomechanical variables between initial ground contact and peak vertical ground reaction force are meritorious, no study to date has researched if other biomechanical events outside of this period contribute to footwear condition differences. Early or late changes in joint biomechanics can potentially contribute to explaining the differences around the initial landing phase. It would be of interest to describe the periods surrounding the above-mentioned epoch and further determine the instances where differences begin and end on a temporal scale. This potentially will assist researchers in determining the period in the gait cycle that may influence these discrete events of interest. It also would be of interest to describe the differences in muscle activity that may are associated with running in the barefoot or shod condition, as peak and average amplitude differences have been found previously in habitually shod runners when running barefoot or shod [12], [13], [14]. Where lower tibialis anterior, lateral gastrocnemius and biceps femoris activity was found when barefoot over the entire period of stance.

The aim of this study is to describe the differences between barefoot and shod kinematics, kinetics and electromyography over the gait cycle in habitually shod runners using one-dimensional statistical parametric mapping (1DSPM) [3]. Specifically, we aim to investigate variables during swing that may discriminate between the two footwear conditions. It was hypothesized that kinematic differences between shod and barefoot running would be found beyond stance phase and that kinetic differences between conditions would be restricted to the this period.