ECSS Paris 2023: OP-BM19
INTRODUCTION: This study introduces a lab-on-the-field approach to analyze the biomechanics of foot positioning during trail running. To overcome the inherent limitations of traditional laboratory-based assessments while recording high-quality data, we moved traditional lab equipment directly onto the field. METHODS: We instrumented a 25-meter-long outdoor dirt track with a slope of 21% with a large Kistler force plate and 6 Oqus300 Qualisys cameras. Five recreational trail runners (180.6±1.3cm, 74±9.5kg) wore standard trail running shoes (Evadict MT2 2021) with holes cut in the upper for retroreflective markers. An additional in-shoe Pedar plantar pressure system was used. After a 10-minute warm-up, participants walked (W) and ran (R) up (U) and down (D) the 25m slope until 5 valid trials of each locomotion (WU, WD, RU, RD) were recorded. They were asked to walk and run at a comfortable speed. Weather conditions during the data collection. This implies that the kinematics data quality was poor due to mud that obstructed some foot markers. However, the present experiment gives the possibility to examine the mapping of the local constraint applied to the shoe. First, we determined force distribution applied by the foot to the shoe thanks to instrumented insoles. Then, we modified the plantar pressure intensity thanks to the force plate normal data. Finally, we interpreted the tangential force on the foot by using the relative plantar pressure distribution applied to the mediolateral and anteroposterior axes of the force plate. The axis of the insole relative to the force plate was corrected through available kinetic data of the foot. RESULTS: Both WD and RD presented impact peaks associated with rearfoot strike patterns whereas WU and RU did not show any impact peak. During WU, the higher constraints were localized under the 1st and 2nd metatarsal bones and the hallux with the local force vectors pointing backward. During RU, the higher constraints were localized under the th 1rst and 2nd metatarsal bones with relatively less pressure under the hallux with the local force vectors pointing backward and slightly laterally. During WD, the majority of the constraints were localized under the rearfoot with the local force vectors pointing forward. During RD, the pressure distribution was similar to WD with additional pressure under the forefoot with forefoot local force vectors pointing forward and medially. CONCLUSION: Although the kinematic data were not available, the present results are of great interest for grip shoe design. We also proved the feasibility of measuring outdoor in-ground reaction force and plantar pressure in a trail-running-like environment and combined them to get relevant data for shoe design. Thus, the special and simple set-up to secure and embed the force plate into the ground while safely measuring force under all weather conditions might be of interest to other research teams.
Read CV Cédric MORIOECSS Paris 2023: OP-BM19
INTRODUCTION: Eliud Kipchoge broke the 2-hour marathon barrier in 2019 wearing a forefoot air-cushioned carbon plate running shoe (FA). Running economy accurately predicts shoe-induced changes in long-distance running performance (1). Forefoot air-cushioned carbon plate running shoes can further improve running economy. The increase in bending stiffness induced by carbon plates in running shoes is an effective way to improve running economy (2), while the increase in bending stiffness may lead to a decrease in negative work and an increase in positive work at the metatarsophalangeal joints (3, 4). Therefore, the aim of this study was to investigate the effect of a forefoot air-cushioned carbon plate running shoe on running economy and lower extremity joint work. METHODS: Fourteen male recreational marathon runners performed running trials in a forefoot air-cushioned carbon plate running shoe and a carbon plate running shoe (CP). The Subjects ran a 3-minute test at 13 km/h in each shoe condition, followed by a 3-minute rest. Oxygen consumption was recorded using a gas metabolic analyser and the mean steady-state oxygen consumption for the last 1 min of each trial was calculated as RE. Lower limb kinematics and ground reaction forces at 13 km/h in each shoe condition were recorded simultaneously, and lower extremity joint work during the stance phase was calculated.Shapiro-Wilk tests were performed to test for normality of the variables of interest. If a Shapiro-Wilk test revealed a normal distribution, a paired t-test was performed to test for significant differences between shoe conditions; otherwise, the Wilcoxon signed-rank test was used. The significance level α was set to 0.05. RESULTS: The forefoot rebound coefficient, bending stiffness, and weight were increased in FA. Oxygen consumption was lower when running in FA than in CP (FA: 41.49±3.08, CP: 42.29±3.34ml/kg/min; P=0.038). Running in FA, resulted in significantly higher total lower extremity joint positive work (FA:1.345±0.189, CP:1.248±0.161 J/kg; P=0.019), higher metatarsophalangeal joint positive work (FA:0.012±0.007, CP: 0.007±0.004; P=0.001), higher ankle joint positive work (FA:0.833±0.139, CP:0.768±0.125; P=0.027), and higher knee joint positive work (FA:0.285±0.090, CP: 0.258±0.076 J/kg; P=0.025). There were no differences in total lower extremity joint negative work, negative metatarsophalangeal joint work, negative ankle joint work, negative knee joint work, negative hip joint work, and positive hip joint work during the stace phase when amateur runners were running in both pairs of shoes. CONCLUSION: Running economy increased in amateur marathon runners wearing forefoot air-cushioned carbon running shoes. Positive work at the lower extremity joint increased during the stance phase of running in a forefoot air-cushioned carbon running shoe. The improved energy storage and return of the lower extremity joint during running in forefoot air-cushioned carbon running shoes may be the main reason for the improved running economy.
Read CV Qinyu XuECSS Paris 2023: OP-BM19
INTRODUCTION: Footwear, surface and running intensity are all known to influence the foot-strike pattern adopted when running (Lieberman et al., 2015). Studies comparing foot-strike patterns in shod and barefoot runners often use a common intensity (Cheung et al., 2017) and or a common surface (Lai et al., 2020). To the best of our knowledge, there has not been a study which observes runner’s intuitive running speed and foot-strike pattern at a variety of intensities and on different surfaces whilst shod and barefoot. A study like this, may shed light on how runners self-regulate speed and foot strike at varying intensities and in various footwear-surface conditions. The aim of this study was to measure runner’s intuitive running speed and foot-strike pattern when asked to run at a variety of intensities (according to rate of perceived exertion; RPE) on two different surfaces (Firm, track and Soft, grass) whilst shod and barefoot. METHODS: Five recreationally trained long distance runners (males, n=3; females, n=2; age=50.8±16.4years; height=173.8±4.6m; weight=75.97±12.03kg) were recruited for this pilot study. This study consisted of four sessions with a 1-week wash out period in between. In each session, participants commenced with a 6-minute warm up of light intensity (RPE 11) shod running on the tartan track and were given a 3-minute rest before completing all four footwear-surface conditions. Participants were randomly assigned to one of four conditions in order to limit the order effect. The four conditions were: shod on track, barefoot on track, shod on grass and barefoot on grass. Each condition lasted 3 minutes and a 3-minute rest was given in between each condition. Participants were instructed to pace their running speed corresponding to the given RPE level on the day of visit (Day 1, RPE 11; Day 2, RPE 13; Day 3, RPE 15; Day 4, RPE 17). Distance covered and foot-strike pattern were recorded during each trial. Speed was calculated from distance covered divided by three minutes (Speed = Distance ÷ Time). Differences in foot-strike count were calculated in relative percentages (%). Each participant generated 16 data sets (4 conditions, 4 intensities) meaning data presented comes from 80 data sets in total. RESULTS: Runners ran furthest whilst shod on the tartan track (RPE 11, 2.89±0.31m/s; RPE 13, 3.41±0.21m/s; RPE 15, 3.58±0.24m/s; RPE 17, 3.77±0.31m/s). There was a higher prevalence of rear-foot strike count (~89%) when shod regardless of the surface or running intensity used. There was a tendency toward increased mid-foot strike count when running barefoot (~47%) and this increased further when running barefoot on the track (~61%). CONCLUSION: This pilot study reports greater variance in the foot-strike pattern adopted by runners when running barefoot. This may be due to greater sensitivity to sensory stimuli as surface and or running intensity changes in the barefoot condition. These findings should be interpreted cognisant of the small sample (n=5) used in this pilot study.
Read CV Jia Wei SiowECSS Paris 2023: OP-BM19