Every month, XSENSOR's Sports Performance Science Contributor, Antonio Robustelli, MSc, CSCS (Sports Performance Scientist & Technologist with OmniAthlete Performance Concept), will offer his take on essential and recommended reading, research, and review for plantar pressure applications using gait analysis for athletes.
Be sure to tune in to get the abstracts, summaries, and key takeaways or read the full studies at your own pace.
Research Title: Arch-Support Insoles Benefit the Archery Performance & Stability of Compound Archers
Authors: Wu T.T., Lo S.L., Chen H., Yang J.S., Peng H.T.
Journal: International Journal of Environmental Research & Public Health
Publication Year: 2022
Abstract
The purpose of this study was to analyze the effects of the use of arch-support insoles on the archery performance and center of plantar pressure (CoP) excursion in compound archers. Fifteen highly skilled compound archers were the subjects. A pressure plate was used to measure the CoP excursion and percentage distribution of plantar pressure. The parameters were compared between archers wearing flat and arch-support insoles using a paired-sample t-test. The results demonstrated that the shooting score in archers wearing the arch-support insole was significantly greater than in those wearing the flat insoles. The CoP excursion of the left foot, right foot, and both feet in archers wearing the arch-support insole were significantly smaller than in those wearing the flat insole. The distributed percentage of the plantar pressure showed that the arch-support insole significantly reduced the plantar pressure in the left posterior zone by 3.54% compared with the flat insole, and increased the plantar pressure in the right anterior zone by 2.54%. The principal conclusion was that compound archers wearing arch-support insoles during the arrow-release process can reduce the CoP excursion of the foot and increase their shooting score. The plantar pressure was distributed evenly in arch-support insoles.
Why the Study Is Relevant
This study aims to analyze the effects of the use of arch-support insoles in performance and stability of compound archers.
The research addresses an important topic in archery performance, however the design of the study seems to have few limitations even if the findings shows a significant p-value (< 0.05).
The study has not an experimental design, in fact no control group has been used; furthermore, there is no mention about the technical characteristics of the insoles used in the testing protocol.
Summary
Archery athletes requires optimal balance and stability in order to shoot an arrow and the excursion of the CoP is one of the main causes of tilting in shooting posture and instability during shooting movement.
The authors of the study tried to investigate whether specific interventions like using arch-support insoles can positively affect the excursion of the CoP thus improving stability and performance.
Key Takeaways
- Stability and shooting scores of compound archers increases with the use of arch-support insoles.
- Arch-support insoles reduces anterior-posterior sway.
- Arch-support insoles reduces plantar pressure of the left posterior zone while increasing it in the right anterior zone.
Read the full study.
Research Title: Long Distance Running Increases Plantar Pressures beneath the Metatarsal Heads: A Barefoot Walking Investigation of 200 Marathon Runners
Authors: Nagel A., Fernholz F., Kibele C., Rosenbaum D.
Journal: Gait & Posture
Publication Year: 2008
Abstract
Background: The growing popularity of endurance sports activities is associated with a growing number of metatarsal stress fractures in recreational runners. Excessive foot loading has been suggested as a potential cause for these problems [Bennell, K, Matheson G, Meeuwisse W, Brukner P. Risk factors for stress fractures. Sports Med 1999;28(2):91-122]. Therefore, the question arises whether long distance running affects foot loading characteristics like ground reaction forces and peak pressure in specific areas of the foot.
Purpose: To investigate the effects of long distance running on plantar pressure patterns before and after a marathon race.
Study Design: Repeated measurements of recreational runners before and after a marathon race.
Methods: Two hundred participants of the third Muenster marathon, 2004, were measured before and after the race with plantar pressure measurements during barefoot walking on a capacitive platform. The ratio between forefoot and toe loading was calculated to assess a suggested loading shift between these areas.
Results: The results of the whole group of participants revealed a significant difference in foot loading characteristics before and after the race. Post-race peak pressure and impulse values were higher in the forefoot regions and reduced under the toes.
Conclusions: The increased peak pressure under the metatarsal heads after the race indicates a load shift from the toes to the metatarsal heads. This suggests an increased loading of the metatarsal bones and could explain the increased incidence of metatarsal stress fractures in long distance runners.
Why the Study Is Relevant
The aim of this study is to assess changes in plantar pressure values in a fatigued state after long distance running.
The paper tries to investigate a really relevant topic in endurance running, which is the incidence of metatarsal and stress fractures.
However, while the research design benefits of a very large sample size (n=200), it has some limitations that negatively affect the overall quality of the study.
The main limitation is that plantar pressure measurements weren’t taken during the race with sensorized insoles into the shoes but rather before and after the race by walking barefoot on a pressure platform: it goes without saying that such a measurement does not reflect the real dynamics of foot strike during the race and don’t adds any useful information for the adoption of preventive strategies.
Summary
Stress fractures of the metatarsal bones are reported as one of the most common overuse injuries in long distance running. Causes of injuries are multifactorial and include mechanical loading, muscle fatigue, foot type, step length as well as frequency and duration of training.
The authors of the study investigated the effects of fatigue after a race on plantar loading in order to better understand how to intervene with preventive strategies to decrease the injury risk.
Key Takeaways
- A marathon race leads to changes in peak pressure and impulse values under the forefoot and toes.
- With increasing fatigue, loads are transferred from toes to the forefoot, thus increasing bending load on metatarsal heads.
Read the full study.
Research Title: Effect of Pressure Insole Sampling Frequency on Insole-Measured Peak Force Accuracy during Running
Authors: Elstub L.J., Grohowski L.M., Wolf D.N., Owen M.K., Noehren B., Zelik K.E.
Journal: Journal of Biomechanics
Publication Year: 2022
Abstract
Pressure sensing insoles enable us to estimate forces under the feet during activities such as running, which can provide valuable insight into human movement. Pressure insoles also afford the opportunity to collect more data in more representative environments than can be achieved in laboratory studies. One key challenge with real-world use of pressure insoles is limited battery life which restricts the amount of data that can be collected on a single charge. Reducing sampling frequency is one way to prolong battery life, at the cost of decreased measurement accuracy, but this trade-off has not been quantified, which hinders decision-making by researchers and developers. Therefore, we characterized the effect of decreasing sampling frequency on peak force estimates from pressure insoles (Novel Pedar, 100 Hz) across a range of running speeds and slopes. Data were down sampled to 50, 33, 25, 20, 16 and 10 Hz. Force peaks were extracted due to their importance in biomechanical algorithms trained to estimate musculoskeletal forces and were compared with the reference sampling frequency of 100 Hz to compute relative errors. Peak force errors increased exponentially from 0.7% (50 Hz) to 9% (10 Hz). However, peak force errors were <3% for all sampling frequencies down to 20 Hz. For some pressure insoles, sampling rate is inversely proportional to battery life. Therefore, these findings suggest that battery life could be increased up to 5x at the expense of 3% errors. These results are encouraging for researchers aiming to deploy pressure insoles for remote monitoring or in longitudinal studies.
Why the Study Is Relevant
The aim of this study was to investigate the effects of decreasing sampling frequency on the accuracy of peak force values measured with pressure insoles.
The research problem focuses on a hot topic for researchers and practitioners as well as plantar pressure technology manufacturers.
However the study design suffers from some limitations as follows:
- The authors considered only the sampling frequency of the device without taking into account the resolution (i.e. the number of sensels per sensor).
- Measurements were taken only at certain speed threshold related to walking and running gait, whereas sprinting gait has not been investigated.
Summary
Plantar pressure insoles allows to measure pressure and force under the feet during dynamic activities such as walking and running, thus providing unparalleled insights into human movement and performance.
The authors of this study tried to investigate the effect of various sampling frequency on the accuracy of peak force measurement from pressure insoles.
Key Takeaways
- Average errors for active peak force estimates were <3% for all sampling frequency down to 20 Hz, relative to the reference 100Hz frequency.
Read the full study.