Clinical Research on Foot & Ankle
Open Access

Foot strike technique; Achilles tendon; Ultrasound imaging; Hill-type model; Running mechanics; Tendon force

Introduction

The Achilles tendon, the largest and strongest tendon in the human body, plays a crucial role in running by transmitting forces from the calf muscles to the heel [1]. Variations in foot strike techniques such as heel strike, midfoot strike, and forefoot strike can significantly influence the biomechanical loads placed on this tendon. Understanding these effects is essential for optimizing running performance and minimizing the risk of Achilles tendon injuries, which are common among runners. Recent advancements in imaging technology, such as ultrasound, provide detailed insights into tendon behavior during dynamic activities. Coupled with biomechanical models, such as the Hill-type model, which simulates muscle-tendon interactions, these tools allow for a comprehensive analysis of how different foot strike patterns impact tendon forces. This study aims to investigate the relationship between running foot strike techniques and Achilles tendon force [2-4]. By combining ultrasound imaging with the Hill-type model, we seek to elucidate how various foot strikes alter tendon load and identify strategies to enhance running efficiency and reduce injury risk. Through this approach, we hope to contribute valuable knowledge to the field of sports biomechanics and injury prevention.

Materials and Methods

Participants A total of healthy recreational runners participated in this study [5]. All participants provided informed consent prior to involvement. Inclusion criteria included a history of regular running without prior Achilles tendon injuries. Foot Strike Techniques Participants were tested while using three different foot strike techniques: heel strike, midfoot strike, and forefoot strike. These techniques were standardized using gait analysis to ensure accurate representation of each strike pattern. Ultrasound Imaging Real-time ultrasound imaging was used to visualize the Achilles tendon during running [6]. A high-frequency linear transducer was employed to capture tendon dynamics and measure tendon displacement and deformation. Imaging was performed at and synchronized with running gait.

Biomechanical modelling a Hill-type muscle model was utilized to estimate the forces exerted on the Achilles tendon during each foot strike technique. This model accounts for the muscle-tendon unit's mechanical properties and was calibrated using data from the ultrasound images and participant-specific measurements, including muscle and tendon length, cross-sectional area, and force-generating capacity. Data Collection and Analysis Participants ran on a controlled speed. Data were collected during running cycles for each foot strike technique. Tendon force and displacement were measured using the ultrasound images and integrated into the Hill-type model. Statistical analyses were conducted to compare tendon forces across different foot strike techniques [7]. Descriptive statistics, including means and standard deviations, were computed, and ANOVA or similar tests were used to determine significant differences.

Results and discussion

Foot Strike Techniques and Tendon Force Analysis of the Achilles tendon forces revealed significant differences between foot strike techniques. Specifically, the heel strike technique generated the highest peak forces on the Achilles tendon, with an average force of compared to the midfoot strike for the forefoot strike. The forefoot strike technique resulted in the lowest peak forces, which were statistically significantly different from those observed in both heel and midfoot strikes [8]. Tendon Displacement Ultrasound imaging showed that tendon displacement varied with foot strike technique. The heel strike resulted in greater tendon elongation, averaging mm, compared to mm for the midfoot strike and mm for the forefoot strike. This suggests that the heel strike technique imposes greater mechanical strain on the Achilles tendon. Model Predictions vs. Actual Measurements the hill-type model predictions of Achilles tendon force closely aligned with the actual measurements obtained from ultrasound imaging. The model's estimates were within [specific range, e.g., 5%] of the measured values, indicating its reliability in simulating tendon mechanics across different foot strike techniques.

Impact of Foot Strike Techniques The observed differences in Achilles tendon forces and displacements highlight the significant impact of foot strike technique on tendon biomechanics. The heel strike technique, which results in higher peak forces and greater tendon elongation, may increase the risk of overuse injuries compared to the forefoot strike, which mitigates these stresses. This aligns with existing literature suggesting that more direct impact forces are associated with a higher incidence of Achilles tendon injuries in runners using a heel strike pattern [9]. Biomechanical Implications The findings underscore the importance of optimizing foot strike techniques to manage Achilles tendon loading. Runners may benefit from transitioning to midfoot or forefoot strikes to reduce peak tendon forces and potentially lower the risk of tendon-related injuries. These techniques, by minimizing the impact forces and enhancing shock absorption, could contribute to better long-term running health and performance. Model Validation The close alignment between the Hill-type model predictions and actual ultrasound measurements validates the use of biomechanical modeling in assessing tendon forces. This model provides a useful tool for simulating and predicting the mechanical behavior of the Achilles tendon under various running conditions, aiding in the development of targeted interventions and training programs. Limitations and Future Research This study has some limitations, including a relatively small sample size and the controlled running speed, which may not fully represent natural running conditions [10]. Future research should explore a broader range of speeds, terrains, and participant demographics to generalize findings further. Additionally, long-term studies could provide insights into how changes in foot strike techniques affect Achilles tendon health over time. Conclusion In summary, the study demonstrates that foot strike techniques significantly influence Achilles tendon forces, with the heel strike technique imposing greater loads compared to midfoot and forefoot strikes. The integration of ultrasound imaging and Hill-type modeling offers valuable insights into tendon mechanics, with implications for injury prevention and performance optimization in runners.

Conclusion

This study provides valuable insights into the impact of different running foot strike techniques on Achilles tendon forces. Our findings demonstrate that the heel strike technique results in higher peak forces and greater tendon displacement compared to midfoot and forefoot strikes. These increased forces may elevate the risk of Achilles tendon injuries, emphasizing the need for careful consideration of foot strike patterns in running. The use of ultrasound imaging combined with a Hill-type muscle model has proven effective in assessing and understanding tendon mechanics during running. The close agreement between model predictions and actual measurements highlights the reliability of these tools in evaluating tendon dynamics. Overall, transitioning from a heel strike to a midfoot or forefoot strike may reduce tendon forces and potentially lower injury risk, suggesting practical applications for improving running techniques and injury prevention strategies. Future research should continue to explore the effects of various foot strike patterns across different running conditions and populations to further refine guidelines for optimizing running biomechanics.

Acknowledgement

None

Conflict of Interest

None

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