Impact of Achilles Tendon Rupture on Running Mechanics
Overview of the Achilles Tendon
The Achilles tendon, recognized as the strongest and largest tendon in the human body, connects the calf muscles to the heel bone. It plays a vital role in running by providing power to the ankle muscles. Despite its strength, the Achilles tendon is susceptible to injury due to the high tension experienced during sports activities, particularly running and jumping, compounded by its limited blood supply. Over the past three decades, the incidence of Achilles tendon ruptures has surged, with rates increasing from 2 to 22 per 100,000 person-years, primarily affecting athletes.
Career Impact on Athletes
Following an Achilles tendon rupture, approximately 30% of athletes face career termination. However, many are still able to engage in an active lifestyle. Research indicates that such injuries lead to various mechanical, anatomical, and neuromuscular changes within the calf muscles. These changes can result in Achilles tendon weakness when the foot is flexed, reduced endurance, decreased ankle joint range of motion, elongated Achilles tendon, and stiffness in the affected tendon. Additionally, individuals with a history of an Achilles tendon rupture are 176 times more likely to experience a rupture in the opposite tendon.
Joint Mechanics in Recovered Athletes
Research Study Overview
A study conducted in the Czech Republic and published in the Journal of Foot and Ankle Research examined the lower extremity mechanics of runners who had previously suffered an Achilles tendon rupture, compared to healthy controls. The study involved 22 participants aged 22 to 50 years, with 11 having recovered from an Achilles tendon rupture and matched with 11 healthy individuals based on age, sex, mass, height, exercise type, footfall pattern, and lateral dominance.
Data Collection and Analysis
Participants in the Achilles tendon rupture group provided data on their footfall patterns and weekly running activities. Ultrasonography was used to measure the length of their Achilles tendon, while a high-speed motion capture system assessed the running kinetics and kinematics of their hip, ankle, and knee.
Effects on the Gait Cycle
Understanding Running Biomechanics
Running biomechanics involve the gait cycle, which consists of two phases: the stance phase (when part of the foot contacts the ground) and the swing phase (when the foot is in the air). The cycle commences when one foot touches the ground and concludes when the same foot returns to the ground.
Key Findings from the Study
The study revealed that athletes who had previously experienced an Achilles tendon rupture showed a reduced ankle range of motion, increased knee range of motion, and overextension of the knee upon initial ground contact with the affected limb. Additionally, this group exhibited longer tendon lengths and decreased strength in their calf muscles, along with a 22% increase in hip joint movement on the opposite side of the body compared to healthy controls. This compensatory mechanism suggests that individuals may adjust their running style to mitigate the risk of reinjury.
Study Limitations
The study’s cross-sectional design prevents researchers from definitively attributing the observed results to the injury. Variability in surgical techniques among different surgeons and the differing time intervals between surgery and study participation also pose limitations.
Recommendations for Athletes
Avoiding High-Risk Sports
While modifying running styles post-Achilles tendon rupture may help avoid re-injury, it could also increase susceptibility to other injuries, such as those affecting the knee or the opposite Achilles tendon. Researchers advocate for strategies to prevent tendon elongation and maintain strength and range of motion in surrounding muscles during rehabilitation, as these factors may contribute to altered running mechanics. Furthermore, individuals recovering from an Achilles tendon rupture are advised to steer clear of high-performance activities that present a significant risk of knee or tendon injuries.
Further Reference
This article is based on research by Jandacka D, Silvernail JF, Uchytil J, Zahradnik D, Farana R, and Hamill J. titled “Do athletes alter their running mechanics after an Achilles tendon rupture?” published in the Journal of Foot and Ankle Research on November 28, 2017. DOI: 10.1186/s13047-017-0235-0.