Original Article: NTNU Office of Public Affairs
[This report was provided by the research team of Associate Professor Lee Heng-Ju, Department of Physical Education and Sport Sciences.] (English Version Powered by ChatGPT, Edited by Serena H.)
This research study aimed to test the functional forward jump-landing performance of athletes with varying degrees of ankle sprains to examine postural stability abilities among chronic ankle instability (CAI) athletes, potential risk individuals (copers), and healthy athletes.
The study used the Cumberland Ankle Instability Tool (CAIT) as the primary research instrument, recruiting 30 collegiate-level athletes. Each group—CAI, potential (coper), and healthy—consisted of 10 participants who performed forward jump-landing movements, had participants instructed to jump and land on one foot, maintaining balance for five seconds to collect biomechanical data for analysis across the three groups.
Results showed that the healthy group exhibited greater center of pressure displacement and velocity as well as higher vertical and overall stability indices, along with greater vertical ground reaction forces upon landing.
This led to a significantly higher loading rate during landing. In contrast, athletes with ankle instability effectively reduced landing loading rate and peak forces, which facilitated better postural stability. This suggests that the CAI group adopted a unique landing cushioning strategy.
The study concluded that athletes with ankle instability developed a specialized inter-joint coordination strategy during recovery which benefits postural stability and balance during landing.
The ankle joint is one of the lower limb joints that is repeatedly engaged during contact with the ground. In sports activities, frequent and continuous landing movements can easily lead to lateral ankle sprains.
Symptoms of ankle instability often include swelling, stiffness, and even a sensation of the ankle “giving way.” These symptoms may stem from ligament injuries, insufficient neuromuscular control, delayed motor response time, poor balance, or impaired proprioception. Ankle sprains most commonly affect trunk stability through postural balance; thus, ankle instability can be assessed through balance performance.
This study investigates postural stability in athletes with varying degrees of ankle sprain by categorizing them into healthy, coper, and chronic ankle instability (CAI) groups and subjecting them to a forward jump landing functional test. The goal is to identify dynamic postural stability parameters that can serve as quantifiable indicators of ankle instability, thereby providing a stronger reference for future related research.
This study primarily targeted student-athletes from collegiate varsity teams (elite collegiate level), using the Cumberland Ankle Instability Tool (CAIT) as the inclusion and exclusion criteria for participant selection.
From 185 questionnaires, 30 eligible athletes were recruited and divided into three groups of ten: healthy, coper, and unstable. The healthy group had no history of ankle sprain; the coper group had experienced one ankle sprain episode with no recurrence for over 12 months; the unstable group had multiple ankle sprains accompanied by a sense of ankle weakness.
To ensure consistency between questionnaire responses and actual ankle stability, all participants underwent clinical assessment by a certified athletic trainer. This included the anterior drawer test for the anterior talofibular ligament and the talar tilt test for the calcaneofibular ligament, providing a basis for categorizing ankles as stable or unstable. Athletes in the unstable group tested positive in physical assessments, while those in the healthy and coper groups tested negative.
The test movement in this study involved a forward jump with single-leg landing using the injured side to maintain balance. Participants initiated the forward jump by taking off on the uninjured leg, clearing a 15 cm hurdle, and then landed on the injured leg on a force plate, maintaining balance for five seconds (see Figure 1). The test was conducted barefoot, and data collection was considered complete after three successful trials.
A Kistler force plate was used to collect ground reaction force data upon landing, sampled at 1000 Hz. Kinematic data were captured using ten Vicon infrared cameras at a frequency of 200 Hz, tracking 3D coordinates of reflective markers. By incorporating center of mass parameters, body sway could be directly assessed. The dynamic postural stability index (DPSI) was used to quantify stability changes along three axes, while kinetic analysis assessed the magnitude of ground reaction forces. The study aimed to quantify the balance ability of athletes with ankle instability using four different postural stability parameters.
The study found that the ankle instability group demonstrated significantly better balance performance than the healthy group in the DPSI index (see Figure 2), along with significantly lower landing loading rates and force peaks. An especially interesting finding was that the coper group, which had experienced only one previous sprain, exhibited biomechanical characteristics similar to those of the instability group. This suggests that ankle sprains may be an irreversible process, affecting landing mechanics and balance control regardless of the number of occurrences.
Athletes with ankle sprains appear to adopt more conservative balance control strategies; however, whether this affects athletic performance remains to be explored in future studies.
Comparison of experimental parameters revealed that center of mass movement could not distinguish differences among the ankle instability groups. Similarly, peak vertical landing force failed to reflect the nuances of landing dynamics. While landing loading rate provided insight into the impact severity on the lower limbs, it did not account for horizontal or anterior-posterior forces.
However, the DPSI, with its anterior-posterior, medial-lateral, and vertical indices, allows investigation of landing effects across all three axes. By integrating these indices, researchers can more directly assess overall dynamic postural stability, enabling more precise comparisons. Thus, this study recommends the use of DPSI in future kinematic and kinetic research comparisons.
This study showed that, during forward jump landing tasks, athletes with greater ankle instability demonstrated better dynamic postural stability. Future research will further examine joint movement patterns and neuromuscular activation efficiency in the lower limbs, aiming to develop comprehensive strategies for evaluating post-injury recovery in athletes with ankle sprains.
Source: Research Highlights, Office of Research and Development
Original link: https://rh.acad.ntnu.edu.tw/tw/article/content/99
Original publication: https://www.airitilibrary.com/Publication/alDetailedMesh?DocID=15633470-201906-201907030011-201907030011-156-172
Lee Heng-Ju | Associate Professor at Department of Physical Education and Sport Sciences
Lee Heng-Ju earned his Ph.D. in Biomechanics from the University of Oregon, USA, and is currently an Associate Professor at the Department of Physical Education and Sport Sciences at NTNU, President of the Taiwan Society of Sports Injury Prevention, Executive Board Member of the World Federation of Athletic Training & Therapy (WFATT), Deputy Executive Director of the LOHAS EMBA Program at NTNU, and also serves as a performance trainer for professional baseball players including Tzu-Wei Lin, Chia-Hao Sung, Kuo-Hui Kao, and Che-Hsuan Lin.