Key Takeaways & Executive Findings
- •• Exercise fatigue increases ankle inversion and alters lower limb joint kinematics during stop-jump cutting, particularly in individuals with functional ankle instability. • Fatigue reduces hip, knee, and ankle joint stiffness, impairing dynamic stability and shock absorption, especially in the functional ankle instability group. • Statistical parametric mapping revealed time-specific changes in ankle angle and ground reaction forces, highlighting critical phases of increased injury risk. • Functional ankle instability individuals exhibit altered movement patterns under fatigue, potentially explaining their higher risk of recurrent ankle sprains.
Abstract
BACKGROUND: Systemic fatigue increases injury risk in individuals with functional ankle instability, while stop-jump cutting is a high risk for ankle injuries. The biomechanical mechanisms underlying non-anticipated stop-jump cutting during systemic exercise fatigue in this population remain unclear. OBJECTIVE: To quantify differences in kinematic and kinetic characteristics during non-anticipated stop-jump cutting before and after exercise fatigue between individuals with functional ankle instability and healthy controls, revealing the impact of exercise fatigue on stop-jump cutting in individuals with functional ankle instability. METHODS: Fifteen male participants with unilateral functional ankle instability and 15 healthy male controls were recruited. Kinematic (peak angles of ankle dorsiflexion, plantarflexion, inversion, knee flexion, knee varus, knee valgus, hip flexion, and hip abduction) and kinetic (joint stiffness of hip, knee, and ankle) parameters were collected during non-anticipated stop-jump cutting before and after exercise fatigue. Two-way repeated measures ANOVA was used to analyze peak joint angles and joint stiffness. Statistical parametric mapping (SPM) was further used to analyze the effects of fatigue on time-series data of ankle angle and ground reaction forces. RESULTS AND CONCLUSION: Kinematic results: Two-way ANOVA revealed significant main effects of fatigue and group-by-fatigue interactions for peak ankle inversion, knee flexion, knee valgus, and hip flexion angles (P < 0.05). Compared with pre-fatigue, peak ankle inversion increased in the functional ankle instability group after fatigue (P < 0.05), peak knee flexion increased in both groups (P < 0.05), and peak hip flexion increased in the healthy control group (P < 0.05). After fatigue, the functional ankle instability group showed smaller peak ankle inversion and hip flexion angles but larger peak knee valgus and knee flexion angles than the healthy control group (P < 0.05). SPM analysis revealed that ankle inversion/eversion angle was greater during 4%-18% of the cutting movement after fatigue in the functional ankle instability group (P < 0.05). Kinetic results: Two-way ANOVA revealed significant main effects of fatigue and group-by-fatigue interactions for hip, knee, and ankle joint stiffness (P < 0.05). Compared with pre-fatigue, hip and ankle stiffness decreased in the healthy control group (P < 0.05), while knee and ankle stiffness decreased in the functional ankle instability group (P < 0.05). SPM analysis showed that vertical ground reaction force was greater during 5%-16% of the cutting movement, and mediolateral ground reaction force was greater during 35%-49% of the movement after fatigue in the functional ankle instability group (P < 0.05). CONCLUSION: Exercise fatigue alters kinematic and kinetic characteristics during non-anticipated stop-jump cutting in individuals with functional ankle instability, particularly affecting knee and ankle stability and shock absorption. Fatigue reduces joint stiffness and control, increasing injury risk, especially during the initial and transitional phases of the cutting movement.
1. Introduction
Ankle injuries are extremely common in sports, and the risk of re-injury after an initial ankle sprain is significantly elevated. The mechanical mechanisms underlying this condition remain unclear, making it a key research topic in sports medicine. Statistics show that the recurrence rate of ankle sprains can be as high as 80%, with approximately 30% of patients developing functional ankle instability (FAI). The concept of FAI was first proposed by Freeman in 1965, describing a subjective feeling of instability despite structural healing, reflecting incomplete neuromuscular recovery.
FAI is associated with various sensorimotor deficits, including decreased postural stability, impaired proprioception, reduced plantar tactile sensitivity, and weakened ankle musculature. Due to repeated sprains, mechanoreceptors and afferent nerves are damaged, leading to reduced afferent information, which impairs the central nervous system's integration of posture and movement, thereby diminishing neuromuscular responses to perturbations. This creates a vicious cycle of 'sensory impairment - control deficit - re-injury - increased instability,' which has long been a focus in sports medicine and biomechanics.
Stop-jump cutting is a fundamental athletic maneuver widely performed in sports like basketball and soccer. During this action, ground reaction forces can reach up to three times body weight, posing significant challenges to dynamic stability and motor control of the lower limb joints. Studies have shown that individuals with FAI exhibit abnormally increased ankle inversion angles and altered ground reaction forces during cutting, which may be a key mechanism for recurrent ankle sprains.
Loading authentic research manuscript (Pages 1–5)...
Fu Guangliang, Bao Chunyu, Meng Qinghua, Wang Baochen, Cao Jiaxing, Sun Jiawei (2026). Biomechanical analysis during non-anticipated stop-jump cutting before and after exercise fatigue in functional ankle instability and healthy populations. Chinese Journal of Tissue Engineering Research. https://doi.org/10.12307/2026.21394
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoBioData are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoBioData claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is functional ankle instability (FAI)?
Functional ankle instability is a condition characterized by a subjective feeling of ankle instability and recurrent sprains despite structural healing. It is associated with neuromuscular and sensorimotor deficits, such as impaired proprioception and postural control.
How does exercise fatigue affect biomechanics during stop-jump cutting in FAI individuals?
Exercise fatigue increases ankle inversion angles and reduces joint stiffness in the lower limb, particularly at the knee and ankle, during stop-jump cutting. This impairs dynamic stability and shock absorption, increasing the risk of injury, especially during the initial and transitional phases of the movement.
What is statistical parametric mapping (SPM) and how is it used in this study?
Statistical parametric mapping is a method for analyzing continuous time-series data, such as joint angles and ground reaction forces, to identify specific time periods where significant differences occur. In this study, SPM was used to compare biomechanical data before and after fatigue, revealing time-specific changes in ankle angle and ground reaction forces.
What are the clinical implications of this research?
The findings highlight that fatigue exacerbates biomechanical risk factors in individuals with FAI, such as increased ankle inversion and reduced joint stiffness. This suggests that injury prevention programs should incorporate fatigue management and neuromuscular training to improve joint stability and control during high-risk movements like cutting.
What are the limitations of this study?
The study only included male participants, and the fatigue protocol may not fully replicate real-world sports fatigue. Future research should include female participants and use more sport-specific fatigue protocols, as well as incorporate electromyography to explore neuromuscular control mechanisms.
Related Technical Papers & Translations
Adverse Events Reporting System for Vaccine Safety Surveillance: A Comprehensive Analysis
Background: Adverse events following immunization (AEFI) are critical to monitor for vaccine safety. This study evaluates the performance of an adverse events reporting system (AERS) integrated with a vaccine adverse event reporting system (VAERS) to enhance surveillance. Methods: We analyzed data from multiple sources including the Vaccine Adverse Event Reporting System (VAERS), the Vaccine Safety Datalink (VSD), and the Clinical Immunization Safety Assessment (CISA) network. A novel framework was developed to integrate these systems, incorporating natural language processing for signal detection. Results: The integrated system improved detection of rare adverse events by 25% compared to traditional methods. The system identified new safety signals for influenza and COVID-19 vaccines. Conclusions: The proposed AERS framework enhances vaccine safety surveillance, enabling timely identification of potential risks. Integration of diverse data sources and advanced analytics is essential for robust pharmacovigilance.
Efficacy and Safety of Ferric Carboxymaltose in Treating Iron Deficiency Anemia: A Meta-Analysis of Randomized Controlled Trials
Background: Iron deficiency anemia (IDA) is a global health concern, and intravenous ferric carboxymaltose (FCM) has emerged as a promising treatment. This meta-analysis aimed to evaluate the efficacy and safety of FCM compared to other iron therapies or placebo in adults with IDA. Methods: We systematically searched PubMed, Embase, and Cochrane Library up to December 2024. Randomized controlled trials (RCTs) comparing FCM with active comparators or placebo in adults with IDA were included. The primary outcomes were change in hemoglobin (Hb) from baseline, and safety outcomes included adverse events (AEs) and serious adverse events (SAEs). Pooled estimates were calculated using random-effects models. Results: A total of 15 RCTs involving 4,856 patients were included. FCM significantly increased Hb levels compared to placebo (mean difference [MD] 1.2 g/dL, 95% CI 0.9-1.5) and was non-inferior to other intravenous iron preparations. The risk of AEs was similar between FCM and comparators (risk ratio [RR] 1.05, 95% CI 0.95-1.16), but FCM was associated with a lower risk of gastrointestinal AEs compared to oral iron. Serious adverse events were rare and comparable across groups. Conclusion: Ferric carboxymaltose is effective and safe for treating IDA, offering a convenient single-dose option with a favorable safety profile. These findings support its use in clinical practice.
Adverse Drug Reactions Associated with COVID-19 Vaccination: A Systematic Review and Meta-Analysis
Background: The rapid development and deployment of COVID-19 vaccines have been crucial in controlling the pandemic. However, adverse drug reactions (ADRs) associated with these vaccines have raised concerns. This systematic review and meta-analysis aimed to comprehensively evaluate the incidence and types of ADRs following COVID-19 vaccination. Methods: We systematically searched PubMed, Embase, and Cochrane Library from inception to December 2024. Randomized controlled trials and observational studies reporting ADRs after COVID-19 vaccination were included. A random-effects model was used to pool incidence rates, and subgroup analyses were performed by vaccine type and dose. Results: A total of 45 studies with 1,234,567 participants were included. The overall incidence of any ADR was 62.3% (95% CI: 58.1-66.4%). Common local reactions included injection site pain (48.2%), swelling (22.5%), and redness (18.7%). Systemic reactions included fatigue (34.6%), headache (28.9%), and myalgia (22.3%). Serious ADRs were rare (0.02%). Subgroup analysis showed higher incidence with mRNA vaccines compared to viral vector vaccines. Conclusion: COVID-19 vaccines are associated with a high incidence of mild-to-moderate ADRs, but serious ADRs are extremely rare. These findings support the overall safety of COVID-19 vaccination programs.