Yumeng Li

Does chronic ankle instability influence lower extremity muscle activation of females during landing

Much remains unclear about how chronic ankle instability (CAI) could affect knee muscle activations and interact with knee biomechanics. Therefore, the purpose of this study was to assess the influence of CAI on the lower extremity muscle activation at the ankle and knee joints during landings on a tilted surface. A surface electromyography system and two force plates were used to collect lower extremity muscle activation of 21 young female individuals with CAI and 21 pair-matched controls during a double-leg landing with test limb landing on the tilted surface. In the pre-landing phase, compared to controls, CAI participants displayed a reduced ankle evertor activation that could place CAI at a high risk of giving way or sprain injury. In the landing phase, an increased tibialis anterior activation of CAI led to increased co-contraction of ankle muscles in the sagittal and frontal plane. A greater ankle muscle co-contraction could increase the ankle stability during landings but may adversely influence the knee muscle activations (e.g., a greater co-contraction ratio of quadriceps to hamstrings). Relevant training programs (e.g., increasing pre-landing peroneal activation, and optimizing activation ratio of quadriceps to hamstrings) may help individuals with CAI improving ankle stability and reduce atypical knee loading during landings.

Lower extremity kinematics of curve sprinting displayed by runners using a transtibial prosthesis

ABSTRACT The purpose of the study was to determine if the kinematics exhibited by skilled runners wearing a unilateral, transtibial prosthesis during the curve section of a 200-m sprint race were influenced by interaction of limb-type (prosthetic limb (PROS-L) vs. nonprosthetic limb (NONPROS-L)) and curve-side (inside and outside limb relative to the centre of the curve). Step kinematics, toe clearance and knee and hip flexion/extension, hip ab/adduction for one stride of each limb were generated from video of 13 males running the curve during an international 200 m transtibial-classified competition. Using planned comparisons (P < 0.05), limb-type and curve-side interactions showed shortest support time and lowest hip abduction displacement by outside-NONPROS-L; shortest step length and longest time to peak knee flexion by the inside-PROS-L. For limb-type, greater maximum knee flexion angle and lower hip extension angles and displacement during support and toe clearance of PROS-Ls occurred. For curve-side, higher hip abduction angles during non-support were displayed by inside-limbs. Therefore, practitioners should consider that, for curve running, these kinematics are affected mostly by PROS-L limitations, with no clear advantage of having the PROS-L on either side of the curve.

Biomechanics of ankle giving way: A case report of accidental ankle giving way during the drop landing test

Background Several case studies observed that the lateral ankle sprain resulted from a sudden increase in ankle inversion accompanied by internal rotation. However, without sufficient ankle kinetics and muscle activity information in the literature, the detailed mechanism of ankle sprain is still unrevealed. The purpose of our case report is to present 2 accidental ankle giving way incidents for participants with chronic ankle instability (CAI) and compare to their normal trials with data of kinematics, kinetics, and electromyography (EMG). Case description Two young female participants accidentally experienced the ankle giving way when landing on a 25° lateral-tilted force plate. 3D kinematics, kinetics, and muscle activity were recorded for the lower extremity. Qualitative comparisons were made between the giving way trials and normal trials for joint angles, angular velocities, moments, centers of pressure and EMG linear envelopes. Results One participants giving way trial displayed increased ankle inversion and internal rotation angles in the pre-landing phase and at initial contact compared to her normal trials. Another participants giving way trial exhibited greater hip abduction angles and delayed activation of the peroneus longus muscle in the pre-landing phase versus her normal trials. Conclusion A vulnerable ankle position (i.e., more inverted and internally rotated), and a late activation of peroneus activity in the pre-landing phase could result in the ankle giving way or even sprains. A neutral ankle position and early activation of ankle evertors before landing may be helpful in preventing ankle sprains.

Cross-cultural adaptation and validation of an ankle instability questionnaire for use in Chinese-speaking population

Background The Identification of Functional Ankle Instability (IdFAI) is a valid and reliable tool to identify chronic ankle instability; however, it was developed in English, thus limiting its usage only to those who can read and write in English. The objectives of our study were to (1) cross-culturally adapt a Chinese (Mandarin) version of the IdFAI and (2) determine the psychometric properties of the Chinese version IdFAI. Methods The cross-cultural adaptation procedures used by the investigators and translators followed previously published guidelines and included 6 stages: (1) initial translation, (2) synthesis of the translations, (3) back translation, (4) developing the pre-final version for field testing, (5) testing the pre-final version, and (6) finalizing the Chinese version of IdFAI (IdFAI-C). Five psychometric properties of the IdFAI-C were assessed from results of 2 participant groups: bilingual (n = 20) and Chinese (n = 625). Results A high degree of agreement was found between the English version of IdFAI and IdFAI-C (intra-class correlation2,1 = 0.995). An excellent internal consistency (Cronbachs α = 0.89), test–retest reliability (intra-class correlation2,1 = 0.970), and construct validity (r(625) = 0.67) was also found for the IdFAI-C. In addition, the results of exploratory and confirmatory factor analysis indicated that ankle instability was the only construct measured from the IdFAI. Conclusion The IdFAI-C is a highly reliable and valid self-report questionnaire that can be used to assess ankle instability. Therefore, we suggest that it can be used to effectively and accurately assess chronic ankle instability in clinical settings for Chinese-speaking individuals.

Intratrunk Coordination During High-Effort Treadmill Running in Individuals With Spinal Fusion for Adolescent Idiopathic Scoliosis

The purpose of the study was to determine if the intratrunk coordination of axial rotation exhibited by individuals with spinal fusion for adolescent idiopathic scoliosis (SF-AIS) during running varies from healthy individuals and how the coordination differs among adjacent trunk-segment pairs. Axial rotations of trunk segments (upper, middle, lower trunk) and pelvis were collected for 11 SF-AIS participants and 11 matched controls during running. Cross-correlation determined the phase lag between the adjacent segment motions. The coupling angle was generated using the vector coding method and classified into 1 of the 4 major, modified coordination patterns: in-phase, anti-phase, superior, and inferior phase. Two-way, mixed-model ANCOVA was employed to test phase lag, cross-correlation r, and time spent in each major coordination pattern. A significantly lower phase lag for SF-AIS was observed compared with controls. Qualitatively, there was a tendency that SF-AIS participants spent less time in anti-phase for middle-lower trunk and lower trunk-pelvis coordinations compared to controls. Phase lag and anti-phase time was significantly increased from cephalic to caudal segment pairs, regardless of group. In conclusion, SF-AIS participants and controls displayed similar patterns of intra-trunk coordination; however, the spinal fusion hindered decoupling of intra-trunk motions particularly between the lower trunk-pelvic motion.