Corticospinal activity during a single-leg stance in people with chronic ankle instability

Purpose:The aim of the study was to determine whether corticospinal excitability and inhibition of the tibialis anterior during single-leg standing differs among individuals with chronic ankle instability(CAI),lateral ankle sprain copers,and healthy controls.Methods:Twenty-three participants with CAI,23 lateral ankle sprain copers,and 24 healthy control participants volunteered.Active motor threshold(AMT),normalized motor-evoked potential(MEP),and cortical silent period(CSP)were evaluated by transcranial magnetic stimulation while participants performed a single-leg standing task.Results:Participants with CAI had significantly longer CSP at 100%of AMT and lower normalized MEP at 120%of AMT compared to lateral ankle sprain copers(CSP100%:p=0.003;MEP120%:p=0.044)and controls(CSP100%:p=0.041;MEP120%:p=0.006).Conclusion:This investigation demonstrate altered corticospinal excitability and inhibition of the tibialis anterior during single-leg standing in participants with CAI.Further research is needed to examine the effects of corticospinal maladaptations to motor control of the tibial anterior on postural control performance in those with CAI.     

A lateral ankle sprain during a lateral backward step in badminton: A case report of a televised injury incident

BackgroundThis study presents a kinematic analysis of an acute lateral ankle sprain incurred during a televised badminton match. The kinematics of this injury were compared to those of 19 previously reported cases in the published literature.MethodsFour camera views of an acute lateral ankle sprain incurred during a televised badminton match were synchronized and rendered in 3-dimensional animation software. A badminton court with known dimensions was built in a virtual environment, and a skeletal model scaled to the injured athlete's height was used for skeletal matching. The ankle joint angle and angular velocity profiles of this acute injury were compared to the summarized findings from 19 previously reported cases in the published literature.ResultsAt foot strike, the ankle joint was 2° everted, 33° plantarflexed, and 18° internally rotated. Maximum inversion of 114° and internal rotation of 69° was achieved at 0.24 s and 0.20 s after foot strike, respectively. After the foot strike, the ankle joint moved from an initial position of plantarflexion to dorsiflexion—from 33° plantarflexion to 53° dorsiflexion (range = 86°). Maximum inversion, dorsiflexion, and internal rotation angular velocity were 1262°/s, 961°/s, and 677°/s, respectively, at 0.12 s after foot strike.ConclusionA forefoot landing posture with a plantarflexed and internally rotated ankle joint configuration could incite an acute lateral ankle sprain injury in badminton. Prevention of lateral ankle sprains in badminton should focus on the control and stability of the ankle joint angle during forefoot landings, especially when the athletes perform a combined lateral and backward step.     

Neuromuscular control during stepping down in continuous gait in individuals with and without ankle instability

Abstract

Ankle sprains are a common injury and those affected are at a risk of developing chronic ankle instability (CAI). Complications of an acute sprain include increased risk of re-injury and persistent disability; however, the exact link between ankle sprains and chronic instability has yet to be elucidated. The purpose of this study was to investigate neuromuscular control (including kinematics, kinetics and EMG) during stepping down from a curb, a common yet challenging daily activity, in persons with ankle instability (n = 11), those with a history of ankle sprain without persistent instability, called ankle sprain “copers” (CPRs) (n = 9) and uninjured controls (CTLs) (n = 13). A significant group difference was noted as the CPR group demonstrated increased tibialis anterior activity in both the preparatory (pre-touchdown) and reactive (post-touchdown) phases when compared to healthy and unstable groups (P < 0.05). It follows that the CPR group also demonstrated a significantly less plantar-flexed position at touchdown than the other two groups (P < 0.05). This is a more stable position to load the ankle and this strategy differed from that used by participants with CAI and uninjured CTLs. These findings provide insight into the neuromuscular control strategies of CPRs, which may allow them to more appropriately control ankle stability following sprains.     

External ankle taping does not alter lower extremity side-step cut and straight sprint biomechanics in young adult males

Abstract

Lateral ankle sprains (LAS) are one of the most common musculoskeletal injuries and as a response, clinicians often use external ankle taping prophylactically to reduce the prevalence of injuries. External ankle taping techniques have been shown to significantly reduce passive ankle range of motion; however, there is limited research on the effects of external ankle taping on lower extremity kinematics or kinetics during sport specific tasks. Therefore, our objective was to compare the effects of external ankle taping on ankle, knee and hip kinematics and kinetics compared to no taping during an anticipated sidestep cutting task and a straight sprint task. We conducted a cross-over laboratory study with 16 healthy males. Three-dimensional kinematics and kinetics were collected with a motion capture system and in-ground force plate during 5 trials of a sprint and anticipated side-step cut with or without external ankle taping. Group means and associated 90% confidence intervals were plotted across 100 data points for each task, significance being identified when the confidence intervals did not overlap for three consecutive data points. No significant kinetic or kinematic differences were identified between conditions for the tasks. External ankle taping does not influence lower extremity biomechanics during a control cutting task.     

Risk factors for chronic ankle instability after first episode of lateral ankle sprain: A retrospective analysis of 362 cases

BackgroundChronic ankle instability (CAI) is a common sequela following an acute lateral ankle sprain (LAS). To treat an acute LAS more effectively and efficiently, it is important to identify patients at substantial risk for developing CAI. This study identifies magnetic resonance imaging (MRI) manifestations for predicting CAI development after a first episode of LAS and explores appropriate clinical indications for ordering MRI scans for these patients.MethodsAll patients with a first-episode LAS who received plain radiograph and MRI scanning within the first 2 weeks after LAS from December 1, 2017 to December 1, 2019 were identified. Data were collected using the Cumberland Ankle Instability Tool at final follow-up. Demographic and other related clinical variables, including age, sex, body mass index, and treatment were also recorded. Univariable and multivariable analyses were performed successively to identify risk factors for CAI after first-episode LAS.ResultsA total 131 out of 362 patients with a mean follow-up of 3.0 ± 0.6 years (mean ± SD; 2.0–4.1 years) developed CAI after first-episode LAS. According to multivariable regression, development of CAI after first-episode LAS was associated with 5 prognostic factors: age (odds ratio (OR) = 0.96, 95% confidence interval (95%CI): 0.93–1.00, p = 0.032); body mass index (OR = 1.09, 95%CI: 1.02–1.17, p = 0.009); posterior talofibular ligament injury (OR = 2.17, 95%CI: 1.05–4.48, p = 0.035); large bone marrow lesion of the talus (OR = 2.69, 95%CI: 1.30–5.58, p = 0.008), and Grade 2 effusion of the tibiotalar joint (OR = 2.61, 95%CI: 1.39–4.89, p = 0.003). When patients had at least 1 positive clinical finding in the 10-m walk test, anterior drawer test, or inversion tilt test, they had a 90.2% sensitivity and 77.4% specificity in terms of detecting at least 1 prognostic factor by MRI.ConclusionMRI scanning is valuable in predicting CAI after first-episode LAS for those patients with at least 1 positive clinical finding in the 10-m walk test, anterior drawer test, and inversion tilt test. Further prospective and large-scale studies are necessary for validation.     

Fatigue increases ankle sprain risk in badminton players: A biomechanical study

ABSTRACT

Ankle sprains are the most common injury in regular badminton players and usually occur at the end of a match or training. The purpose of the present study was to examine the influence of fatigue produced by badminton practice on the lower limb biomechanics of badminton players. It was hypothesized that fatigue induces ankle kinematic and lower leg muscle activity changes which may increase the risk of ankle sprain. Ankle kinematics, ankle kinetics and muscles activities of 17 regular badminton players were recorded during lateral jumps before and after an intense badminton practice session. Post-fatigue, ankle inversion at foot strike and peak ankle inversion increased (+2.6°, p = 0.003 and +2.5°, p = 0.005, respectively). EMG pre-activation within 100 ms before foot landing significantly decreased after fatigue for soleus (?23.4%, p = 0.031), gastrocnemius lateralis (?12.2%, p = 0.035), gastrocnemius medialis (?23.3%, p = 0.047) and peroneus brevis (?17.4%, p = 0.036). These results demonstrate impaired biomechanics of badminton players when fatigue increases, which may cause a greater risk of experiencing an ankle sprain injury.     

Noise-enhanced dynamic single leg balance in subjects with functional ankle instability

BackgroundStochastic resonance stimulation (SRS) transmits subsensory electrical Gaussian white noise into the body to enhance sensorimotor function. This therapy has improved static single leg balance in subjects with functional ankle instability. However, the effect of this stimulation on dynamic single leg balance is not known. Improvements in dynamic single leg balance with SRS may have implications for enhancing functional rehabilitation for ankle instability. Thus, the purpose of this study was to determine the effects of SRS on dynamic single leg balance in subjects with functional ankle instability.MethodsThis study was an experimental research design and data were collected in a sports medicine research laboratory. Twelve subjects with functional ankle instability (69 ± 15 kg; 173 ± 10 cm; 21 ± 2 years) reported a history of ankle sprains and instability at the ankle with physical activity. A single leg jump-landing test was used to assess dynamic balance. Subjects were required to jump between 50% and 55% of the maximal vertical jump height, land on a single leg atop a force plate, and stabilize as quickly as possible. Jump-landing tests were performed with and without SRS. Three trials were performed for each treatment condition (SRS and control). A randomized block design was used to determine test order. Anterior/posterior and medial/lateral time-to-stabilization were computed to assess dynamic balance. Lesser time indicated better stability. One-tailed paired samples t tests were used for analysis (α ≤ 0.05).ResultsSRS improved anterior/posterior time-to-stabilization (stochastic resonance = 1.32 ± 0.31 s, control = 1.74 ± 0.80 s, p = 0.03), but did not enhance medial/lateral time-to-stabilization (stochastic resonance = 1.95 ± 0.40 s, control = 1.92 ± 0.48 s, p = 0.07).ConclusionClinicians might use SRS to facilitate balance improvements with sagittal plane dynamic single leg balance exercises that patients may not be able to perform otherwise.     

慢性踝关节不稳人群的筛选及分型标准研究进展

踝关节扭伤被认为是最常发生的反复损伤。32%~74%的急性踝关节扭伤患者会转变为慢性踝关节不稳。由于慢性踝关节不稳的专业术语、定义以及在ICF（International Classification of Functioning, Disability, and Health）模式下的损伤因素均未达成统一看法,研究人员及临床从业者对其了解甚少。基于国际足踝联盟（International Ankle Consortium）提出的慢性踝关节不稳筛选标准、Hertel提出的慢性踝关节不稳模型及Hiller改良后的模型,为今后慢性踝关节不稳的相关研究提供筛选标准并针对性指导临床治疗。     

Examining the intrinsic foot muscles’ capacity to modulate plantar flexor gearing and ankle joint contributions to propulsion in vertical jumping

BackgroundDuring human locomotion, a sufficiently stiff foot allows the ankle plantar flexors to generate large propulsive powers. Increasing foot stiffness (e.g., via a carbon plate) increases the ankle's external moment arm in relation to the internal moment arm (i.e., increasing gear ratio), reduces plantar flexor muscles’ shortening velocity, and enhances muscle force production. In contrast, when activation of the foot's intrinsic muscles is impaired, there is a reduction in foot and ankle work and metatarsophalangeal joint stiffness. We speculated that the reduced capacity to actively control metatarsophalangeal joint stiffness may impair the gearing function of the foot at the ankle.MethodsWe used a tibial nerve block to examine the direct effects of the intrinsic foot muscles on ankle joint kinetics, in vivo medial gastrocnemius’ musculotendinous dynamics, and ankle gear ratio on 14 participants during maximal vertical jumping.ResultsUnder the nerve block, the internal ankle plantar flexion moment decreased (p = 0.004) alongside a reduction in external moment arm length (p = 0.021) and ankle joint gear ratio (p = 0.049) when compared to the non-blocked condition. Although medial gastrocnemius muscle–tendon unit and fascicle velocity were not different between conditions, the Achilles tendon was shorter during propulsion in the nerve block condition (p < 0.001).ConclusionIn addition to their known role of regulating the energetic function of the foot, our data indicate that the intrinsic foot muscles also act to optimize ankle joint torque production and leverage during the propulsion phase of vertical jumping.     

Development of a fulcrum methodology to replicate the lateral ankle sprain mechanism and measure dynamic inversion speed

When the ankle is forced into inversion, the speed at which this movement occurs may affect the extent of injury. The purpose of this investigation was to develop a fulcrum device to mimic the mechanism of a lateral ankle sprain and to determine the reliability and validity of the temporal variables produced by this device. Additionally, this device was used to determine if a single previous lateral ankle sprain or ankle taping effected the time to maximum inversion and/or mean inversion speed. Twenty-six participants (13 with history of a single lateral ankle sprain and 13 with no history of injury) completed the testing. The participants completed testing on three separate days, performing 10 trials with the fulcrum per leg on each testing day, and tape was applied to both ankles on one testing day. No significant interactions or main effects were found for either previous injury or ankle taping, but good reliability was found for time to maximum inversion (ICC = .81) and mean inversion speed (ICC = .79). The findings suggest that although neither variable was influenced by the history of a single previous lateral ankle sprain or ankle taping, both variables demonstrated good reliability and construct validity, but not discriminative validity.     

The effects of postseason break on stabilometric performance in female volleyball players

Ankle sprain is a common injury in volleyball. Poor stabilometric performance (SP) is associated with high risks of sustaining ankle sprain. Balance training can improve SP and reduce ankle sprain, but no research has studied the effects of detraining on SP in highly trained athletes. The purpose of this study was to determine the effects of one-month postseason break on SP in female volleyball players. Eleven NCAA female volleyball players participated in two eye-closed single-leg stance tests before and after a one-month postseason break. Stance time, center of pressure (COP) area, COP standard deviation, and COP mean velocity were assessed during the tests. During the postseason break, subjects conducted self-selected exercise and the average training duration was 87% lower compared to the competition season. Subjects demonstrated significant increases in anterioposterior (A/P) COP standard deviation (1.6 ± 0.4 vs. 1.8 ± 0.4 cm, p = 0.05), mediolateral (M/L) COP velocity (6.5 ± 1.5 vs. 7.1 ± 1.3 cm/s, p = 0.05), and overall COP velocity (10.1 ± 2.0 vs. 11.6 ± 1.9 cm/s, p = 0.02) after postseason break. SP decreased in highly trained female volleyball players after one-month postseason break. The decrease in SP indicated a possible increased risk for ankle sprain injury.     

Effect of turf on the cutting movement of female football players

PurposeThe globalisation of artificial turf and the increase in player participation has driven the need to examine injury risk in the sport of football. The purpose of this study was to investigate the surface–player interaction in female football players between natural and artificial turf.MethodsEight university level female football players performed an unanticipated cutting manoeuvre at an angle of 30° and 60°, on a regulation natural grass pitch (NT) and a 3G artificial turf pitch (AT). An automated active maker system (CodaSport CXS System, 200 Hz) quantified 3D joint angles at the ankle and knee during the early deceleration phase of the cutting, defined from foot strike to weight acceptance at 20% of the stance phase. Differences were statistically examined using a two-way (cutting angle, surface) ANOVA, with an α level of p < 0.05 and Cohen's d effect size reported.ResultsA trend was observed on the AT, with a reduction in knee valgus and internal rotation, suggesting a reduced risk of knee injury. This findings highlight that AT is no worse than NT and may have the potential to reduce the risk of knee injury. The ankle joint during foot strike showed large effects for an increase dorsiflexion and inversion on AT. A large effect for an increase during weight acceptance was observed for ankle inversion and external rotation on AT.ConclusionThese findings provide some support for the use of AT in female football, with no evidence to suggests that there is an increased risk of injury when performing on an artificial turf. The ankle response was less clear and further research is warranted. This initial study provides a platform for more detailed analysis, and highlights the importance of exploring the biomechanical changes in performance and injury risk with the introduction of AT.     

Relationship of proprioception,cutaneous sensitivity,and muscle strength with the balance control among older adults

BackgroundBalance impairment is one of the strongest risk factors for falls. Proprioception, cutaneous sensitivity, and muscle strength are 3 important contributors to balance control in older adults. The relationship that dynamic and static balance control has to proprioception, cutaneous sensitivity, and muscle strength is still unclear. This study was performed to investigate the relationship these contributors have to dynamic and static balance control.MethodsA total of 164 older adults (female = 89, left dominant = 15, age: 73.5 ± 7.8 years, height: 161.6 ± 7.1 cm, weight: 63.7 ± 8.9 kg, mean ± SD) participated in this study. It tested the proprioception of their knee flexion/extension and ankle dorsi/plantarflexion, along with cutaneous sensitivity at the great toe, first and fifth metatarsals, arch, and heel, and the muscle strength of their ankle dorsi/plantarflexion and hip abduction. The Berg Balance Scale (BBS) and the root mean square (RMS) of the center of pressure (CoP) were collected as indications of dynamic and static balance control. A partial correlation was used to determine the relationship between the measured outcomes variables (BBS and CoP-RMS) and the proprioception, cutaneous sensitivity, and muscle strength variables.ResultsProprioception of ankle plantarflexion (r = –0.306, p = 0.002) and dorsiflexion (r = –0.217, p = 0.030), and muscle strength of ankle plantarflexion (r = 0.275, p = 0.004), dorsiflexion (r = 0.369, p < 0.001), and hip abduction (r = 0.342, p < 0.001) were weakly to moderately correlated with BBS. Proprioception of ankle dorsiflexion (r = 0.218, p = 0.020) and cutaneous sensitivity at the great toe (r = 0.231, p = 0.041) and arch (r = 0.285, p = 0.002) were weakly correlated with CoP-RMS in the anteroposterior direction. Proprioception of ankle dorsiflexion (r = 0.220, p = 0.035), knee flexion (r = 0.308, p = 0.001) and extension (r = 0.193, p = 0.040), and cutaneous sensitivity at the arch (r = 0.206, p = 0.028) were weakly to moderately correlated with CoP-RMS in the mediolateral direction.ConclusionThere is a weak-to-moderate relationship between proprioception and dynamic and static balance control, a weak relationship between cutaneous sensitivity and static balance control, and a weak-to-moderate relationship between muscle strength and dynamic balance control.     

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

BackgroundThe 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.MethodsThe 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).ResultsA high degree of agreement was found between the English version of IdFAI and IdFAI-C (intra-class correlation_2,1 = 0.995). An excellent internal consistency (Cronbach's α = 0.89), test–retest reliability (intra-class correlation_2,1 = 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.ConclusionThe 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.     

Age-related changes in proprioception of the ankle complex across the lifespan

BackgroundAnkle complex proprioceptive ability, needed in active human movement, may change from childhood to elderly adulthood; however, its development across all life stages has remained unexamined. The aim of the present study was to investigate the across-the-lifespan trend for proprioceptive ability of the ankle complex during active ankle inversion movement.MethodsThe right ankles of 118 healthy right-handed participants in 6 groups were assessed: children (6–8 years old), adolescents (13–15 years old), young adults (18–25 years old), middle-aged adults (35–50 years old), old adults (60–74 years old), and very old adults (75–90 years old). While the participants were standing, their ankle complex proprioception was measured using the Active Movement Extent Discrimination Apparatus.ResultsThere was no significant interaction between the effects of age group and gender on ankle proprioceptive acuity (F (5, 106) = 0.593, p = 0.705, η²_p = 0.027). Simple main effects analysis showed that there was a significant main effect for age group (F (5, 106) = 22.521, p < 0.001, η²_p = 0.515) but no significant main effect for gender (F (1,106) = 2.283, p = 0.134, η²_p = 0.021) between the female (0.723 ± 0.092, mean ± SD) and the male (0.712 ± 0.083) participants. The age-group factor was associated with a significant linear downward trend in scores (F (1, 106) = 10.584, p = 0.002, η²_p = 0.091) and a strong quadratic trend component (F (1,106) = 100.701, p < 0.001, η²_p = 0.480), producing an asymmetric inverted-U function.ConclusionThe test method of the Active Movement Extent Discrimination Apparatus is sensitive to age differences in ankle complex proprioception. For proprioception of the ankle complex, young adults had significantly better scores than children, adolescents, old adults, and very old adults. The middle-aged group had levels of ankle proprioceptive acuity similar to those of the young adults. The scores for males and females were not significantly different. Examination of the range of the scores in each age group highlights the possible level that ankle complex movement proprioceptive rehabilitation can reach, especially for those 75–90 years of age.     

Response to: Caution needed when interpreting muscle activity patterns during extremely low pedaling cadence

Background:One-legged pedaling is of interest to elite cyclists and clinicians.However,muscular usage in 1-legged vs.2-legged pedaling is not fully understood.Thus,the study was aimed to examine changes in leg muscle activation patterns between 2-legged and 1-legged pedaling.Methods:Fifteen healthy young recreational cyclists performed both 1-legged and 2-legged pedaling trials at about 30 Watt per leg.Surface electromyography electrodes were placed on 10 major muscles of the left leg.Linear envelope electromyography data were integrated to quantify muscle activities for each crank cycle quadrant to evaluate muscle activation changes.Results:Overall,the prescribed constant power requirements led to reduced downstroke crank torque and extension-related muscle activities(vastus lateralis,vastus medialis,and soleus)in 1-legged pedaling.Flexion-related muscle activities(biceps femoris long head,semitendinosus,lateral gastrocnemius,medial gastrocnemius,tensor fasciae latae,and tibialis anterior)in the upstroke phase increased to compensate for the absence of contralateral leg crank torque.During the upstroke,simultaneous increases were seen in the hamstrings and uni-articular knee extensors,and in the ankle plantarflexors and dorsiflexors.At the top of the crank cycle,greater hip flexor activity stabilized the pelvis.Conclusion:The observed changes in muscle activities are due to a variety of changes in mechanical aspects of the pedaling motion when pedaling with only 1 leg,including altered crank torque patterns without the contralateral leg,reduced pelvis stability,and increased knee and ankle stiffness during the upstroke.     

Student Interest in Activities in a Secondary Physical Education Curriculum: An Analysis of Student Subjectivity

Abstract

Previous studies that have examined self-efficacy–performance relationships have used novice performers. It is unclear if these findings would generalize to “experienced” performers. Based on Bandura's self-efficacy theory, this study was designed to investigate (a) the effects of false information feedback on self-efficacy beliefs and subsequent weightlifting performance, and (b) whether self-efficacy or past performance is most related to subsequent weightlifting performance. Experienced weightlifters engaged in six performance sessions, each consisting of a one-repetition-maximum bench press. Male subjects (N = 36) were randomly assigned to one of three treatment groups: accurate performance information, false information that they lifted more than their actual lift, or false information that they lifted less than their actual lift. Before each session, subjects indicated the amount of weight they were 100%, 75%, and 50% confident they could lift. Results replicated existing research findings regarding deception and performance; false positive feedback increased future bench press performance. In addition, results indicated that past weightlifting performance accounted for nearly all of the variance in subsequent performance. This finding is discussed in light of the difficulty in extending the predictions of self-efficacy theory to sport settings where athletes have gained experience by undergoing repeated training trials.     

踝关节稳定程度差异对侧跳落地缓冲模式影响的研究

目的:探讨不同踝关节稳定程度对侧跳落地缓冲时姿势稳定策略与神经肌肉控制的影响。方法:36名男性大学高水平运动员为受试者,按照踝关节不稳定程度分为12人健康组(CON)、12人隐患组(LAT)和12人不稳定组(CAI),以随机顺序执行4次单足连续侧跳动作,涉及外侧侧向跳动作(SHL)与内侧侧向跳动作(SHM)。使用VICON三维动作捕捉系统、KISTLER测力板与DELSYS无线表面肌电收集下肢生物力学参数;使用独立样本单因子方差分析(one-way ANOVA)比较各组在起跳后落地5个阶段的下肢关节运动学参数、动力学参数及肌肉激活水平。结果:1)下肢矢状面肌群激活程度与踝关节肌肉共同收缩率,对CAI组的动态姿势稳定扮演重要角色,以SHL落地的踝关节外翻动作能降低踝关节内翻扭伤风险;2)在SHL落地模式下,CAI组髋关节内收动作可能会引起踝关节内翻动作,侧跳落地的踝关节内翻角速度出现较早且快速的特征是CAI组反复扭伤的关键;3)踝关节策略主要影响压力中心(COP)参数,髋关节策略则能改变质量中心(COM);CON组侧跳的落地缓冲与姿势控制能力不及CAI稳定;SHM落地模式是踝关节内翻扭伤的高风险动作。结论:CAI组运动员即便在扭伤康复后,仍存在再次扭伤的可能,可针对踝关节活动范围与神经肌肉控制进行强化与训练,避免反复损伤。     

Tai Ji Quan as an exercise modality to prevent and manage cardiovascular disease: A review

BackgroundRegular exercise is beneficial for adults with cardiovascular disease (CVD) and CVD risk factors. Tai Ji Quan is popular among older adults and may offer additional exercise options. The present article aims to review the scientific literature published within the past decade on Tai Ji Quan as an exercise modality to prevent and manage CVD.MethodsAn electronic literature search of four databases (PubMed, CINAHL, PsycINFO, and AMED) was conducted from April 2003 through March 2013. Studies that examined Tai Ji Quan, were published in English, and specified a target study population of participants with a known CVD condition (e.g., coronary artery disease, chronic heart failure, or stroke) or studies conducted among participants with a CVD risk factor (e.g., hypertension, dyslipidemia, or impaired glucose metabolism) were included.ResultsA total of 20 studies met the inclusion criteria: 11 randomized clinical trials, seven quasi-experimental studies and two cross-sectional studies. The effect of Tai Ji Quan was examined on more than 20 different study variables among persons with coronary artery disease (n = 5 studies), chronic heart failure (n = 5 studies), stroke (n = 4 studies), and CVD risk factors (n = 6 studies). These studies were conducted primarily in Asia (n = 9, 45%) or the United States (n = 8, 40%). Overall, participants enrolled in Tai Ji Quan had better outcomes, though mixed results were reported.ConclusionCollectively, these studies indicate that Tai Ji Quan is a safe form of exercise to prevent and manage CVD. Further research is needed with more rigorous study designs, larger sample sizes, adequate Tai Ji Quan exercise doses, and carefully chosen outcome measures that assess the mechanisms as well as the effects of Tai Ji Quan, before widespread recommendations can be made.