Altered visual focus on sensorimotor control in people with chronic ankle instability

The purpose of this investigation was to examine the effects of the combination of chronic ankle instability (CAI) and altered visual focus on strategies for dynamic stability during a drop-jump task. Nineteen participants with self-reported CAI and 19 healthy participants performed a drop-jump task in looking-up and looking-down conditions. For the looking-up condition, participants looked up and read a random number that flashed on a computer monitor. For the looking-down condition, participants focused their vision on the force plate. Sagittal- and frontal-plane kinematics in the hip, knee and ankle were calculated at the time points of 100 ms pre-initial foot contact to ground and at IC. The resultant vector time to stabilisation was calculated with ground reaction force data. The CAI group demonstrated less hip flexion at the point of 100 ms pre-initial contact (P < 0.01), and less hip flexion (P = 0.03) and knee flexion at initial contact (P = 0.047) compared to controls. No differences in kinematics or dynamic stability were observed in either looking-up or looking-down conditions (P > 0.05). Altered visual focus did not influence movement patterns during the drop-jump task, but the presence of CAI did. The current data suggests that centrally mediated changes associated with CAI may lead to global alterations in the sensorimotor control.     

Lower extremity joint coupling variability during gait in young adults with and without chronic ankle instability

Chronic ankle instability (CAI) is a condition resulting from a lateral ankle sprain. Shank-rearfoot joint-coupling variability differences have been found in CAI patients; however, joint-coupling variability (VCV) of the ankle and proximal joints has not been explored. Our purpose was to analyse VCV in adults with and without CAI during gait. Four joint-coupling pairs were analysed: knee sagittal-ankle sagittal, knee sagittal-ankle frontal, hip frontal-ankle sagittal and hip frontal-ankle frontal. Twenty-seven adults participated (CAI:n = 13, Control:n = 14). Lower extremity kinematics were collected during walking (4.83 km/h) and jogging (9.66 km/h). Vector-coding was used to assess the stride-to-stride variability of four coupling pairs. During walking, CAI patients exhibited higher VCV than healthy controls for knee sagittal-ankle frontal in latter parts of stance thru mid-swing. When jogging, CAI patients demonstrated lower VCV with specific differences occurring across various intervals of gait. The increased knee sagittal-ankle frontal VCV in CAI patients during walking may indicate an adaptation to deal with the previously identified decrease in variability in transverse plane shank and frontal plane rearfoot coupling during walking; while the decreased ankle-knee and ankle-hip VCV identified in CAI patients during jogging may represent a more rigid, less adaptable sensorimotor system ambulating at a faster speed.     

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.     

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.     

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.     

Knee joint coordination during single-leg landing in different directions

ABSTRACT

Knee joint coordination during jump landing in different directions is an important consideration for injury prevention. The aim of the current study was to investigate knee and hip kinematics on the non-dominant and dominant limbs during landing. A total of 19 female volleyball athletes performed single-leg jump-landing tests in four directions; forward (0°), diagonal (30° and 60°) and lateral (90°) directions. Kinematic and ground reaction force data were collected using a 10-camera Vicon system and an AMTI force plate. Knee and hip joint angles, and knee angular velocities were calculated using a lower extremity model in Visual3D. A two factor repeated measures ANOVA was performed to explore limb dominance and jump direction. Significant differences were seen between the jump directions for; angular velocity at initial contact (p < 0.001), angular velocity at peak vertical ground reaction force (p < 0.001), and knee flexion excursion (p = 0.016). Knee coordination was observed to be poorer in the early phase of velocity-angle plot during landing in lateral direction compared to forward and diagonal directions. The non-dominant limb seemed to have better coordination than the dominant limb during multi-direction jump landing. Therefore, dominant limbs appear to be at a higher injury risk than non-dominant limbs.     

Increased dietary carbohydrate and endurance during single-leg cycling using a limb with normal muscle glycogen concentration

The purpose of this study was to test the hypothesis that increased availability of blood-borne glucose would improve endurance after carbohydrate loading. A single-leg exercise model was employed, taking advantage of the fact that supercompensation of muscle glycogen occurs only in a previously exercised limb. Endurance time to exhaustion at 70% of maximal oxygen uptake (VO2 max) was determined for 11 males and three females who were then allocated to a control group or a high-carbohydrate (CHO) group. For 3 days following Test 1 the control group maintained a prescribed normal diet whilst the CHO group increased the proportion of energy derived from carbohydrate (62.1 +/- 4.3% cf. 43.9 +/- 2.0%, P less than 0.01). The endurance test was then repeated using the leg that was inactive during Test 1. Endurance time was increased on Test 2 (123.7 +/- 43.2 min cf. 98.5 +/- 21.9 min, P less than 0.05 one-tailed test) for the CHO group but not for the control group (101.8 +/- 21.7 min cf. 107.5 +/- 9.1 min, NS). There was no indication of enhanced carbohydrate metabolism during Test 2 for the CHO group but mean heart rate was lower during Test 2 than during Test 1 (145 +/- 14 beat min-1 cf. 152 +/- 12 beat min-1, P less than 0.05). These results suggest that the prior consumption of a high-carbohydrate diet improves endurance during high-intensity cycling with a limb with normal muscle glycogen concentration.     

Chronic ankle instability is associated with proprioception deficits: A systematic review and meta-analysis

Background:Acute ankle injury causes damage to joint mechanoreceptors and deafferentation and contributes to proprioception deficits in patients with chronic ankle instability(CAI).We aimed to explore whether deficits of proprioception,including kinesthesia and joint position sense(JPS),exist in patients with CAI when compared with the uninjured contralateral side and healthy people.We hypothesized that proprioception deficits did exist in patients with CAI and that the deficits varied by test methodologies.Methods:The study was a systematic review and meta-analysis.We identified studies that compared kinesthesia or JPS in patients with CAI with the uninjured contralateral side or with healthy controls.Meta-analyses were conducted for the studies with similar test procedures,and narrative syntheses were undertaken for the rest.Results:A total of 7731 studies were identified,of which 30 were included for review.A total of 21 studies were eligible for meta-analysis.Compared with the contralateral side,patients with CAI had ankle kinesthesia deficits in inversion and plantarflexion,with a standardized mean difference(SMD)of 0.41 and 0.92,respectively,and active and passive JPS deficits in inversion(SMD=0.92 and 0.72,respectively).Compared with healthy people,patients with CAI had ankle kinesthesia deficits in inversion and eversion(SMD=0.64 and 0.76,respectively),and active JPS deficits in inversion and eversion(SMD=1.00 and 4.82,respectively).Proprioception deficits in the knee and shoulder of patients with CAI were not statistically significant.Conclusion:Proprioception,including both kinesthesia and JPS,of the injured ankle of patients with CAI was impaired,compared with the uninjured contralateral limbs and healthy people.Proprioception varied depending on different movement directions and test methodologies.The use of more detailed measurements of proprioception and interventions for restoring the deficits are recommended in the clinical management of CAI.     

Unpredictable shoe midsole perturbations provide an instability stimulus to train ankle posture and motion during forward and lateral gym lunges

ABSTRACT

Unstable footwear may enhance training effects to the lower-limb musculature and sensorimotor system during dynamic gym movements. This study compared the instability of an unstable shoe with irregular midsole deformations (IM) and a control shoe (CS) during forward and lateral lunges. Seventeen female gym class participants completed two sets of ten forward and lateral lunges in CS and IM. Ground reaction forces, lower-limb kinematics and ankle muscle activations were recorded. Variables around initial ground contact, toe-off, descending and ascending lunge phases were compared statistically (p < .05). Responses to IM compared to CS were similar across lunge directions. The IM induced instability by increasing the vertical loading rate (p < .001, p = .009) and variability of frontal ankle motion during descending (p = .001, p < .001) and ascending phases (p = .150, p = .003), in forward and lateral lunges, respectively. At initial ground contact, ankle adjustments enhanced postural stability in IM. Across muscles, there were no activation increases, although results indicate peroneus longus activations increased in IM during the ascending phase. As expected, IM provided a more demanding training stimulus during lunge exercises and has potential to reduce ankle injuries by training ankle positioning for unpredictable instability.     

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.     

Estimating physical activity in youth using an ankle accelerometer

This study developed and validated a vector magnitude (VM) two-regression model (2RM) for use with an ankle-worn ActiGraph accelerometer. For model development, 181 youth (mean ± SD; age, 12.0 ± 1.5 yr) completed 30 min of supine rest and 2–7 structured activities. For cross-validation, 42 youth (age, 12.6 ± 0.8 yr) completed approximately 2 hr of unstructured physical activity (PA). PA data were collected using an ActiGraph accelerometer, (non-dominant ankle) and the VM was expressed as counts/5-s. Measured energy expenditure (Cosmed K4b²) was converted to youth METs (MET_y; activity VO₂ divided by resting VO₂). A coefficient of variation (CV) was calculated for each activity to distinguish continuous walking/running from intermittent activity. The ankle VM sedentary behavior threshold was ≤10 counts/5-s, and a CV≤15 counts/5-s was used to identify walking/running. The ankle VM2RM was within 0.42 MET_y of measured MET_y during the unstructured PA (P > 0.05). The ankle VM2RM was within 5.7 min of measured time spent in sedentary, LPA, MPA, and VPA (P > 0.05). Compared to the K4b², the ankle VM2RM provided similar estimates to measured values during unstructured play and provides a feasible wear location for future studies.     

Influence of single-leg training on muscle metabolism and endurance during exercise with the trained limb and the untrained limb

We have previously shown that single-leg training results in improved endurance for exercise with the untrained leg (UTL) as well as for exercise with the trained leg (TL). The purpose of this study was to see whether the improved endurance of the untrained leg could be explained on the basis of changes in muscle metabolism. Exercise time to exhaustion at 80% of maximum oxygen uptake (VO2 max) was determined for each leg separately, pre- and post-training. Muscle metabolite concentrations were measured pre- and post-training in biopsy samples obtained immediately before this endurance test and at the pre-training point of exhaustion (END1). After six weeks of single-leg training endurance time was increased for both the UTL and the TL (UTL 34.0 +/- 16.4 min vs 97.9 +/- 26.3 min, P less than 0.01; TL 28.3 +/- 10.1 min vs 169.0 +/- 32.6 min, P less than 0.01). No changes in muscle metabolite concentrations were found in resting muscle. Training increased muscle ATP (P less than 0.05) and glycogen (P less than 0.01) concentrations and decreased muscle lactate concentration (P less than 0.05) in the TL at END1. No significant changes in muscle metabolite concentrations were found for the UTL. The improved endurance of the contralateral limb after single-leg training could not be explained on the basis of changes in muscle metabolism.     

Kinematic and kinetic differences in the execution of vertical jumps between people with good and poor ankle joint dorsiflexion

Abstract

The aim of the present study was to investigate the kinematic and kinetic differences in the execution of vertical jumps between individuals with good and poor ankle dorsiflexion. Fifteen physical education students were assigned to the flexible group (FG), while another 15 were assigned to the inflexible group (IFG). The two groups executed countermovement jumps (CMJ) and drop jumps from a 60 cm height (DJ60). For the CMJ, the FG jumped higher (32.0 ± 4.0 cm vs. 30.2 ± 4.9 cm, P = 0.27) and used a greater range of motion in all leg joints. The IFG jumpers raised their heels off the ground and had a greater horizontal distance between the centre of mass of the trunk and the centre of the hip joint (L_CMh 25.6 ± 3.4 cm vs. 30.9 ± 4.3 cm, P < 0.001). In the DJ60 the FG jumped higher (22.4 ± 5.9 cm vs. 19.5 ± 4.6 cm, P = 0.14) with a greater vertical shift of the body centre of mass (BCM) (S = 0.45 ± 0.11 cm vs. 0.36 ± 0.05 cm, P < 0.01) and better joint coordination. The IFG jumpers changed the position of their trunk and heels depending on the jump type. Trainers should reconsider the technical issues of vertical jumps according to the flexibility of the ankle joint.     

Is high soleus muscle activity during the stance phase of the running cycle a potential risk factor for the development of medial tibial stress syndrome? A prospective study

ABSTRACT

To assess the impact of lower-leg muscle activity during the stance phase of running on the development of medial tibial stress syndrome (MTSS), in 123 healthy participants (18.2 ± 0.8 years), dynamic and static foot posture, and soleus and tibialis anterior muscle activity during the stance phase of running were measured before a 17-week track- and field-course. After the course, MTSS was identified in 20.5% of the participants. MTSS participants had a higher body mass (ES = 1.13), body mass index (BMI) (ES = 1.31), lower previous vigorous physical activity level (ES = 0.84) and VO_2max (ES = 0.61), greater dynamic foot pronation (ES = 0.66), higher soleus peak EMG amplitude during the absorption (ES = 0.60) and propulsion phases (ES = 0.56) of running, and a history of MTSS (OR = 6.38) (p < 0.05). Stepwise logistic regression showed BMI, dynamic foot index, soleus peak EMG amplitude during propulsion, MTSS history and previous vigorous physical activity were predictors of MTSS. The model predicted 96.6% of the healthy participants and 56.5% of the MTSS participants and correctly classified 88.4% of overall cases. Coaches and sports-medicine professionals that screen for injury risk should consider adopting a comprehensive evaluation that includes these parameters.     

Association between knee-to-hip flexion ratio during single-leg vertical landings,and strength and range of motion in professional soccer players

Abstract

The aim of this study was to test the correlation between knee-to-hip flexion ratio during a single leg landing task and hip and knee strength, and ankle range of motion. Twenty-four male participants from a professional soccer team performed a continuous single leg jump-landing test during 10s, while lower limb kinematics data were collected using a motion analysis system. After biomechanical testing, maximal isometric hip (abduction, extension, external rotation), knee extension and flexion strength were measured. Maximum ankle dorsiflexion range of motion was assessed statically using the weight bearing lunge test. Pearson correlation coefficients were calculated to determine the associations between the predictor variables (knee and hip strength, and ankle ROM) and the main outcome measure (knee-to-hip flexion ratio). Correlation between knee-to-hip flexion ratio and hip abductors strength was significant (r = ?0.47; p = 0.019). No other significant correlations were observed among the variables (p > 0.05). These results demonstrated that a lower hip abductors strength in male soccer players was correlated with a high knee-to-hip flexion ratio during landing from a single leg jump, potentially increasing knee overload by decreasing energy absorption at the hip. The results provide a novel proposal for the functioning of hip muscles to control knee overload.     

The BASES expert statement on exercise therapy for people with chronic kidney disease

Chronic kidney disease (CKD) is becoming a serious health problem throughout the world and is one of the most potent known risk factors for cardiovascular disease, which is the leading cause of morbidity and mortality in this patient population. Physical inactivity has emerged as a significant and independent risk factor for accelerated deterioration of kidney function, physical function, cardiovascular function and quality of life in people in all stages of CKD. CKD specific research evidence, combined with the strong evidence on the multiple health benefits of regular and adequate amounts of PA in other cardiometabolic conditions, has resulted in physical inactivity being identified by national and international CKD clinical practice guidelines as one of the multiple risk factors that require simultaneous and early intervention for optimum prevention/management of CKD. Despite this realisation, physical inactivity is not systematically addressed by renal care teams. The purpose of this expert statement is therefore to inform exercise and renal care specialists about the clinical value of exercise therapy in CKD, as well as to provide some practical recommendations on how to more effectively translate the existing evidence into effective clinical practice.     

Ankle taping can reduce external ankle joint moments during drop landings on a tilted surface

Ankle taping is commonly used to prevent ankle sprains. However, kinematic assessments investigating the biomechanical effects of ankle taping have provided inconclusive results. This study aimed to determine the effect of ankle taping on the external ankle joint moments during a drop landing on a tilted surface at 25°. Twenty-five participants performed landings on a tilted force platform that caused ankle inversion with and without ankle taping. Landing kinematics were captured using a motion capture system. External ankle inversion moment, the angular impulse due to the medio-lateral and vertical components of ground reaction force (GRF) and their moment arm lengths about the ankle joint were analysed. The foot plantar inclination relative to the ground was assessed. In the taping condition, the foot plantar inclination and ankle inversion angular impulse were reduced significantly compared to that of the control. The only component of the external inversion moment to change significantly in the taped condition was a shortened medio-lateral GRF moment arm length. It can be assumed that the ankle taping altered the foot plantar inclination relative to the ground, thereby shortening the moment arm of medio-lateral GRF that resulted in the reduced ankle inversion angular impulse.     

Coping by individuals with physical disabilities with perceived challenge in physical activity: are people consistent?

This study examined coping and affective experience to perceived challenge in physical activity settings in 30 individuals with physical disabilities in three separate situations over 6 months. On every occasion, each individual was asked to report the most challenging physical activity of the preceding week and indicate how he or she coped with the challenge and what affective states were experienced. Coping was measured using a modification of Carver, Scheier, and Weintraub's (1989) COPE inventory. Self-reported mood was assessed using the Positive Affect Negative Affect Schedule (Watson, Clark, & Tellegen, 1988). The data indicated that perceived challenge was characterized by high levels of positive affect. Generalizability theory, used to determine the relative stability of coping strategies, indicated that individuals with physical disabilities did not consistently use the same coping skill strategies across settings.