Copers adopt an altered dynamic postural control compared to individuals with chronic ankle instability and controls in unanticipated single-leg landing

Directional deficits in reactive postural control during perturbations among groups of chronic ankle instability, ankle sprain coper, and healthy control

Unanticipated postural control measures may better identify mechanisms of ankle sprains in real-life situations. The purpose of this study was to identify directional deficits in reactive postural control during unanticipated horizontal perturbations among groups of chronic ankle instability (CAI), ankle sprain coper, and healthy control. Sixty-eight volunteers (24 CAI patients, 23 ankle sprain copers, and 21 healthy controls) participated in this study. The participants performed a single-leg stance with unanticipated horizontal perturbations in four random directions of anterior, posterior, medial, and lateral. Anterior-posterior time to stabilization (APTTS) and medial-lateral time to stabilization (MLTTS) were calculated as an indicator of reactive postural control during horizontal perturbations. A significant interaction effect of the group x perturbation directions (3 × 4) was found. Both CAI and ankle sprain coper groups showed longer APTTS and MLTTS during medial and lateral horizontal perturbations compared to the healthy control group. However, no difference was found in APTTS and MLTTS during anterior and posterior horizontal perturbations between three groups. Directional deficits in reactive postural control during medial and lateral perturbations could result from sensorimotor dysfunction as consequences of lateral ankle sprains in the CAI and ankle sprain groups.

The Relationship Between the Kinetic Parameters, Electromyography Activity, and Kinesiophobia Among Copers, Chronic Ankle Instability, and Healthy Subjects During Gait Initiation: A Cross-Sectional Study

CONTEXT

Following a lateral ankle sprain, chronic ankle instability (CAI) subjects show recurrent episodes of giving way, while copers do not exhibit giving way and overcome the challenging condition of postural control. During gait initiation (GI), individuals with CAI reveal shorter center of pressure (COP) displacement and earlier muscle activity compared with healthy controls. Copers have not been previously compared with healthy controls and individuals with CAI during GI.

DESIGN

The study design was cross-sectional.

METHOD

Sixty participants (20 CAI, 20 copers, and 20 healthy controls) with a right (dominant) limb injury participated in the study based on inclusion and exclusion criteria. The short form of the Tampa Scale of Kinesiophobia was filled out. Participants performed GI with the nonaffected leg on the force plate that was synchronized with Electromyography Megawin for 2 strides. GI was divided into 3 phases based on COP excursion (S1, S2, and S3). Onset time and electromyography activity of both soleus and tibialis anterior muscles were analyzed along with maximum and mean excursion and velocity of COP excursion in the anterior-posterior and medial-lateral directions and the total phases of GI.

RESULTS

The results indicated that the copers had a significantly higher peak of COP excursion in the medial-lateral direction during S2 (P = .029), S3 (P = .018), and total phases (P = .018) of GI compared with the individuals with CAI. Additionally, individuals with CAI showed earlier activation of the right soleus compared with healthy controls (P = .022). There was a significant difference in short form of the Tampa Scale of Kinesiophobia scores between individuals with CAI and other groups (P < .001).

CONCLUSION

The findings demonstrated that individuals with CAI had earlier soleus activation and supraspinal alteration compared with controls. Copers who had lower Tampa Scale of Kinesiophobia scores exhibited an increased peak of COP excursion in the medial-lateral direction during GI compared with individuals with CAI.

Decreased proprioception is associated with inferior postural control during unplanned landing in individuals with chronic ankle instability

Poor postural control during jump landing may increase ankle sprain incidences among people with chronic ankle instability (CAI). The effects of anticipation on it and its relationship with proprioception need further examination. Fifteen participants with CAI and 15 healthy controls were recruited to perform single-leg jump landings when knowing the landing side before (planned) or after (unplanned) take-off respectively, along with a step-down proprioception test differentiating four inclination platforms (inverted 12°, 14°, 16° and 18°). Ground reaction force data (peak force, loading rate and time of stabilisation) during landings and proprioception scores were collected and analysed. The CAI group exhibited a higher loading rate (59.6 ± 7.6 vs 49.4 ± 6.7 N/kg*seconds, p = 0.011) and longer medial-lateral time to stabilisation (4.82 ± 0.69 vs 4.11 ± 0.47 seconds, p = 0.023) compared to the control group during an unplanned landing. Furthermore, the above variables were negatively correlated with the step-down proprioception score only in the unplanned condition but not in the planned condition. CAI participants had inferior medial-lateral time-to-stabilisation and loading attenuation during unplanned jump landing than healthy controls, which were associated with decreased proprioception, highlighting the importance of addressing proprioception to improve balance control during unpredictable landing situations.

The Influence of Ankle Mobility and Foot Stability on Jumping Ability and Landing Mechanics: A Cross-Sectional Study

Practicing physical activities or sports that involve frequent jumping and landing can strain the muscles and joints of the lower limbs, especially in those who do not have adequate physical preparation. The objective of this study was to (a) determine the correlation between ankle range of motion (ROM) and landing stability following jumps; (b) assess the association between the jump height in a counter-movement jump (CMJ) test and ankle ROM; and (c) examine the connection between stabilometry during specific jumps movements present in many sports and in ankle stabilization. Sixty-two healthy amateur volleyball players participated in the study (age: thirty-seven females and twenty-five males; age (years): 16.5 ± 4.25; height (cm): 166 ± 11.4; weight (Kg): 61.6 ± 13.7). Participants were recruited for the study in collaboration with student sports associations. The evaluations encompassed the measurement of ankle joint mobility for both lower limbs using an inertial sensor, a static baropodometric and stabilometric analysis using a pressure platform, and the CMJ test using the Microgate system. After the assessments, participants performed a "specific jump landing task". Significant correlations were found between foot range of motion (ROM) and counter-movement jump (CMJ) performance. Specifically, the ROM of the right foot had a strong correlation with the CMJ (r = 0.81, p < 0.001), while the left foot ROM showed a moderate correlation (r = 0.46, p < 0.001). The specific jump task revealed substantial changes in stabilometry parameters, particularly during forward hops compared to lateral jumps. Dorsiflexion ROM significantly impacts jumping ability. Evaluating landing patterns and stabilometry during targeted activities can help optimize training, improve dynamic balance, and reduce ankle injury risk.

Ankle inversion proprioception measured during stair descent can identify chronic ankle instability

BACKGROUND

Individuals with chronic ankle instability (CAI) may experience recurrent ankle sprains and symptoms during daily activities such as stair descent, where the associated proprioceptive deficit is largely unevaluated.

OBJECTIVES

To evaluate the reliability and validity of an ankle inversion discrimination apparatus for stair descent, and examine whether proprioceptive scores from this apparatus are associated with patient-reported symptoms.

DESIGN

Cross-sectional study.

METHOD

Sixty-six participants volunteered in this study. The ankle inversion discrimination apparatus was purpose-built to assess ankle proprioception across four positions of ankle inversion (10°, 12°, 14°, and 16°) during stair descent. The Area Under the Receiver Operating Curve (AUC) was employed as the ankle proprioceptive discrimination score.

RESULTS

Test-retest reliability ICC (3,1) for the whole group was 0.825, with 0.747 for the non-CAI group (95%CI = 0.331-0.920) and 0.701 for CAI (95%CI = 0.242-0.904). The CAI group performed at a significantly lower level than non-CAI on the ankle inversion discrimination apparatus for stair descent assessment (0.769 ± 0.034 vs. 0.830 ± 0.035, F = 33.786, p < 0.001). CAIT scores were strongly and significantly correlated with scores from this apparatus (Spearman's rho = 0.730, p < 0.001).

CONCLUSIONS

The ankle inversion discrimination apparatus for stair descent is reliable and valid for assessing task-specific ankle proprioceptive impairments in CAI. The strong and significant relationship found between ankle proprioception during stair descent and the severity of CAI suggests that rehabilitation programs focusing on deficits in ankle inversion proprioception during stair descent may improve self-reported instability in CAI.

Exploring the interplay between ankle muscle strength, postural control, and pain intensity in chronic ankle instability: A comprehensive analysis

Background

Chronic Ankle Instability (CAI) is a common musculoskeletal condition characterized by recurring ankle sprains and impaired postural control (PC). Understanding the relationship between ankle muscle strength, PC, and the role of pain is essential for effective management.

Objectives

This prospective cross sectional study aimed to 1. Compare ankle isometric muscle strength (IMS) and PC between CAI and asymptomatic sides. 2. Assess the correlations between ankle IMS and PC and explore the potential mediating effect of pain in individuals with CAI.

Methods

A total of 44 individuals with CAI, were enrolled in the study. Ankle IMS (dorsiflexors, plantar flexors, invertors, and evertors) was measured using a dynamometer, while PC was evaluated using sway parameters (anterior-posterior and medial-lateral sway, ellipse area). Pain levels were reported using a Visual Analog Scale.

Results

The CAI ankles exhibited significantly lower ankle IMS in all muscle groups compared to the asymptomatic ankles (p < 0.001). Additionally, the CAI side showed increased postural sway and a larger ellipse area (p < 0.001), indicating reduced PC. Negative correlations were observed between ankle IMS and PC parameters on the CAI side, with dorsiflexor strength showing correlations ranging from -0.423 to -0.387, plantar flexor strength ranging from -0.423 to -0.371, invertor strength ranging from -0.412 to -0.238, and evertor strength ranging from -0.451 to -0.365 (p < 0.001). Mediation analysis revealed that pain played a significant mediating role in connecting ankle IMS and PC parameters among individuals with CAI, with statistical significance (p < 0.05).

Conclusions

Individuals with CAI exhibit weaker ankle IMS and diminished PC in comparison to their healthy side. Moreover, pain was identified as a mediator in the relationship between ankle IMS and PC in CAI. These findings underscore the importance of addressing both ankle IMS and pain in the rehabilitation and management of CAI.

Using clinician-oriented and laboratory-oriented assessments to study dynamic stability of individuals with chronic ankle instability

To compare the dynamic stability of lower extremities between Copers and individuals with chronic ankle instability (CAI) using clinician-oriented assessments (Y-balance test, YBT) and laboratory-oriented assessments (time to stabilization, TTS). 90 participants (Copers, 45; CAIs, 45) were recruited and measured by YBT and TTS to evaluate dynamic stability. The difference of dynamic stability between Copers and CAIs was examined using a two-factor MANOVA. Only for females in anterior direction, YBT scores for the AS side of Copers were significantly higher than that of CAIs. For males, the TTS of CAIs was significantly shorter than that of Copers in the anterior, lateral, and medial direction separately. For females, the TTS of CAIs is also significantly shorter than that of Copers in the anterior, lateral, and medial direction separately. There are opposite results when evaluating the dynamic stability difference between Copers and CAIs using YBT and TTS.

Characteristics of muscle synergy and anticipatory synergy adjustments strategy when cutting in different angles

BACKGROUND

Cutting is a quick change of direction that challenges body balance and stability. As the cut-angle increases, the elite athlete can achieve higher performance by pre-adjusting the posture of the lower limb joints. However, it is unclear how the cut-angle affects the neuromuscular control of cutting and the step before cutting, which is essential for daily training and preventing injury in large-angle cutting.

RESEARCH QUESTION

The purpose of this study was to determine how neuromuscular control strategies change under different angles for cutting and the step before cutting METHODS: Non-negative matrix factorisation and K-means clustering were used to extract muscle synergy in the trunk and lower limbs of 12 athletes when cutting at different angles. Uncontrolled manifold analysis was used to clarify whether the muscle synergy fluctuations in the step before cutting were beneficial in stabilising the COP during the cutting.

RESULTS

This study found that the angle did not affect the number of muscle synergies either in the cutting or the step before the cutting. As the angle increases, the activation timing of synergy module 2 during cutting moves forward and is tightly integrated with module 1. The combined synergy at 90° accounted for the largest proportion of either cutting or the step before cutting and had a lower synergy index.

SIGNIFICANCE

Muscle synergy can respond to large-angle cutting through flexible combinations. The muscle synergy for 90° cutting is less regular and has a lower degree of anticipatory synergy adjustments, which may result in poorer postural stability and an increased risk of lower limb joint injury during cutting.

Regional plantar forces and surface geometry variations of a chronic ankle instability population described by statistical shape modelling

BACKGROUND

Understanding detailed foot morphology as well as regional plantar forces could provide insight into foot function and provide recommendation for footwear design for chronic ankle instability (CAI) people.

RESEARCH QUESTION

This study presented 3-dimensional statistical shape models of feet from three different populations including CAI, copers and healthy individuals, with regional plantar forces also acquired.

METHODS

Sixty-six males (22 participants per group) were included in this study to capture 3-dimensional foot shapes under a standing condition and regional plantar forces during a cutting maneuver. Principal component analysis was performed to generate a mean foot shape of each group as well as modes of variations. A generalized procrustes analysis was used to achieve rapid registration of mean shapes. Besides, regional plantar forces and contact duration among these three populations were compared.

RESULTS

For 3-dimensional foot shapes, although no significant differences of the average distance between each mode and mean shape were found among three populations, there were subtle variations in mean shapes. The CAI population presented a more bulging of the lateral malleolus; copers were characterized by the flexion of the lesser toes, a more bulging of the medial foot in the sagittal plane; and healthy individuals showed a greater heel width and a more bulging of the heel in the sagittal plane. In terms of plantar forces, healthy individuals had significantly greater summated plantar forces and greater plantar forces in the lateral heel area during the early contact phase compared to copers and CAI participants.

SIGNIFICANCE

Overall, this study suggested that repetitive ankle sprains may lead to the bulging of the lateral malleolus. Further, CAI and copers seem to stabilize the ankle joint by medially shifting the center of pressure compared to healthy individuals under the static and less challenging dynamic conditions.

The Influence of Experience on Neuromuscular Control of the Body When Cutting at Different Angles

Cutting is an offensive technique commonly used in football and basketball to pass the opponent's defence by changing direction quickly in running. This paper aims to investigate the effect of experience and angle on the neuromuscular control strategies of the trunk and lower limbs during cutting. Non-negative matrix factorisation and K-means were used to extract muscle synergies (muscles that are activated in parallel) of 12 subjects with cut experience and 9 subjects without experience based on the sEMG signal collected from cutting at three cut angles (45°, 90°, and 135°), which was also mapped into the spinal motor output. Uncontrolled manifold analysis was used to establish the relationship between muscle synergies and COP. This study found that experienced subjects tended to use the lower limb muscles rather than the postural muscles as stabiliser muscles compared to novices. Experienced subjects can recruit an additional set of muscle synergy to cope with large-angle cuts. In addition, experienced subjects can activate the second muscle synergy, involving the hip and ankle stabilisation muscles, in advance to improve postural stability when cutting in large-angle. Synergy index of experienced subjects dropped rapidly before the quick stop and was relatively high during the change of direction. These results suggest that experience can modify the postural stabilisation mechanisms during cutting, and prompt the lower limb muscle synergy to produce anticipatory adjustment to improve postural stability in the anterior-posterior and internal-external directions.

The impact of unexpected platform perturbation on ankle proprioception ability in static and dynamic starting positions

AIMS

To examine the relationship between ankle proprioception and the ability to maintain balance with increased magnitudes of unexpected perturbations; and to compare the participants' ability to maintain balance following perturbations when starting from static and dynamic positions.

METHODS

Sixty physical education students (average 24.6 years) were tested for proprioception ability (AUC scores) and balance challenges presented on a perturbation treadmill. The degree at which participants lost postural balance was recorded in seven starting positions: standing-eyes-open (SO), standing-eyes-closed (SC), tandem-dominant (TD), tandem non-dominant, (TND) single-leg lateral side perturbation (SLP), single-leg medial side perturbation (SMP), and walking. Perturbation scores were analysed divided by tertiles. Multidimensional Unfolding SPSS Statistics 25 (PREFSCAL) was used to examine the relationships between data sets.

RESULTS

AUC scores of both dominant and non-dominant legs were significantly correlated with SO (r = 0.316; r = 0.445), SC (r = 0.364; r = 0.413), TD (r = 0.346; r = 0.308), and walking (r = 0.265; r = 0.439), respectively. In the dominant-leg, AUC scores of individuals with below-median SO scores were significantly worse compared to those with median SO scores (p = .046). In the non-dominant leg, individuals with above-median SC had significantly better AUC scores compared to those with lower-than-median SC (p = .008). Those with median and above-median SO and walking achieved better AUC scores than those with below-median (SO: p = .049, p = .004; walking: p = .016, p < .001, respectively). In dimension I, the SLP and SMP were located opposite one another; in dimension II, the TD and TND were located at the upper side, whereas SC, SO and walking were at the lowest side.

CONCLUSIONS

AUC scores were significantly correlated with the level at which postural balance was lost, whereby the better the proprioception ability, the better the ability to maintain balance. As such, the ability to maintain balance is harder in tandem positions than in standing and walking positions. This ability differed when perturbations were to the lateral or medial sides.

Coper has altered foot joint coordination pattern compared to individuals with chronic ankle instability during running

BACKGROUND

There is limited information regarding the cause for the different etiologies in individuals with initial lateral ankle sprains (LAS) who have chronic ankle instability (CAI) and no recurrence or instability for > 12 months (copers) following initial LAS. Assessing the movement patterns of copers and individuals with CAI and LAS recurrence is essential for identifying the mechanical factors that affect patient outcomes.

RESEARCH QUESTION

Does coordination and coordination variability of rearfoot, midfoot, and forefoot present a potentially causative pattern for CAI or coper?

METHODS

This cross-sectional study included 35 males who were divided into the CAI (n = 13), coper (n = 12), and control group (n = 10). Participants performed rearfoot strike running on the treadmill at a fixed speed of 3.5 m/s. The coupling angle between the rearfoot, midfoot, and forefoot, representing intersegmental coordination, was calculated using the modified vector coding technique and categorized into four coordination patterns. The coupling angle standard deviation served represented coordination variability during the stance phase.

RESULTS

One control participant and one CAI participant were excluded, and final analyses were performed on the CAI (n = 12), coper (n = 12), and control (n = 9) groups. During late stance, the coper group showed a significantly greater proportion of in-phase with distal dominancy (p = 0.02, effect size=0.17) and a significantly lower proportion of in-phase with proximal dominancy (p = 0.05, effect size=0.17), than the CAI group. During the early stance, the coper group showed a significantly lower proportion of anti-phase with distal dominancy than the CAI group (p = 0.03, effect size=0.18). There were no differences in intra-foot variability among the groups.

SIGNIFICANCE

The intra-foot coordination observed in the coper group suggests that this movement pattern may reduce the risk of ankle sprains.