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

Effects of transcranial direct current stimulation combined with Bosu ball training on the injury potential during drop landing in people with chronic ankle instability

Purpose

To investigate the effects of transcranial direct current stimulation (tDCS) combined with Bosu ball training on the injury potential during drop landing in people with chronic ankle instability (CAI).

Methods

A total of 40 participants with CAI were recruited and randomly divided into the tDCS + Bosu and Bosu groups. The people in the tDCS + Bosu group received intervention of tDCS combined with Bosu ball training, and those in the Bosu group received intervention of sham tDCS and Bosu ball training, for 6 weeks with three 20-min sessions per week. Before (week0) and after (week7) the intervention, all participants drop-landed on a trap-door device, with their affected limbs on a moveable platform, which could be flipped 24° inward and 15° forward to mimic an ankle inversion condition. The kinematic data were captured using a twelve-camera motion capture system. Two-way ANOVA with repeated measures was used to analyze data.

Results

Significant group-by-intervention interactions were detected in the peak ankle inversion angular velocity (p = 0.047, η2 p = 0.118), the time to peak ankle inversion (p = 0.030, η2 p = 0.139), and the plantarflexion angle at the moment of peak ankle inversion (p = 0.014, η2 p = 0.173). Post hoc comparisons showed that compared with week0, the peak ankle inversion angular velocity and the plantarflexion angle at the moment of peak ankle inversion were reduced, the time to peak ankle inversion was advanced in both groups at week7, and the changes were greater in the tDCS + Bosu group compared to the Bosu group. And, a significant intervention main effect was detected in the peak ankle inversion angle in the two groups (p < 0.001, η2 p = 0.337).

Conclusion

Compared with the Bosu ball training, the tDCS combined with Bosu ball training was more effective in reducing the injury potential during drop landing in people with CAI.

The relationship between ankle landing kinematics, isokinetic strength, muscle activity, and the prevalence of lower extremity injuries in university-level netball players during a single season

Background

Safe landing in netball is fundamental. Research on the biomechanics of multidirectional landings is lacking, especially among netball players. Furthermore, few studies reporting the associations between ankle kinematics, isokinetic ankle muscle strength, muscle activities, and injury prevalence in South African netball have been undertaken.

Objectives

To determine the relationships between ankle kinematics, kinetics, isokinetic strength, and muscle activity during jump-landing tasks, as well as the prevalence of lower extremity injuries in university-level netball players during a single season.

Methods

This cross-sectional repeated-measure study consisted of ten university-level female netball players. The injury prevalence data was collected during the 2022 netball season. The ankle muscle activity, kinematic, and kinetic data were collected during multidirectional single-leg landing and muscle strength was collected from plantar- and dorsiflexion trials.

Results

Netball players' ankle strength was generally below average. There was evidence of negative correlations between the ankle range of motion (ROM), isokinetic strength, and muscle activity amplitudes. A lack of evidence prevented the conclusion that lower extremity dominance predisposed players to injury, and that any specific body part was more likely to be injured among netball players.

Conclusion

Landing forces and muscle activity are direction-dependent, especially for the dominant limb. Lower extremity strength and neuromuscular control (NMC) across multiple jump-landing directions should be an area of focus for female netball players.

Patients with chronic ankle instability exhibit increased sensorimotor cortex activation and correlation with poorer lateral balance control ability during single-leg stance: a FNIRS study

Introduction

Chronic Ankle Instability (CAI) is a musculoskeletal condition that evolves from acute ankle sprains, and its underlying mechanisms have yet to reach a consensus. Mounting evidence suggests that neuroplastic changes in the brain following ankle injuries play a pivotal role in the development of CAI. Balance deficits are a significant risk factor associated with CAI, yet there is a scarcity of evidence regarding the sensorimotor cortical plasticity related to balance control in affected individuals. This study aims to evaluate the differences in cortical activity and balance abilities between patients with CAI and uninjured individuals during a single-leg stance, as well as the correlation between these factors, in order to elucidate the neurophysiological alterations in balance control among patients with CAI.

Methods

The study enrolled 24 patients with CAI and 24 uninjured participants. During single-leg stance, cortical activity was measured using a functional near-infrared spectroscopy (fNIRS) system, which included assessments of the pre-motor cortex (PMC), supplementary motor area (SMA), primary motor cortex (M1), and primary somatosensory cortex (S1). Concurrently, balance parameters were tested utilizing a three-dimensional force platform.

Results

Independent sample t-tests revealed that, compared with the uninjured individuals, the patients with CAI exhibited a significant increase in the changes of oxyhemoglobin concentration (ΔHbO) during single-leg stance within the left S1 at Channel 5 (t = 2.101, p = 0.041, Cohen's d = 0.607), left M1 at Channel 6 (t = 2.363, p = 0.022, Cohen's d = 0.682), right M1 at Channel 15 (t = 2.273, p = 0.029, Cohen's d = 0.656), and right PMC/SMA at Channel 11 (t = 2.467, p = 0.018, Cohen's d = 0.712). Additionally, the center of pressure root mean square (COP-RMS) in the mediolateral (ML) direction was significantly greater (t = 2.630, p = 0.012, Cohen's d = 0.759) in the patients with CAI. Furthermore, a moderate positive correlation was found between ML direction COP-RMS and ΔHbO2 in the M1 (r = 0.436; p = 0.033) and PMC/SMA (r = 0.488, p = 0.016), as well as between anteroposterior (AP) direction COP-RMS and ΔHbO in the M1 (r = 0.483, p = 0.017).

Conclusion

Patients with CAI demonstrate increased cortical activation in the bilateral M1, ipsilateral PMC/SMA, and contralateral S1. This suggests that patients with CAI may require additional brain resources to maintain balance during single-leg stance, representing a compensatory mechanism to uphold task performance amidst diminished lateral balance ability in the ankle joint.

Chronic ankle instability affects the association between knee joint angle and loading: musculoskeletal simulation study

The purpose of this study was to calculate and compare (1) knee loads, (2) muscle-specific contributions to knee loads, and (3) effects of knee flexion angle on knee loads and muscle-specific load contributions during a forward jump-landing task in people with and without chronic ankle instability (CAI). Eight CAI patients and seven healthy controls performed a forward jump-landing task. We collected 3D kinematics, ground reaction force, and muscle activation and used musculoskeletal modeling. The results showed that only healthy controls exhibited an association between knee flexion angle and knee compressive impulse (r = 0.854, p = .014). The lack of association in CAI group may lead to knee instability and increase knee injury risk in people with CAI.

Effects of anticipation on joint kinematics during inversion perturbation in individuals with chronic ankle instability

BACKGROUND

Although chronic ankle instability (CAI) patients display altered reactive joint kinematics after inversion perturbation, little is known about the effects of anticipation on reactive joint kinematics among CAI, coper, and control groups.

OBJECTIVE

To assess changes in reactive joint kinematics after different inverted landing situations including planned- and unplanned-condition among groups of CAI, coper, and control.

METHODS

Sixty-six volunteers participated (22 per group). Participants completed three trials of both planned and unplanned single-leg landing onto an inverted force platform while reactive joint kinematic data were collected from initial-contact to 200 ms after initial-contact. Two-way repeated measures ANOVAs were used to examine the differences between condition (planned-, unplanned-conditions) and group (CAI, coper, control).

RESULTS

There were significant group by condition interactions for total ankle displacement in the frontal plane (p < 0.01) and maximum ankle inversion velocity (p = 0.01). CAI patients displayed increased ankle displacement (p < 0.01) and maximum inversion velocity (p < 0.01) under the unplanned condition compared to the planned condition. However, copers did not show any differences in ankle displacement and maximum inversion velocity between the two conditions.

CONCLUSIONS

CAI patients displayed greater changes in ankle joint displacement and maximum ankle inversion velocity occurred after inversion perturbation under unplanned condition compared with copers and controls. Current data suggest that altered reactive joint kinematics under the unanticipated condition in CAI patients may contribute to the condition of CAI after ankle sprains. Clinicians should focus on rehabilitation programs to recover and/or develop feedback control for CAI patients during functional movements under unanticipated condition to prevent further injuries.

Lower Limb Biomechanics During Drop-Jump Landings on Challenging Surfaces in Individuals With Chronic Ankle Instability

CONTEXT

Individuals with chronic ankle instability (CAI) exhibit impaired lower limb biomechanics during unilateral drop-jump landings on a flat surface. However, lower limb biomechanical adaptations during unilateral drop-jump landings on more challenging surfaces, such as those that are unstable or inclined, have not been described.

OBJECTIVE

To determine how unilateral drop-jump landing surfaces (flat, unstable, and inclined) influence lower limb electromyography, kinematics, and kinetics in individuals with CAI.

DESIGN

Descriptive laboratory study.

SETTING

Biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 22 young adults (age = 24.9 ± 4.9 years, height = 1.68 ± 0.08 m, mass = 70.6 ± 11.4 kg) with CAI.

INTERVENTION(S)

Participants completed 5 trials each of unilateral drop-jump landings on a flat surface (DROP), an unstable surface (FOAM), and a laterally inclined surface (WEDGE).

MAIN OUTCOME MEASURE(S)

Electromyography of the gluteus medius, vastus lateralis, gastrocnemius medialis, peroneus longus, and tibialis anterior muscles was recorded. Ankle and knee angles and moments were calculated using a 3-dimensional motion-analysis system and a force plate. Biomechanical variables were compared among tasks using 1-dimensional statistical nonparametric mapping.

RESULTS

During DROP, greater ankle-dorsiflexion and knee-extension moments were observed than during FOAM and WEDGE and greater vastus lateralis muscle activity was observed than during FOAM. Greater ankle-inversion and plantar-flexion angles were noted during FOAM and WEDGE than during DROP. Peroneus longus muscle activity was greater during DROP than during FOAM. During FOAM, greater ankle-inversion and knee-extension angles and ankle-inversion and internal-rotation moments, as well as less peroneus longus muscle activity, were present than during WEDGE.

CONCLUSIONS

The greater ankle-inversion and plantar-flexion angles as well as the lack of increased peroneus longus muscle activation during the FOAM and WEDGE conditions could increase the risk of recurrent lateral ankle sprain in individuals with CAI. These findings improve our understanding of the changes in lower limb biomechanics when landing on more challenging surfaces and will help clinicians better target deficits associated with CAI during rehabilitation.

Jump landing among chronic ankle instability individuals who did or did not attend rehabilitation at the time of injury

OBJECTIVES

The purpose was to compare vertical ground reaction forces and sagittal-plane energy dissipation patterns of the lower extremity during a single-limb jump-stabilization task between individuals with chronic ankle instability who did or did not attend rehabilitation after their initial ankle sprain.

DESIGN

Cross-sectional.

SETTING

Research laboratory.

PARTICIPANTS

Eight participants with chronic ankle instability who did and 12 participants who did not attend rehabilitation were enrolled.

MAIN OUTCOME MEASURES

Normalized vertical ground reaction force data were used to calculate the average loading rate, time to peak force, and the peak force. Sagittal plane kinematics and joint moments at the ankle, knee, and hip, were used to calculate each joint's relative energy dissipation at 50, 100, 150, and 200 ms post-landing.

RESULTS

Participants who attended rehabilitation had a slower average loading rate (P = 0.025) and smaller peak vertical ground reaction force (P = 0.025). The average relative energy dissipation at the knee was higher in those who attended rehabilitation at the 100 ms (P = 0.041), 150 ms (P = 0.046), and 200 ms (P = 0.042) time intervals.

CONCLUSIONS

Attending rehabilitation after an ankle sprain may have a beneficial effect on jump-stabilization outcomes among individuals with chronic ankle instability.

Effects of Knee Joint Angle and Contraction Intensity on the Triceps Surae Stiffness

Purpose: Monitoring the contractility of muscles assists the clinician in understanding how muscle functions as part of the kinetic system. This study investigated the effect of knee joint angles under different resistance on the stiffness of the medial gastrocnemius (MG), lateral gastrocnemius (LG), and soleus (SOL) muscles using the shear wave elastography (SWE) technique.

Methods: A total of 22 females were recruited. During isometric plantar flexion, at knee 0-degree (fully extended) and knee 90-degree (flexed 90°), the shear modulus on the MG, LG, and SOL was measured by shear wave elastography at no contraction and two intensities (40% and 80%) of maximal voluntary contraction (MVC). Shear modulus is a mechanical parameter to describe stiffness, and stiffness is a proxy for muscle contractility.

Results: There were moderate-to high-positive correlations between the active stiffness of triceps surae muscles and isometric contraction intensity (r: 0.57–0.91, p＜0.001). The active stiffness in MG and LG with extended knees was higher than that with flexed knees (p＜0.001). The active stiffness in SOL with flexed knee was higher than that with extended knee (p＜0.001).

Conclusion: Active stiffness can be considered a quantitative indicator generated by the force output of the triceps surae. Different knee joint angles cause three triceps surae muscles to exhibit non-uniform mechanical properties, which may explain part of the mechanism of soft tissue injury during physical exercise.

Female athletes with ligament dominance exhibiting altered hip and ankle muscle co-contraction patterns compared to healthy individuals during single-leg landing

BACKGROUND

Anterior cruciate ligament (ACL) injury is one of the most serious knee injuries and occurs frequently during exercise. Altered hip and ankle muscle co-contraction patterns may contribute to dynamic knee valgus and ACL injury mechanisms. Lack of dynamic control of ground reaction force (GRF) is known to be contributing factor for ACL injury by placing excessive force on passive structures. Muscle co-contraction is a dynamic mechanism for GRF absorption. Therefore, any alterations in co-contraction might be a risk factor for ACL injury. Ligament dominance is a term to define individuals who rely more on ACL ligament for GRF control.

RESEARCH QUESTION

This study aimed to compare the muscle co-contraction patterns of distal and proximal knee muscles during single leg landing in female athletes with and without ligament dominance.

METHODS

This is a cross-sectional study. A total of 54 female athletes were assigned to the healthy (n = 27) and ligament dominance (n = 27) group based on their Tuck Jump test scores. The electromyography activity of the gluteus medius, adductor longus, tibialis anterior, peroneus longus, medial and lateral gastrocnemius was measured by an electromyography in drop down a 30-cm-high stair. A Multivariate Analysis of Variance (MANOVA) was used for statistical analysis (p ≤ 0.05).

RESULTS

The two groups demonstrated an overall significantly different muscle co-contraction patterns (P < 0.05). There was a decreased in co-contraction of proximal group and an increased co-contraction in the distal muscles in ligament dominant group.

SIGNIFICANCE

The findings have provided evidence to support the notion of neuromuscular imbalances in ligament dominance deficit. These findings can be useful for the coaches and experts to design preventive exercises and modify the current programs for the people affected by ligament dominance.

Effects of Isometric Plantar-Flexion on the Lower Limb Muscle and Lumbar Tissue Stiffness

Purpose: This study investigated the effects of isometric plantar-flexion against different resistances on the thoracolumbar fascia (TLF), erector spinae (ES), and gastrocnemius stiffness by shear wave elastography (SWE). The purpose was to explore the interaction between the lower limb muscle and lumbar tissue in the myofascial tensegrity network.

Methods: Twenty healthy young female were recruited in this study. The stiffness of the TLF, ES, medial gastrocnemius (MG), and lateral gastrocnemius (LG) was measured by SWE under four isometric plantar-flexion resistance conditions. The resistance conditions involved 0% maximum voluntary isometric contraction (MVIC), 20% MVIC, 40% MVIC, and 60% MVIC.

Results: There was a strong correlation between the stiffness change of MG and that of TLF (r = 0.768–0.943, p &lt; 0.001) and ES (r = 0.743–0.930, p &lt; 0.001), while it was moderate to strong correlation between MG and that of LG (r = 0.588–0.800, p &lt; 0.001). There was no significant difference in the stiffness between the nondominant and dominant sides of TLF and ES under the resting position (p &gt; 0.05). The increase in stiffness of the TLF, ES, MG, and LG, with MVIC percentage (p &lt; 0.05), and the stiffness of TLF and ES on the nondominant side is much higher than that on the dominant side.

Conclusions: Our data shows that isometric plantar-flexion has a significant effect on the stiffness of the lumbar soft tissue and gastrocnemius. The gastrocnemius has a strong correlation with the stiffness changes of TLF and ES, which provides preliminary evidence for exploring the myofascial tensegrity network between the dorsal side of the lower limb muscle and lumbar tissue.

Electromiographic activity during single leg jump in adolescent athletes with chronic ankle instability: A pilot study

Chronic ankle instability (CAI) is a common condition in athletes, which can alter the muscular activity of lower limb during jump. The objective of the study was to verify the magnitude of activation, onset timing and order of recruitment of the proximal and local muscles to the ankle of young athletes with CAI during a single leg vertical jump. Thirty-seven athletes were selected and divided into: 1) CAI group and 2) control group. An electromyographic evaluation was performed during the jump on force plate. The muscles evaluated were the proximal muscles - gluteus medius (GMed), rectus femoris (RF) and local ankle muscles - tibialis anterior (TA), peroneus longus (PL) and lateral gastrocnemius (LG). In propulsion, the CAI group showed early activation of all evaluated muscles, when compared to control group (p = 0.05). No diferences were found between groups concerning magnitude of electromyographic signal and order of muscle recruitment. During landing, an increase in magnitude of the electromyographic signal of TA in the CAI group was observed and no diferences were found between groups for onset activation and order of muscle recruitment. The results can be applied to athletes' rehabilitation through specific neuromuscular control exercises, such as reaction time and local and proximal joint stabilization to optimize muscle performance and injury incidence. Therefore, in the single leg vertical jump athletes with CAI presented higher activation of the TA in the landing and an early activation of the GMed, RF, TA, PL and LG in propulsion in relation to control group.

Muscle activations during functional tasks in individuals with chronic ankle instability: a systematic review of electromyographical studies

BACKGROUND

It has been reported that individuals with chronic ankle instability (CAI) show motor control abnormalities. The study of muscle activations by means of surface electromyography (sEMG) plays a key role in understanding some of the features of movement abnormalities.

RESEARCH QUESTION

Do common sEMG activation abnormalities and strategies exists across different functional movements?

METHODS

Literature review was conducted on PubMed, Web-of-Science and Cochrane databases. Studies published between 2000 and 2020 that assessed muscle activations by means of sEMG during any type of functional task in individuals with CAI, and used healthy individuals as controls, were included. Methodological quality was assessed using the modified Downs&Black checklist. Since the methodologies of different studies were heterogeneous, no meta-analysis was conducted.

RESULTS

A total of 63 articles investigating muscle activations during gait, running, responses to perturbations, landing and hopping, cutting and turning; single-limb stance, star excursion balance task, forward lunges, ball-kicking, y-balance test and single-limb squatting were considered. Individuals with CAI showed a delayed activation of the peroneus longus in response to sudden inversion perturbations, in transitions between double- and single-limb stance, and in landing on unstable surfaces. Apparently, while walking on ground there are no differences between CAI and controls, walking on a treadmill increases the variability of muscles activations, probably as a "safety strategy" to avoid ankle inversion. An abnormal activation of the tibialis anterior was observed during a number of tasks. Finally, hip/spine muscles were activated before ankle muscles in CAI compared to controls.

CONCLUSION

Though the methodology of the studies herein considered is heterogeneous, this review shows that the peroneal and tibialis anterior muscles have an abnormal activation in CAI individuals. These individuals also show a proximal muscle activation strategy during the performance of balance challenging tasks. Future studies should investigate whole-body muscle activation abnormalities in CAI individuals.

Ankle Stability and Movement Coordination Impairments: Lateral Ankle Ligament Sprains Revision 2021

This revised clinical practice guideline (CPG) addresses the distinct but related lower extremity impairments of those with a first-time lateral ankle sprain (LAS) and those with chronic ankle instability (CAI). Depending on many factors, impairments may continue following injury. While most individuals experience resolution of symptoms, complaints of instability may continue and are defined as CAI. The aims of the revision were to provide a concise summary of the contemporary evidence since publication of the original guideline and to develop new recommendations or revise previously published recommendations to support evidence-based practice. J Orthop Sports Phys Ther 2021;51(4):CPG1-CPG80. doi:10.2519/jospt.2021.0302.

Individuals with chronic ankle instability exhibit altered ankle kinematics and neuromuscular control compared to copers during inversion single-leg landing

OBJECTIVES

This study compares the ankle kinematics and muscle activities of the individuals with chronic ankle instability (CAI), coper, and control groups in normal and inversion single-leg landings.

DESIGN

cross-sectional study; SETTING: Biomechanics laboratory.

PARTICIPANTS

Physically active adults with CAI (N = 12); and coper (N = 12) and control (N = 12) groups.

MAIN OUTCOME MEASURES

The participants performed normal and inversion single-leg landing. The muscle activity 200 ms before and after landing of the tibialis anterior, the medial gastrocnemius, and the fibularis longus (FL) were recorded. The FL latency, sagittal and frontal co-contraction indexes (CCI), ankle inversion angle at the initial contact, and the maximum inversion angle were recorded.

RESULTS

Significantly longer FL latency, decreased FL muscle activity, frontal CCI, and an increased maximum inversion angle at post-landing were discovered during inversion single-leg landing in the CAI group compared to the coper and control groups. However, no significant difference was observed among the CAI and coper groups during normal single-leg landing.

CONCLUSION

These results suggest prolonged FL latency and altered ankle kinematics suggest an increased risk of recurrent lateral ankle sprains in CAI with inversion single-leg landing.

Joint Coordination and Stiffness During Landing in Individuals With Chronic Ankle Instability

The purpose of the present study was to examine the effect of chronic ankle instability (CAI) on lower-extremity joint coordination and stiffness during landing. A total of 21 female participants with CAI and 21 pair-matched healthy controls participated in the study. Lower-extremity joint kinematics were collected using a 7-camera motion capture system, and ground reaction forces were collected using 2 force plates during drop landings. Coupling angles were computed based on the vector coding method to assess joint coordination. Coupling angles were compared between the CAI and control groups using circular Watson-Williams tests. Joint stiffness was compared between the groups using independent t tests. Participants with CAI exhibited strategies involving altered joint coordination including a knee flexion dominant pattern during 30% and 70% of their landing phase and a more in-phase motion pattern between the knee and hip joints during 30% and 40% and 90% and 100% of the landing phase. In addition, increased ankle inversion and knee flexion stiffness were observed in the CAI group. These altered joint coordination and stiffness could be considered as a protective strategy utilized to effectively absorb energy, stabilize the body and ankle, and prevent excessive ankle inversion. However, this strategy could result in greater mechanical demands on the knee joint.

Neuromuscular control of the ankle during pre-landing in athletes with chronic ankle instability: Insights from statistical parametric mapping and muscle co-contraction analysis

OBJECTIVE

The present study aimed to compare the neuromuscular control of the muscles around the ankle between athletes with CAI and without history of any ankle sprain (Non-CAI) by using statistic parametric mapping (SPM) and co-contraction analyses.

DESIGN

Cross-sectional study; Setting: Laboratory; Participants: 40 athletes (20 CAI, 20 Non-CAI) were pair-matched for age and gender.

MAIN OUTCOME MEASURES

Neuromuscular control was examined using surface electromyography (EMG) amplitude and muscle co-contraction 200 ms before foot-contact with the ground during a jump-landing task.

RESULTS

The EMG amplitude of tibialis anterior, peroneus longus, and gastrocnemius medialis were analyzed using statistic parametric mapping. The CAI group exhibited decreased EMG amplitude of peroneus longus during preparation for foot-contact. There were no significant co-contraction differences between groups.

CONCLUSIONS

Our findings demonstrate that SPM combined with the co-contraction provides a comprehensive EMG analysis to detect the differences of neuromuscular control between athletes with and without chronic ankle instability. Additionally, this finding indicates that CAI contributed to altered neuromuscular control during the pre-landing phase, which may contribute to re-injury mechanisms.

Unilateral jump landing neuromechanics of individuals with chronic ankle instability

OBJECTIVES

To assess the neuromechanical (kinematic, kinetic and electromyographic (EMG)) differences between individuals with and without chronic ankle instability (CAI) during unilateral jump landing.

DESIGN

Case-control study.

METHODS

Kinematic, kinetic and EMG data of 32 participants with CAI and 31 control participants were collected during unilateral side jump landing (SIDE) and unilateral drop landing on three surfaces (even (DROP), unstable (FOAM) and laterally inclined (WEDGE)). Each participant had to complete five trials of each task in a randomised sequence. To compare the neuromechanical differences between groups, a one-dimensional statistical non-parametric mapping analysis was performed.

RESULTS

Compared to the control group, the CAI group exhibited increased biceps femoris muscle activity during the preactivation and landing phases, decreased gluteus medius and peroneus longus muscles activity during the preactivation phase and increased knee extension moment during the landing phase of the WEDGE task. The CAI group also exhibited increased ankle dorsiflexion during the landing phase of the FOAM task and decreased vastus lateralis muscle activity during the preactivation phase of the DROP task. Finally, the CAI group exhibited decreased biceps femoris muscle activity during the preactivation and landing phases and decreased gluteus medius muscle activity during the preactivation phase of the SIDE task compared to the control group.

CONCLUSIONS

Individuals with CAI present neuromechanical differences during unilateral jump landing compared to healthy individuals. The results of this study will improve our understanding of underlying deficits associated with CAI and will help researchers and clinicians to better target them during rehabilitation.

Chronic Ankle Instability Does Not Influence Tibiofemoral Contact Forces During Drop Landings Using a Musculoskeletal Model

The purpose of the study was to compare the tibiofemoral contact forces of participants with chronic ankle instability versus controls during landings using a computer-simulated musculoskeletal model. A total of 21 female participants with chronic ankle instability and 21 pair-matched controls performed a drop landing task on a tilted force plate. A 7-camera motion capture system and 2 force plates were used to test participants' lower-extremity biomechanics. A musculoskeletal model was used to calculate the tibiofemoral contact forces (femur on tibia). No significant between-group differences were observed for the peak tibiofemoral contact forces (P = .25-.48) during the landing phase based on paired t tests. The group differences ranged from 0.05 to 0.58 body weight (BW). Most participants demonstrated a posterior force (peak, ∼1.1 BW) for most duration of the landing phase and a medial force (peak, ∼0.9 BW) and large compressive force (peak, ∼10 BW) in the landing phase. The authors conclude that chronic ankle instability may not be related to the increased tibiofemoral contact forces or knee injury mechanisms during landings on the tilted surface.

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 participant's 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 participant's 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.

Co-activation patterns of gastrocnemius and quadriceps femoris in controlling the knee joint during walking

Muscular co-activation is a well-known mechanism for lower limb joint stabilization in both healthy and pathological individuals. This muscular feature appears particularly important for the knee joint, not only during challenging motor tasks such as cutting and landing but also during walking, due to knee cyclic loading. Gastrocnemius acts on the knee joint with a flexor activity and co-activations with quadriceps muscles lead to greater knee ligament strain with respect to an isolated burst of either muscle. Thus, this study aimed to assess possible co-activations between gastrocnemius and quadriceps muscles during walking. Five co-activation periods were assessed: during early stance (identified in 5.7 ± 5.1% of total strides), early and late foot-contact (88.9 ± 8.9% and 8.9 ± 8.2%), push-off (23.9 ± 12.2%) and late swing (29.0 ± 16.1%). Outcomes showed that late foot-contact and swing co-activations could deserve particular attention: in both cases the knee joint was close to the full extension (around 3.5° and 6°, respectively) and thus, considering also the anterior tibia translation due to the quadriceps activity, the simultaneous gastrocnemius burst could lead to an enhanced knee ligaments elongation. Findings of this study represent the first attempt to provide a reference knee joint co-activation framework, useful also for further evaluation in cohorts with knee failures.