Lower Extremity Muscle Activation during the Star Excursion Balance Test in Patients with Chronic Ankle Instability and Copers.

Background and Objectives: The aim of this study was to assess the impact of ankle muscles on performance of the Star Excursion Balance Test (SEBT) among individuals with stable ankles, a history of ankle sprain, and chronic ankle instability (CAI). Materials and Methods: Sixty subjects (twenty per group) performed the SEBT in each of the anterior (A), posteromedial (PM), and posterolateral (PL) directions. Normalized maximum reach distance (NMRD) and normalized mean amplitude of the tibialis anterior (NMA_TA), fibularis longus (NMA_FL), and medial gastrocnemius (NMA_MG) were measured during performance of the SEBT. Results: Copers have greater NMRD than subjects with stable ankles and those with CAI, and subjects with stable ankles also have greater NMRD than those with CAI in only the PL direction. Subjects with stable ankles and those with CAI showed greater NMA_TA than copers. The A direction showed greater NMA_TA than the PM and PL directions. Copers showed greater NMA_FL than subjects with stable ankles. Subjects with CAI showed greater NMA_MG than copers and subjects with stable ankles. The A and PL directions showed greater NMA_MG than the PM direction. Conclusions: Overall, copers and/or subjects with CAI demonstrated altered neuromuscular function by compensating for their ankle muscles when compared to subjects with stable ankles due to a history of ankle sprain.

Static Postural Stability in Chronic Ankle Instability, an Ankle Sprain and Healthy Ankles.

To identify the single leg balance (SLB) test that discriminates among healthy, coper, and chronic ankle instability (CAI) groups and to determine effects of ankle muscles on the balance error scoring system (BESS) among the three populations. 60 subjects (20 per group) performed the SLB test with eyes open (EO) and eyes closed (EC). Normalized mean amplitude (NMA) of the tibia anterior (TA), fibularis longus (FL), and medial gastrocnemius (MG) muscles and BESS were measured while performing the SLB test. The coper group had a lower error score than the CAI group in the EC. NMA was greater in the CAI group compared to in the healthy and coper groups regardless of muscle type. NMA of the TA was less than the PL and MG regardless of the group in the EO. The CAI group demonstrated greater NMAs of the PL and MG than the healthy and coper groups in the EC. The CAI group demonstrated greater NMA of the PL and MG by compensating their ankle muscles in the EO and EC. BESS suggests that the coper group may have coping mechanisms to stabilize static postural control compared to the CAI group. The EC may be better to detect static postural instability in the CAI or coper group.

Foot and Shank Coordination During Walking in Copers Compared With Patients With Chronic Ankle Instability and Controls.

Background: Chronic ankle instability (CAI) alters sensorimotor function and joint coordination, but ankle coordination during walking in copers (patients with a history of ankle sprain without any residual symptoms of CAI) remains unknown. Purpose: To identify foot and shank coordination patterns that discriminate among individuals with CAI, copers, and healthy controls and to investigate whether copers display a different strategy to overcome altered sensorimotor function after a lateral ankle sprain compared with individuals with CAI and healthy controls. Study Design: Controlled laboratory study. Methods: A total of 51 participants (17 participants with CAI, 17 copers, 17 healthy controls) walked on an instrumented treadmill at a fixed speed of 1.20 m/s for a 10-second trial, from which 8 consecutive gait cycles were extracted for analysis. Heel strike and toe-off were identified for each stance phase, and each stance phase was normalized to 100 time frames. A curve analysis was performed to detect group mean differences in vector coding coupling angles and coordination variabilities for sagittal plane ankle motion/transverse plane tibial plane motion (SAK/TT) and frontal plane ankle motion/transverse plane tibial motion (FAK/TT) with 90% CIs. Results: During the terminal stance, CAI and coper groups demonstrated an inversion-tibial external rotation coupling, while controls displayed a dorsiflexion-tibial internal rotation strategy. During midstance, there were no differences between the coper, CAI, or control groups. At 0% to 20% of stance, the CAI group showed the most variability, while copers showed the least. During midstance, both copers and controls displayed an increase in variability earlier than the CAI group. The CAI group displayed a peak in variability from 39% to 43% of stance, which was greater than copers. During the propulsive phase (from heel-off to toe-off), the CAI group showed greater SAK/TT variability than both copers and controls. Similar to SAK/TT variability, the CAI group showed an earlier peak in FAK/TT variability compared with controls. Conclusion: The CAI, coper, and control groups displayed different ankle joint coupling patterns and coordination variability during a walking gait cycle. Clinical Relevance: Copers may have the ability to alter their coordination during walking, which may help us understand the underlying mechanism of CAI.

Ankle Coordination in Chronic Ankle Instability, Coper, and Control Groups in Running.

PURPOSE: Coordination and coordination variability have been used as a measure of the function and flexibility of the sensorimotor system during running. Chronic ankle instability (CAI) is associated with altered sensorimotor system function compared with individuals without CAI. Copers may have adopted protective sensorimotor adaptations to prevent repeated ankle sprains; however, their coordination strategies between the foot and shank have not been investigated. We compared joint coupling angles and coordination variability using vector coding between individuals with CAI, copers, and controls. METHODS: Seventeen individuals with CAI, 17 copers, and 17 controls ran on the treadmill at a fixed speed of 2.68 m·s. A 10-s trial of continuous data was collected for kinematic analysis. The first five complete strides were used for vector coding. Means of the vector coding angles and variability of frontal plane ankle motion/transverse plane tibia motion and sagittal plane ankle motion/transverse plane tibia motion (SAK/TT) were calculated. A curve analysis with 90% confidence intervals was performed to detect differences between groups. RESULTS: Controls demonstrated greater angles of SAK/TT than individuals with CAI and greater angles of FAK/TT than copers during the second half of stance. In general, the control group demonstrated greater variability than individuals with CAI and copers, and copers demonstrated greater variability than individuals with CAI. CONCLUSIONS: Chronic ankle instability and copers demonstrated different coordination strategies than controls during loading and propulsion, adding evidence to support a sensorimotor deficit or compensation. Further, limited variability in people with history of CAI during impact and midstance may contribute to higher risk of reinjury, and be an important area for further research.

Influence of Aging on Lower Extremity Sagittal Plane Variability During 5 Essential Subphases of Stance in Male Recreational Runners.

BACKGROUND: Interjoint coordination variability is a measure of the ability of the human system to regulate multiple movement strategies. Normal aging may reduce variability, resulting in a less adaptive system. Additionally, when older runners are asked to run at speeds greater than preferred, this added constraint may place older runners at greater risk for injury. OBJECTIVES: To examine the influence of normal aging on coordination variability across 5 distinct subphases of stance in runners during preferred and fixed speeds. METHODS: Twelve older (60 years of age or older) and 12 younger (30 years of age or younger) male recreational runners volunteered for this cross-sectional study. Three-dimensional gait analyses were collected at preferred and fixed speeds. Stance phase was divided into 5 subphases: (SP1) loading response, (SP2) peak braking, (SP3) peak compression, (SP4) midstance, and (SP5) peak propulsion. Continuous relative phase variability for sagittal plane joint pairs-hip-knee, knee-ankle, and hip-ankle-was calculated. Repeated-measures linear mixed models were employed to compare variability for each joint pair. RESULTS: An age-by-stance subphase interaction was found for knee-ankle (P<.01) and hip-ankle (P<.01) pairs, while main effects for age and stance subphase were found for the hip-knee pair (P<.05). Specifically, loading response and peak braking variability were lower in older runners and greater across stance for knee-ankle and hip-ankle pairs, while midstance was lowest in the hip-knee pair for older and younger runners. No effects for running pace were found. CONCLUSION: Less adaptive movement strategies seen in older runners may partially contribute to the increased eccentric stresses during periods of high load. J Orthop Sports Phys Ther 2019;49(3):171-179. Epub 30 Nov 2018. doi:10.2519/jospt.2019.8419.

Inter-joint coordination patterns differ between younger and older runners.

Older runners are at greater risk of certain running-related injuries. Previous work demonstrated that aging influences running biomechanics, and suggest a compensatory relation between changes in the proximal and distal joints. Previous comparisons of interjoint coordination strategies between young and older runners could potentially have missed relevant differences by averaging coordination measures across time. OBJECTIVE: To compare coordination strategies between male runners under the age of 30 to those over the age of 60. METHODS: Twelve young (22 ±â€¯3 yrs, 1.80 ±â€¯0.07 m, 78.0 ±â€¯12.1 kg) and 12 older (63 ±â€¯3 yrs, 1.78 ±â€¯0.06 m, 73.2 ±â€¯15.8 kg) male runners ran at 3.35 m/s on an instrumented treadmill. Ankle frontal plane, tibial transverse plane, knee sagittal plane, and hip frontal plane motion were measured. Inter-joint coordination was calculated using a modified vector coding technique. Coordination patterns and variability time series were compared between groups throughout stance using ANOVA for circular data. RESULTS: At the ankle, older runners use in-phase propulsion (inversion, tibia external rotation) pattern following midstance (46-47% stance) while young runners are still in an in-phase collapse pattern (eversion, tibia external rotation). In coordination of the knee and hip, older runners maintained an in-phase collapse pattern (knee flexion, hip adduction) approaching midstance (35-37% stance), while younger runners use an out of phase strategy (knee extension, hip adduction). In coordination of the ankle and hip in the frontal plane, older runners again maintained an in phase collapse pattern up to midstance (34-39% stance), while younger runners used an out of phase strategy (ankle inversion, hip adduction). Variability was similar between age groups. CONCLUSION: Older runners appear to display altered coordination patterns during mid-stance, which may indicate protective biomechanical adaptations. These changes may also have implications for performance in older runners.

Influence of rest interval on foot-tibia coordination with chronic ankle instability during the Star Excursion Balance Test.

The purpose of this study was to determine whether different rest intervals affect performance on the Star Excursion Balance Test (SEBT) associated with chronic ankle instability (CAI) and whether foot-tibia coordination can be associated factors that may help discriminate between individuals with and without CAI during the SEBT. Participants included forty-eight individuals with (n = 24) and without CAI (n = 24). Subjects completed 3 trials in each of the 3 reach directions (anteromedial, medial, posteromedial) in random order. A total of three visits were required to complete the 3 rest interval conditions (10, 20, 40 s). Coupling angles (CA) of tibial internal rotation/dorsiflexion (TIR/DF) and tibial internal rotation/eversion (TIR/EV) were calculated and compared between groups in each direction for each rest interval. Individuals with CAI showed greater CAs of TIR/DF in the M direction (p = 0.01) and of TIR/EV in the P direction (p = 0.04) than healthy individuals in 20 s rest interval time. Overall, joint CAs were different between healthy individuals and those with CAI during the SEBT regardless of rest interval. Based on these results, rest interval and a natural result of CAI could alter ankle joint coordination in comparison of healthy individuals when performing the SEBT.

Kinematic predictors of loading during running differ by demographic group.

OBJECTIVES: To investigate whether previously-determined kinematic predictors of kinetics during running differ between demographic groups. PARTICIPANTS: Young male (n = 13, age = 22 (2) yrs), young female (n = 13, age = 25 (4) yrs), older male (n = 13, age = 50 (4) yrs) and older female (n = 13, age = 52 (3) yrs) runners. MAIN OUTCOME MEASURES: Sagittal plane kinematics and kinetics were assessed while participants ran at their preferred pace. Linear regression models were developed to predict kinetics in each group using kinematics as independent variables. RESULTS: Step length was positively associated with magnitude of at least one kinetic variable in all groups. Step position was inversely associated with vertical ground reaction force variables in all groups. Step frequency and CoM excursion were also important to all groups, however direction of the associations varied. Foot angle at initial contact was important to all groups except older females. Peak knee flexion was most important to older females, but was not important to any other groups. CONCLUSION: Optimal parameters for gait analysis of runners may depend on demographics of the individual. This provides insight for clinicians into the most effective evaluation and interventions strategies for different types of runners.

The effect of variable rest intervals and chronic ankle instability on triplanar ankle motion during performance of the Star Excursion Balance Test.

Inadequate rest intervals may contribute to impaired performance during functional tests. However, the effect of different rest intervals on performance of the SEBT in individuals with and without CAI is not known. Our purposes were to determine whether different rest intervals impact ankle kinematics during the SEBT and whether there differences between those two populations. 24 controls and 24 CAI completed 3 trials in 3 reach directions (anteromedial; AM, medial; M, posteromedial; PM). The order of rest intervals and reach distance were randomized and counterbalanced. Three visits were required to complete the 3 rest interval conditions (10, 20, 40s). Rest interval did not impact ankle kinematics between controls and CAI during the SEBT. Dorsiflexion (DF) (AM:partial η2=0.18; M:partial η2=0.23; PM:partial η2=0.23) for all directions and tibial internal rotation (TIR) excursions (AM:partial η2=0.20) for AM direction were greater in individuals with CAI regardless of rest interval length. Rest intervals ranging from 10 to 40s did not influence ankle kinematics. Differences exist in DF and TIR between controls and CAI during the SEBT. These findings suggest that clinicians can use any rest interval between 10 and 40s when administrating the SEBT. However, triplanar motion differs during a complex functional movement in controls compared to CAI.