Reactive Postural Responses Research Articles

Standing Reactive Postural Responses of Lower Limbs With and Without Self-Balance Assistance in Individuals With Spinal Cord Injury Receiving Epidural Stimulation.

Spinal cord epidural stimulation can promote the recovery of motor function in individuals with severe spinal cord injury (SCI) by enabling the spinal circuitry to interpret sensory information and generate related neuromuscular responses. This approach enables the spinal cord to generate lower limb extension patterns during weight bearing, allowing individuals with SCI to achieve upright standing. We have shown that the human spinal cord can generate some standing postural responses during self-initiated body weight shifting. In this study, we investigated the ability of individuals with motor complete SCI receiving epidural stimulation to generate standing reactive postural responses after external perturbations were applied at the trunk. A cable-driven robotic device was used to provide constant assistance for pelvic control and to deliver precise trunk perturbations while participants used their hands to grasp onto handlebars for self-balance support (hands-on) as well as when participants were without support (free-hands). Five individuals with motor complete SCI receiving lumbosacral spinal cord epidural stimulation parameters specific for standing (Stand-scES) participated in this study. Trunk perturbations (average magnitude: 17 ± 3% body weight) were delivered randomly in the four cardinal directions. Participants attempted to control each perturbation such that upright standing was maintained and no additional external assistance was needed. Lower limb postural responses were generally more frequent, larger in magnitude, and appropriately modulated during the free-hands condition. This was associated with trunk displacement and lower limb loading modulation that were larger in the free-hands condition. Further, we observed discernible lower limb muscle synergies that were similar between the two perturbed standing conditions. These findings suggest that the human spinal circuitry involved in postural control retains the ability to generate meaningful lower limb postural responses after SCI when its excitability is properly modulated. Moreover, lower limb postural responses appear enhanced by a standing environment without upper limb stabilization that promotes afferent inputs associated with a larger modulation of ground reaction forces and trunk kinematics. These findings should be considered when developing future experimental frameworks aimed at studying upright postural control and activity-based recovery training protocols aimed at promoting neural plasticity and sensory-motor recovery.

Effects of transcranial electrical stimulation of the right posterior parietal cortex on physical control responses

The posterior parietal cortex plays an important role in postural stability by adapting to changes in input from the visual, vestibular, and proprioceptive systems. However, little is known regarding whether transcranial electrical stimulation of the posterior parietal cortex affects reactive postural responses. This study aimed to investigate changes in physical control responses to anodal and cathodal transcranial direct current stimulation and transcranial random noise stimulation of the right posterior parietal cortex using a simultaneous inertial measurement unit. The joint movements of the lower limb of 33 healthy volunteers were measured while standing on a soft-foam surface with eyes closed during various stimulation modalities. These modalities included anodal, cathodal transcranial direct current stimulation, and sham stimulation in Experiment 1, and transcranial random noise and sham stimulations in Experiment 2. The results showed that cathodal stimulation significantly decreased the joint angular velocity in the hip rotation, ankle inversion-eversion, and abduction–adduction directions compared to anodal or sham stimulation in Experiment 1. In contrast, there were no significant differences in physical control responses with transcranial random noise stimulation coeducation in Experiment 2. These findings suggest that transcranial electrical stimulation of the right posterior parietal cortex may modulate physical control responses; however, the effect depends on the stimulus modality.

Perturbation-based balance training leads to improved reactive postural responses in individuals with Parkinson's disease and freezing of gait.

Perturbation-based balance training (PBT) exposes individuals to a series of sudden upright balance perturbations to improve their reactive postural responses. In this study, we aimed to evaluate the effect of a short PBT program on body balance recovery following a perturbation in individuals with freezing of gait due to Parkinson's disease. Volunteers (mean age = 64 years, SD = 10.6) were pseudorandomly assigned either to a PBT (n = 9) or to a resistance training (RT, n = 10) group. PBT was implemented through balance perturbations varying in the kind, direction, side, and magnitude of support base displacements. Both groups exercised with progressive difficulty/load activities twice a week for four weeks. Specific gains and generalization to dual-tasking and faster-than-trained support base displacements were evaluated 24 h after the end of the training, and retention was evaluated after 30 days of no training. Results showed that, compared to RT, PBT led to more stable postural responses in the 30-day retention evaluation, as indicated by decreased CoP displacement, velocity, and time to direction reversal and reduced numbers of near-falls. We found no transfer either to a dual-task or to a higher perturbation velocity. In conclusion, a training program based on diverse unpredictable balance perturbations improved the stability of reactive postural responses to those perturbations suffered during the training, without generalization to more challenging tasks.

Reactive postural responses predict risk for acute musculoskeletal injury in collegiate athletes.

Examine if objective assessments of reactive postural responses, quantified using wearable inertial measurement units, are associated with the risk for acute lower extremity musculoskeletal injuries in collegiate athletes. Prospective survival analysis. 191 Division I National Collegiate Athletic Association athletes completed an instrumented version of a modified Push and Release (I-mP&R) test at the beginning of their competitive season. The I-mP&R was performed with eyes closed under single- and dual-task (concurrent cognitive task) conditions. Inertial measurement units recorded acceleration and angular velocity data that was used to calculate time-to-stability. Acute lower extremity musculoskeletal injuries were tracked from first team activity for six months. Cox proportional hazard models were used to determine if longer times to stability were associated with faster time to injury. Longer time-to-stability was associated with increased risk of injury; every 250 ms increase in dual-task median time-to-stability was associated with a 36% increased risk of acute, lower-extremity musculoskeletal injury. Tests of reactive balance, particularly under dual-task conditions, may be able to identify athletes most at risk of acute lower extremity musculoskeletal injury. Clinically-feasible, instrumented tests of reactive should be considered in assessments for prediction and mitigation of musculoskeletal injury in collegiate athletes.

Machine Learning and Wearable Sensors for the Early Detection of Balance Disorders in Parkinson's Disease.

Dynamic posturography combined with wearable sensors has high sensitivity in recognizing subclinical balance abnormalities in patients with Parkinson's disease (PD). However, this approach is burdened by a high analytical load for motion analysis, potentially limiting a routine application in clinical practice. In this study, we used machine learning to distinguish PD patients from controls, as well as patients under and not under dopaminergic therapy (i.e., ON and OFF states), based on kinematic measures recorded during dynamic posturography through portable sensors. We compared 52 different classifiers derived from Decision Tree, K-Nearest Neighbor, Support Vector Machine and Artificial Neural Network with different kernel functions to automatically analyze reactive postural responses to yaw perturbations recorded through IMUs in 20 PD patients and 15 healthy subjects. To identify the most efficient machine learning algorithm, we applied three threshold-based selection criteria (i.e., accuracy, recall and precision) and one evaluation criterion (i.e., goodness index). Twenty-one out of 52 classifiers passed the three selection criteria based on a threshold of 80%. Among these, only nine classifiers were considered "optimum" in distinguishing PD patients from healthy subjects according to a goodness index ≤ 0.25. The Fine K-Nearest Neighbor was the best-performing algorithm in the automatic classification of PD patients and healthy subjects, irrespective of therapeutic condition. By contrast, none of the classifiers passed the three threshold-based selection criteria in the comparison of patients in ON and OFF states. Overall, machine learning is a suitable solution for the early identification of balance disorders in PD through the automatic analysis of kinematic data from dynamic posturography.

Reactive Postural Responses Are Slower In Acutely Concussed Collegiate Athletes: Preliminary Results

Abnormal balance is a common clinical sign of mild traumatic brain injury (mTBI). Despite the clinical utility of reactive balance testing in other balance impaired populations, current clinical testing for mTBI does not include reactive postural responses (RPR) which may be more representative of a competitive athletic environment.PURPOSE: To examine differences in RPR in athletes with mTBI compared to healthy controls at three time points: within 48 hours after mTBI (Acute), within 24 hours of beginning return-to-play protocol (PreRTP), within 24 hours of being cleared for full return to competition (PostRTP).METHODS: RPR in 24 collegiate athletes with mTBI (F = 12, age 19.42 ± 1.28 years, BMI 25.18 ± 3.38 kg/m2) and 19 healthy controls (F = 8, age 19.67 ± 1.56 years, BMI 24.36 ± 2.98 kg/m2) were assessed using the Push and Release, with eyes closed, under single (ST) and dual-task (DT; concurrent verbal cognitive task) conditions at three time points after-mTBI (acute, PreRTP, PostRTP). Inertial sensors on the sternum, lumbar, and feet were used to assess time to stabilization (TTS). A sensor on the tester’s hand determined release time. Standardized effect sizes, mean differences, and confidence intervals were calculated for each time point for both tasks. RESULTS: There was a median of six days between PreRTP and PostRTP. The mTBI group had longer ST TTS (1.09 ± 0.315 s) than healthy controls (0.904 ± 0.157 s) at the acute time point by 0.187 s (Cohen’s d (d) = 0.73; 95% CI: [0.179, 0.204]), at PreRTP by 0.069 s (d = 0.32; 95% CI: [0.053, 0.084]) and shorter TTS at PostRTP by 0.034 s (d = -0.166; 95%CI: [-0.048,-0.019]). The mTBI group had longer DT TTS (1.23 ± 0.31 s) than healthy controls (0.984 ± 0.207 s) at the acute time point by 0.248 s (d = 0.92; 95% CI: [0.230, 0.267]), at PreRTP by 0.035 s (d = 0.18 ;95% CI: [0.021, 0.048]) and at PostRTP by 0.036 s (d = 0 .18 ; 95%CI: [0.022, 0.050]). CONCLUSIONS: There was a large difference in RPR between athletes with mTBI and healthy controls at the acute time point for both ST and DT; athletes with mTBI had slower time to stabilization. Differences in RPR were small at PreRTP and PostRTP for both ST and DT. These preliminary results suggest that mTBI affects reactive postural responses acutely following mTBI but these responses recover over time. Supported by PAC 12 Student Athlete Health & Wellbeing

Reactive Balance Responses After Mild Traumatic Brain Injury: A Scoping Review.

Balance testing after concussion or mild traumatic brain injury (mTBI) can be useful in determining acute and chronic neuromuscular deficits that are unapparent from symptom scores or cognitive testing alone. Current assessments of balance do not comprehensively evaluate all 3 classes of balance: maintaining a posture; voluntary movement; and reactive postural response. Despite the utility of reactive postural responses in predicting fall risk in other balance-impaired populations, the effect of mTBI on reactive postural responses remains unclear. This review sought to (1) examine the extent and range of available research on reactive postural responses in people post-mTBI and (2) determine whether reactive postural responses (balance recovery) are affected by mTBI. Scoping review. Studies were identified using MEDLINE, EMBASE, CINAHL, Cochrane Library, Dissertations and Theses Global, PsycINFO, SportDiscus, and Web of Science. Inclusion criteria were injury classified as mTBI with no confounding central or peripheral nervous system dysfunction beyond those stemming from the mTBI, quantitative measure of reactive postural response, and a discrete, externally driven perturbation was used to test reactive postural response. A total of 4747 publications were identified, and a total of 3 studies (5 publications) were included in the review. The limited number of studies available on this topic highlights the lack of investigation on reactive postural responses after mTBI. This review provides a new direction for balance assessments after mTBI and recommends incorporating all 3 classes of postural control in future research.

Migraine With Aura Is Related to Delayed Motor Control Reaction and Imbalance Following External Perturbations.

Background: It is evidenced that migraineurs present balance deficits. However, the balance recovery following unexpected ground perturbations, which reflect conditions of everyday activities, has not been investigated in this population.Aim: We aimed to assess the reactive postural responses among patients with migraine with and without aura, chronic migraine, and controls. We further aimed to assess the factors associated with greater self-report of falls.Methods: Ninety patients diagnosed by headache specialists were equally classified into three migraine subgroups according to the presence of aura and chronic migraine. Thirty controls were also recruited. All participants underwent the motor control test (MCT) and adaptation test (ADT) protocols of dynamic posturography tests (EquiTest®, NeuroCom, USA). Clinical and headache features and information on falls in the previous year, fear of falling, and vestibular symptoms were also assessed.Results: Patients with aura presented a greater sway area in most of the MCT conditions than the other three groups (p = 0.001). The aura group also presented delayed latency responses after perturbations compared with controls and patients without aura (p < 0.03). In the ADT, a greater sway area was observed in patients with aura than in groups without aura, chronic migraine, and controls (p < 0.0001). The MCT and ADT sway area, the frequency of aura, and the fear of falling explained 46% of the falls in the previous 12 months.Conclusion: Patients with aura exhibited greater delay and sway area after unexpected ground perturbations than controls and other migraine subgroups, which are related to the reported number of falls.

Early balance impairment in Parkinson’s Disease: Evidence from Robot-assisted axial rotations

ObjectiveEarly postural instability (PI) is a red flag for the diagnosis of Parkinson’s disease (PD). Several patients, however, fall within the first three years of disease, particularly when turning. We investigated whether PD patients, without clinically overt PI, manifest abnormal reactive postural responses to ecological perturbations resembling turning. MethodsFifteen healthy subjects and 20 patients without clinically overt PI, under and not under L-Dopa, underwent dynamic posturography during axial rotations around the longitudinal axis, provided by a robotic mechatronic platform. We measured reactive postural responses, including body displacement and reciprocal movements of the head, trunk, and pelvis, by using a network of three wearable inertial sensors. ResultsPatients showed higher body displacement of the head, trunk and pelvis, and lower joint movements at the lumbo-sacral junction than controls. Conversely, movements at the cranio-cervical junction were normal in PD. L-Dopa left reactive postural responses unchanged. ConclusionsPatients with PD without clinically overt PI manifest abnormal reactive postural responses to axial rotations, unresponsive to L-Dopa. The biomechanical model resulting from our experimental approach supports novel pathophysiological hypotheses of abnormal axial rotations in PD. SignificancePD patients without clinically overt PI present subclinical balance impairment during axial rotations, unresponsive to L-Dopa.

Postural Responses to Sudden Horizontal Perturbations in Tai Chi Practitioners

Tai Chi has been shown to elicit numerous positive effects on health and well-being. In this study, we examined reactive postural control after sudden unloading horizontal perturbations, which resembled situations encountered during Tai Chi. The study involved 20 participants, 10 in the Tai Chi group (age: 37.4 ± 7.8 years), who had been regularly training the push-hand technique for at least 7 years, and 10 in the control group, consisting of healthy adults (age: 28.8 ± 5.0). Perturbations were applied at three different positions (hips, shoulders, and arms) via the load-release paradigm. Twenty measurements were carried out for each perturbation position. We measured peak vertical and horizontal forces on the ground (expressed percentage of body mass (%BM)), peak center of pressure displacement and peak horizontal and vertical velocities at the knee, hip and shoulder joints. The Tai Chi group exhibited smaller increases in vertical ground reaction forces when perturbations were applied at the hips (11.5 ± 2.1 vs. 19.6 ± 5.5 %BW; p = 0.002) and the arms (14.1 ± 4.2 vs. 23.2 ± 8.4 %BW; p = 0.005). They also responded with higher horizontal force increase after hip perturbation (16.2 ± 3.2 vs. 13.1 ± 2.5 %BW; p < 0.001). Similar findings were found when observing various outcomes related to velocities of vertical movement. The Tai Chi group also showed lower speeds of backward movement of the knee (p = 0.005–0.009) after hip (0.49 ± 0.13 vs. 0.85 ± 0.14 m/s; p = 0.005) and arm perturbations (0.97 ± 0.18 vs. 1.71 ± 0.29 m/s; p = 0.005). Center of pressure displacements were similar between groups. Our study demonstrated that engaging in Tai Chi could be beneficial to reactive postural responses after sudden perturbations in a horizontal direction; however, future interventional studies are needed to directly confirm this. Moreover, because of the age difference between the groups, some confounding effects of age cannot be ruled out.

The balance function is associated with frailty in community-dwelling older women.

Conditions underlying balance impairment should be identified to improve knowledge regarding clinical interventions for frail older adults. This study aims to explore the relationship between balance functions and frailty by using the brief balance evaluation systems test (BESTest), which can assess biomechanical constraints, stability limits/verticality, anticipatory postural adjustments (APAs), reactive postural responses, sensory orientation and stability in gait. A total of 75 community-dwelling older women were included in this cross-sectional study. We evaluated frailty by using the Kihon checklist and assessed the participants' balance functions by using the Brief BESTest. We performed the Mann-Whitney U test and receiver operating characteristic curve analysis to compare each balance function between frail and nonfrail participants. Twenty-two of the 75 (29.3%) participants were included in the frailty group. We noted significant differences between the frailty and nonfrailty groups with regard to stability limit, APAs, sensory orientation, and stability in gait (P = 0.010, 0.001, 0.008 and <0.001, respectively). In terms of determining frailty and nonfrailty, APAs and stability in gait were moderately accurate (the area under the curve = 0.730 and 0.713, respectively). APAs showed the highest sensitivity (0.864), whereas stability limits, sensory orientation, and stability in gait showed the highest specificity (0.943, 0.849 and 0.868, respectively). Thus, frail and nonfrail older adults showed significantly different balance functions, such as stability limits, APAs, sensory orientation and stability in gait. The Brief BESTest is useful for evaluating balance functions in relation to frailty.

Torque responses to in-place-perturbations in people with multiple sclerosis

BackgroundAutomatic postural responses are critical to prevent falls after a loss of balance. Although responses have been shown to be delayed in people with multiple sclerosis (PwMS), the degree to which other aspects of these movements are impacted by MS remains unknown. Research QuestionDo responses to in-place support-surface perturbations differ in PwMS compared to neurotypical adults? Are these responses related to a functional measure of postural response performance- center of mass (COM) displacement?. Method52 PwMS and 20 neurotypical, age-matched adults (NA) experienced backward support surface perturbations resulting in forward loss of balance and requiring an in-place response. Center of pressure (COP) and torque were calculated from force plates while center of mass (COM) approximations were collected via motion capture. Primary outcomes were maximal torque production at the foot and its timing, rate, and onset. ResultsPwMS and NA demonstrated no differences in maximal torque production (p = 0.79), timing of maximal torque (p = 0.29), rate of torque development (p = 0.76), or the onset of AP COP movement (p = 0.44). There was a significant negative association between the rate of torque development and forward COM displacement in both groups (Control: r=-0.64, p = 0.002; MS: r=-0.35, p = 0.01). Larger maximal torque production was also associated with smaller COM displacement in PwMS (r=-0.33, p = 0.02). ConclusionTorque profiles in response to backward support surface translations resulting in feet in-place responses were similar in people with mild MS and neurotypical adults. The rate of development and maximal torque were however correlated to functional postural response outcomes. These findings suggest that while not worse in PwMS during in-place perturbations, force-responses seem to be important predictors of the effectiveness of reactive postural control responses.

Vigor of reactive postural responses is set from feedback and feedforward processes.

I explore a distinct perspective from that brought in the book by arguing that in postural control our organism selects the vigor of reactive responses guided by an optimization rule considering first the required postural response for balance recovery as indicated by afferent information from a myriad of sensory receptors, and second the history of previous responses to similar perturbations.

Reactive Postural Responses After Mild Traumatic Brain Injury and Their Association With Musculoskeletal Injury Risk in Collegiate Athletes: A Study Protocol.

Background: Deficits in neuromuscular control are widely reported after mild traumatic brain injury (mTBI). These deficits are speculated to contribute to the increased rate of musculoskeletal injuries after mTBI. However, a concrete mechanistic connection between post-mTBI deficits and musculoskeletal injuries has yet to be established. While impairments in some domains of balance control have been linked to musculoskeletal injuries, reactive balance control has received little attention in the mTBI literature, despite the inherent demand of balance recovery in athletics. Our central hypothesis is that the high rate of musculoskeletal injuries after mTBI is in part due to impaired reactive balance control necessary for balance recovery. The purpose of this study is to (1) characterize reactive postural responses to recover balance in athletes with recent mTBI compared to healthy control subjects, (2) determine the extent to which reactive postural responses remain impaired in athletes with recent mTBI who have been cleared to return to play, and (3) determine the relationship between reactive postural responses and acute lower extremity musculoskeletal injuries in a general sample of healthy collegiate athletes.Methods: This two-phase study will take place at the University of Utah in coordination with the University of Utah Athletics Department. Phase 1 will evaluate student-athletes who have sustained mTBI and teammate-matched controls who meet all the inclusion criteria. The participants will be assessed at multiple time points along the return-to-play progress of the athlete with mTBI. The primary outcome will be measures of reactive postural response derived from wearable sensors during the Push and Release (P&R) test. In phase 2, student-athletes will undergo a baseline assessment of postural responses. Acute lower extremity musculoskeletal injuries for each participant will be prospectively tracked for 1 year from the date of first team activity. The primary outcomes will be the measures of reactive postural responses and the time from first team activity to lower extremity injury.Discussion: Results from this study will further our understanding of changes in balance control, across all domains, after mTBI and identify the extent to which postural responses can be used to assess injury risk in collegiate athletes.

Lower-limb coordination during gait: The effects of age and walking surface

Automatic postural responses are critical to prevent falls after a loss of balance. Although responses have been shown to be delayed in people with multiple sclerosis (PwMS), the degree to which other aspects of these movements are impacted by MS remains unknown.Do responses to in-place support-surface perturbations differ in PwMS compared to neurotypical adults? Are these responses related to a functional measure of postural response performance- center of mass (COM) displacement?.52 PwMS and 20 neurotypical, age-matched adults (NA) experienced backward support surface perturbations resulting in forward loss of balance and requiring an in-place response. Center of pressure (COP) and torque were calculated from force plates while center of mass (COM) approximations were collected via motion capture. Primary outcomes were maximal torque production at the foot and its timing, rate, and onset.PwMS and NA demonstrated no differences in maximal torque production (p = 0.79), timing of maximal torque (p = 0.29), rate of torque development (p = 0.76), or the onset of AP COP movement (p = 0.44). There was a significant negative association between the rate of torque development and forward COM displacement in both groups (Control: r=-0.64, p = 0.002; MS: r=-0.35, p = 0.01). Larger maximal torque production was also associated with smaller COM displacement in PwMS (r=-0.33, p = 0.02).Torque profiles in response to backward support surface translations resulting in feet in-place responses were similar in people with mild MS and neurotypical adults. The rate of development and maximal torque were however correlated to functional postural response outcomes. These findings suggest that while not worse in PwMS during in-place perturbations, force-responses seem to be important predictors of the effectiveness of reactive postural control responses.

Relationship between different methods to measure ankle range of motion in children with idiopathic toe walking

Automatic postural responses are critical to prevent falls after a loss of balance. Although responses have been shown to be delayed in people with multiple sclerosis (PwMS), the degree to which other aspects of these movements are impacted by MS remains unknown.Do responses to in-place support-surface perturbations differ in PwMS compared to neurotypical adults? Are these responses related to a functional measure of postural response performance- center of mass (COM) displacement?.52 PwMS and 20 neurotypical, age-matched adults (NA) experienced backward support surface perturbations resulting in forward loss of balance and requiring an in-place response. Center of pressure (COP) and torque were calculated from force plates while center of mass (COM) approximations were collected via motion capture. Primary outcomes were maximal torque production at the foot and its timing, rate, and onset.PwMS and NA demonstrated no differences in maximal torque production (p = 0.79), timing of maximal torque (p = 0.29), rate of torque development (p = 0.76), or the onset of AP COP movement (p = 0.44). There was a significant negative association between the rate of torque development and forward COM displacement in both groups (Control: r=-0.64, p = 0.002; MS: r=-0.35, p = 0.01). Larger maximal torque production was also associated with smaller COM displacement in PwMS (r=-0.33, p = 0.02).Torque profiles in response to backward support surface translations resulting in feet in-place responses were similar in people with mild MS and neurotypical adults. The rate of development and maximal torque were however correlated to functional postural response outcomes. These findings suggest that while not worse in PwMS during in-place perturbations, force-responses seem to be important predictors of the effectiveness of reactive postural control responses.

Sections of the Brief-Balance Evaluation Systems Test Relevant for Discriminating Fast Versus Slow Walking Speeds in Community-Dwelling Older Women.

Walking speed can be used to identify characteristics of frailty in older adults. It has a strong positive correlation with balance abilities. The Brief-Balance Evaluation Systems Test (Brief-BESTest) was developed to assess functions of the 6 balance control systems in a short time. However, for community-dwelling older adults, the relationship between walking speed and the Brief-BESTest needs to be clarified. Even the cutoff scores for each Brief-BESTest section should be indicated for physical therapists to effectively evaluate balance deficits. Our objective was to establish cutoff scores for individual Brief-BESTest sections, determine fast or slow walkers in community-dwelling older adults, and investigate the relationship between balance control systems and walking speed. In a cross-sectional study involving 55 participants 77 years and older, the Brief-BESTest was evaluated after grouping the participants based on their walking speeds in public community centers. We compared the age, history of falls, handgrip strength, quadriceps strength, appendicular skeletal muscle mass index, comfortable walking speeds, and the Brief-BESTest scores between the fast- and slow-walking groups by using the independent t test, Fisher exact test, or Mann-Whitney U test. We also determined the receiver operating characteristic curves, and calculated the cutoff, area under the curve (AUC), sensitivity, and specificity of each section. All sections of the Brief-BESTest, except Section 1 (Biomechanical Constraints) were able to differentiate between fast and slow walkers in community-dwelling older women. Section VI (Stability in Gait) showed the highest AUC (0.83) and the cutoff score for the fast- and slow-walker groups was 3.0 points (sensitivity = 0.85, specificity = 0.81). Sections III, IV, and V (Anticipatory, Reactive, and Sensory Orientation, respectively) had moderate AUC (0.71-0.72). Sections I and II (Stability Limits) showed weak correlations with the walking speed. Three sections (III, anticipatory postural adjustments; IV, reactive postural responses; and VI, stability in gait) could differentiate between fast and slow walkers. Section VI was a particularly important balance function measurement that differentiated the walking speed with the highest accuracy. Therefore, it should be a primary focus when physical therapists treat community-dwelling older adults.

Changes in the range of angular variation of the ankle, knee, hip and neck joints related to the awareness of an impending perturbation

ObjectivesChallenging quiet standing tasks for the ankle, knee, hip, and neck joints were used to test the effect of pre-cueing on the reaction time of articular stabilization strategies. MethodWe assessed balance recovery in 15 subjects who were exposed to backward translations on a movable platform during two conditions: alerted, where participants gazed at a countdown light that pre-cued the onset of the platform translation; and unalerted, without onset time pre-cue. ResultsWe compared the angular variation of the ankle, knee, hip, and neck joints between the two conditions over four window epochs (0–50 ms; 50–100 ms; 100–150 ms; 150–200 ms). When comparing the window epochs of the ankle and hip joints between conditions, a significant effect was observed in the first and second windows. In the second and third windows, a significant effect was only observed in the alerted group, thereby indicating a faster stability for alerted condition. No significant effect was observed for the knee joint, while a significant effect was observed in the neck joint during the third and fourth windows of the alerted condition. ConclusionsPre-cueing can modify the synergies of the automatic reactive postural responses, prioritizing the stabilization of main joints such as the ankle and hip over that of the neck and knee. It was suggested that joint stabilization in the hip occurred due to the involuntary anticipation preprogrammed in the cortex by the visual pre-cue.

Reactive Postural Responses In Collegiate Athletes

Athletes frequently need to recover balance after an external disturbance during tasks with high cognitive demand. Mobility impaired populations demonstrate deficits in reactive postural responses to backward and lateral perturbations but, little is known about postural responses in college athletes. PURPOSE: To examine differences in direction and task (single [ST] and dual task [DT]) in reactive postural response measures during the push-and-release (P&R) test. METHODS: Reactive postural responses in 98 healthy (F=42, age 19.3 ± 1.60 years, BMI 23.56 ± 3.29 kg/m2) college athletes were assessed using the P&R in four directions (forward, backward, right, left), with eyes closed, under ST and DT (concurrent verbal cognitive task) conditions. Inertial sensors on the sternum, lumbar, right tibia, and feet were used to assess step initiation latency, time of first heel contact (HC), and time to stabilization (TTS). A sensor on the tester’s hand determined release time. Linear mixed models with random intercepts were used to determine if postural response measures differed by direction and task. RESULTS: There was a significant interaction between direction and task for HC (p=0.04), with the largest difference in DT and ST in the forward direction (95%CI = [0.05, 0.08]), and the smallest difference in the backward direction (95%CI = [0.02, 0.05]). There were also significant main effects for direction (p <0.0001) and task (p<0.0001) for each postural response (latency, HC, TTS). Means adjusted for age, sex, and BMI are presented below.CONCLUSION: Postural responses differ by direction during the P&R in college athletes. The largest differences were between the forward and backward directions. These directions may be most sensitive to detecting changes in reactive postural control; future work will examine the utility of the P&R for return-to-play decisions. Supported by PAC 12 (PI: Fino, Dibble); University of Utah Study Design and Biostatistics Center (UL1TR002538)

Reactive Balance Differences Between Collegiate Sports

Static and dynamic postural stability have been characterized in athletes and shown to differ across sports. However, these tests of stability may not specifically capture the balance required for reactive athletic movements. The Push-and-Release (P&R) test is a standardized clinical tool used to assess reactive postural control in balance-impaired populations. PURPOSE: To examine differences between sport team and task (single [ST] and dual task [DT]) in reactive postural response measures. METHODS: 40 healthy, male athletes (age 18.50 ± 0.75; body mass index [BMI] 24.11 ± 2.38) were recruited from 3 collegiate teams: baseball (n=12), lacrosse (n=17), and swimming (n=11). Reactive postural responses were assessed using the P&R in backward and forward directions under ST and DT (concurrent verbal cognitive task) conditions. All conditions were performed with eyes closed. Inertial sensors on the sternum, lumbar, feet, and right tibia were used to assess step latency (L), time of first heel contact (HC), and time to stabilization (TTS). A sensor on the tester’s hand was used to determine release time. To assess if postural response measures differ by sport and task, linear mixed effects models with random intercepts and stratified by direction (forward or backward), were used and adjusted for age and BMI. RESULTS: Lacrosse players had faster L compared to baseball players in the forward direction (p=0.018). No other differences by sport were observed. In the forward direction, DT outcomes were slower than ST outcomes (L: p<0.0001; HC: p=0.0004; TTS: p=0.0064). In the backward direction, L was slower in the DT condition (p=0.0034), but no task differences were found for HC or TTS (p=0.0628 and p=0.8733, respectively). CONCLUSION: In the forward direction only, DT slowed all postural responses. While L differed between lacrosse and baseball in the forward direction, no other differences were found across sports. As most outcomes were unaffected by sport, the P&R may be a clinically relevant assessment in athletics. However, due to the limited sample size, caution should be applied when interpreting these findings and future studies are needed. Supported by PAC 12 Student Athlete Health & Wellbeing (PI: Fino, Dibble) and University of Utah Study Design and Biostatistics Center through NCATS Grant 8UL1TR000105.