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Background: Longevity is increasing worldwide due to improvements in healthcare and living standards. Aging is often associated with disability and multiple health concerns. To address these challenges, effective interventions are essential. This study investigated potential age-related declines in gait, balance, and strength. We also sought to assess any relationships between these three parameters and explore potential differences between women and men., Methods: Healthy individuals over 50 years of age were recruited for this cross-sectional study. Upper extremity (grip) strength and lower extremity (knee) strength of the dominant side were measured. Static balance was performed on the force plate in different situations each for 30 seconds: bilateral stance with eyes open, bilateral stance with eyes closed, as well as dominant leg and non-dominant leg unilateral stance with eyes open. Gait was measured during level walking using an optical motion capture system. Additionally, the dynamic stability margin (DSM) was calculated for the level walking trials., Results: The study results indicated that gait parameters were not significantly affected by age (p≥0.12), while knee and grip strength, along with several balance parameters, showed a significant decline with age. All individuals were able to maintain their bipedal balance, but their center of pressure movement increased significantly by age (p≤0.028). Z-scores were calculated to compare significant age parameters. Unipedal stance time was found to be the most affected by age compared to other contributing factors (p≤0.001). The duration of unipedal balance showed the most significant change per decade (non-dominant: -0.62 SDs; dominant: -0.53 SDs), while strength measures exhibited the lowest amount of change per decade (grip strength: -0.34 SDs; knee strength: -0.26 SDs). Sex differences were observed exclusively in strength parameters, with no discernible impact on the decline in balance parameters., Conclusions: These findings suggest that the duration of unipedal stance can serve as a reliable and gender-independent measure of neuromuscular aging for both elderly male and female subjects., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Rezaei et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Trunk postural control (TPC) is critical in maintaining balance following perturbations (i.e., avoiding falls), and impaired among persons with lower extremity trauma, contributing to elevated fall risk. Previously, a fall-prevention program improved TPC in individuals with unilateral transtibial amputation following trip-inducing perturbations. However, it is presently unclear if these improvements are task specific., Research Question: Do improvements to TPC gained from a fall-prevention program translate to another task which assesses TPC in isolation (i.e., unstable sitting)? Secondarily, can isolated TPC be used to identify who would benefit most from the fall-prevention program?, Methods: Twenty-five individuals (21 male/4 female) with lower extremity trauma, who participated in a larger fall-prevention program, were included in this analysis. Trunk flexion and flexion velocity quantified TPC following perturbation; accelerometer-based sway parameters quantified TPC during unstable sitting. A generalized linear mixed-effects model assessed training-induced differences in TPC after perturbation; a generalized linear model assessed differences in sway parameters following training. Spearman's rho related training-induced changes to TPC following perturbation (i.e., the difference in TPC measures at pre- and post-training assessments) with pre- vs. post-training changes to sway parameters during unstable sitting (i.e., the difference in sway parameters at pre- and post-training assessments) as well as pre-training sway parameters with the pre- vs. post-training differences in TPC following perturbation., Results: Following training, trunk flexion angles decreased, indicating improved TPC; however, sway parameters did not differ pre- and post-training. In addition, pre- vs. post-training differences in TPC following perturbation were neither strongly nor significantly correlated with sway parameters. Moreover, pre-training sway parameters did not correlate with pre- vs. post-training differences in trunk flexion/flexion velocity., Significance: Overall, these results indicate that improvements to TPC gained from fall-prevention training are task-specific and do not translate to other activities. Moreover, isolated TPC measures are not able to identify individuals that benefit most from the fall-prevention program., (Published by Elsevier B.V.)

Background: Falls are a leading cause of injury in older women. Stepping thresholds quantify balance-reaction capabilities. It is unclear how such evaluations predict falls in comparison to, or as a complement to, other objective measures of gait, standing postural control, strength, and balance confidence., Aims: The objective of this study was to determine if stepping thresholds are prospectively related to falls in older women., Methods: For this prospective cohort study, 125 ambulatory, community-dwelling women, age ≥ 65 years were recruited. Using a treadmill to deliver perturbations to standing participants, we determined anteroposterior single- and multiple-stepping thresholds. Here, thresholds represent the minimum perturbation magnitudes that consistently evoke one step or multiple steps. In addition, gait kinematics, obstacle-crossing kinematics, standing sway measures, unipedal stance time, the functional reach, lower extremity isometric strength, grip strength, balance confidence, and fall history were evaluated. Falls were prospectively recorded for one year., Results: Seventy-four participants (59%) fell at least once. Posterior single-stepping thresholds were the only outcome that predicted future fall status (OR = 1.50, 95% CI 1.01-2.28; AUC = .62). A multivariate approach added postural sway with eyes closed as a second predictive variable, although predictive abilities were not meaningfully improved., Discussion: These results align with the previous evidence that reactive balance is a prospective indicator of fall risk. Unlike previous studies, strength scaled to body size did not contribute to fall prediction., Conclusion: Posterior single-stepping thresholds held a significant relationship with future fall status. This relationship was independent of, and superior to that of, other measures of standing balance, gait, strength, and balance confidence.

Background: Research has shown that postural perturbation training reduces falls. Trunk kinematics, at recovery step, are key outcome measures. Fall prevention training programs are being developed for routine clinical care. In these programs, the subject is positioned on a treadmill and subjected to forward and backward disturbances which simulate trips and slips. The patient wears a safety vest attached to an overhead harness to create a secure environment. Motion capture is used to measure trunk kinematics., Research Question: It is important to verify that trunk kinematics are independent of harness configuration. The purpose of this study was to compare the trunk flexion angle and angular velocity at recovery step after forward and backward disturbances on a treadmill measured by motion capture with the harness in both a fixed and free position., Methods: Ten healthy young adults (5/10 female, age: 29.2 ± 6.3 years, BMI: 24.2 ± 2.4) participated in this study. The subjects had retro-reflective markers placed on key anatomical landmarks to measure trunk kinematics. The participants experienced forward and backward disturbances, which incrementally increased in intensity until the harness clearly supported the subjects for three disturbances in both directions. The order of harness configurations was randomized across subjects and each subject participated in two consecutive rounds of disturbances, one round for each harness configuration. Equivalence testing was performed to demonstrate that the harness configurations were equivalent (α = 0.05)., Results and Significance: The Equivalence Test demonstrated that the trunk angle (TA) and angular velocity (TAV) were equivalent for the different harness configurations. The 95% Confidence Intervals (TA: [-2, 1], TAV: [-18, 16]) were within the equivalence interval (TA: [-3, 3], TAV: [-20, 20]) and the p-Values (TA: 0.008, TAV: 0.034) were less than alpha. Trunk kinematics are independent of overheard harness configurations during treadmill induced disturbances for clinical postural perturbation training., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Treadmill-induced postural perturbations are a promising tool in assessing and reducing the risk of falls. We evaluated the accuracy with which two treadmills (Simbex ActiveStep ® and an AMTI instrumented treadmill) achieved commanded displacements, peak velocities, and average initial accelerations. To do so, we included a range of perturbation magnitudes (20, 30, and 40 cm displacements) applied in unweighted and weighted (body mass = 46-84 kg) conditions. Across treadmills and perturbation magnitudes, absolute errors in displacement (< 0.5 cm) and peak velocity (< 4 cm/s) were small (relative error < 5%). Between-treadmill differences in displacement and peak velocity were marginal (< 3%), regardless of the perturbation magnitude and participant body mass. Observed accelerations were more than 5% smaller than commanded values. The front, but not back, AMTI belt demonstrated less acceleration accuracy than the ActiveStep ® (≈ 5% difference). In summary, both treadmills demonstrated a reasonable, consistent level of accuracy in delivering postural perturbations., (Copyright © 2019 IPEM. Published by Elsevier Ltd. All rights reserved.)

Background: Compensatory stepping thresholds evaluate the response to postural disturbances. Although such fall-recovery measures are a promising indicator of fall risk, the relationships between stepping thresholds and other measures used to predict falls are not well established., Research Question: We sought to quantify the relationships between stepping thresholds and other measurements used to assess fall risk in older women, a population at high risk for falls and related injuries, including fractures., Methods: We studied 112 ambulatory, community-dwelling women, age 65 years or older. Using a treadmill to deliver standing postural disturbances, we determined anterior and posterior single-stepping and multiple-stepping thresholds. These thresholds represented the magnitude of the disturbance that elicited one step or more than one step, respectively. We also assessed balance confidence, functional reach, unipedal stance time, isometric strength, obstacle crossing, postural sway, and gait kinematics. Outcomes were normalized to body size., Results: After accounting for age, stepping thresholds were, at most, moderately correlated (Pearson partial correlation coefficients r = 0.20 to 0.40 and r = -0.21 to -0.31) to several assessments of gait, postural control, and strength. Approximately 24-52% of the variance in stepping thresholds was explained by a combination of age and other fall risk assessments, which frequently consisted of balance confidence, unipedal stance time, obstacle crossing, the Romberg ratio of postural sway, and/or strength., Significance: Our results suggest that anteroposterior fall-recovery ability, as assessed by stepping thresholds, can only be partially inferred from age and a combination of assessments of sway, strength, unipedal tasks, and balance confidence. Compensatory stepping thresholds may provide information on stability maintenance unique from other assessments of fall risk. Further investigation would be necessary to determine whether stepping thresholds are better predictors of falls in older women., (Copyright © 2018. Published by Elsevier B.V.)

Objective: We sought to characterize the circumstances, orientations, and impact locations of falls in community-dwelling, ambulatory, older women., Methods: For this longitudinal, observational study, 125 community-dwelling women age≥65years were recruited. Over 12-months of follow-up, fall details were recorded using twice-monthly questionnaires., Results: More than half (59%) of participants fell, with 30% of participants falling more than once (fall rate=1.3 falls per person-year). Slips (22%) and trips (33%) accounted for the majority of falls. Approximately 44% of falls were forward in direction, while backward falls accounted for 41% of falls. About a third of all falls were reported to have lateral (sideways) motion. Subjects reported taking a protective step in response to 82% of forward falls and 37% of backward falls. Of falls reporting lateral motion, a protective step was attempted in 70% of accounts. Common impact locations included the hip/pelvis (47% of falls) and the hand/wrist (27%). Backwards falls were most commonly reported with slips and when changing direction, and increased the risk of hip/pelvis impact (OR=12.6; 95% CI: 4.7-33.8). Forward falls were most commonly reported with trips and while hurrying, and increased the risk of impact to the hand/wrist (OR=2.6; 95% CI: 1.2-5.9)., Conclusion: Falls in older ambulatory women occur more frequently than previously reported, with the fall circumstance and direction dictating impact to common fracture locations. Stepping was a common protective recovery strategy and that may serve as an appropriate focus of interventions to reduce falls in this high risk population., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Unlabelled: The role of the spine as a gait stabilizer is essential. Dynamic assessment, while walking, might provide complementary data to improve spinal deformity management. The aim of this paper was to review spine dynamic behavior and the various methods that have been used to assess gait dynamic balance in order to explore the consequences of spinal deformities while walking. A review was performed by obtaining publications from five electronic databases. All papers reporting pathological or non-pathological spine dynamic behavior during gait and dynamic balance assessment methods were included. Sixty articles were selected. Results varied widely according to pathologies, study conditions, and balance assessment techniques. Three methods assessing dynamic stability during gait were identified: local-orbital dynamic stability, tri-axial accelerometry, and dynamic stability margin. Data from conventional gait analysis techniques were established essentially for scoliosis and low back pain, but they do not assess specific consequences on gait dynamic balance. Three techniques investigate gait dynamic balance and have been validated in normal subjects. Further investigations need to be performed for validation in spinal pathologies as well as the value for clinical practice., Level of Evidence: Level IV., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)

The purpose of this study was to evaluate the test-retest, intra-rater reliability and agreement of compensatory stepping thresholds. A protocol was developed to establish anteroposterior single-stepping thresholds, anteroposterior multiple-stepping thresholds, and lateral single-stepping thresholds. Healthy, young subjects stood on a microprocessor-controlled treadmill, and responded to three series of progressively challenging surface translations. Subjects were instructed to "try not to step" when establishing single-stepping thresholds or "try to take only one step" when establishing multiple-stepping thresholds. Stepping thresholds were defined as the minimum disturbance magnitude that consistently elicited a single or second compensatory step. Thresholds were expressed as the ankle torque necessary to maintain upright posture. Thresholds studied included anterior single-stepping thresholds (τ = 273.0 ± 82.3 N m), posterior single-stepping, thresholds (τ = 235.5 ± 98.0 N m), anterior multiple-stepping thresholds (τ = 977.0 ± 416.3 N m), posterior multiple-stepping thresholds (τ = 701.9 ± 237.5 N m), stability-side lateral single-stepping thresholds (τ = 225.7 ± 77.7 Nm), and mobility-side lateral single-stepping thresholds (τ = 236.8 ± 85.4 N m). Based on intraclass correlation coefficients (ICC) and Bland-Altman plots, all thresholds demonstrated excellent reliability (ICC(2,1) = 0.87-0.97) and agreement. These results suggest that compensatory stepping thresholds have sufficient repeatability to be used in clinical and research-related assessments of fall-risk. Additional study is needed to determine the intra- and inter-rater reliabilities and validity of thresholds specific to the patient populations of interest., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The purpose of this study was to evaluate the effects of compensatory-step training of healthy, mobile, young-to-middle aged people with unilateral, transfemoral or knee disarticulation amputations. Outcomes of interest included recovery success, reliance on the prosthesis, and the kinematic variables relevant to trip recovery. Over the course of six training sessions, five subjects responded to postural disturbances that necessitated forward compensatory steps to avoid falling. Subjects improved their ability to recover from these postural disturbances without falling or hopping on the non-prosthetic limb. Subjects improved their compensatory stepping response by decreasing trunk flexion and increasing the sagittal plane distance between the body center of mass and the stepping foot. In response to more challenging disturbances, these training-related improvements were not observed for the initial step with the non-prosthetic limb. Regardless of the stepping limb, step length and the change in pelvic height were not responsive to training. This study exhibits the potential benefits of a compensatory-step training program for amputees and informs future improvements to the protocol., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The purpose of this report is to provide novel findings from the kinematics of five amputees following a laboratory-induced trip. Only amputees with a unilateral, transfemoral or knee disarticulation amputation were included in this study. When the prosthesis was obstructed, all subjects used a lowering strategy, resulting in three harness-assisted recoveries and one fall. When the non-prosthetic limb was obstructed, one subject fell using an elevating strategy, one subject fell using a lowering strategy, and one subject, who was harness-assisted, used a hopping strategy. These results can be used to guide further studies of how to limit prosthetic knee flexion due to weight-bearing during a lowering strategy, implement compensatory step training to reduce fall risk, and identify appropriate, context-specific recovery strategies for people with transfemoral or knee disarticulation amputations., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Objective: The aim of the study was to determine the proportion of body weight borne through the lower limbs in persons with complete motor paraplegia using a standing frame, with and without the support of their arms. We also examined the effect of low-magnitude whole-body vibration on loads borne by the lower limbs., Design: Vertical ground reaction forces (GRFs) were measured in 11 participants (six men and five women) with paraplegia of traumatic origin (injury level T3-T12) standing on a low-magnitude vibrating plate using a standing frame. GRFs were measured in four conditions: (1) no vibration with arms on standing frame tray, (2) no vibration with arms at side, (3) vibration with arms on tray, and (4) vibration with arms at side., Results: GRF with arms on tray, without vibration, was 0.76 ± 0.07 body weight. With arms at the side, GRF increased to 0.85 ± 0.12 body weight. With vibration, mean GRF did not significantly differ from no-vibration conditions for either arm positions. Oscillation of GRF with vibration was significantly different from no-vibration conditions (P < 0.001) but similar in both arm positions., Conclusions: Men and women with paraplegia using a standing frame bear most of their weight through their lower limbs. Supporting their arms on the tray reduces the GRF by approximately 10% body weight. Low-magnitude vibration provided additional oscillation of the load-bearing forces and was proportionally similar regardless of arm position.

Background: Microprocessor-controlled knee joints appeared on the market a decade ago. These joints are more sophisticated and more expensive than mechanical ones. The literature is contradictory regarding changes in gait and balance when using these sophisticated devices., Methods: This study employed a crossover design to assess the comparative performance of a passive mechanical knee prosthesis compared to a microprocessor-controlled knee joint in 15 subjects with an above-knee amputation. Objective measurements of gait and balance were obtained., Results: Subjects demonstrated significantly improved gait characteristics after receiving the microprocessor-controlled prosthetic knee joint (p<0.01). Improvements in gait were a transition from a hyperextended knee to a flexed knee during loading response which resulted in a change from an internal knee flexor moment to a knee extensor moment. The participants' balance also improved (p<0.01). All conditions of the Sensory Organization Test (SOT) demonstrated improvements in equilibrium score. The composite score also increased., Conclusions: Transfemoral amputees using a microprocessor-controlled knee have significant improvements in gait and balance.

Stance control knee orthoses (SCOs) have become very popular recently. However, there is little information regarding opinions of actual orthosis users. The purpose of this study was to quantify the users' opinions of a SCO, and see whether factors found important for knee orthoses in past studies hold true for a stance control orthosis as well. A standardized survey was employed as part of a larger field trial study of the Dynamic Knee Brace System, a SCO developed by the authors. The Dynamic Knee Brace System scored well in areas of effectiveness, operability, and dependability, but areas in need of improvement included weight, cosmesis, and donning and doffing. These findings match well with previous knee orthosis studies. This study shows that wearing a stance control knee orthosis can be a positive experience for an orthosis user.

This controlled trial was designed to investigate the influence of osteoporosis-related kyphosis (O-K) on falls. Twelve community-dwelling women with O-K (Cobb angle, 50-65 degrees measured from spine radiographs) and 13 healthy women serving as controls were enrolled. Mean age of the O-K group was 76 years (+/-5.1), height 158 cm (+/-5), and weight 61 kg (+/-7.9), and mean age of the control group was 71 years (+/-4.6), height 161 cm (+/-3.8), and weight 66 kg (+/-11.7). Quantitative isometric strength data were collected. Gait was monitored during unobstructed level walking and during stepping over an obstacle of four different heights randomly assigned (2.5%, 5%, 10%, and 15% of the subject's height). Balance was objectively assessed with computerized dynamic posturography consisting of the sensory organization test. Back extensor strength, grip strength, and all lower extremity muscle groups were significantly weaker in the O-K group than the control group (P <0.05), except right ankle plantar flexors (P =0.09). There was a significant difference in the anteroposterior and mediolateral displacements and velocities. The O-K subjects had less anteroposterior displacement, greater mediolateral displacement, reduced anteroposterior velocity, and increased mediolateral velocity compared with controls for all conditions of unobstructed and obstructed level walking. Obstacle height had a significant effect on all center-of-mass variables. The O-K subjects had significantly greater balance abnormalities on computerized dynamic posturography than the control group (P =0.002). Data show that thoracic hyperkyphosis on a background of reduced muscle strength plays an important role in increasing body sway, gait unsteadiness, and risk of falls in osteoporosis.

This study was performed to investigate whether elderly patients with imbalance can be distinguished from healthy elderly subjects by comparing their whole body center of mass (COM) motion in the medio-lateral (M-L) direction during obstacle crossing. Nine healthy elderly adults and six elderly patients having complaints of 'dizziness' or 'unsteadiness' during walking (three with bilateral/unilateral vestibular weakness and three with unclear diagnosis) were recruited to perform unobstructed level walking and crossing of obstacles set to 2.5, 5, 10 and 15% of each subject's height. Kinematics of the COM was calculated using a weighted sum average of a 13-segment biomechanical model. There were no significant group differences for the temporal-distance gait parameters during all testing conditions. However, elderly patients with balance disorders demonstrated significantly greater and faster lateral motion of the COM when crossing over obstacles. These measurements distinguish elderly patients with imbalance from healthy elderly subjects. Furthermore, the increased M-L motion of the COM during obstacle crossing showed a positive correlation with an increased M-L range of motion of the swing foot trajectory. This increase in M-L motion indicates a compensatory adjustment in the swing foot trajectory to land the swing foot at an appropriate location that would establish a new base of support to counter the balance disturbance in the frontal plane.

Objective: To assess the sensations of instability that many patients report after traumatic brain injury (TBI)., Design: A controlled study., Setting: A motion analysis and vestibular and balance laboratory., Participants: Twenty subjects, 10 with TBI and complaints of instability, and 10 without TBI., Interventions: Balance and gait analysis., Main Outcome Measures: Dizziness Handicap Inventory (DHI), caloric irrigation, optokinetic testing, Dix-Hallpike Test, posturography, and center of mass (COM) movement., Results: Subjects were well matched in terms of age, height, weight, and gender. DHI scores of those with and without TBI differed significantly (32.2+/-23.0 vs 0.2+/-0.63, P<.001). Caloric and optokinetic circularvection testing were abnormal only in subjects with TBI (8/10 and 4/10, respectively). Benign paroxysmal positioning vertigo was present in only 3 subjects with TBI, and this either resolved spontaneously (n=1) or was successfully treated (n=2). Composite posturography scores of those with and without TBI differed significantly (69.6+/-35.8 vs 79.5+/-40.5, P=.02). Gait parameters also differed significantly between the groups (P=.05), with the subjects with TBI having lower anterior and posterior and higher medial and lateral COM displacements and velocities., Conclusions: Patients' complaints of instability after TBI may have objective correlates and may be rectifiable. Balance and gait testing in these patients is warranted., (Copyright 2003 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation)

Tripping over obstacles and imbalance during gait were reported as two of the most common causes of falls in the elderly. Imbalance of the whole body during obstacle crossing may cause inappropriate movement of the lower extremities and result in foot-obstacle contact. Thus, this study was performed to investigate the effect of obstacle height on the motion of the whole body's center of mass (COM) and its interaction with the center of pressure (COP) of the stance foot while negotiating obstacles. Six healthy young adults were instructed to perform unobstructed level walking and to step over obstacles of heights corresponding to 2.5, 5, 10, and 15% of the subject's height, all at a comfortable self-selected speed while walking barefoot. A 13-link biomechanical model of the human body was used to compute the kinematics of the whole body's COM. Stepping over the higher obstacles resulted in significantly greater ranges of motion of the COM in the anterior-posterior and vertical directions, a greater velocity of the COM in the vertical direction, and a greater anterior-posterior distance between the COM and COP. In contrast, the motion of the COM in the medial-lateral direction was less likely to be affected when negotiating obstacles of different heights.