Biomechanical Balance Measures During Timed Up and Go Test Improve Prediction of Prospective Falls in Older Adults.

OBJECTIVE: To assess the feasibility of using biomechanical gait balance measures, the frontal and sagittal plane center of mass (COM)-Ankle angles, to prospectively predict recurrent falls in community-dwelling older adults. DESIGN: A cohort study with a 1-year longitudinal follow-up. Logistic regression was used to test the ability of the COM-Ankle angles to predict prospective falls. SETTING: General community. PARTICIPANTS: Sixty older adults over the age of 70 years were recruited using a volunteer sample. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE(S): Biomechanical balance parameters: the sagittal and frontal plane COM-Ankle angles during the sit-to-walk and turning phases of the timed Up and Go test. The COM-Ankle angles are the inclination angles of the line formed by the COM and lateral ankle (malleolus) marker of the stance foot in the sagittal and frontal planes. We also included the following clinical balance tests in the analysis: Activity-Specific Balance Confidence, Berg Balance Scale, Fullerton Advanced Balance scale, and timed Up and Go test. Their abilities to predict falls served as a reference for the biomechanical balance parameters. RESULTS: When the biomechanical gait balance measures were added to all the confounders, the explained variance was increased from 25.3% to 50.2%. Older adults who have a smaller sagittal plane COM-Ankle angle at seat-off, a greater frontal plane COM range of motion during STW and a smaller frontal plane angle during turning were more likely to become recurrent fallers. CONCLUSION(S): Our results indicated that dynamic biomechanical balance parameters could provide valuable information about a participant's future fall risks beyond what can be explained by demographics, cognition, depression, strength, and past fall history. Among all biomechanical parameters investigated, frontal plane COM motion measures during STW and turning appear to be the most significant predictors for future falls.

Center of mass motion and plantar pressure distribution during walking in overweight individuals.

BACKGROUND: Gait imbalance has been reported in overweight individuals and could further impair their mobility and quality of life. As the feet are the most distal part of the body and sensitively interface with external surroundings, evaluating the plantar pressure distribution can provide critical insights into their roles in regulating gait balance control. Therefore, the purpose of this study was to evaluate the effect of body weight and different gait speeds on the plantar pressure distribution and whole-body center of mass (COM) motion during walking. METHODS: Eleven overweight individuals (OB) and 13 non-overweight individuals (NB) walked on a 10-meter walkway at three speed conditions (preferred, 80% and 120% of preferred speed). Gait balance was quantified by the mediolateral COM sway. Plantar pressure data were obtained using wireless pressure-sensing insoles that were inserted into a pair of running shoes. Analysis of variance models were used to examine the effect of body size, gait speeds, or their interactions on peak mediolateral COM and peak plantar pressure during walking. RESULTS: Significant group effects of peak plantar pressure under the lateral forefoot (P = 0.03), lateral midfoot (P = 0.02), and medial heel (P = 0.02) were observed. However, the mediolateral COM motion and spatiotemporal gait parameters only revealed significant speed effects. SIGNIFICANCE: Findings from this study indicated that overweight individuals exhibited increased plantar pressure under the lateral aspect of the foot, particularly during the late stance phase of walking, in an effort to maintain a comparable mediolateral COM motion to that of non-overweight individuals. Such elevated pressure in overweight individuals may potentially increase the risk of musculoskeletal pathology in the long term. The identified patterns are noteworthy as they have practical implications for designing targeted interventions and improving the overall health of individuals with a high BMI.

Dual task cost in adults with persistent concussion symptoms.

BACKGROUND: Persistent concussion symptoms (PCS) negatively affects common activities of daily living including deficits in both single and dual-task (DT) gait. DT gait deficits are present post-concussion; however, task prioritization and the effects of differing cognitive challenge remain unexplored in the PCS population. RESEARCH QUESTION: The purpose of this study was to investigate single and dual-task gait performance in individuals with persistent concussion symptoms and to identify task priorization strategies during DT trials. METHODS: Fifteen adults with PCS (age: 43.9+11.7 y.o.) and 23 healthy control participants (age: 42.1+10.3 y.o.) completed five trials of single task gait followed by fifteen trials of dual task gait along a 10-m walkway. The cognitive challenges consisted of five trials each of visual stroop, verbal fluency, and working memory cognitive challenges. Groups were compared on DT cost stepping characteristics with independent samples t-test or Mann-Whitney U tests. RESULTS: There were significant overall gait Dual Task Cost (DTC)difference between groups for gait speed (p = 0.009, d=0.92) and step length (p = 0.023, d=0.76). Specific to each DT challenge, PCS participants were slower during Verbal Fluency (0.98 + 0.15 m/s and 1.12 + 0.12 m/s, p = 0.008; d=1.03), Visual Stroop (1.06 + 0.19 m/s and 1.20 + 0.12 m/s, p = 0.012, d=0.88), and Working Memory (1.02 + 0.15 m/s and 1.16 + 0.14 m/s, p = 0.006, d=0.96). There were significant cognitive DTC differences between groups for WM accuracy (p = 0.008, d=0.96), but not for VS accuracy (p = 0.841, d=0.061) or VF total words (p = 0.112, d=0.56). SIGNIFICANCE: The PCS participants displayed a posture-second strategy whereby gait performance generally decreased in the absence of cognitive changes. However, during the Working Memory DT, PCS participants had a mutual interference response whereby both motor and cognitive performance decreased suggesting the cognitive task plays a key role in the DT gait performance of PCS patients.

Contribution of lower extremity muscles to center of mass acceleration during walking: Effect of body weight.

Overweight or obesity is known to be associated with altered activations of lower extremity muscles. Such changes in muscular function may lead to the development of mobility impairments or joint diseases. However, little is known about how individual lower extremity muscles contribute to the whole-body center of mass (COM) control during walking and the effect of body weight. This study examined the contribution of individual lower extremity muscle force to the COM accelerations during walking in overweight and non-overweight individuals. Musculoskeletal simulations were performed for the stance phase of walking with data collected from 11 overweight and 13 non-overweight adults to estimate lower extremity muscle forces and their contributions to the COM acceleration. Mean time-series data from each parameter were compared between body size groups using Statistical Parametric Mapping. Compared to the non-overweight group, the overweight group revealed a greater gastrocnemius contribution to the mediolateral (p = 0.006) and vertical (p < 0.001) COM accelerations during mid-stance, and had a lower vastus contribution to the anteroposterior COM acceleration (p < 0.001) during pre-swing. Increased contributions from the large posterior calf muscles to the mediolateral COM acceleration may be related to efforts to alleviate COM sway in overweight individuals.

Inter-joint coordination variability during a sit-to-stand fatiguing protocol.

A repetitive sit-to-stand (STS) task is often used as a fatiguing protocol. Although post-fatigue reductions in muscle strength have been frequently used to indicate fatigue, little is known about changes in body movement during the fatiguing process. This study examined changes in variability of hip-knee and knee-ankle coordination during the STS fatiguing course in 15 young (age: 26.7 ± 5.8 years; 9 females, 6 males) and 15 older adults (age: 69.3 ± 5.7 years; 9 females, 6 males). Participants were asked to perform repetitive STS movements until exhaustion or for 30 min at a self-selected pace. Motion data from 3 consecutive STS cycles were extracted from every minute during the entire fatiguing course and time normalized to STS duration and dummy coded as five stages: 0-20, 20-40, 40-60, 60-80, and 80-100% of the course. Outcome variables were hip-knee and knee-ankle inter-joint coordination variabilities. A 2*5 mixed-effect ANOVA was used to examine changes in variability during different stages of the course in young and older adults. No Age × Time interactions were found in either hip-knee or knee-ankle coordination variability. The hip-knee coordinative variability significantly increased along the STS fatiguing course regardless of age, and the knee-ankle variability from standing to sitting was also higher at the ending, when compared to the beginning, of the fatiguing protocol. The impact of fatigue during repetitive STS protocol is not only limited to a force production decline but also manifested as increased coordinative variability, which could be considered as a fatigue indicator.

Gait balance control after fatigue: Effects of age and cognitive demand.

BACKGROUND: Fatigue is a commonly mentioned symptom in older adults, and walking under the influence of fatigue frequently occurs in daily activities. Studies have reported individual effects from fatigue or cognitive demand on gait performance. However, the information on how fatigue and cognitive demand interact to affect gait balance control is still lacking. RESEARCH QUESTION: How does fatigue affect walking balance control in young and older adults with and without performing a concurrent cognitive task? METHODS: We collected and analyzed motion data from 17 young and 17 older adults, who performed over-ground walking with and without a concurrent working memory test, before and after been fatigued by performing repetitive sit-to-stand movements. Three-way ANOVAs were used for statistical analysis with Age (young and older adults), Fatigue (pre- and post-fatigue), and Task (single-task and dual-task) as factors. RESULTS: From pre- to post-fatigue, an increased gait velocity was observed during dual-task walking regardless of age (p = .02). Only young adults demonstrated a significant increase in mediolateral center of mass displacement (M-L CoM) at post-fatigue (p = .019). Accuracies of the working memory test were not affected by Age, Task, or Fatigue. SIGNIFICANCE: Our findings revealed that gait balance control, as measured by the M-L CoM, deteriorated post-fatigue in young adults. Older adults maintained their mediolateral body sway from pre-fatigue to post-fatigue. Fatigue effects were not further exacerbated during dual-task walking, and similar cognitive performance was maintained as performance fatigability increased.

Discriminating features of ground reaction forces in overweight old and young adults during walking using functional principal component analysis.

BACKGROUND: Limited attention has been paid to age- or body size-related changes in the ground reaction forces (GRF) during walking despite their strong associations with lower limb injuries and pathology. RESEARCH QUESTION: Do the features of GRF during walking associate with age or body size? METHODS: Fifty-four participants were subdivided into four groups according to their age and body size: overweight old (n = 12), non-overweight old (n = 13), overweight young (n = 13), and non-overweight young (n = 16). Participants were asked to walk at their self-selected speeds on level ground with force plates embedded in the center of walkway. Functional principal component analysis (FPCA) was performed to extract major modes of variation and functional principal component scores (FPCs) in three-dimensional GRFs. Analysis of variance models were employed to investigate the effect of age, body size, or their interactions on the FPCs of each component of the GRF, with the adjustment to gait speed. RESULTS: Significant age and body size effects were observed in FPC1 across all three-dimensional GRF. Both overweight and older groups showed greater braking force after heel-strike and greater propulsive forces during pre-swing when compared to the non-overweight and younger groups, respectively. The overweight old group displayed greater medial forces during mid-stance and the overweight young group showed prominently larger medial forces during pre-swing, while non-overweight old showed a tendency of flatter medial-lateral GRF waveforms during the entire stance phase. FPC2 revealed that only body size had an effect on three-dimensional GRF with the highest FPC2 scores in the overweight old group. SIGNIFICANCE: Three-dimensional GRF during walking could be altered by the body size and age, which were more pronounced in the overweight and older group. The more dynamic GRF pattern with greater and/or lower peaks could be contributing factors to the increased joint load and injury rates observed in overweight aged individuals.

Lower limb muscle activation in response to balance-perturbed tasks during walking in older adults: A systematic review.

BACKGROUND: Declines in muscular function may hinder our ability to properly respond balance perturbations during walking. Examining age-related differences in muscle activation during balance-perturbed walking could be an important summary of literature to guide future clinical or scientific research. RESEARCH QUESTION: Are there differences in lower limb muscle activation between young and older adults when responding to balance perturbations during walking? METHODS: A literature search was conducted in October 2020 to identify relevant articles using Pubmed, Scopus, Web of Science, Ovid EMBASE, and CINAHL. Inclusion criteria were defined to identify studies investigating lower limb muscle activation in healthy older adults during balance-perturbed walking. Data extraction was independently performed by both authors. Outcome measures included key findings of lower limb muscle activations during walking and balance-related tasks (e.g. multidirectional perturbations, different speeds, cognitive tasks, slippery/slopes, and obstacles). RESULTS: This article reviewed fourteen studies including 230 older adults (age: 70 ± 4.5, females: 124 [53.9%]) and 230 young adults (age: 23 ± 2.0, females: 113 [49.1%]). The overall quality of included studies was fair, with a mean score of 76%. Twelve lower limb muscles were assessed during balance-perturbed walking. All studies reported electromyographic measurements, including magnitude, timing, co-contraction indices, and variability of activation. SIGNIFICANCE: Compared to young adults, older adults demonstrated different adaptations in lower limb muscle activation during balance-perturbed walking. Co-contraction of ankle and knee joint muscles had more conclusive results, with the majority reporting an increased co-contraction in older adults, especially when balance is perturbed by a physical task. These data suggest that coordination between agonist and antagonist muscles is important to provide necessary stabilization during balance-perturbed walking.

Implementing an Online Virtual Falls Prevention Intervention During a Public Health Pandemic for Older Adults with Mild Cognitive Impairment: A Feasibility Trial.

PURPOSE: This study evaluates the feasibility of delivering a virtual (online) falls prevention intervention for older adults with mild cognitive impairment (MCI). METHODS: Community-dwelling older adults with MCI (mean age = 76.2 years, 72% women) were randomized to either a Tai Ji Quan (n = 15) or stretching group (n = 15) and participated in 60-minute virtual exercise sessions, via Zoom, twice weekly for 24 weeks. The primary outcome was the incidence of falls. Secondary outcomes were the number of fallers and changes from baseline in the 4-Stage Balance Test, 30-second chair stands, and Timed Up and Go Test under both single- and dual-task conditions. RESULTS: The intervention was implemented with good fidelity, an overall attendance rate of 79%, and 13% attrition. Compared with stretching, Tai Ji Quan did not reduce falls (incidence rate ratio = 0.58; 95% confidence interval [CI], 0.32 to 1.03) or the number of fallers (relative risk ratio = 0.75; 95% CI, 0.46 to 1.22) at week 24. The Tai Ji Quan group, however, performed consistently better than the stretching group in balance (between-group difference in change from baseline, 0.68 points; 95% CI, 0.12 to 1.24), 30-second chair stands (1.87 stands; 95% CI, 1.15 to 2.58), and Timed Up and Go under single-task (-1.15 seconds; 95% CI, -1.85 to -0.44) and dual-task (-2.35; 95% CI, -3.06 to -1.64) conditions. No serious intervention-related adverse events were observed. CONCLUSION: Findings from this study suggest the feasibility, with respect to intervention fidelity, compliance, and potential efficacy, of implementing an at-home, virtual, interactive Tai Ji Quan program, delivered in real-time, as a potential balance training and falls prevention intervention for older adults with MCI. The study provides preliminary data to inform future trials.

Efficacy of exercise-based interventions in preventing falls among community-dwelling older persons with cognitive impairment: is there enough evidence? An updated systematic review and meta-analysis.

OBJECTIVE: Exercise prevents falls in the general older population, but evidence is inconclusive for older adults living with cognitive impairment. We performed an updated systematic review and meta-analysis to assess the potential effectiveness of interventions for reducing falls in older persons with cognitive impairment. METHODS: PubMed, EMBASE, CINAHL, Scopus, CENTRAL and PEDro were searched from inception to 10 November 2020. We included randomised controlled trials (RCTs) that evaluated the effects of physical training compared to a control condition (usual care, waitlist, education, placebo control) on reducing falls among community-dwelling older adults with cognitive impairment (i.e. any stage of Alzheimer's disease and related dementias, mild cognitive impairment). RESULTS: We identified and meta-analysed nine studies, published between 2013 and 2020, that included 12 comparisons (N = 1,411; mean age = 78 years; 56% women). Overall, in comparison to control, interventions produced a statistically significant reduction of approximately 30% in the rate of falls (incidence rate ratio = 0.70; 95% CI, 0.52-0.95). There was significant between-trial heterogeneity (I2 = 74%), with most trials (n = 6 studies [eight comparisons]) showing no reductions on fall rates. Subgroup analyses showed no differences in the fall rates by trial-level characteristics. Exercise-based interventions had no impact on reducing the number of fallers (relative risk = 1.01; 95% CI, 0.90-1.14). Concerns about risk of bias in these RCTs were noted, and the quality of evidence was rated as low. CONCLUSIONS: The positive statistical findings on reducing fall rate in this meta-analysis were driven by a few studies. Therefore, current evidence is insufficient to inform evidence-based recommendations or treatment decisions for clinical practice.PROSPERO Registration number: CRD42020202094.

Using IMU-based kinematic markers to monitor dual-task gait balance control recovery in acutely concussed individuals.

BACKGROUND: Concussion may result in acutely impaired dynamic balance control that can persist up to two months post injury. Such impairment has been detected using sophisticated whole body center of mass kinematic metrics derived from camera-based motion analysis under a dual-task paradigm. However, wearable sensor kinematics for describing gait imbalance is lacking. METHODS: This study employed a longitudinal design. Gait balance control of acutely concussed and healthy matched control participants was assessed at five post-injury time points (within 72 h of injury, at one week, two weeks, one month, and two months). Tri-axial accelerations and angular velocities were collected with a dual-task gait protocol using an inertial measurement unit placed over the fifth lumbar vertebra. FINDINGS: Eight consistent gait event specific peak accelerations and six peak angular velocities measured by the inertial measurement unit were examined. Peak yaw and roll angular velocities at heel strike and peak roll angular velocities during early single-support, distinguished healthy from concussed participants across the two month post-injury period, while peak vertical acceleration at the end of terminal stance peak medial-lateral acceleration to the right during loading response showed promise. INTERPRETATION: Utilization of peak accelerations and angular velocities collected from a single inertial measurement unit placed over the fifth lumbar vertebra in a divided attention paradigm may offer a clinically feasible method for detecting subtle changes in gait balance control in concussed individuals.

Concussed athletes walk slower than non-concussed athletes during cognitive-motor dual-task assessments but not during single-task assessments 2 months after sports concussion: a systematic review and meta-analysis using individual participant data.

OBJECTIVES: To determine whether individuals who sustained a sports concussion would exhibit persistent impairments in gait and quiet standing compared to non-injured controls during a dual-task assessment . DESIGN: Systematic review and meta-analysis using individual participant data (IPD). DATA SOURCES: The search strategy was applied across seven electronic bibliographic and grey literature databases: MEDLINE, EMBASE, CINAHL, SportDISCUS, PsycINFO, PsycARTICLES and Web of Science, from database inception until June 2017. ELIGIBILITY CRITERIA FOR STUDY SELECTION: Studies were included if; individuals with a sports concussion and non-injured controls were included as participants; a steady-state walking or static postural balance task was used as the primary motor task; dual-task performance was assessed with the addition of a secondary cognitive task; spatiotemporal, kinematic or kinetic outcome variables were reported, and; included studies comprised an observational study design with case-control matching. DATA EXTRACTION AND SYNTHESIS: Our review is reported in line with the Preferred Reporting Items for Systematic review and Meta-Analyses-IPD Statement. We implemented the Risk of Bias Assessment tool for Non-randomised Studies to undertake an outcome-level risk of bias assessment using a domain-based tool. Study-level data were synthesised in one of three tiers depending on the availability and quality of data: (1) homogeneous IPD; (2) heterogeneous IPD and (3) aggregate data for inclusion in a descriptive synthesis. IPD were aggregated using a 'one-stage', random-effects model. RESULTS: 26 studies were included. IPD were available for 20 included studies. Consistently high and unclear risk of bias was identified for selection, detection, attrition, and reporting biases across studies. Individuals with a recent sports concussion walked with slower average walking speed (χ2=51.7; df=4; p<0.001; mean difference=0.06 m/s; 95% CI: 0.004 to 0.11) and greater frontal plane centre of mass displacement (χ2=10.3; df=4; p=0.036; mean difference -0.0039 m; 95% CI: -0.0075 to -0.0004) than controls when evaluated using a dual-task assessment up to 2 months following concussion. SUMMARY/CONCLUSIONS: Our IPD evidence synthesis identifies that, when evaluated using a dual-task assessment, individuals who had incurred a sports concussion exhibited impairments in gait that persisted beyond reported standard clinical recovery timelines of 7-10 days. Dual-task assessment (with motion capture) may be a useful clinical assessment to evaluate recovery after sports concussion. PROTOCOL PRE-REGISTRATION: This systematic review was prospectively registered in PROSPERO CRD42017064861.

A case-control study of gait balance control in veterans with chronic symptoms following mTBI.

BACKGROUND: Numerous investigations suggest mild traumatic brain injury (mTBI) may result in persistent gait balance control deficits. Furthermore, military Veterans with symptoms of chronic mTBI often present with physical symptoms that may be associated with impaired gait balance control which may lead to prolonged recovery, difficulty performing activities of daily living, and increased disability. It is therefore important to objectively quantify gait balance deficits in Veterans with chronic mTBI. RESEARCH QUESTION: Is gait balance control impaired in a group of Veterans with chronic symptoms of mTBI when compared to healthy matched Veterans? METHODS: Eight Veterans with symptoms of chronic mTBI (1 F/7 M) and eight healthy matched Veterans (1 F/7 M) completed a gait balance assessment under single- (ST) and dual-task (DT) conditions. Gait balance control was quantified with whole body center of mass (COM) total medial-lateral (ML) displacement and peak ML velocity, which were calculated from camera-based motion capture. RESULTS: Veterans with chronic mTBI walked with greater ML COM displacement (approximately 25 % increase) in both ST and DT walking (main effect of group, p = 0.018) when compared to healthy Veterans. The peak ML COM velocity was affected for both groups by performing a concurrent cognitive task (interaction effect, p = .012). Slower ML COM velocities in healthy Veterans suggest the adoption of a conservative balance control strategy, while faster ML COM velocities for Veterans with chronic mTBI may indicate a diminished ability to control ML momentum. SIGNIFICANCE: Increased frontal plane COM motion under both ST and DT walking was observed in Veterans with chronic mTBI symptoms many years after injury. This suggests gait balance control may be adversely affected during divided attention gait and highlights the need for comprehensive gait analysis in the management of these individuals.

Dual-Task Walking Capacity Mediates Tai Ji Quan Impact on Physical and Cognitive Function.

PURPOSE: Emerging evidence indicates exercise training improves mobility and cognition and reduces falls in older adults, but underlying mechanisms are not well understood. This study tested the hypothesis that change in dual-task walking capacity mediates the positive effect of Tai Ji Quan and multimodal exercise on physical performance, activity confidence, global cognition, and falls among community-dwelling older adults at high risk of falling. METHODS: We conducted a secondary analysis of a 6-month randomized clinical trial comparing Tai Ji Quan: Moving for Better Balance (TJQMBB) and multimodal exercise to stretching exercise in a sample of 670 adults older than 70 yr who had a history of falls or impaired mobility. Distal outcome measures, ascertained at a 12-month follow-up, were the Short Physical Performance Battery, Activities-Specific Balance Confidence, Montreal Cognitive Assessment, and falls. The mediator hypothesized to account for the intervention effects was dual-task cost estimated by calculating changes in gait speed from single-task to dual-task walking from baseline to the end of intervention. RESULTS: At 12 months, compared with stretching exercise, multimodal exercise significantly improved Short Physical Performance Battery and Activities-Specific Balance Confidence outcomes and reduced the number of falls (P < 0.05). However, it did not lower dual-task cost or mediate the intervention effects on distal outcomes. In contrast, TJQMBB significantly reduced dual-task cost relative to multimodal and stretching exercises (P < 0.05) which in turn resulted in improvements in lower-extremity physical performance, activity confidence, global cognitive function, and reductions in falls (P < 0.05) during follow-up. CONCLUSIONS: Enhanced dual-task walking capacity as a result of Tai Ji Quan training mediated improvements in physical and cognitive outcomes in older adults at high risk of falling.

Reliability and practical clinical application of an accelerometer-based dual-task gait balance control assessment.

BACKGROUND: Gait balance control assessment using whole body center of mass (COM) kinematic measures in concussed individuals reveals persistent balance deficits up to two months post-injury. A reliable and clinically practical gait balance control assessment leveraging similar kinematic measures is necessary to improve concussion assessment and management. RESEARCH QUESTION: Can peak accelerations collected during a dual-task (DT) gait assessment from a single low back placed accelerometer be measured reliably on different days, by different raters, in different environments, and be practically applied in a Division One (D1) athletics program? METHODS: A single accelerometer placed on the low back over the L5 vertebra was utilized with a DT gait analysis protocol. Twenty (10 F) healthy participants performed the assessment in a laboratory and non-laboratory environment, on two separate days, and with two different raters. Eight gait event specific peak accelerations along three orthogonal axes were collected. In addition, data were collected from a cohort of 14 D1 female soccer players during a single assessment to explore the practical clinical application. RESULTS: Cronbach's α values for the eight metrics ranged from 0.881 to 0.980 and ICC values from 0.868 to 0.987. Average assessment time for the 14 D1 female athletes was 8.50 ± 0.58 min, and significant differences between walking conditions were identified for Vert Accel 1 (p < .01), Vert Accel 2 (p = .01), and A-P Accel (p < .01). SIGNIFICANCE: High Cronbach's α and ICC values coupled with a short assessment time and sensitivity to differences in gait balance control indicate our testing apparatus and protocol are both reliable and clinically practical. Additionally, gait event specific peak accelerations from a single accelerometer can detect subtle changes in gait balance control and may facilitate improvements in sport-related concussion diagnosis and return to activity decision making.

Sex differences in lower extremity coordinative variability during running.

BACKGROUND: Differences in coordinative variability have been previously reported between healthy and injured runners. Many running-related injuries have a sex bias, particularly patellofemoral pain (PFP), as female runners are approximately twice as likely to develop PFP compared to males. However, very little is currently known regarding sex differences in coordinative variability during running. RESEARCH QUESTION: Are there sex differences in continuous relative phase (CRP) variability for pelvis-thigh and thigh-shank couplings during the stance phase of running? METHODS: Pelvis, thigh, and shank segment kinematics were collected on 15 female and 15 male subjects during overground running at a self-selected easy pace (2.39-3.56 m/s) using a 10-camera 3D motion capture system. Continuous relative phase (CRP) variability was calculated between the pelvis-thigh and thigh-shank, and averaged during four distinct stance sub-phases. A mixed effects linear model compared CRP variability between sexes at each stance sub-phase. RESULTS: Compared to males, females displayed significantly lower pelvis-thigh CRP variability in the transverse plane during the loading response phase, and significantly lower thigh-shank CRP variability in the sagittal plane during the loading response and pre-swing phases. SIGNIFICANCE: Lower coordinative variability in females during the loading response for two couplings may provide additional insight into the sex bias for developing certain running-related injuries. However, any injury implications from these results are speculative and should be interpreted with caution.

Effectiveness of Tai Ji Quan vs Multimodal and Stretching Exercise Interventions for Reducing Injurious Falls in Older Adults at High Risk of Falling: Follow-up Analysis of a Randomized Clinical Trial.

Importance: Exercise has been shown to reduce injurious falls in older adults. Evidence, however, is lacking regarding the types of intervention that are most effective in preventing injurious falls among older adults at high risk of falling. Objective: To determine the longer-term effectiveness of therapeutic tai ji quan intervention vs multimodal exercise and stretching exercise in decreasing injurious falls among older adults at high risk of falling. Design, Setting, and Participants: This trial involves a prespecified analysis with the data analyzed by intent-to-treat. Follow-up analysis of a single-blind randomized trial conducted in community settings of 7 urban and suburban cities in Oregon from February 20, 2015, to September 15, 2018, compared a therapeutic tai ji quan intervention with multimodal exercise and stretching exercise. Eligible participants were community-dwelling adults aged at least 70 years who were considered by a clinician to be at high risk of falling because they had fallen during the preceding year or who had impaired mobility with scores higher than 13.5 seconds on the Timed Up & Go test. Participants were randomized to 1 of the 3 interventions and were assessed monthly after randomization for 12 months, encompassing a 6-month active intervention phase and a 6-month after intervention follow-up phase. Interventions: The 3 group-based interventions were therapeutic tai ji quan (Tai Ji Quan: Moving for Better Balance [TJQMBB]), multimodal exercise, and stretching exercise, each implemented twice weekly in 60-minute sessions for 24 weeks. Main Outcomes and Measures: Primary outcomes were the incidence of moderate and serious injurious falls at 12 months, measured as incidence rate ratios (IRRs). Results: Of the 1147 persons screened, 670 (mean [SD] age, 77.7 [5.6] years; 436 women [65.1%]) were randomly assigned to 1 of 3 intervention groups: 224 persons in TJQMBB, 223 in multimodal exercise, and 223 in stretching exercise. At 12 months, the unadjusted IRR for moderate injurious falls was lower in the TJQMBB (IRR, 0.51; 95% CI, 0.35-0.74; P < .001) and multimodal exercise (IRR, 0.62; 95% CI, 0.42-0.89; P = .01) groups compared with the stretching exercise group. There was no difference between TJQMBB and multimodal exercise groups (IRR, 0.85; 95% CI, 0.58-1.25; P = .42). Both TJQMBB and multimodal exercise significantly reduced serious injurious falls (TJQMBB: IRR, 0.25 [95% CI, 0.13-0.48; P < .001]; multimodal: IRR, 0.56 [95% CI, 0.33-0.94; P = .03]) compared with stretching exercise. Use of TJQMBB was more effective than multimodal exercise (IRR, 0.47; 95% CI, 0.24-0.92; P = .03) in reducing serious injurious falls. Conclusions and Relevance: For preventing injurious falls, including those that resulted in medical treatment, TJQMBB intervention was found to be superior to multimodal and stretching exercises for older adults at high risk of falling. The findings appear to strengthen the clinical use of TJQMBB as a single exercise intervention to prevent injurious falls in this population. Trial Registration: ClinicalTrials.gov Identifier: NCT02287740.

Cost-Effectiveness of a Therapeutic Tai Ji Quan Fall Prevention Intervention for Older Adults at High Risk of Falling.

BACKGROUND: Data on the cost-effectiveness of proven fall prevention exercise interventions are limited. We aimed to establish the cost-effectiveness of Tai Ji Quan: Moving for Better Balance (TJQMBB) compared with a conventional exercise intervention for older adults at high risk of falling. METHODS: We conducted a trial-based cost-effectiveness analysis involving 670 older adults who had a history of falling or impaired mobility. Participants received one of three interventions-TJQMBB, multimodal exercise, or stretching exercise (control)-each of which was implemented twice weekly for 24 weeks. The primary cost-effectiveness measure was the incremental cost per additional fall prevented, comparing TJQMBB and multimodal exercise to Stretching and TJQMBB to multimodal exercise, with a secondary measure of incremental cost per additional quality-adjusted life-year (QALY) gained. The intervention was conducted between February 2015 and January 2018, and cost-effectiveness was estimated from a health care system perspective over a 6-month time horizon. RESULTS: The total cost to deliver the TJQMBB intervention was $202,949 (an average of $906 per participant); for multimodal exercise, it was $223,849 ($1,004 per participant); and for Stretching, it was $210,468 ($903 per participant). Incremental cost-effectiveness ratios showed that the multimodal exercise was cost-effective ($850 per additional fall prevented; $27,614 per additional QALY gained) relative to Stretching; however, TJQMBB was the most economically dominant strategy (ie, having lower cost and being clinically more efficacious) compared with multimodal and stretching exercises with regard to cost per additional fall prevented and per additional QALY gained. TJQMBB had a 100% probability of being cost-effective, relative to Stretching, at a threshold of $500 per each additional fall prevented and $10,000 per additional QALY gained. Sensitivity analyses showed the robustness of the results when extreme cases, medical costs only, and missing data were considered. CONCLUSIONS: Among community-dwelling older adults at high risk for falls, TJQMBB is a cost-effective means of reducing falls compared with conventional exercise approaches. TRIAL REGISTRATION: Clinicaltrials.gov (NCT02287740).

Effects of transcranial direct current stimulation over right posterior parietal cortex on attention function in healthy young adults.

Attention involves three distinct networks for alerting, orienting, and executive control. Interventions targeting the specific attentional networks remain lacking. Transcranial direct current stimulation (tDCS) has been shown to modulate cortical excitability, which potentially serves as an interventional tool to treat individuals with attention impairment. The purpose of this study was to examine the effects of applying tDCS over the right posterior parietal cortex (PPC) on the performance of the three attentional networks. Twenty-six healthy young adults performed the Attention Network Test before and after anodal or sham tDCS stimulation over the right PPC. The alerting, orienting, and executive effects were assessed before and after the stimulation. The results demonstrated that the orienting effect was significantly improved after real tDCS relative to sham, whereas the alerting and executive control effects remained unaffected. Consistent with previous clinical and functional imaging studies, this suggests that the right PPC is actively engaged with the spatial orienting of attention.