Footprint evidence of early hominin locomotor diversity at Laetoli, Tanzania.

Bipedal trackways discovered in 1978 at Laetoli site G, Tanzania and dated to 3.66 million years ago are widely accepted as the oldest unequivocal evidence of obligate bipedalism in the human lineage1-3. Another trackway discovered two years earlier at nearby site A was partially excavated and attributed to a hominin, but curious affinities with bears (ursids) marginalized its importance to the paleoanthropological community, and the location of these footprints fell into obscurity3-5. In 2019, we located, excavated and cleaned the site A trackway, producing a digital archive using 3D photogrammetry and laser scanning. Here we compare the footprints at this site with those of American black bears, chimpanzees and humans, and we show that they resemble those of hominins more than ursids. In fact, the narrow step width corroborates the original interpretation of a small, cross-stepping bipedal hominin. However, the inferred foot proportions, gait parameters and 3D morphologies of footprints at site A are readily distinguished from those at site G, indicating that a minimum of two hominin taxa with different feet and gaits coexisted at Laetoli.

Movement as a Gateway to Participation for Individuals With Neuromotor Conditions: A Scoping Review.

PURPOSE: The purpose of this scoping review was to examine and analyze the developmental and rehabilitation literature related to movement and participation at key points of transition for individuals with neuromotor conditions. METHODS: Arksey and O'Malley's scoping review protocol was applied, and 37 articles were included. Extracted data included population, developmental transition points, movement opportunity, type of participation, and outcome measures. RESULTS: Most studies covered developmental transition points; none examined transitions as a variable for participation outcomes. Physical activity/exercise was the most common movement opportunity. Most publications used formal outcome measures of participation; others used observation or interviews. CONCLUSION: No publications adequately addressed the effect of movement opportunities on participation during developmental transition points.

Association between the Functional Gait Assessment and spatiotemporal gait parameters in individuals with obesity compared to normal weight controls: A proof-of-concept study.

OBJECTIVES: Obesity is a significant global health concern that involves motor impairment, including deficits in gait and balance. A simple tool would be useful to capture gait and balance impairment in obesity. We assessed whether the Functional Gait Assessment (FGA) captures impairment in individuals with obese BMI (≥30 kg/m2) and whether impairment was related to spatiotemporal gait parameters. METHODS: Fourteen individuals with obese BMI and twenty individuals of normal weight underwent the FGA. Spatiotemporal gait parameters were collected while participants walked on a pressure sensitive walkway under five conditions: pre-baseline (flat ground walking), crossing small, medium, and high obstacles, and final-baseline (flat ground walking). RESULTS: Individuals with obesity had lower scores on the FGA (p≤0.001) and showed less efficient spatiotemporal gait parameters than healthy controls, particularly when crossing over obstacles (all ps≤0.05). For participants with obesity, lower FGA scores were associated with decreased gait velocity, but only during obstacle crossing (p≤0.05). CONCLUSIONS: The FGA may be a useful tool to capture gait impairment in populations with obesity. Obstacles may help reveal meaningful gait impairments. To our knowledge, this is the first study to examine the FGA in individuals with obesity, and represents a proof-of-concept that motivates further validation studies.

Effects of obesity class on flat ground walking and obstacle negotiation.

OBJECTIVES: Although much is known about the impact of obesity on gait, not much is understood about how classes of obesity affect movement. The purpose of this study was to examine the effects of weight classification on walking. METHODS: Sixty-seven women with normal BMI (n=13), overweight/Class I obesity (n=18), Class II obesity (n=16), and Class III obesity (n=20) participated. Gait parameters (velocity and percent of the gait cycle spent in swing and stance phases) were collected as participants walked on flat ground and crossed three obstacle heights. RESULTS: Adults with normal BMI had faster velocities (F(3,63)=12.60, p=.000017), shorter portions of the gait cycle spent in stance (F(3,62)=7.29, p=.00029), and a larger percent of the gait cycle spent in swing than those with higher BMI scores (F(3,62)=5.43, p=.002). Adults with overweight/Class I obesity had faster velocities than those with Class III obesity (p=.000082, d=1.20) as well as less variable velocities than those with Class II (p=.002, d=-.40) and Class III (p=.01, d=-1.0) obesity. No differences in velocity were found between those with Class II and Class III obesity (p=.12, d=.57). CONCLUSIONS: These results suggest the need to encourage adults to decrease overweight/Class I obesity but that an equally important goal is to prevent an increase in BMI leading to Class II obesity.

The effects of practice schedules on the process of motor adaptation.

OBJECTIVES: Walking is a well-practiced skill but requires adapting steps online to meet external constraints. The objective of this study was to examine the effects of types of practice schedules (i.e., blocked versus random practice) on the process of adapting and generalizing motor actions. METHODS: To examine how practice schedules influence the process of adaptation and generalization during walking, 60 young, healthy adults walked to normal, slow, and fast metronome paces: 30 with blocked practice and 30 with random practice. Paces were interspersed with 2 carryover trials with no beat. Subsequent paces were a test of generalizing adaptation from the old to the new metronome pace. RESULTS: The results showed that participants who received blocked practice acclimated more quickly to the metronome beat. Specifically, the blocked practice group altered their walking more quickly during the fast metronome pace. In contrast, the random practice group matched the metronome beat more quickly during the slow pace. Participants who received blocked practice demonstrated carryover effects during carryover trials after walking to the metronome. CONCLUSIONS: These findings extend an understanding of how the process of adaptation unfolds over time with the imposition of timing constraints.

Effects of additional anterior body mass on gait.

BACKGROUND: Gradual increases in mass such as during pregnancy are associated with changes in gait at natural velocities. The purpose of this study was to examine how added mass at natural and imposed slow walking velocities would affect gait parameters. METHODS: Eighteen adult females walked at two velocities (natural and 25 % slower than their natural pace) under four mass conditions (initial harness only (1 kg), 4.535 kg added anteriorly, 9.07 kg added anteriorly, and final harness only (1 kg)). We collected gait kinematics (100 Hz) using a motion capture system. RESULTS: Added anterior mass decreased cycle time and stride length. Stride width decreased once the mass was removed (p < .01). Added mass resulted in smaller peak hip extension angles (p < .01). The imposed slow walking velocity increased cycle time, double limb support time and decreased stride length, peak hip extension angles, and peak plantarflexion angles (p < .01). With added anterior mass and an imposed slow walking velocity, participants decreased cycle time when mass was added and increased cycle time once the mass was removed (p < .01). CONCLUSIONS: Gait adaptations may be commensurate with the magnitude of additional mass when walking at imposed slow versus natural velocities. This study presents a method for understanding how increased mass and imposed speed might affect gait independent of other effects related to pregnancy. Examining how added body mass and speed influence gait is one step in better understanding how women adapt to walking under different conditions.

The relationship between foot arch measurements and walking parameters in children.

BACKGROUND: Walking mechanics are influenced by body morphology. Foot arch height is one aspect of body morphology central to walking. However, generalizations about the relationship between arch height and walking are limited due to previous methodologies used for measuring the arch and the populations that have been studied. To gain the knowledge needed to support healthy gait in children and adults, we need to understand this relationship in unimpaired, typically developing children and adults using dynamic measures. The purpose of the current study was to examine the relationship between arch height and gait in a sample of healthy children and adults using dynamic measures. METHODS: Data were collected from 638 participants (n = 254 children and n = 384 adults) at the Museum of Science, Boston (MOS) and from 18 4- to 8-year-olds at the Motor Development and Motor Control Laboratories. Digital footprints were used to calculate two arch indices: the Chippaux-Smirak (CSI) and the Keimig Indices (KI). The height of the navicular bone was measured. Gait parameters were captured with a mechanized gait carpet at the MOS and three-dimensional motion analyses and in-ground force plates in the Motor Development and Motor Control Laboratories. RESULTS: Linear regression analyses on data from the MOS confirmed that as age increases, step length increases. With a linear mixed effect regression model, we found that individuals who took longer steps had higher arches as measured by the KI. However, this relationship was no longer significant when only adults were included in the model. A model restricted to children found that amongst this sample, those with higher CSI and higher KI values take longer relative step lengths. Data from the Motor Development and Motor Control Laboratories showed that both CSI and KI added to the prediction; children with lower anterior ground reaction forces had higher CSI and higher KI values. Arch height indices were correlated with navicular height. CONCLUSIONS: These results suggest that more than one measure of the arch may be needed elucidate the relationship between arch height and gait.

Changes in Gait with Anteriorly Added Mass: A Pregnancy Simulation Study.

During pregnancy, the female body experiences structural changes, such as weight gain. As pregnancy advances, most of the additional mass is concentrated anteriorly on the lower trunk. The purpose of this study is to analyze kinematic and kinetic changes when load is added anteriorly to the trunk, simulating a physical change experienced during pregnancy. Twenty healthy females walked on a treadmill while wearing a custom made pseudo-pregnancy sac (1 kg) under 3 load conditions: sac-only condition, 10-lb condition (4.535 kg added anteriorly), and 20-lb condition (9.07 kg added anteriorly), used to simulate pregnancy in the second trimester and at full-term pregnancy, respectively. The increase in anterior mass resulted in kinematic changes at the knee, hip, pelvis, and trunk in the sagittal and frontal planes. In addition, ankle, knee, and hip joint moments normalized to baseline mass increased with increased load; however, these moments decreased when normalized to total mass. These kinematic and kinetic changes may suggest that women modify gait biomechanics to reduce the effect of added load. Furthermore, the increase in joint moments increases stress on the musculoskeletal system and may contribute to musculoskeletal pain.

Factors Mediating or Moderating the Effects of Obesity on Walking: Targeting Areas for Rehabilitation.

Increased physical activity, such as walking, is often prescribed to address obesity. Several factors that may influence the connection between obesity and walking include the biomechanics of gait, pain, depressive symptoms, physical health, and activity. The objective of this study was to assess the moderation and mediation effects of knee pain and buckling, depressive symptoms, physical activity, and physical health on spatiotemporal gait parameters in individuals with obesity. Forty participants with obesity performed a task in which they walked on flat ground and crossed an obstacle. Measures of knee pain and buckling, depressive symptoms, physical activity, and physical health were collected. We conducted mediation analyses with knee buckling and pain as mediators of the effect of the BMI on spatiotemporal gait parameters. Moderation analyses were performed with depressive symptoms, physical activity, and physical health as moderators of the effect of BMI on spatiotemporal gait parameters. We found that depressive symptoms and physical health moderated the relationship between BMI and Step Width in people with obesity. These effects were pronounced when participants crossed an obstacle. In conclusion, depressed mood and physical health influence the relationship between obesity and walking. These factors present potential avenues for rehabilitation interventions to aid individuals with obesity.

A Fall Prevention Feasibility Trial for People With HIV and Alcohol Use.

Alcohol contributes to higher fall risk in people living with HIV (PLWH), yet fall prevention trials for PWH with alcohol use are lacking. To assess the feasibility of conducting a randomized controlled trial of a 10-week online fall prevention intervention tailored for PLWH with alcohol use. The intervention consisted of weekly virtual group discussions, individual phone check-ins, and home exercises. Of those eligible, 53.5% (23/43) enrolled (12 to the intervention and 11 to control). Mean age was 58 years; 82.6% had a past 6-month fall; 65.2% had alcohol use disorder; and 95.7% completed postintervention assessments. The intervention was highly rated (Client Satisfaction Questionnaire-8 score M = 30.4, SD = 1.6) with a wide range of group and individual phone session attendance. Preliminary analyses suggest the intervention may reduce the odds of falling and alcohol use frequency. Findings support the feasibility of a larger randomized trial. ClinicalTrials.gov Identifier: NCT04804579.

A fall prevention feasibility trial for people with HIV and alcohol useAlcohol contributes to higher fall risk in people living with HIV (PLWH), yet fall prevention studies for PLWH with alcohol use are lacking. We conducted a 10-week online fall prevention intervention for PLWH (n = 23) with recent alcohol use to assess if the intervention was feasible and acceptable for PLWH. The intervention consisted of weekly virtual group discussions and individual phone check-ins with an occupational therapist and a customized home exercise program. The mean age was 58 years. Almost all fell in the past 6 months (82.6%), had impaired physical functioning (91.3%), and had alcohol use disorder (65.2%). Participants reported high intervention satisfaction. Preliminary analyses suggest that the intervention may reduce the odds of falling and alcohol use frequency. Findings support the feasibility of an online fall prevention intervention study for PLWH.

Brief communication: a midtarsal (midfoot) break in the human foot.

The absence of a midtarsal break has long been regarded as a derived feature of the human foot. Humans possess a rigid midfoot that acts as an efficient lever during the propulsive phase of bipedal gait. Non-human primates, in contrast, have a more mobile midfoot that is adaptive for tree climbing. Here, we report plantar pressure and video evidence that a small percentage of modern humans (n = 32/398) possess both elevated lateral midfoot pressures and even exhibit midfoot dorsiflexion characteristic of a midtarsal break. Those humans with a midtarsal break had on average a significantly flatter foot than those without. Midtarsal breakers also had significantly more medial weight transfer (pronation) during the stance phase of gait than those without this midfoot mobility. These data are in accordance with Elftman (Clin Orthop 16 (1960) 41-45) who suggested that pronation aligns the axes of the transverse tarsal joint, permitting elevated midfoot mobility.

Birth and developmental correlates of birth weight in a sample of children with potential sensory processing disorder.

BACKGROUND: Most research examining birth history (i.e. related birth complications) and developmental milestone achievement follow outcomes for infants at-risk with very specific birth weight categories and gestational age classifications. The purpose of this study was to examine how birth weight relates to infants' birth histories and developmental milestone achievement when they fall into a variety of birth weight and gestational age categories. METHODS: In the current study, we examined birth histories and onset ages for developmental milestones by analyzing a convenience sample of anonymous existing data from 663 developmental histories completed by parents at the time of an initial evaluation at a pediatric outpatient occupational therapy clinic. Infants fell into 3 birth weight categories; low birth weight (LBW), normal birth weight (NBW), and high birth weight (HBW) and 3 gestational age classifications considered with birth weight; small for gestational age (SGA), appropriate for gestational age (AGA), and large for gestational age (LGA). RESULTS: NBW, AGA, and SGA infants with related birth complications had lower birth weights than infants without birth complications. Larger birth weights were associated with earlier ages for independent sitting for HBW infants, earlier ages for eating solids for NBW infants, and earlier walking onsets for LBW and NBW infants. Higher birth weights were also linked with rolling at a younger age for LGA infants, earlier walking and speaking words for AGA infants, and sooner independent sitting for SGA and AGA infants. CONCLUSIONS: Our findings suggest that birth weight and gestational age categories provide unique insights into infants' birth history and developmental milestone achievement.

Factors contributing to whether or not people with obesity undergo bariatric surgery.

BACKGROUND: Bariatric surgery has been suggested as a safe and effective way to treat obesity by facilitating weight loss, but factors that predict the likelihood of bariatric surgery are unknown. The objective of this study was to describe factors associated with individuals with obesity that influence their decision to undergo bariatric surgery. SUBJECTS AND METHODS: The study design was a cross-sectional study and participants were recruited via a survey link posted on the Obesity Action Coalition website. Demographic data, medical data, weight loss program data, and reports of personal experiences were gathered via an online survey. A multivariate logistic regression model was conducted to examine predictors associated with bariatric surgery (N = 4192). RESULTS: Participants who took phentermine (OR=2.983), Phentermine-topiramate (Qsymia) (OR=2.863), Naltrexone-bupropion (Contrave) (OR=3.246), or Liraglutide (Saxenda) (OR=2.144) had a higher likelihood of undergoing bariatric surgery for weight loss. Participants with type 2 diabetes (OR=1.728), post-traumatic stress disorder (PTSD) (OR=1.489), or COVID-19 (OR=3.852) had a higher likelihood of undergoing bariatric surgery while sleep apnea (OR=0.760) was associated with a lower likelihood of receiving surgery. Those who used MyFitnessPal™ (OR=2.232), Noom™ (OR=1.400), Jenny Craig™ (OR=1.533), or Keto (OR=1.664) for weight loss had a higher likelihood of obtaining bariatric surgery. Personal trauma experiences of sexual abuse (OR=1.982) and physical abuse (OR=1.490) were more associated with participants who underwent surgery. CONCLUSIONS: A variety of characteristics were associated with decisions to undergo bariatric surgery. These findings may help to determine ways to support individuals who are considering bariatric surgery.

The effect of trunk and shank position on the hip-to-knee moment ratio in a bilateral squat.

OBJECTIVES: The effect of knee position on joint moments during squats has been studied; however, the effect of trunk angle has been less well investigated. This study evaluated the effect of both trunk and knee sagittal plane position on the distribution of moments between the hip and knee extensors during the bilateral squat. DESIGN: Observational study. SETTING: Biomechanics laboratory. PARTICIPANTS: One hundred individuals performed bilateral squats. MAIN OUTCOME MEASURES: Motion and force data were collected using motion capture and force plates. Trunk and shank angles and hip and knee moments were calculated. A linear regression was used to associate the ratio between the hip and knee moments (hip-to-knee moment ratio) with the sagittal plane trunk and shank angles, while accounting for six squat depths (between 60° and 110° of knee flexion) and side. RESULTS: Trunk angle and shank angle each contributed to the hip-to-knee moment ratio (P < .001) with trunk accounting for a higher proportion of variance than the other variables. The hip-to-knee moment ratio increased with increasing trunk angle and with decreasing shank angle. CONCLUSIONS: This large cohort study supports the use of trunk position to instruct squat technique with the goal of modifying hip and knee moments.

Oromotor skills in autism spectrum disorder: A scoping review.

Oromotor functioning plays a foundational role in spoken communication and feeding, two areas of significant difficulty for many autistic individuals. However, despite years of research and established differences in gross and fine motor skills in this population, there is currently no clear consensus regarding the presence or nature of oral motor control deficits in autistic individuals. In this scoping review, we summarize research published between 1994 and 2022 to answer the following research questions: (1) What methods have been used to investigate oromotor functioning in autistic individuals? (2) Which oromotor behaviors have been investigated in this population? and (3) What conclusions can be drawn regarding oromotor skills in this population? Seven online databases were searched resulting in 107 studies meeting our inclusion criteria. Included studies varied widely in sample characteristics, behaviors analyzed, and research methodology. The large majority (81%) of included studies report a significant oromotor abnormality related to speech production, nonspeech oromotor skills, or feeding within a sample of autistic individuals based on age norms or in comparison to a control group. We examine these findings to identify trends, address methodological aspects hindering cross-study synthesis and generalization, and provide suggestions for future research.

Quantifying the effects of body mass index on safety: reliability of a video coding procedure and utility of a rhythmic walking task.

OBJECTIVES: To evaluate the association between body mass index (BMI) and motor actions related to safety risks (primary aim), and to examine the reliability of a video coding procedure and the utility of a rhythmic walking task in identifying safety risks (secondary aims). DESIGN: Using a cross-sectional design, participants were filmed during a rhythmic walking task at slow, normal, and fast audio metronome paces. A video coding procedure was used to quantify signs of safety risks from the videotaped sessions. SETTING: Motor development laboratory in a university. PARTICIPANTS: Adults (N=32) with normal (n=15) and overweight (n=17) BMI scores participated. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Chi-squared analyses were conducted to compare the occurrence of coded motor actions (forward and lateral tripping) between participants with normal and overweight BMI scores. A kappa coefficient was computed as a measure of interrater reliability on the video codes. RESULTS: Participants who were overweight exhibited more safety risks compared with participants with normal BMI scores at the slow (χ(2)(1,N=32)=3.94, P<.05, d=.75) and fast (χ(2)(1,N=32)=3.85, P<.05, d=.74) metronome paces. Interrater reliability was high (κ=.90, P<.01). CONCLUSIONS: In support of the primary aim, the findings show a relationship between overweight BMI scores and safety risks. Toward the secondary aims, the results demonstrate that a video coding procedure can be reliably used to assess safety risks and that creating tasks appropriate for assessing safety risks in overweight adults is needed.

Changes in Gait Self-Efficacy, Fear of Falls, and Gait Four and Eight Months after Bariatric Surgery.

After bariatric surgery, individuals improve walking characteristics related to fall risk. However, little is known about psychosocial factors, such as gait self-efficacy and fear of falling, after surgery. Our objectives were to (1) examine how weight loss affects psychosocial factors and gait four and eight months after bariatric surgery, as well as (2) determine if there is a relationship between gait self-efficacy and fear of falling. Fourteen adults scheduled to undergo bariatric surgery completed three visits: before surgery, four and eight months after surgery. Gait self-efficacy was measured with the Modified Gait Efficacy Scale, and fear of falls was measured with the Tinetti Falls Efficacy Scale. Gait measures were collected during five conditions: initial baseline and final baseline on flat ground, and crossing obstacles of three heights. Gait self-efficacy or fear of falling did not change after surgery. However, both four and eight months after surgery, higher gait self-efficacy and lower fear of falling were correlated with longer and faster steps during all conditions (all ps < 0.05). Focusing interventions on psychosocial measures related to gait may yield longer lasting improvements in walking after surgery, ultimately resulting in a decreased fall risk and higher quality of life.

The effect of obesity on whole-body angular momentum during steady-state walking.

BACKGROUND: Individuals with obesity demonstrate deficits in postural stability, leading to increased fall risks. Controlling whole-body angular momentum is essential for maintaining postural stability during walking and preventing falls. However, it is unknown how obesity impacts whole-body angular momentum during walking. RESEARCH PURPOSE: To investigate the change in angular momentum about the body's COM during walking in individuals with different degrees of obesity. METHODS: Thirty-eight young adults with different body mass index (BMI) scores walked barefoot at their preferred speed on a treadmill for 2 min. The whole-body angular momentum has been quantified from ground reaction force and moment data to capture the rotational behavior of walking in individuals with obesity without relying solely on placing markers on anatomical landmarks. RESULTS: We found that adults with higher BMI scores walked slower with shorter step length, wider step width, and longer double support time (ps<.01). Ranges of the frontal- and transverse-plane angular momentum were greater in adults with higher BMI scores (ps<.01), while no difference was observed between BMI groups in the total sum of changes in whole-body angular momentum in any plane (ps>.05). SIGNIFICANCE: Obesity not only decreased walking speed but also limited the ability to control mediolateral stability during walking. Investigating how obesity affects whole-body angular momentum may help better understand why adults with obesity have atypical gait with poor balance, address fall risk factors, and facilitate participation in physical activities.

Neuroimaging Techniques as Descriptive and Diagnostic Tools for Infants at Risk for Autism Spectrum Disorder: A Systematic Review.

Autism Spectrum Disorder (ASD) has traditionally been evaluated and diagnosed via behavioral assessments. However, increasing research suggests that neuroimaging as early as infancy can reliably identify structural and functional differences between autistic and non-autistic brains. The current review provides a systematic overview of imaging approaches used to identify differences between infants at familial risk and without risk and predictive biomarkers. Two primary themes emerged after reviewing the literature: (1) neuroimaging methods can be used to describe structural and functional differences between infants at risk and infants not at risk for ASD (descriptive), and (2) neuroimaging approaches can be used to predict ASD diagnosis among high-risk infants and developmental outcomes beyond infancy (predicting later diagnosis). Combined, the articles highlighted that several neuroimaging studies have identified a variety of neuroanatomical and neurological differences between infants at high and low risk for ASD, and among those who later receive an ASD diagnosis. Incorporating neuroimaging into ASD evaluations alongside traditional behavioral assessments can provide individuals with earlier diagnosis and earlier access to supportive resources.

Changes in dynamic balance control in adults with obesity across walking speeds.

Adults with obesity have gait instability, leading to increased fall risks and decreased physical activity. Whole-body angular momentum (WBAM) is regulated over a gait cycle, essential to avoid a fall. However, how obese adults regulate WBAM during walking is unknown. The current study investigated changes in WBAM about the body's center of mass (COM) during walking in obese and non-obese adults across different walking speeds. Twenty-eight young adults with obesity and normal weight walked barefoot at a fixed walking speed (FWS, 1.25 m/s) and at five different speeds based on their preferred walking speed (PWS): 50, 75, 100, 125, and 150 % of PWS. Adults with obesity walked slower with shorter step length, wider step width, and longer double support time (p < 0.01). The ranges of frontal- and transverse-plane WBAM were greater in obese adults (p < 0.01). We also found that the range of frontal-plane WBAM did not significantly change with walking speed (p > 0.05), while the range of transverse-plane WBAM increased with walking speed (p < 0.01). The ranges of frontal- and transverse-plane WBAM increased with the mediolateral ground reaction force and mediolateral moment arm (p < 0.01), which may be most affected by lateral foot placement relative to the body's COM. Our findings suggest that controlling mediolateral stability during walking is more challenging in obese adults, independent of their slow walking speed. Understanding whole-body rotational dynamics observed in obese walking provides an insight into the biomechanical link between obesity and gait instability, which may help find a way to reduce fall risks and increase physical activity.