The impact of obesity on gait stability in older adults

Comparative analysis of postural stability and risk of falling and developing disability among overweight and obese women over 40 years

BACKGROUND

Increased body mass index (BMI) adversely affects the mechanics of the musculoskeletal system. It is known that obese people have poorer postural stability and mobility-related outcomes compared to normal weight people, but there is limited research comparing overweight and class 1 obese people, two consecutive and prevalent BMI categories.

AIMS

To compare postural stability, functional mobility, and risk of falling and developing disability between overweight and obese women, and to investigate the relationship of BMI and body weight with the outcomes.

METHODS

Thirty women with class 1 obesity and 30 overweight women were included. Standing postural stability with eyes-open and eyes-closed and stability limits were assessed using the Prokin system. The Timed Up and Go Test (TUG) was used to assess functional mobility and risk of falling (≥11 s) and developing disability (≥9 s).

RESULTS

The average center of pressure displacements on the y-axis (COPY) obtained during quiet standing with both eyes-open and eyes-closed were higher in obese women than overweight women (p < 0.05) and the effect sizes were moderate for the results. The COPY values in the eyes-open and eyes-closed conditions were correlated with BMI (r = 0.295 and r = 0.285, p < 0.05). Furthermore, the COPX value in the eyes-open condition and the TUG score were correlated with body weight (r = 0.274 and r = 0.257, p < 0.05).

CONCLUSIONS

Obese women had poorer static standing stability in the anteroposterior direction than overweight women, while functional mobility and risk of falling and developing disability did not differ. Furthermore, BMI and body weight were related to poorer static standing stability.

Android obesity could be associated with a higher fall risk than gynoid obesity following a standing-slip: A simulation-based biomechanical analysis

It is well recognized that overall obesity increases fall risk. However, it remains unknown if the obesity-induced increase in the fall risk depends upon the adipose distribution (or obesity type: android vs. gynoid). This pilot study examined the effects of fat deposition region on fall risk following a standing-slip trial in young adults with simulated android or gynoid adiposity. Appropriate external weights were attached to two groups of healthy young lean adults at either the abdomen or upper thigh region to simulate android or gynoid adiposity, respectively, with a targeted body mass index of 32 kg/m2. Under the protection of a safety harness, both groups were exposed to an identical standing-slip on a treadmill with a maximum slip distance of 0.36 m. The primary (dynamic gait stability) and secondary (latency, length, duration, and speed of the recovery step, slip distance, and trunk velocity) outcome variables on the slip trial were compared between groups. The results revealed that the android group was more unstable with a longer slip distance and a slower trunk flexion velocity than the gynoid group at the recovery foot liftoff after the slip onset. The android group initiated the recovery step later but executed the step faster than the gynoid group. Biomechanically, the android adipose tissue may be associated with a higher fall risk than the gynoid fat tissue. Our findings could provide preliminary evidence for considering fat distribution as an additional fall risk factor to identify older adults with obesity at a high fall risk.

Development of soft tissue asymmetry indicators to characterize aging and functional mobility

Introduction: The aging population poses significant challenges to healthcare systems globally, necessitating a comprehensive understanding of age-related changes affecting physical function. Age-related functional decline highlights the urgency of understanding how tissue composition changes impact mobility, independence, and quality of life in older adults. Previous research has emphasized the influence of muscle quality, but the role of tissue composition asymmetry across various tissue types remains understudied. This work develops asymmetry indicators based on muscle, connective and fat tissue extracted from cross-sectional CT scans, and shows their interplay with BMI and lower extremity function among community-dwelling older adults. Methods: We used data from 3157 older adults from 71 to 98 years of age (mean: 80.06). Tissue composition asymmetry was defined by the differences between the right and left sides using CT scans and the non-Linear Trimodal Regression Analysis (NTRA) parameters. Functional mobility was measured through a 6-meter gait (Normal-GAIT and Fast-GAIT) and the Timed Up and Go (TUG) performance test. Statistical analysis included paired t-tests, polynomial fitting curves, and regression analysis to uncover relationships between tissue asymmetry, age, and functional mobility. Results: Findings revealed an increase in tissue composition asymmetry with age. Notably, muscle and connective tissue width asymmetry showed significant variation across age groups. BMI classifications and gait tasks also influenced tissue asymmetry. The Fast-GAIT task demonstrated a substantial separation in tissue asymmetry between normal and slow groups, whereas the Normal-GAIT and the TUG task did not exhibit such distinction. Muscle quality, as reflected by asymmetry indicators, appears crucial in understanding age-related changes in muscle function, while fat and connective tissue play roles in body composition and mobility. Discussion: Our study emphasizes the importance of tissue asymmetry indicators in understanding how muscle function changes with age in older individuals, demonstrating their role as risk factor and their potential employment in clinical assessment. We also identified the influence of fat and connective tissue on body composition and functional mobility. Incorporating the NTRA technology into clinical evaluations could enable personalized interventions for older adults, promoting healthier aging and maintaining physical function.

Overweight in elderly increases postural instability during sit-to-stand test: a Kinect-based assessment

BACKGROUND

Being overweight increases the risk of falls and subsequent injuries. However, conventional functional balance tests may not be appropriate for this population as body weight can affect test performance. Thus, it is crucial to develop reliable methods for assessing balance ability in overweight individuals.

AIM

The purpose of this study was to utilize a portable gaming device (Kinect Xbox 360) to measure the center of mass (CoM) of elderly individuals and compare the results between normal weight and overweight elderly women.

METHODS

The study included 64 female elderly individuals who were divided into two groups: 32 normal weight and 32 overweight subjects, matched for age (matched pairs design). The study collected the body's CoM during the five-time sit-to-stand test (FTSST) using Kinect camera. Additionally, the participants underwent the time up and go test (TUGT) and one-leg standing balance (OLSB) tests. The Kinect Xbox 360 demonstrated high test-retest reliability for measuring body's center of mass sway, with ICC3,1 value of 0.982 in the vertical direction, 0.983 in the mediolateral (ML) direction, and 0.997 in the anteroposterior (AP) direction. Additionally, the technical error of measurement (TEM) was very low at 0.006, 0.002, and 0.004, respectively. The % coefficient of variation ranged from 1.31% to 5.68%, indicating good measurement consistency.

RESULTS

Overweight individuals took longer to complete FTSST and TUGT compared to normal weight individuals, but no significant difference was observed in OLSB tests. Moreover, overweight elderly individuals had greater sway length in the ML and AP directions compared to normal weight elderly individuals.

DISCUSSION AND CONCLUSION

Overweight elderly individuals had poorer balance than their normal weight counterparts when using Kinect camera. The researchers suggest that Kinect device can be a cost-effective alternative to measure balance performance among overweight elderly in the community-based setting.

Influence of Concurrent Exercise Training on Ankle Muscle Activation during Static and Proactive Postural Control on Older Adults with Sarcopenic Obesity: A Multicenter, Randomized, and Controlled Trial

Sarcopenic obesity (SO), characterized by age-related muscle loss and excess body fat, significantly impairs postural control. However, limited research has explored the effects of concurrent exercise training on neuromuscular strategies during postural control in older adults with SO. The study enrolled 50 older adults with SO, split into an intervention group (IG, n = 25, mean age = 76.1 ± 3.5 years; mean BMI = 34.4 ± 4.0 kg/m2) and a control group (CG, n = 25, mean age = 75.9 ± 5.4 years; mean BMI = 32.9 ± 2.3 kg/m2). Participants in the IG were engaged in 60-min Total Mobility Plus Program (TMP) sessions three times a week for four months, while the CG maintained their typical daily activities. Standardized evaluations were conducted both before and after the intervention. These assessments included the Romberg and Timed Up and Go (TUG) tests, as well as the measurement of Center of Pressure (CoP) displacements parameters under various conditions. Additionally, ankle muscle activities were quantified during postural control evaluations and maximal voluntary contractions of plantar and dorsal flexors. Post-intervention results revealed a significant reduction of the standing time measured in the Romberg (-15.6%, p < 0.005) and TUG (-34.6%, p < 0.05) tests. Additionally, CoP area and velocity were notably reduced in various conditions (p < 0.05). Postural control improvements were associated with an increase of strength (p < 0.05) and decrease of ankle muscle activation (p < 0.05). These findings highlight the reversibility of neuromuscular system alterations associated with the synergistic effects of sarcopenia and obesity, emphasizing the trainability of postural control regulation within this population. By incorporating these insights into clinical practice and public health strategies, it seems possible to optimize the health and well-being of older adults with SO.

The impact of obesity on static and proactive balance and gait patterns in sarcopenic older adults: an analytical cross-sectional investigation

Background

Obesity is increasingly recognized as a significant factor in the susceptibility of older adults to falls and related injuries. While existing literature has established a connection between obesity and reduced postural stability during stationary stances, the direct implications of obesity on walking dynamics, particularly among the older adults with sarcopenia, are not yet comprehensively understood.

Objective

Firstly, to investigate the influence of obesity on steady-state and proactive balance, as well as gait characteristics, among older adults with sarcopenic obesity (SO); and secondly, to unearth correlations between anthropometric characteristics and balance and gait parameters in the same demographic.

Methods

A cohort of 42 participants was categorized into control (CG; n = 22; age = 81.1 ± 4.0 years; BMI = 24.9 ± 0.6 kg/m²) and sarcopenic obese (SOG; n = 20; age = 77.7 ± 2.9 years; BMI = 34.5 ± 3.2 kg/m²) groups based on body mass index (BMI, kg/m²). Participants were assessed for anthropometric data, body mass, fat and lean body mass percentages (%), and BMI. Steady-state balance was gauged using the Romberg Test (ROM). Proactive balance evaluations employed the Functional Reach (FRT) and Timed Up and Go (TUG) tests. The 10-m walking test elucidated spatiotemporal gait metrics, including cadence, speed, stride length, stride time, and specific bilateral spatiotemporal components (stance, swing, 1st and 2nd double support, and single support phases) expressed as percentages of the gait cycle.

Results

The time taken to complete the TUG and ROM tests was significantly shorter in the CG compared to the SOG (p < 0.05). In contrast, the FRT revealed a shorter distance achieved in the SOG compared to the CG (p < 0.05). The CG exhibited a higher gait speed compared to the SOG (p < 0.05), with shorter stride and step lengths observed in the SOG compared to the CG (p < 0.05). Regarding gait cycle phases, the support phase was longer, and the swing phase was shorter in the SOG compared to the CG group (p < 0.05). LBM (%) showed the strongest positive correlation with the ROM (r = 0.77, p < 0.001), gait speed (r = 0.85, p < 0.001), TUG (r = -0.80, p < 0.001) and FRT (r = 0.74, p < 0.001).

Conclusion

Obesity induces added complexities for older adults with sarcopenia, particularly during the regulation of steady-state and proactive balance and gait. The percentage of lean body mass has emerged as a crucial determinant, highlighting a significant impact of reduced muscle mass on the observed alterations in static postural control and gait among older adults with SO.

Intelligent Care Management for Diabetic Foot Ulcers: A Scoping Review of Computer Vision and Machine Learning Techniques and Applications

Ten percent of adults in the United States have a diagnosis of diabetes and up to a third of these individuals will develop a diabetic foot ulcer (DFU) in their lifetime. Of those who develop a DFU, a fifth will ultimately require amputation with a mortality rate of up to 70% within five years. The human suffering, economic burden, and disproportionate impact of diabetes on communities of color has led to increasing interest in the use of computer vision (CV) and machine learning (ML) techniques to aid the detection, characterization, monitoring, and even prediction of DFUs. Remote monitoring and automated classification are expected to revolutionize wound care by allowing patients to self-monitor their wound pathology, assist in the remote triaging of patients by clinicians, and allow for more immediate interventions when necessary. This scoping review provides an overview of applicable CV and ML techniques. This includes automated CV methods developed for remote assessment of wound photographs, as well as predictive ML algorithms that leverage heterogeneous data streams. We discuss the benefits of such applications and the role they may play in diabetic foot care moving forward. We highlight both the need for, and possibilities of, computational sensing systems to improve diabetic foot care and bring greater knowledge to patients in need.

Contributing factors to postural stability in Prader-Willi syndrome

BACKGROUND

Prader-Willi Syndrome (PWS) is a rare neurodevelopmental disorder affecting multiple functional parameters. This study examined postural stability and associated gait and neuromuscular factors in young adults with PWS.

METHODS

Participants included 10 adults with PWS [7 M/3F; Body Fat % 40.61 ± 7.79]; ten normal weight (NW) adults [7 M/3F; Body Fat % 23.42 ± 7.0]; ten obese (OB) adults [7 M/3F; Body Fat % 42.40 ± 5.62]. Participants completed the Sensory Organization Test (SOT)®. Condition (C) specific and a composite equilibrium score (CES) were calculated (maximum = 100). Quadriceps strength was assessed using an isokinetic dynamometer. Three-dimensional gait analyses were completed along a 10 m walkway using a motion capture system and two force plates. A gait stability ratio (GSR) was computed from gait speed and step length (steps/m).

RESULTS

The PWS group had lower scores for C1, C3, C4 and CES compared to the NW (p < .039 for all) and lower scores for C4 and CES than the OB (p < .019 for both) groups, respectively. In C5 (eyes closed, sway-referenced support) and C6 (sway-referenced vision and support), 33.3% of participants with PWS fell during the first trial in both conditions (X2 [2] 7.436, p = .024) and (X2 [2] 7.436, p = .024) but no participant in the other groups fell. Those with PWS showed higher GSR than participants with NW (p = .005) and those with obesity (p = .045).

CONCLUSION

Individuals with PWS had more difficulty maintaining standing balance when relying on information from the somatosensory (C3), visual-vestibular (C4) and vestibular systems (C5, C6). A more stable walk was related to shorter steps, slower velocity and reduced peak quadriceps torque. Participation in multisensory activities that require appropriate prioritization of sensory system(s) input for controlling balance in altered sensory environments should be routinely included. In addition, exercises targeting muscular force and power should be included as part of exercise programming in PWS.

Prevalence and Trends of Slow Gait Speed in the United States

Gait speed is a simple, effective indicator of age-related disease and disability. We sought to examine the prevalence and trends of slow gait speed in older Americans. Our unweighted analytic sample included 12,427 adults aged ≥ 65 years from the 2006-2016 waves of the Health and Retirement Study. Gait speed was measured in participant residences. Persons with gait speed < 0.8 or <0.6 m/s were slow. Sample weights were used to generate nationally representative estimates. The overall estimated prevalence of slow gait speed with the <0.8 m/s cut-point was 48.6% (95% confidence interval (CI): 47.4-49.8) in the 2006-2008 waves yet was 45.7% (CI: 44.3-47.1) in the 2014-2016 waves, but this downward trend was not statistically significant (p = 0.06). The estimated prevalence of slowness with the <0.6 m/s cut-point was 21.3% (CI: 20.4-22.3) for the 2006-2008 waves, 18.5% (CI: 17.5-19.4) for the 2010-2012 waves, and 19.2% (CI: 18.2-20.2) for the 2014-2016 waves, but there were again no significant trends (p = 0.61). Our findings showed that the estimated prevalence of slow gait speed in older Americans is pronounced, and different cut-points largely inform how slowness is categorized. Continued surveillance of slowness over time will help guide screening for disablement and identify sub-populations at greatest risk for targeted interventions.

Role of age and sex in the association between BMI and functional limitations in stroke patients: Cross-sectional analysis in three European and US cohorts

BACKGROUND

A U- or J-shaped association between BMI and different post-stroke outcomes is suggested. Thus, the aim is to evaluate the association between BMI with ADL, IADL and mobility limitations in the ageing post-stroke population at different ages, as well as the differences in this association by sex.

METHODS

A total of 5,468 participants with stroke and 21,872 without stroke over 50 years of age were assessed for the number of limitations in basic or instrumental activities of daily living (ADL/IADL) as well as mobility tasks. The association between BMI at the interview (continuous time-dependent variable) and the level of limitations was assessed using a linear mixed model stratified by sex and stroke status.

RESULTS

The association between BMI and ADL/IADL and mobility limitations were found to be significant in both men and women regardless of stroke status (p<0.001 for all). The association differs between those who have suffered a stroke and those who have not (p<0.001 for all). In ADL/IADL limitations, men with stroke showed a transition from an inverted J-shape to a U-shape association with age. In women, the BMI showed a less pronounced association between BMI and ADL/IADL limitations compared to men but with similar trends. A effect of sex was observed in the association between BMI and mobility, with women with and without stroke showing a linear association that differed from the inverted J-shaped or U-shaped association of men.

CONCLUSION

Our results suggest that BMI is associated with limitations in ADL, IADL and mobility in stroke patients. In addition, this association differs between men and women and is also influenced by age.

Effect of Gait Alteration on Fatigability during Walking in Adult Women with High Body Fat Composition

Background and Objective: The risk factors for injury due to alterations in gait efficiency and fatigability during walking are a rising concern. Therefore, the aims of this study were to characterize the changes in gait pattern and performance fatigability among adult women with a high body fat percentage and to study the association between the gait pattern and performance fatigability during walking. Materials and Methods: A total of 160 adult women were enrolled in the study and were divided into two groups: a high-body-fat percentage group (HBF; n = 80; fat% = 42.49 ± 3.51) and a comparison group with a normal body fat percentage (NBF; n = 80; fat% = 29.68 ± 4.30). The 10 min walking test (10-MWT) was used to measure performance fatigability. Treadmill-based gait analysis was used for the acquisition of gait parameters. The correlation between the variables was examined using Pearson’s correlation coefficient. Forward stepwise linear regression was carried out to examine the association between all independent variables, and performance fatigability was adjusted for age and height. The level of statistical significant was set at p-value < 0.05 in all analyses. Results: The mean performance fatigability during the 10-MWT was reported to be high (1.4 ± 0.13) among the participants with HBF, as compared with a fatigability of 1.25 ± 0.11 in the NBF group. The data analysis of the spatial parameters indicated that stride length and step length were statistically smaller in the participants with HBF, as compared with the NBF group. The effects of average maximum force, speed, cadence, step length, and stride length explained the variation in the performance fatigability by 61% (p = 0.007). Conclusion: The findings of this study showed that gait alteration due to excess body fat induced a reduction in performance, as reflected by the high fatigability performance during walking. The study demonstrated a significant association between the severity of performance fatigability and spatial gait parameters.

Determination of the Predictors with the Greatest Influence on Walking in the Elderly

Background and Objectives: Previous studies have revealed that independent variables (lower extremity strength, postural control ability, and body composition) influence gait performance and variability, but the difference in the relative influence between these variables is unclear. Hence, this study determines the variable that is the most influential predictor of gait performance and variability among potential independent variables in the elderly. Materials and Methods: Seventy-eight subjects aged ≥60 years participated. For each subject, the gait variables and lower extremity muscle strength were measured using an accelerometer worn on both feet during a 6-minute walk and a manual force sensor, respectively. The static balance ability was measured through two force plates, and the body composition was measured by applying bioelectrical impedance analysis. Linear regression analyses were performed stepwise to determine whether these variables affect gait performance and variability. Results: After adjusting for sex and gait performance, the ankle strength, body fat mass, mean velocity in the medial-lateral direction, ankle plantar flexion strength, and girth were predictors of gait speed dorsiflexion, gait performance, swing width of the gait performance, walking speed, and gait variability, respectively. Conclusions: Overall, gait performance in the elderly is related to muscle strength, postural control, and body composition in a complex manner, but gait variability appears to be more closely related to ankle muscle strength. This study provides further evidence that muscle strength is important in motor function and stability.

Nonlinear Dynamic Measures of Walking in Healthy Older Adults: A Systematic Scoping Review

Background: Maintaining a healthy gait into old age is key to preserving the quality of life and reducing the risk of falling. Nonlinear dynamic analyses (NDAs) are a promising method of identifying characteristics of people who are at risk of falling based on their movement patterns. However, there is a range of NDA measures reported in the literature. The aim of this review was to summarise the variety, characteristics and range of the nonlinear dynamic measurements used to distinguish the gait kinematics of healthy older adults and older adults at risk of falling. Methods: Medline Ovid and Web of Science databases were searched. Forty-six papers were included for full-text review. Data extracted included participant and study design characteristics, fall risk assessment tools, analytical protocols and key results. Results: Among all nonlinear dynamic measures, Lyapunov Exponent (LyE) was most common, followed by entropy and then Fouquet Multipliers (FMs) measures. LyE and Multiscale Entropy (MSE) measures distinguished between older and younger adults and fall-prone versus non-fall-prone older adults. FMs were a less sensitive measure for studying changes in older adults’ gait. Methodology and data analysis procedures for estimating nonlinear dynamic measures differed greatly between studies and are a potential source of variability in cross-study comparisons and in generating reference values. Conclusion: Future studies should develop a standard procedure to apply and estimate LyE and entropy to quantify gait characteristics. This will enable the development of reference values in estimating the risk of falling.

The Effect of Body Composition on Gait Variability Varies with Age: Interaction by Hierarchical Moderated Regression Analysis

Although body composition has been found to affect various motor functions (e.g., locomotion and balance), there is limited information on the effect of the interaction between body composition and age on gait variability. The purpose of this study was to determine the effect of body composition on gait according to age. A total of 80 men (40 young and 40 older males) participated in the experiment. Body composition was measured using bioelectrical impedance analysis (BIA), and gait parameters were measured with seven-dimensional inertial measurement unit (IMU) sensors as each participant walked for 6 min at their preferred pace. Hierarchical moderated regression analysis, including height as a control variable and age as a moderator variable, was performed to determine whether body composition could predict gait parameters. In young males, stride length decreased as body fat percentage (BFP) increased (R² = 13.4%), and in older males, stride length decreased more markedly as BFP increased (R² = 26.3%). However, the stride length coefficient of variation (CV) of the older males increased significantly as BFP increased (R² = 16.2%), but the stride length CV of young males did not change even when BFP increased. The increase in BFP was a factor that simultaneously caused a decrease in gait performance and an increase in gait instability in older males. Therefore, BFP is more important for a stable gait in older males.

Bariatric surgery and exercise: A pilot study on postural stability in obese individuals

This study aimed to analyze the changes in postural stability of individuals with obesity after bariatric surgery, and the effect of three months of regular exercise on the static postural stability. Twenty-two subjects (7 females and 15 males) aged 31 to 68 years (Body mass index 35-55 kg.m-2) completed the study. Participants were divided into two groups: one group participated in an exercise program after the bariatric surgery (n = 10; age 48.9 ± 7.5 years; Body mass index 42 ± 5.6 kg.m-2) while the second group did not exercise at all after bariatric surgery (n = 12; age 44.7 ± 13.6 years, Body mass index 42.6 ± 6.0 kg.m-2). Static postural stability was measured using a Tekscan MobileMat pressure plate before and 4 months after the bariatric surgery. The exercise program included exercising three times a week including: one hour of strengthening, one hour of aerobic group exercise and at least one session of individual exercise at home. There were no significant differences in Center of force sway, Center of force ranges and average speed before and 4 months after bariatric surgery. Also, no effect of exercise was found. Post-pre differences of some parameters were negatively related to age (r from-0.46 to-0.72). Further studies are needed to explore this topic in depth.

Social Capital as a Mediator through the Effect of Education on Depression and Obesity among the Elderly in China

Objectives: Global aging is an increasingly serious problem. The health problems faced by the elderly, such as depression and obesity, require serious consideration. Education, depression and obesity are inextricably linked; for the elderly, education is constant, and the factors which can mediate the relationship between education, depression and obesity are still being discussed by scholars. The mediating effect of social capital is rarely studied. The objective of this study was to assess the mediating role of cognitive social capital and structural social capital, as well as the effect of education on depression and obesity among the elderly using China Family Panel Studies (CFPS) data. Methods: In total, 4919 respondents were included in the final analysis. Education was measured by years of schooling. Trust and participation were used as measures of cognitive social capital and structural social capital. Depression symptoms and BMI were used as outcomes. Structural equation models were developed to examine the direct and indirect effect of social capital and education on health outcomes. Results: Education was negatively correlated with depression symptom (r = −0.15, p < 0.001), while education was positively correlated with BMI (r = 0.08, p < 0.001). Older adults with a higher education level have higher cognitive social capital (r = 0.11, p < 0.001) and structural social capital (r = 0.20, p < 0.001). Social capital plays a mediatory role. Older adults with higher social capital have a lower risk of depression (cognitive: r = −0.23, p < 0.001; structural: r = −0.03, p < 0.01) but a higher risk of obesity (cognitive: r = 0.06, p < 0.01; structural: r = 0.03, p < 0.01). For depression, the mediating function of cognitive social capital (a1b1= −0.025) is stronger than that of structural social capital (a2b2 = −0.006). While, for obesity, the effects of both cognitive and structural social capital are the same (a1c1 = a2c2 = 0.005). Conclusions: Social capital as a mediator through the effect of education on depression and obesity among the elderly in China. Meanwhile, using the positive effects of social capital to avoid negative effects should also be seriously considered.

Older but not younger adults rely on multijoint coordination to stabilize the swinging limb when performing a novel cued walking task

Motor flexibility, the ability to employ multiple motor strategies to meet task demands, may facilitate ambulation in complex environments that constrain movements; loss of motor flexibility may impair mobility. The purpose of this study was to determine the effects of obesity (a specific model of mobility impairment) and advanced age on motor flexibility during a task that constrained foot placement while walking. Twenty-one community-dwelling obese (OB) and 25 normal weight (NW) older adults (46 total older adults-OA) and 10 younger adults (YA) walked normally on a treadmill (baseline) then walked while stepping on lighted cues projected onto the treadmill at locations corresponding to average foot placement during normal walking (cued). The uncontrolled manifold (UCM) analysis was used to partition total variance in a set of seven lower-limb segment angles into components that did ("bad" variance) and did not ("good" variance) affect step-to-step variance in the trajectory of the swing foot. Motor flexibility was operationalized as an increase (baseline to cued) in total variance with an increase in good variance that exceeded the change in bad variance. There was no significant group × walking task interaction for total and good variance for OB vs NW, but there was a strong and significant interaction effect for OA vs YA (p < 0.01; Cohen's d > 1.0). Whereas YA reduced both good and bad variance, OA increased good variance beyond the change in bad variance. In OA, these changes were associated with several functional measures of mobility. Cued walking may place greater demands on OA requiring greater reliance on motor flexibility, although otherwise healthy older obese adults may be able to compensate for functional and cognitive declines associated with obesity by increasing motor flexibility under such tasks. The extent to which motor flexibility is employed during novel or constrained tasks may be a biomarker of healthy aging and a target for (re)habilitation.

Postural Stability in Obese Preoperative Bariatric Patients Using Static and Dynamic Evaluation

INTRODUCTION

Globally, 300 million adults have clinical obesity. Heightened adiposity and inadequate musculature secondary to obesity alter bipedal stance and gait, diminish musculoskeletal tissue quality, and compromise neuromuscular feedback; these physiological changes alter stability and increase injury risk from falls. Studies in the field focus on obese patients across a broad range of body mass indices (BMI >30 kg/m2) but without isolating the most morbidly obese subset (BMI ≥40 kg/m2). We investigated the impact of obesity in perturbing postural stability in morbidly obese subjects elected for bariatric intervention, harboring a higher-spectrum BMI.

SUBJECTS AND METHODS

Traditional force plate measurements and stabilograms are gold standards employed when measuring center of pressure (COP) and postural sway. To quantify the extent of postural instability in subjects with obesity before bariatric surgery, we assessed 17 obese subjects with an average BMI of 40 kg/m2 in contrast to 13 nonobese subjects with an average BMI of 30 kg/m2. COP and postural sway were measured from static and dynamic tasks. Involuntary movements were measured when patients performed static stances, with eyes either opened or closed. Two additional voluntary movements were measured when subjects performed dynamic, upper torso tasks with eyes opened.

RESULTS

Mean body weight was 85% (p < 0.001) greater in obese than nonobese subjects. Following static balance assessments, we observed greater sway displacement in the anteroposterior (AP) direction in obese subjects with eyes open (87%, p < 0.002) and eyes closed (76%, p = 0.04) versus nonobese subjects. Obese subjects also exhibited a higher COP velocity in static tests when subjects' eyes were open (47%, p = 0.04). Dynamic tests demonstrated no differences between groups in sway displacement in either direction; however, COP velocity in the mediolateral (ML) direction was reduced (31%, p < 0.02) in obese subjects while voluntarily swaying in the AP direction, but increased in the same cohort when swaying in the ML direction (40%, p < 0.04).

DISCUSSION AND CONCLUSION

Importantly, these data highlight obesity's contribution towards increased postural instability. Obese subjects exhibited greater COP displacement at higher AP velocities versus nonobese subjects, suggesting that clinically obese individuals show greater instability than nonobese subjects. Identifying factors contributory to instability could encourage patient-specific physical therapies and presurgical measures to mitigate instability and monitor postsurgical balance improvements.