Balance control impairment in obese individuals is caused by larger balance motor commands variability

Sarcopenic obesity defined by the ESPEN and EASO consensus statement in older women: Risk of falls and bone mineral density implications

PURPOSE

To apply the ESPEN-EASO diagnostic criteria for Sarcopenic Obesity (SO) in older women and to assess its association with the risk of falls, fear of falls (FOF), and bone mineral density (BMD).

METHODS

After exclusion criteria, 232 women aged ≥60 years (68.2 ± 6.1) were enrolled in the study. Volunteers had handgrip strength (HGS; dynamometer) and body composition assessed by DXA before risk of falls was evaluated using the QuickScreen and FOF evaluated by the Falls Efficiency Scale. SO was defined according to the ESPEN-EASO algorithm, which includes reduced HGS and fat-free mass, and elevated fat mass.

RESULTS

The prevalence of SO was 6.5 %, which was associated with a higher proportion of fallers in the previous year (X2 6.2, P = 0.04), reduced reaction time (X2 6.2, P = 0.04), reduced sit-to-stand performance (X2 6.2, P = 0.04), and a higher probability of falls [ꭓ2(6) = 17.689, p = 0.004]. FOF was lower in the eutrophic group (ꭓ2(2) = 15,662, p < 0,001) than both the obesity (p = 0.001) and SO (p = 0.05) groups. For total and femoral neck BMD, the eutrophic group presented significantly lower values (1.05 and 0.79 g/cm2) than the obesity group (1.10 and 0.87 g/cm2), but similar to the SO group (1.02 and 0.83 g/cm2). These results remained significant after adjustments for potential confounders.

CONCLUSIONS

SO specified by the ESPEN-EASO framework was associated with a higher risk of falls but not with increased FOF than obesity alone. The favorable influence of overweight and obesity on BMD seems to be attenuated in individuals with SO. Our findings support the clinical significance of the ESPEN-EASO definition.

Effect of Corrective Exercise on Static Balance, Food Consumption, and Body Composition in the Early Period After Bariatric Surgery

PURPOSE

To determine the impact of corrective exercise program applied during the period of rapid weight loss following bariatric surgery on static balance, dietary intake, and body composition.

MATERIALS AND METHODS

Participants who had undergone Sleeve Gastrectomy (SG) surgery were divided into as Corrective Exercise Group (CEG), and Control Group (CG). CEG underwent a 12-week supervised corrective exercise program. Body composition and static balance of all participants were assessed before and after the study. Their physical activity levels and dietary intake were also evaluated.

RESULTS

Following of the corrective exercise program, both groups exhibited significant reductions in body weight, BMI, fat mass, fat percentage, muscle mass, waist circumference-to-height ratio, and visceral adiposity values (p < 0.05). Additionally, the CEG showed increase in lean body mass percentage (p < 0.001). In measurements related to static balance, values for eyes-closed perimeter (p = 0.015), eyes-closed (p = 0.006), eyes-open (p = 0.028) ellipses area, average F-B speed, and eyes-open center of pressure in the X-axis (C.O.P.X.) sway distance significantly decreased in both groups (p = 0.025). However, the difference in eyes-open C.O.P.X. sway distance was found to be higher in the CG (mean difference = 8.67; p = 0.034). Postoperatively, there were significant decreases in energy, protein, fat, CHO (carbohydrate), CHO percentage, fiber, and iron values, while protein percentage (p < 0.001), vitamin D (p = 0.003), and B12 (p < 0.001) values increased.

CONCLUSION

It has been observed that the corrective exercise program implemented in the early postoperative period following SG surgery had a positive impact on eyes-open static balance.

Body composition, balance, functional capacity and falls in older women

BACKGROUND

The aim of this study was to examine the association of body composition, muscle strength, balance, and functional capacity on falls and fall injuries among community-dwelling older women.

METHODS

The study comprised of a 2-year randomized controlled trial involving 914 women with an average age of 76.5 (SD = 3.3) years at baseline. The women were assigned to exercise intervention (n = 457) and control groups (n = 457). Clinical measurements were conducted at baseline, 12 months and 24 months.

RESULTS

During the 2-year follow up, total of 546 women (59.7%) sustained a fall. The total number of falls was 1380 and out of these, 550 (40%) of falls were non-injurious and 745 (54%) were injurious. Higher femoral neck bone mineral density (BMD) was associated with a higher overall risk of falls [RR = 2.55 (95% CI = 1.70-3.84, p < 0.001)], but was a protective factor for severe fall injuries [RR = 0.03 (95% CI = 0.003-0.035, p < 0.01)]. Slower Timed Up and Go (TUG) was associated with an increased overall risk of falls [RR = 1.07 (95% CI = 1.05-1.10, p < 0.001)] and injuries requiring medical attention [RR = 1.10 (95% CI = 1.02-1.19, p = 0.02)]. Longer single leg standing time was a protective factor for falls [RR = 0.99 (95% CI = 0.99-1.00, p < 0.01)] and overall injurious falls [RR = 0.99 (95% CI = 0.99-1.00, p = 0.02)].

CONCLUSION

For postmenopausal women with higher femoral neck BMD appear to sustain more falls, but have a lower risk of severe fall injuries. Better TUG and single leg standing time predict lower risk of falls and fall injuries.

The influence of obesity and fat distribution on ankle muscle coactivation during gait

BACKGROUND

Excessive body weight is associated with gait alterations. In none of previous studies, body fat distribution has been considered as a factor that could change gait parameters and induce different neuromuscular adaptations.

OBJECTIVE

This multicenter, analytical, and cross-sectional study aimed to investigate the influence of the body mass distribution on gait parameters and ankle muscle coactivation in obese individuals.

METHODS

Three distinct groups were included in the study: a non-obese control group (CG, n = 15, average age = 32.8 ± 6.5 years, BMI = 21.4 ± 2.2 kg/m2), an obese-android group characterized by a Waist to Hip Ratio (WHR) greater than 1 (OAG, n = 15, age = 32.4 ± 3.9 years, BMI = 41.4 ± 3.9 kg/m2, WHR = 1.2 ± 0.2), and an obese-gynoid group with a WHR less than 1 (OGG, n = 15, age = 35.4 ± 4.1 years, BMI = 40.0 ± 5.7 kg/m2, WHR = 0.82 ± 0.3). All participants walked on an instrumented gait analysis treadmill at their self-selected walking speed for one minute. Spatiotemporal parameters, walking cycle phases, vertical ground reaction force (GRFv) and center of pressure (CoP) velocity were sampled from the treadmill software. Electromyography (EMG) activity of the gastrocnemius medialis (GM), the soleus (SOL) and tibialis anterior (TA) were collected during walking and used to calculate coactivation indexes (CI) between ankle plantar and dorsal flexors (GM/TA and SOL/TA) for the different walking cycle phases.

RESULTS

Compared to OAG, OGG walked with shorter and larger strides, lower CoP velocity and GRFv. During the single support phase, SOL/TA coactivation was higher in OAG compared to OGG (p < .05). During the propulsion phase, SOL/TA coactivation was higher in OGG compared to OAG (p < .05).

CONCLUSION

Gait parameters and ankle muscle coactivation in obese individuals seem to be strongly dependent on body mass distribution. From the biomechanical point of view, body mass distribution changes gait strategies in obese individuals inducing different neuromuscular adaptations during the single support and propulsion phases.

Dynapenic Abdominal Obesity Increases Risk for Falls Among Adults Aged ≥50 Years: A Prospective Analysis of the Irish Longitudinal Study on Ageing

BACKGROUND

There is a scarcity of studies examining the longitudinal relationship between dynapenic abdominal obesity (DAO; ie, impairment in muscle strength and high waist circumference) and future fall risk. Therefore, we aimed to investigate the prospective association between DAO at baseline and falls occurring during 2 years of follow-up in a nationally representative sample of middle-aged and older individuals from Ireland.

METHODS

Data from 2 consecutive waves of the Irish Longitudinal Study on Ageing survey were analyzed. Dynapenia was defined as handgrip strength of <26 kg for men and <16 kg for women. Abdominal obesity was defined as a waist circumference of >88 cm for women and >102 cm for men. DAO was assessed at Wave 1 (2009-2011) and was defined as having both dynapenia and abdominal obesity. Falls occurring between Wave 1 and Wave 2 (2012-2013) were self-reported. Multivariable logistic regression analysis was conducted.

RESULTS

Data on 5 275 individuals aged ≥50 years were analyzed (mean [standard deviation {SD}] age 63.2 [8.9] years; 48.8% males). After adjustment for potential confounders, compared to no dynapenia and no abdominal obesity at baseline, DAO was significantly associated with 1.47 (95% confidence interval [CI]: 1.14-1.89) times higher odds for falls at 2-year follow-up. Dynapenia alone (odds ratio [OR] = 1.08; 95% CI: 0.84-1.40) and abdominal obesity alone (OR = 1.09; 95% CI: 0.91-1.29) were not significantly associated with falls at follow-up.

CONCLUSIONS

DAO increased the risk for falls among middle-aged and older adults in Ireland. Interventions to prevent or reverse DAO may be beneficial for fall reduction.

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.

Dynapenic abdominal obesity and susceptibility to fall: a prospective analysis of the Osteoarthritis Initiative

Background

The prediction of the risk of falling remains a challenge in geriatric medicine and the identification of new potential reversible risk factors is a public health priority. In this study, we aim to investigate the association between DAO (dynapenic abdominal obesity) and incident falls in a large sample of people with knee OA (osteoarthritis) or at high risk for this condition, over 8 years of follow-up.

Methods

DAO was defined using a waist circumference more than 102 cm in men and 88 cm in women and a concomitant presence of dynapenia, defined as a time over 15 s in the five times chair stands time. Falls, during follow-up, were recorded using self-reported information in the previous year. A logistic binary regression analysis was run, adjusted for potential confounders at the baseline, reporting the data as odds ratios (ORs) with their 95% confidence intervals (CIs).

Results

Overall, 3,844 subjects were included, majority of whom had abdominal obesity. Across the 8 years of follow-up, 2,695 participants fell vs. 1,149 not reporting any fall. Taking those without DAO as reference, the presence of only dynapenia was not associated with risk of falls (OR = 1.18;95%CI: 0.73-1.91; p = 0.50), whilst the presence of abdominal obesity (OR = 1.30; 95%CI: 1.09-1.56; p = 0.004) and DAO (OR = 1.31; 95%CI:1.01-1.73; p = 0.04) were significantly associated with a higher risk of incident falls.

Conclusion

DAO significantly increased risk of falls as well as the presence of abdominal obesity.

Overweight Impairs Postural Control of Female Night Workers

Objectives  To verify the relationships between sleep duration (Total Sleep Time - TST) and postural control of female night workers before and after shift. As well as, to verify if there is an influence of the body mass index (BMI) on the postural control of these female workers before and after shift. Methods  A total of 14 female night workers (mean age: 35.0 ± 7.7 years) were evaluated. An actigraph was placed on the wrist to evaluate the sleep-wake cycle. The body mass and height were measured, and BMI was calculated. Postural control was evaluated by means of a force platform, with eyes opened and eyes closed before and after the 12-hour workday. Results  There was an effect of the BMI on the velocity and the center of pressure path with eyes opened before ( t  = 2.55, p  = 0.02) and after ( t  = 4.10, p  < 0.01) night work. The BMI impaired the velocity and the center of pressure path with eyes closed before ( t  = 3.05, p  = 0.01; t  = 3.04, p  = 0.01) and after ( t  = 2.95, p  = 0.01; t  = 2.94, p  = 0.01) night work. Furthermore, high BMI is associated with female workers' postural sway ( p  < 0.05). Conclusion  Therefore, high BMI impairs the postural control of female night workers, indicating postural instability before and after night work.

Is waist circumference associated with fear of falling in community-dwelling older adults? A cross-sectional study

INTRODUCTION

Fear of falling (FOF) is a prevalent condition among older adults and several variables have been pointed out as risk factors.

OBJECTIVES

To identify the cut-off point on waist circumference (WC), capable of discriminating between older adults with and without FOF, and to test the association between WC and FOF.

METHODS

A cross-sectional observational study was carried out with older adults of both sexes from Balneário Arroio do Silva, Brazil. We used Receiver Operating Characteristic (ROC) curves to determine the cut-off point on WC and logistic regression adjusted for potential confounding variables to test the association.

RESULTS

Older women with WC >93.5 cm [area under the curve: 0.61 (95%CI 0.53; 0.68)] had 3.30 (95%CI 1.53; 7.14) greater chances of having FOF compared with older women with WC ≤93.5 cm. WC was not able to discriminate FOF in older men.

CONCLUSION

WC values >93.5 cm are associated with higher chances of FOF in older women.

Balance ability and all-cause death in middle-aged and older adults: A prospective cohort study

Objective

The present study aimed to explore the relationship between balance ability and all-cause death in middle-aged and elderly people and to provide a basis for formulating a balanced training plan for middle-aged and older people in China.

Methods

Based on data from the China Health and Retirement Longitudinal Study (CHARLS) carried out in the years 2011, 2013, 2015, and 2018, 18,888 participants aged 45 years and above were included. Cox proportional hazard models were designed to evaluate the effect of balance ability on death events.

Results

The present study found that there was an association between balance ability and death among middle-aged and older people. Multivariate Cox proportional hazard regression model analysis showed that the risk of death decreased by 10% (HR = 0.90,95% CI: 0.85-0.95) for every second increase in balance ability. With balance ability <10 s as the reference group, the adjusted HRs were 0.61 (0.44-0.85) among middle-aged and elderly people. The death density of balance ability of <10 s was 73.87 per thousand person-years higher than that of ≥10 s. There was no interaction between balance ability and chronic disease, overweight, and obesity (P > 0.05).

Conclusion

The risk of all-cause death in middle-aged and older people increased with the decrease in balance ability and showed no statistical significance between chronic disease, overweight, and obesity, as corroborated by the present study.

Prediction model of all-cause death based on balance ability among middle-aged and older Chinese adults of overweight and obesity

Background

Advances in studies using body indicators to predict death risk. Estimating the balance ability of death risk in middle-aged and older Chinese adults with overweight and obesity is still challenging.

Methods

A retrospective analysis of the data from the China Health and Retirement Study from January 2011 to December 2018. A total of 8,632 participants were randomly divided into 7:3 a training group and a verification group, respectively. Univariable Cox analysis was used to prescreen 17 potential predictors for incorporation in the subsequent multivariable Cox analysis. Nine variables were included in the nomogram finally and validated with concordance index (C-index), calibration plots, Hosmer-Lemeshow test, and internal validation population.

Results

287 participants were death in the training group. One hundred and thirteen participants were death in the verification group. A total of nine indicators were included in the modeling group, including gender, age, marriage, hypertension, diabetes, stroke, ADL, IADL, and balance ability to establish a prediction model. The nomogram predicted death with a validated concordance index of (C-index = 0.77, 95% CI: 0.74-0.80). The inclusion of balance ability variables in the nomogram maintained predictive accuracy (C-index = 0.77, 95% CI: 0.73-0.82). The calibration curve graph and Hosmer-Lemeshow test (P > 0.05 for both the modeling group and the verification group) showed the model has a good model consistency.

Conclusion

In the present study, we provide a basis for developing a prediction model for middle-aged and older people with overweight and obesity. In most cases, balance ability is more reversible than other predictors.

Childhood Obesity and Incorrect Body Posture: Impact on Physical Activity and the Therapeutic Role of Exercise

Obesity is associated with various dysfunctions of the organism, including musculoskeletal problems. In this narrative review, we aim to consider postural problems in children and adolescents with obesity, focusing on the relationship with its negative impact on physical activity, and to discuss the role of exercise as a therapeutic approach. The body reacts to excess weight by changing its normal balance, and the somatosensory system of children with obesity is forced to make major adjustments to compensate for postural problems. These adaptations become more difficult and tiring if activities that require continuous postural changes and multi-tasking are engaged in. Children with obesity have less body control and functional ability due to the excess fat mass, which reduces their ability to perform motor skills and take part in physical activity. Appropriate early interventions for the management of musculoskeletal problems are needed to ensure healthy growth and to prevent comorbidities in childhood and adulthood. Prevention programs must be based not only on the reduction of body weight but also on the definition of correct postural habits from an early age. It is equally important to provide correct information on the types and doses of physical activity that can help prevent these problems.

Association Between Dynapenic Abdominal Obesity and Fall Risk in Older Adults

Background

In recent years, dynapenic abdominal obesity has received more and more attention. This article aimed to explore the relationship between dynapenic abdominal obesity and fall risk in older adults.

Methods

In this cross-sectional study, according to waist circumference (≥90 cm for men and ≥85 cm for women) and handgrip strength (<28 kg for men and <18 kg for women), 551 older adults were divided into four groups: dynapenic abdominal obese (D/AO), dynapenic nonabdominal obese (D/NAO), nondynapenic abdominal obese (ND/AO) and nondynapenic nonabdominal obese (ND/NAO). Fall risk was measured by the Tinetti performance-oriented mobility assessment (POMA). Binary logistic regression was used to explore the relationship between D/AO and fall risk.

Results

D/AO was related to POMA score (odds ratio [OR]=3.39; 95% confidence interval [CI]: 1.47–7.81; P=0.004) after adjusting the confounding variables. However, D/NAO (OR=1.51; 95% CI:0.69–3.32; P=0.302) and ND/AO (OR=1.48; 95% CI:0.74–2.99; P=0.272) were not associated with POMA score.

Conclusion

This study suggests that older adults with D/AO have a higher risk of falls. Therefore, it is necessary to strengthen the attention to D/AO and relevant interventions should be implemented.

Learned Overweight Internal Model Can Be Activated to Maintain Equilibrium When Tactile Cues Are Uncertain: Evidence From Cortical and Behavioral Approaches

Human adaptive behavior in sensorimotor control is aimed to increase the confidence in feedforward mechanisms when sensory afferents are uncertain. It is thought that these feedforward mechanisms rely on predictions from internal models. We investigate whether the brain uses an internal model of physical laws (gravitational and inertial forces) to help estimate body equilibrium when tactile inputs from the foot sole are depressed by carrying extra weight. As direct experimental evidence for such a model is limited, we used Judoka athletes thought to have built up internal models of external loads (i.e., opponent weight management) as compared with Non-Athlete participants and Dancers (highly skilled in balance control). Using electroencephalography, we first (experiment 1) tested the hypothesis that the influence of tactile inputs was amplified by descending cortical efferent signals. We compared the amplitude of P1N1 somatosensory cortical potential evoked by electrical stimulation of the foot sole in participants standing still with their eyes closed. We showed smaller P1N1 amplitudes in the Load compared to No Load conditions in both Non-Athletes and Dancers. This decrease neural response to tactile stimulation was associated with greater postural oscillations. By contrast in the Judoka's group, the neural early response to tactile stimulation was unregulated in the Load condition. This suggests that the brain can selectively increase the functional gain of sensory inputs, during challenging equilibrium tasks when tactile inputs were mechanically depressed by wearing a weighted vest. In Judokas, the activation of regions such as the right posterior inferior parietal cortex (PPC) as early as the P1N1 is likely the source of the neural responses being maintained similar in both Load and No Load conditions. An overweight internal model stored in the right PPC known to be involved in maintaining a coherent representation of one's body in space can optimize predictive mechanisms in situations with high balance constraints (Experiment 2). This hypothesis has been confirmed by showing that postural reaction evoked by a translation of the support surface on which participants were standing wearing extra-weight was improved in Judokas.

The Influence of Body Fat Distribution on Postural Balance and Muscle Quality in Women Aged 60 Years and Over

The aim of this study was to investigate the influence of body fat distribution on postural balance and lower-limb muscle quality in women aged 60 years and over. Two hundred and twenty-two volunteers took part in this cross-sectional analysis. Participants underwent body fat distribution assessment using dual-energy x-ray absorptiometry and were classified as nonobese, gynoid obese, or android obese. Postural balance was assessed during quiet standing, with and without vision restriction, using a force platform. Specific torque was defined as the ratio of knee extensors peak torque (evaluated by an isokinetic dynamometer) to the lean mass of the same limb (evaluated by dual-energy x-ray absorptiometry). Compared with nonobese participants, both obese groups exhibited higher range of postural sway along the anteroposterior and mediolateral axes (P < .05). However, there were no differences between participants with gynoid and android obesity. The android obese group exhibited greater speed of postural sway in the condition without vision restriction than both nonobese (P = .040) and gynoid obese (P = .004) groups. Regarding muscle quality, only participants with gynoid obesity (P = .004) presented lower specific torque than their nonobese peers. These results may be clinically useful when designing falls prevention exercises targeting the obese population.

Effects of adiposity on postural control and cognition in older adults

BACKGROUND

Understanding the impacts of increased adiposity on postural control and cognitive deficits in adults is critical for health practitioners in recommending or prescribing effective weight loss regimens. Despite prior work in this area, the knowledge of increased adiposity impacts on postural control and cognitive deficits in older adults (OAs) is still limited.

RESEARCH QUESTION

The purposes of the current study were: (a) to assess the relationship between postural measures and adiposity measures by using regression model analyses and, (b) to examine the impacts of increased adiposity and age on cognitive performance.

METHODS

A total of thirty (30) individuals aged 60+ years participated in the study. Participants were classified into three groups based upon their BMI scores at the onset of the study. The normal weight (NW) (BMI: 18.5-24.9 kg/m²), the overweight (OW) (BMI: 25-29.9 kg/m²), and the obese (OB) groups (BMI: 30-40 kg/m²) each had five females and five males. Participants were required to perform two test sessions: (1) anthropometry assessment and body composition scanning; and (2) evaluation of plantar tactile function, postural control, and cognitive function.

RESULTS

Overall, our findings indicate that increased adiposity in OAs is associated with declines in both cognitive function and postural control.

SIGNIFICANCE

Our data also indicate that measures such as BMI and abdominal fat mass amounts/ratios offer the best insight to the impact of adiposity on cognitive function and postural control measures. However, further work is still needed to clarify the mechanistic links between adiposity and cognitive-postural deficits.

Differences in lower extremity muscular coactivation during postural control between healthy and obese adults

INTRODUCTION

It is well established that obesity is associated with deterioration in postural control that may reduce obese adults' autonomy and increase risks of falls. However, neuromuscular mechanisms through which postural control alterations occur in obese adults remain unclear.

OBJECTIVE

To investigate the effects of obesity on muscle coactivation at the ankle joint during static and dynamic postural control.

MATERIALS AND METHODS

A control group (CG; n = 20; age = 32.5 ± 7.6 years; BMI = 22.4 ± 2.2 Kg/m²) and an obese group (OG; n = 20; age = 34.2 ± 5.6 years; BMI = 38.6 ± 4.1 Kg/m²) participated in this study. Static postural control was evaluated by center of pressure (CoP) displacements during quiet standing. Dynamic postural control was assessed by the maximal distance traveled by the CoP during a forward lean test. Electromyography activity data for the gastrocnemius medialis (GM), soleus (SOL) and tibialis anterior (TA) were collected during both quiet standing and forward lean tests. Muscle activities were used to calculate two separate coactivation indexes (CI) between ankle plantar and dorsal flexors (GM/TA and SOL/TA, respectively).

RESULTS

CoP displacements were higher in the OG than in the CG for quiet standing (p < 0.05). When leaning forward, the maximal distance of the CoP was higher in the CG than in the OG (p < 0.05). Only the CI value calculated for SOL/TA was higher in the OG than in the CG for both static and dynamic tasks (p < 0.05). The SOL/TA CI value in the OG was positively correlated with CoP displacements during quiet standing (r = 0.79; p < 0.05).

CONCLUSION

Obesity increases muscle coactivation of the soleus and tibialis anterior muscles at the ankle joint during both static and dynamic postural control. This adaptive neuromuscular response may represent a joint stiffening strategy for enhancing stability. Consequently, increased ankle muscle coactivation could not be considered as a good adaptation in obese adults.

Dynapenic abdominal obesity and the incidence of falls in older women: a prospective study

BACKGROUND

Dynapenic abdominal obesity (D/AO) has been associated with negative outcomes in older people, including trait of falls.

AIMS

To assess the association between D/AO and the incidence of falls over 18 months in older community-dwelling women.

METHODS

A total of 201 older women (67.97 ± 6.02 years; 27.70 kg/m²) underwent waist circumference measurement, and had handgrip strength assessed using a hydraulic dynamometer. Dynapenia was classified using the lower tertile of handgrip strength, while abdominal obesity was considered as a waist circumference > 88 cm. D/AO was the combination of both aforementioned criteria. Volunteers were classified into four groups: normal, abdominal obesity, dynapenic, and D/AO. Participants were then tracked by phone calls for ascertainment of falls during a follow-up period of 18 months. Chi-square and multivariable Cox proportional regressions were conducted.

RESULTS

The overall incidence of falls over the follow-up was 27.5%; and for normal, dynapenic, abdominal obesity, and D/AO were 14.7%, 17.2%, 27.5%, and 40.4% (X² = 8.341; P = 0.039), respectively. D/AO was associated with a higher risk of falls (hazard ratio: 3.595 [95% CI: 1.317-9.815], even after adjustments for age, body mass index, physical activity level, regular use of medications, peripheral sensation, chronic diseases, and history of lower-limbs pain.

CONCLUSIONS

D/AO is more closely related to falls than either dynapenia or abdominal obesity alone, and is independently associated with an increased incidence of falls in older women. These results provide support for the concept that the combined evaluation of muscle strength and central obesity may be clinically relevant in this population.

The Relationship Between Postural Stability, Anthropometry Measurements, Body Composition, and Sport Experience in Judokas with Visual Impairment

Background: Postural stability is quite mandatory when practicing high-performance sports. Investigations of postural stability and related variables in judokas with visual impairment can lead to new training plans targeting the improvement of postural stability and ultimately to enhanced performance. Objectives: To investigate postural stability and its relationship with anthropometric measurements, body composition, and experience in judokas with visual impairment. Methods: Seventeen judokas (70.6% men) with visual impairment participated in this cross-sectional study. The athletes were grouped based on the functional classification of partial (B2/B3, n = 10) and total visual impairment (B1, n = 7). Postural stability was assessed using the elliptical area of the 95% confidence interval (Area) and the average displacement velocity (Vavg) while remaining in a bipedal stance with eyes closed and blindfolded. Body mass, height, circumferences, skinfold thickness and diameters were measured and used to estimate body composition. Between-group comparisons were evaluated using the Mann-Whitney test. Bivariate correlations were determined with Spearman’s correlation coefficient with bootstrap analysis and 95% confidence interval (95% CI) from 500 resamplings. Results: No significant difference was observed between the B1 and B2/B3 groups in relation to postural stability (Area; P = 1.00; Vavg; P = 0.85). Postural stability (Area but not Vavg) correlated positively and moderately (P < 0.05) with anthropometric measurements and negatively with judo experience (practice time). Conclusions: The postural stability of judokas was unrelated to the degree of visual impairment. Postural instability was correlated with anthropometric measurements, mainly body fat and height, and judo experience.

The Association Between Body Adiposity Measures, Postural Balance, Fear of Falling, and Fall Risk in Older Community-Dwelling Women

BACKGROUND AND PURPOSE

Recent investigations demonstrate an association between obesity and the propensity of older adults to fall. The aim of this study was to investigate the association between body adiposity measures, postural balance, fear of falling, and risk of falls in older women.

METHODS

One hundred forty-seven volunteers took part in this cross-sectional study. Participants underwent body composition assessment using dual-energy x-ray absorptiometry and had body mass index, waist circumference (WC), and body adiposity index measured. Postural balance was assessed using a force platform, while fear of falling and risk of falls were, respectively, evaluated by the Falls Efficacy Scale-International and the QuickScreen Clinical Falls Risk Assessment.

RESULTS AND DISCUSSION

All adiposity measures were correlated to at least 1 postural stability parameter and to fear of falling (ρ= 0.163, P < .05 to r = 0.337, P < .001); however, WC was the index most strongly correlated to risk of falls (ρ= 0.325; P < .001). When obesity was classified using WC, it was observed that compared with nonobese individuals (n = 51), obese individuals (n = 96) exhibited greater center of pressure displacement in the anteroposterior and mediolateral axes, especially during conditions with feet apart (P < .05). The obese group also exhibited an increased fear of falling (28.04 vs 24.59; P = .002) and had a higher proportion of individuals with increased fall risk (72% vs 35%; P < .001).

CONCLUSION

In summary, adiposity measures are associated with risk of falls in older women, which might be mediated by reduced postural balance and increased fear of falling. Among these indices, WC, an easy and low-cost assessment, demonstrated the strongest association with falls-related outcomes.

Obesity and falls in older women: Mediating effects of muscle quality, foot loads and postural control

BACKGROUND

Obesity is associated with an increased risk of falls in older women. However, it is not certain whether factors commonly associated with obesity and falls mediate this risk.

RESEARCH QUESTION

Do lower-limb muscle quality, foot loads and postural control mediate the relationship between obesity and falls in women aged 60 years and older?

METHODS

At baseline, 246 female participants underwent obesity screening (BMI≥30 kg/m²), and measurements of muscle quality (isokinetic dynamometer and dual-energy X-ray absorptiometry), foot loads (pressure platform) and postural balance (force platform). Incident falls were recorded at the end of the 18-month follow-up period via participant recall. To test whether, and to what extent, biomechanical factors mediated the relationship between obesity and falls, the Natural Indirect Effects (NIE), Natural Direct Effect (NDE) and proportion mediated were calculated using the counterfactual approach. Significance level was set at p < .05.

RESULTS

204 participants (83 %) completed the follow-up. As expected, obesity was associated with a higher risk of being a faller (RR: 2.13, 95 % CI: 1.39-3.27). Using the counterfactual approach, only specific torque (NIE: 1.11, 95 % CI: 1.01-1.38) and flatfoot (NIE: 1.10, 95 % CI: 1.01-1.32) were significant mediators of the relationship between obesity and falls. Specific torque and flatfoot mediated 19 % and 21 % of the relationship, respectively.

SIGNIFICANCE

Lower-limb muscle quality (specific torque) and foot loads (flatfoot) mediate the relationship between obesity and falls in older women. The inclusion of muscle strengthening and podiatry interventions as part of a fall prevention program may benefit this population.

Balance and musculoskeletal flexibility in children with obesity: a cross-sectional study

BACKGROUND

Studies on the influence of obesity on different physical parameters such as postural balance and musculoskeletal flexibility are limited and have reported varying results.

OBJECTIVES

Measure effect of childhood obesity on balance and musculoskeletal flexibility in Saudi children.

DESIGN

Cross-sectional.

SETTING

Physiotherapy laboratory.

SUBJECTS AND METHODS

The study included a representative sample of Saudi elementary school children selected from a convenience sample of 150 children. Balance was examined using the Biodex balance system. Calf muscle flexibility was measured by the weight-bearing ankle lunge test while the chest flexibility was measured by the chest expansion test.

MAIN OUTCOME MEASURES

Postural stability indices and flexibility parameters.

SAMPLE SIZE

90 elementary school children aged 6 to 11 years, 47 of normal weight and 43 obese children.

RESULTS

All stability indices at different stability levels were significantly impaired in children with obesity ( P≤.05). In terms of musculo-skeletal flexibility, the weight-bearing lunge test distance was shorter in children with obesity ( P=.01). In the chest expansion test, there was no significant difference between the two groups ( P=.32).

CONCLUSIONS

Postural balance at different stability levels was impaired in children with obesity and in all planes. The calf muscles were less flexible in obese children.

LIMITATIONS

Unblinded, convenience sample so findings are not generalizable.

CONFLICT OF INTEREST

None.

Influence of Obesity and Impact of a Physical Activity Program on Postural Control and Functional and Physical Capacities in Institutionalized Older Adults: A Pilot Study

Objective: To evaluate the role of obesity in the effects of physical activity (PA) on postural control and functional and physical capacities in the older adults and to assess the effectiveness of a PA program on these capacities. Methods: Six obese (age = 78.8 [3.7] y; body mass index > 30 kg/m2), 7 overweight (age = 80.9 [2.8] y; 25 < body mass index < 30 kg/m2), and 6 normal weight (age = 80.8 [5.7] y; body mass index < 25 kg/m2) older adults performed the time up and go test, the 6-minute walk test, and the Tinetti test. Static and dynamic (forward leaning) postural control tests were also assessed. All these tests were similarly assessed 4 months later, during which only the obese group and overweight group participated in a PA program. Results: Before PA, results of the time up and go test, 6-minute walk test, Tinetti test, quiet standing, and forward lean tests revealed that physical capacities and static and dynamic postural control were impaired in the obese group when compared to the normal weight group. After PA, results of quiet standing, physical and functional tests were improved for obese group. Conclusions: Obesity is an additional constraint to age-related postural control and functional and physical capacities deteriorations. Nevertheless, a PA program is effective in improving balance and functional capacities in obese older adults.

Children Who Are Overweight Display Altered Vertical Jump Kinematics and Kinetics From Children Who Are Not Overweight

PURPOSE

Children who are overweight typically do not perform motor skills as well as normal-weight peers. This study examined whether vertical jump kinetics and kinematics of children who are overweight differ from nonoverweight peers.

METHODS

Thirty-nine children completed maximum-effort countermovement vertical jumps. Motion capture was used to complete lower extremity kinematic and kinetic analyses.

RESULTS

The overweight group (body mass index ≥ 85th percentile; N = 11; age = 6.5 [1.6] y) jumped lower relative to their mass (0.381 cm/kg lower; P < .001) than normal-weight peers (N = 28; age = 6.4 [1.7] y). Compared with children who are normal weight, children who were overweight exhibited a shallower countermovement (knee: 12° less flexion, P = .02; hip: 10° less flexion, P = .045), lower hip torque (0.06 N·m/kg lower, P = .01) and hip work (40% less work, P = .01), and earlier peak joint angular velocities (knee: 9 ms earlier, P = .001; hip: 14 ms earlier, P = .004).

CONCLUSION

Children who are overweight do not achieve optimal jumping mechanics and exhibit jumping characteristics of an earlier developmental stage compared with their peers. Interventions should help children who are overweight learn to execute a proper countermovement.

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.

Supplementary Motor Area and Superior Parietal Lobule Restore Sensory Facilitation Prior to Stepping When a Decrease of Afferent Inputs Occurs

The weighting of the sensory inputs is not uniform during movement preparation and execution. For instance, a transient increase in the transmission to the cortical level of cutaneous input ~700 ms was observed before participants initiated a step forward. The sensory facilitation occurred at a time when feet cutaneous information is critical for setting the forces to be exerted onto the ground to shift the center of mass toward the supporting side prior to foot-off. Despite clear evidence of task-dependent modulation of the early somatosensory signal transmission, the neural mechanisms are mainly unknown. One hypothesis suggests that during movement preparation the premotor cortex and specifically the supplementary motor area (SMA) can be the source of an efferent signal that facilitates the somatosensory processes irrespectively of the amount of sensory inputs arriving at the somatosensory areas. Here, we depressed mechanically the plantar sole cutaneous transmission by increasing pressure under the feet by adding an extra body weight to test whether the task-dependent modulation is present during step preparation. Results showed upregulation of the neural response to tactile stimulation in the extra-weight condition during the stepping preparation whereas depressed neural response was still observed in standing condition. Source localization indicated the SMA and to a lesser extent the superior parietal lobule (SPL) areas as the likely origin of the response modulation. Upregulating cutaneous inputs (when mechanically depressed) at an early stage by efferent signals from the motor system could be an attempt to restore the level of sensory afferents to make it suitable for setting the anticipatory adjustments prior to step initiation.

Diet induced obesity alters muscle spindle afferent function in adult mice

Populations with obesity are more likely to fall and exhibit balance instability. The reason for this is likely multifactorial, but there is some evidence that sensory function is impaired during obesity. We tested the hypothesis that muscle proprioceptor function is compromised in a mouse model of diet induced obesity. An in vitro muscle-nerve preparation was used to record muscle spindle afferent responses to physiological stretch and sinusoidal vibration. We compared the responses of C57/Bl6 male and female mice on a control diet (10% kcal fat) with those eating a high fat diet (HFD; 60% kcal fat) for 10 weeks (final age 14–15 weeks old). Following HFD feeding, adult mice of both sexes exhibited decreased muscle spindle afferent responses to muscle movement. Muscle spindle afferent firing rates during the plateau phase of stretch were significantly lower in both male and female HFD animals as were two measures of dynamic sensitivity (dynamic peak and dynamic index). Muscle spindle afferents in male mice on a HFD were also significantly less likely to entrain to vibration. Due to the importance of muscle spindle afferents to proprioception and motor control, decreased muscle spindle afferent responsiveness may contribute to balance instability during obesity.

Human Postural Control

From ancient Greece to nowadays, research on posture control was guided and shaped by many concepts. Equilibrium control is often considered part of postural control. However, two different levels have become increasingly apparent in the postural control system, one level sets a distribution of tonic muscle activity (“posture”) and the other is assigned to compensate for internal or external perturbations (“equilibrium”). While the two levels are inherently interrelated, both neurophysiological and functional considerations point toward distinct neuromuscular underpinnings. Disturbances of muscle tone may in turn affect movement performance. The unique structure, specialization and properties of skeletal muscles should also be taken into account for understanding important peripheral contributors to postural regulation. Here, we will consider the neuromechanical basis of habitual posture and various concepts that were rather influential in many experimental studies and mathematical models of human posture control.

The influence of adipose tissue location on postural control

A growing body of evidence suggests, that excessive body weight is inseparably connected with postural instability. In none of previous studies, body weight distribution has been considered as a factor, which may affect results of a static posturography. The purpose of the present study is to quantify some center of foot pressure (COP) characteristics in 40 obese women with android type of obesity (waist-to-hip ratio - WHR≥0.85, BMI: 37.5±5.4) and 40 obese women with gynoid type of obesity (WHR<0.85, BMI: 36.9±5.1). Variables of postural sway were acquired while subjects were standing quietly on a force plate with eyes open and closed. Both in the sagittal and frontal plane sway range, average velocity, and maximal velocity of COP were calculated. Moreover, the total average velocity and total maximal velocity of the COP displacement were computed. Women with abdominal obesity showed a larger sway range in the anterior-posterior plane with eyes open (p<0.0282) and eyes closed conditions (p<0.0115) and a greater maximal COP velocity to compare with subjects with gynoidal obese type (p<0.0112) with eyes closed condition. The postural stability in obese women from the biomechanical point of view is strongly dependent on body distribution. Women with the abdominal obesity type may be exposed to a greater risk of postural instability as compare to women with gynoid fat distribution.

Association of the body mass index with the overall stability index in young adult Saudi males

OBJECTIVES

Studies have focused on obesity-induced balance instability in the older population, which has been understudied in young adults. This study aimed to determine the impact of obesity on dynamic balance in young adult Saudi males.

METHODS

A cross-sectional study of 704 young adult males aged between 18 and 35 years from Umm Al-Qura University, Makkah, KSA, was performed. The obesity-induced balance was evaluated with a Biodex Balance System apparatus with a movable platform, and the overall stability index (OSI) was measured as an indicator of dynamic balance. Participants with a body mass index (BMI) ≥30 kg/m2 were considered obese.

RESULTS

The mean age and BMI of the participants was 20 years and 25.6 kg/m2, respectively. The mean OSI of the entire sample was 0.9, and the OSI values increased significantly (p < 0.001) with increasing BMI. The adjusted correlation between OSI and BMI was 0.487 (p < 0.001). Logistic regression showed that for each one-unit increment in BMI, there was an expected rise of 0.115 units in the OSI value. The receiver operating characteristic curve showed that the optimal threshold of the weight and BMI cutoff points that optimized the OSI values were 18.8 kg/m2 and 54.5 kg, respectively, with high sensitivity and specificity values. In addition, BMI affected approximately 23% of the total variability on balance (partial eta squared = 0.227, p < 0.001).

CONCLUSION

Obesity has a clear impact on dynamic balance in the selected young males. Weight management programs for obese subjects should be encouraged to optimize BMI and weight, which can attenuate balance stability.

Differences in intermittent postural control between normal-weight and obese children

AIM

The main objective of this study was to determine differences in postural control between obese and non-obese children.

METHODS

The study design was cross-sectional, prospective, between-subjects. Postural control variables were obtained from a group of obese children and a normal-weight control group under two different postural conditions: bipedal standing position with eyes open and bipedal standing with eyes closed. Variables were obtained for each balance condition using time domain and sway-density plot analysis of the center of pressure signals acquired by means of a force plate.

RESULTS

Pairwise comparisons revealed significant differences between obese and normal-weight children in mean velocity in antero-posterior and medio-lateral directions, ellipse area and mean distance with both eyes open and eyes closed. Normal-weight subjects obtained lower values in all these variables than obese subjects. Furthermore, there were differences between both groups in mean peaks with eyes open and in mean time with eyes closed.

CONCLUSION

Alterations were detected in the intermittent postural control in obese children. According to the results obtained, active anticipatory control produces higher center of pressure displacement responses in obese children and the periods during which balance is maintained by passive control and reflex mechanisms are of shorter duration.

Neural Consequences of Increasing Body Weight: Evidence from Somatosensory Evoked Potentials and the Frequency-Specificity of Brain Oscillations

Previous studies on the control of human balance suggested that increased pressure under the feet, leading to reduced plantar sole mechanoreceptors sensitivity, increases body sway. Although this suggestion is attracting, it is unclear whether increased plantar sole pressure simply reduces the transmission of plantar sole afferent to the cortex or also alters the sensorimotor integrative mechanisms. Here we used electrical stimulation applied under the sole of the foot to probe the sensorimotor mechanisms processing foot mechanoreceptors. Balance control of healthy individuals was assessed either when wearing a loaded vest or in normal-weight condition. In the Loaded condition, we observed decreased cortical activity over the primary somatosensory cortex (SI) for both an early P₅₀-N₉₀ somatosensory evoked potential (SEP) and for oscillatory brain activity within the gamma band (30–80 Hz). These reductions were interpreted as a disrupted early sensory transmission (i.e., decreased early SEP) leading to a decreased perception of plantar sole sensory information (i.e., decreased gamma band power). These early sensory mechanisms for the Loaded condition were associated with an increase in the late P₁₇₀-N₂₁₀ SEP and oscillatory brain activity within the beta band (19–24 Hz). These neural signatures involved areas which are engaged in sensorimotor integrative processes (secondary somatosensory cortex (SII) and right temporoparietal junction). Altered early and late sensory processes may result from the increase pressure on the mechanoreceptors of the foot sole and not from postural instability per se. Indeed, postural instability with normal weight condition did not lead to SEP changes.

Impact of obesity in elderly patients with postural instability

OBJECTIVE

The aim of the study is to assess whether obesity affects balance in elderly patients with postural instability.

STUDY DESIGN

It is a case-control study, with cases defined by BMI ≥30 kg/m(2), and developed in a third level university hospital.

METHODS

We included 135 patients aged 65 years old or more who presented postural instability. Balance assessment was through the sensory organisation test (SOT), limits of stability (LOS) and rhythmic weight shift (RWS) of computerised dynamic posturography (CDP) and the modified timed up-and-go (TUG) test. The patients also completed the Dizziness Handicap Inventory and short Falls Efficacy Scale-International questionnaire.

RESULTS

Patients with obesity took longer to perform the modified TUG and required more steps. Also these patients had poorer scores in the subjective tests. In the CDP there were no significant differences in the SOT nor the LOS, and only there was a statistical significant difference in the anterior-posterior directional control of the RWS. Obese patients have a higher risk of fallings compared to non-obese patients.

CONCLUSION

In essence, our results indicate that obesity interferes in the balance of elderly patients with postural instability, putting them at a greater risk of fallings, performing worse dynamic tasks and feeling more disabled. Although continued education on training balance may be useful in older population, since the obese group shows more rate of fallers, rehabilitation programmes focus on dynamic tasks in these patients could be useful to reduce their fall risk and improve their quality of life.

Effects of adiposity on postural control and cognition

In the U.S., it is estimated that over one-third of adults are obese (Body Mass Index (BMI)>30kg/m(2)). Previous studies suggest that obesity may be associated with deficits in cognitive performance and postural control. Increased BMI may challenge cognitive and postural performance in a variety of populations; however, most relevant studies have classified participants based on BMI values, which cannot be used to accurately assess the effects of adiposity on cognitive performance and postural control. The objective of the current study was to examine motor and cognitive responses for overweight and obese adults compared to normal weight individuals by using both BMI and adiposity measures. Ten normal weight (BMI=18-24.9kg/m(2)), ten overweight (BMI=25-29.9kg/m(2)), and ten obese (BMI=30-40kg/m(2)) adults were evaluated (age: 24±4 years). Participants were classified into three groups based on BMI values at the onset of the study, prior to body composition analysis. Participants performed (1) working memory task while maintaining upright stance, and (2) a battery of sensorimotor evaluations. Working memory reaction times, response accuracy, center-of-pressure (COP) path length, velocity, migration area, time to boundary values in anterior-posterior direction, and ankle-hip strategy-scores were calculated to evaluate cognitive-motor performance. No significant deficits in working memory performance were observed. Overall, measures of motor function deteriorated as BMI and body fat percentage increased. The relationship between deteriorating postural performance indices and body fat percentage were greater than those found between BMI and postural performance indices.