Center Of Mass Sway Research Articles

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

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

Sway and Acceleration Changes of the Center of Mass during Walking Stance Phase before and after Total Knee Arthroplasty

Elucidating the sway and changes in the acceleration of center of mass (COM) during walking is important for effective gait training and rehabilitation. The objective of this study was to verify the improvement in gait before and after total knee arthroplasty (TKA) from COM sway and the changes in the acceleration of COM during the stance phase of walking. This study included 13 patients (1 male and 12 females) with medial knee osteoarthritis who were hospitalized for TKA. The COM sway during the stance phase of walking was evaluated using root mean square (RMS) normalized by walking speed, and the changes in acceleration were further verified. Lateral and vertical RMS showed significant differences between preoperative and postoperative states and demonstrated low values after TKA. The lateral acceleration at the latter part of the early stance phase demonstrated a significant difference between preoperative and postoperative states. A significant difference was also observed in the lateral acceleration in the late stance phase between the two groups. Improvement in pain and alignment after TKA reduced the lateral sway of COM and the changes in acceleration during the gait stance phase, which is speculated to lead to improvement in gait and prevention of falls.

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

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

Visual oscillation effects on dynamic balance control in people with multiple sclerosis

BackgroundPeople with multiple sclerosis (PwMS) have balance deficits while ambulating through environments that contain moving objects or visual manipulations to perceived self-motion. However, their ability to parse object from self-movement has not been explored. The purpose of this research was to examine the effect of medial–lateral oscillations of the visual field and of objects within the scene on gait in PwMS and healthy age-matched controls using virtual reality (VR).MethodsFourteen PwMS (mean age 49 ± 11 years, functional gait assessment score of 27.8 ± 1.8, and Berg Balance scale score 54.7 ± 1.5) and eleven healthy controls (mean age: 53 ± 12 years) participated in this study. Dynamic balance control was assessed while participants walked on a treadmill at a self-selected speed while wearing a VR headset that projected an immersive forest scene. Visual conditions consisted of (1) no visual manipulations (speed-matched anterior/posterior optical flow), (2) 0.175 m mediolateral translational oscillations of the scene that consisted of low pairing (0.1 and 0.31 Hz) or (3) high pairing (0.15 and 0.465 Hz) frequencies, (4) 5 degree medial–lateral rotational oscillations of virtual trees at a low frequency pairing (0.1 and 0.31 Hz), and (5) a combination of the tree and scene movements in (3) and (4).ResultsWe found that both PwMS and controls exhibited greater instability and visuomotor entrainment to simulated mediolateral translation of the visual field (scene) during treadmill walking. This was demonstrated by significant (p < 0.05) increases in mean step width and variability and center of mass sway. Visuomotor entrainment was demonstrated by high coherence between center of mass sway and visual motion (magnitude square coherence = ~ 0.5 to 0.8). Only PwMS exhibited significantly greater instability (higher step width variability and center of mass sway) when objects moved within the scene (i.e., swaying trees).ConclusionResults suggest the presence of visual motion processing errors in PwMS that reduced dynamic stability. Specifically, object motion (via tree sway) was not effectively parsed from the observer’s self-motion. Identifying this distinction between visual object motion and self-motion detection in MS provides insight regarding stability control in environments with excessive external movement, such as those encountered in daily life.

Influence of Controlled Stomatognathic Motor Activity on Sway, Control and Stability of the Center of Mass During Dynamic Steady-State Balance-An Uncontrolled Manifold Analysis.

Multiple sensory signals from visual, somatosensory and vestibular systems are used for human postural control. To maintain postural stability, the central nervous system keeps the center of mass (CoM) within the base of support. The influence of the stomatognathic motor system on postural control has been established under static conditions, but it has not yet been investigated during dynamic steady-state balance. The purpose of the study was to investigate the effects of controlled stomatognathic motor activity on the control and stability of the CoM during dynamic steady-state balance. A total of 48 physically active and healthy adults were assigned to three groups with different stomatognathic motor conditions: jaw clenching, tongue pressing and habitual stomatognathic behavior. Dynamic steady-state balance was assessed using an oscillating platform and the kinematic data were collected with a 3D motion capturing system. The path length (PL) of the 3D CoM trajectory was used for quantifying CoM sway. Temporal dynamics of the CoM movement was assessed with a detrended fluctuation analysis (DFA). An uncontrolled manifold (UCM) analysis was applied to assess the stability and control of the CoM with a subject-specific anthropometric 3D model. The statistical analysis revealed that the groups did not differ significantly in PL, DFA scaling exponents or UCM parameters. The results indicated that deliberate jaw clenching or tongue pressing did not seem to affect the sway, control or stability of the CoM on an oscillating platform significantly. Because of the task-specificity of balance, further research investigating the effects of stomatognathic motor activities on dynamic steady-state balance with different movement tasks are needed. Additionally, further analysis by use of muscle synergies or co-contractions may reveal effects on the level of muscles, which were not visible on the level of kinematics. This study can contribute to the understanding of postural control mechanisms, particularly in relation to stomatognathic motor activities and under dynamic conditions.

Smart Offloading Boot System for Remote Patient Monitoring: Toward Adherence Reinforcement and Proper Physical Activity Prescription for Diabetic Foot Ulcer Patients.

A critical factor in healing diabetic foot ulcers is patient adherence to offloading devices. We tested a smart offloading boot (SmartBoot) combined with a smartwatch app and cloud dashboard to remotely monitor patient adherence and activity. In addition, the impact of SmartBoot on balance, gait, and user experience was investigated. Fourteen volunteers (31.6±8.7 years; 64% female) performed natural activities (eg, sitting, standing, walking) with and without the SmartBoot for approximately 30 minutes. All participants completed balance tests, 10-meter walking tests at slow, normal, and fast pace while wearing the SmartBoot, and a user experience questionnaire. The accuracy of real-time adherence reporting was assessed by comparing the SmartBoot and staff observation. Center of mass (COM) sway and step counts were measured using a validated wearable system. Average sensitivity, specificity, and accuracy for adherence and non-adherence were 90.6%, 88.0%, and 89.3%, respectively. The COM sway area was significantly smaller with the SmartBoot than without the SmartBoot regardless of test condition. Step count error was 4.4% for slow waking, 36.2% for normal walking, 16.0% for fast walking. Most participants agreed that the SmartBoot is easy to use, relatively comfortable, nonintrusive, and innovative. To our knowledge, this is the first smart offloading system that enables remote patient monitoring and real-time adherence and activity reporting. The SmartBoot enhanced balance performance, likely due to somatosensory feedback. Questionnaire results highlight SmartBoot's technical and clinical potential. Future studies warrant clinical validation of real-time non-adherence alerting to improve wound healing outcomes in people with diabetic foot ulcers.

"Characteristics of Head Center of Mass Sway and Neck Flexor Activity During Compensatory Backward Stepping in the Elderly"

"Characteristics of Head Center of Mass Sway and Neck Flexor Activity During Compensatory Backward Stepping in the Elderly"

Kinematic Analysis of Dance-Based Exergaming: A Cross-Sectional Study.

Recent studies demonstrate improvements in both postural stability and mobility among aging populations and those with stroke who are exposed to dance-based exergaming (DBExG). However, age-related deficits and aging with cortical pathology may lead to distinct movement adaptation patterns during DBExG, which could impact therapeutic outcomes.<br/> Aim: The aim of this study was to examine the movement kinematics (postural stability and mobility) of healthy older adults, older adults with stroke, and young adults for different paces of dance during DBExG.<br/> Method: The study included 33 particpants (11 participant from each group of healthy older adults, older adults with chronic stroke, and healthy young adults) who performed the DBExG using slow- (SP), medium- (MP), and fast-paced (FP) songs with movements in the anteroposterior (AP) and mediolateral (ML) directions. Center of mass (CoM) sway area, excursion (Ex), and peaks as well as hip, knee, and ankle joint excursions were computed.<br/> Results: Results of the study revealed that CoM sway areas and Exs were greater for healthy young adults than for older adults with stroke for the SP dance (p < 0.05) and that there were significantly more AP CoM peaks for young adults than for healthy older adults and those with stroke for the FP dance (p < 0.05). Young adults also exhibited greater hip and ankle Exs than older adults with stroke (p < 0.05) for all song paces. Similarly, knee and ankle Exs were greater for healthy older adults than for older adults with stroke for all song paces (p < 0.05).<br/> Conclusion: The quantitative evaluation and comparison of the movement patterns presented for the three groups could provide a foundation for both assessing and designing therapeutic DBExG protocols for these populations.

Cone of economy classification: evolution, concept of stability, severity level, and correlation to patient-reported outcome scores.

A prospective cohort study OBJECTIVE: To determine a classification system for cone of economy (CoE) measurements that defines clinically significant changes in altered balance and to assess if the CoE measurements directly impacts patients reported outcome measures (PROMs). Preoperative functional data is a crucial component of determining patient disability and prognosis. The CoE has been theorized to be the foundation of biomechanical changes that leads to increased energy expenditure and disability in spine patients. PROMs have been developed to quantify the level of debilitation in spine patients but have various limitations. A total of 423 symptomatic adult patients with spine pathology completed a series of PROMs preoperatively including VAS, ODI, Tampa Scale for Kinesiophobia (TSK), Fear and Avoidance Beliefs Questionnaire (FABQ), and Demoralization (DS). Functional balance was tested in this group using a full-body reflective marker set to measure head and center of mass (CoM) sway. PROMs scores were correlated with the magnitude of the CoE measurements. Patients were separated by the following proposed classification: CoM coronal sway > 1.5cm, CoM sagittal sway > 3.0cm, CoM total sway > 30.0cm, head coronal sway > 3.0cm, head sagittal sway > 6.0cm, and head total sway > 60.0cm. Significant differences were noted in the ODI (< 0.001), FABQ physical activity (< 0.001-0.009), DS (< 0.001-0.023), and TSK (< 0.001-0.032) across almost all planes of motion for both CoM and head sway. The ODI was most sensitive to the difference between groups across CoM and head sway planes with a mean ODI of 47.5-49.5 (p < 0.001) in the severe group versus 36.6-39.3 (p < 0.001) in the moderate group. By classifying CoE measurements by the cutoffs proposed, clinically significant alterations in balance can be quantified. Furthermore, this study demonstrates that across spinal pathology, higher magnitude CoE and range of sway measurements correlate with worsening PROMs. The Haddas' CoE classification system in this study helps to identify patients that may benefit from surgery and guide their postoperative prognosis.

The Effect of Surgical Decompression and Fusion on Functional Balance in Patients With Degenerative Lumbar Spondylolisthesis.

Prospective cohort study. To quantify the effect of lumbar decompression and fusion surgery on balance and stability in patients with degenerative lumbar spondylolisthesis (DLS) and compare them to controls. DLS is a condition in which one vertebra subluxates relative to an adjacent vertebra in the absence of a disruption in the neural arch. While the existing literature demonstrates that decompression and fusion can successfully alleviate pain and reduce disability in patients with DLS, no studies to date have used quantitative dynamic testing to determine the effect of surgery on cone of economy (CoE) measures in this patient population. Forty-five DLS patients performed a series of functional balance tests a week before and 3 months after surgery and were compared to 28 controls. The outcome measures included range of sway (RoS) and total sway for the center of mass (CoM) and head in the sagittal, coronal, and axial planes, along with leg and back Visual Analog Scale (VAS), Oswestry Disability Index (ODI), Fear/Avoidance Behavior Questionnaire (FABQ), Tampa Scale of Kinesophobia (TSK), and Demoralization scale. RoS for the CoM (P < 0.005) and head (P < 0.017) decreased in all planes postoperatively. Reductions in CoM (P = 0.001) and head total sway (P = 0.001) were also observed after surgery. Furthermore, patients with DLS reported strong improvements in VAS low back (P = 0.001), VAS leg (P = 0.001), ODI (P = 0.001), FABQ Physical (P = 0.003), TSK (P = 0.001), and demoralization (P = 0.044) with surgical intervention. Although total sway was reduced after surgery, it did not return to the level of normal controls as demonstrated with more total sway of their CoM (P = 0.002) and head (P = 0.001) as well as more sagittal head RoS (P = 0.048). This study confirms that surgical intervention for degenerative spondylolisthesis is effective at reducing disability, back and leg pain, demoralization, kinesiophobia, and fear-avoidance beliefs related to physical activity in patients with DLS. Furthermore, such patients exhibit a significantly more stable stance after surgery. However, balance parameters did not completely normalize by 3 months postoperatively. 3.

Reductions in body sway responses to a rhythmic support surface tilt perturbation can be caused by other mechanisms than prediction

Studies investigating balance control often use external perturbations to probe the system. These perturbations can be administered as randomized, pseudo-randomized, or predictable sequences. As predictability of a given perturbation can affect balance performance, the way those perturbations are constructed may affect the results of the experiments. In the present study, we hypothesized that subjects are able to adapt to short, rhythmic support surface tilt stimuli, but not to long pseudo-random stimuli. 19 subjects were standing with eyes closed on a servo-controlled platform tilting about the ankle joint axis. Pre and post to the learning intervention, pseudo-random tilt sequences were applied. For the learning phase, a rhythmic and easy-to-memorize 8-s long sequence was applied 75 times, where subjects were instructed to stand as still as possible. Body kinematics were measured and whole body center of mass sway was analyzed. Results showed reduced sway and less forward lean of the body across the learning phase. The sway reductions were similar for stimulus and non-stimulus frequencies. Surprisingly, for the pseudo-random sequences, comparable changes were found from pre- to post-tests. In summary, results confirmed that considerable adaptations exist when exposing subjects to an 8-s long rhythmic perturbation. No indications of predictions of the learning tilt sequence were found, since similar changes were also observed in response to pseudo-random sequences. We conclude that changes in body sway responses following 75 repetitions of an 8-s long rhythmic tilt sequence are due to adaptations in the dynamics of the control mechanism (presumably stiffness).

Effectiveness of Daily Use of Bilateral Custom-Made Ankle-Foot Orthoses on Balance, Fear of Falling, and Physical Activity in Older Adults: A Randomized Controlled Trial

Background: Foot problems are prevalent in older adults, which may increase the risk and concern for falls. Ankle-foot orthoses (AFO) have been shown to be effective in the stabilization of lower extremities, but their long-term effectiveness in improving balance and their potential to encourage older adults to become more physically active are still debated. Objective: This randomized controlled trial investigated the effectiveness of daily use of a custom-made AFO on balance, fear of falling, and physical activity in older adults. Study Design: Forty-four older adults with concern about or at risk for falling were randomly allocated to either the control group (CG; 77.3% female, age 75.6 ± 6.5 years, BMI 29.3 ± 6.4) or the intervention group (IG; 63.6% female, age 73.7 ± 6.3 years, BMI = 27.8 ± 4.8). The IG received walking shoes and bilateral custom-made AFO. The CG received only walking shoes. At the baseline and 6-month follow-ups, balance and physical activity were assessed using validated wearable instrumentation and fear of falling was assessed using the Fall Efficacy Scale-International (FES-I). Adherence and acceptability toward wearing the AFO were assessed using self-reported questionnaires at the 6-month follow-up. Results: No significant between-group difference was observed at baseline (p = 0.144–0.882). Compared to baseline and the CG, hip, ankle, and center-of-mass (COM) sways were significantly reduced at the 6-month follow-up in the IG while standing with the feet together during the eyes-open condition (p = 0.005–0.040). Within the IG, the FES-I was reduced significantly (p = 0.036) and there was an increasing trend in the number of walking bouts with a medium effect size (d = 0.52, p = 0.440) compared to baseline. However, there were no significant changes in FES-I and physical activity measures in the CG (p = 0.122–0.894). The reduction in COM sway in the IG was moderately correlated with adherence (r = –0.484, p = 0.047) and strongly correlated with baseline COM sway (r = –0.903, p < 0.001). Conclusion: Results suggest that bilateral custom-made AFO plus walking shoes is effective in improving balance compared to walking shoes alone, and it significantly reduces the fear of falling, with a nonsignificant but noticeable positive trend in physical activity, compared to baseline. The results also suggest that older adults with poor balance at baseline and higher daily adherence to using the AFO will gain more benefit from the AFO intervention.

Locomotor adaptations to prolonged step-by-step frontal plane trunk perturbations in young adults.

The purpose of this study was to quantify the magnitude and time course of dynamic balance control adaptations to prolonged step-by-step frontal plane forces applied to the trunk during walking. Healthy young participants (n = 10, 5 female) walked on an instrumented split-belt treadmill while an external cable-driven device applied frontal plane forces to the trunk. Two types of forces were applied: 1) forces which accentuated COM movement in the frontal plane (destabilizing) and 2) forces which resisted COM movement in the frontal plane (stabilizing). We quantified dynamic balance control using frontal plane measures of (1) the extent of center of mass (COM) movement over a gait cycle (COM sway), (2) the magnitude of base of support (step width), and (3) cadence. During destabilizing force conditions, COM sway, step width, and cadence increased. In response to stabilizing force conditions, COM sway decreased. In addition, during destabilizing balance conditions participants made quicker adaptations to their step width compared to the time to adapt to stabilizing forces. Taken together, these results provide important insight into differences in dynamic balance control strategies in response to stabilizing and destabilizing force fields.

Small, movement dependent perturbations substantially alter postural control strategy in healthy young adults

Postural control is commonly investigated by observing responses to perturbations. We developed a perturbation paradigm mimicking self-generated errors in weight shifting, which are a common cause of falling among older adults. Our aim was to determine the effects of this small, but complex, perturbation on postural sway of healthy young adults and evaluate the role of vision and cognition during movement dependent perturbations. Fifteen participants stood hip-width apart with their eyes open, closed and while performing two different cognitive tasks. Participants were continuously perturbed by medial-lateral (ML) support surface translations corresponding to, and hence doubling, their own center of mass sway. We analyzed the standard deviation (SD), root mean square (RMS), range, and mean power frequency (MPF) of center of pressure displacements. ML postural sway increased due to the perturbation (SD p ≤ .001, range p < .001, RMS p ≤ .001, MPF p < .001). Cognitive load increased the ML sway range (p = .048). Lack of vision increased ML MPF (p = .001) and anterior-posterior (AP) range (p < .001), SD (p < .001), and RMS (p = .001). Significant interaction of vision with the perturbation was found for the ML range (p = .045) and AP SD (p = .018). The perturbation specifically affected ML postural sway. Increased MPF is indicative of a postural control strategy change, which was insufficient for fully controlling the increased sway. Despite being small, this type of perturbation appears to be challenging for young adults.

Friday, September 28, 2018 4:05 PM–5:05 PM abstracts: cervical myelopathy and deformity: 254. Altered balance in cervical spondylotic myelopathy patients compared to controls

BACKGROUND CONTEXT Balance is defined as the ability of the human body to maintain its center of mass (COM) within the base of support with minimal postural sway. Sway is the movement of the COM in the horizontal plane when a person is standing in a static position. Cervical spondylotic myelopathy (CSM) patients have impaired body balance and proprioceptive loss. PURPOSE To quantify the amount of sway associated with maintaining a balanced posture within the cone of economy (COE) in a group of untreated CSM patients and compare them to matched healthy controls. STUDY DESIGN/SETTING A prospective cohort study. PATIENT SAMPLE Thirty-two CSM patients and sixteen healthy controls (HC). OUTCOME MEASURES Center of mass (COM) and head sway, spine and lower extremityIntegrated Electromyography (iEMG). METHODS Thirty-two CSM patients performed a series of functional balance tests a week before surgery. Sixteen healthy controls (HC) performed a similar balance test. The functional balance test was essentially a Romberg's test in which the patients are required to stand erect with feet together and eyes opened in their self-perceived balanced and natural position for a full minute. All test subjects were fitted to a full body reflective markers set and surface EMG. RESULTS CSM patients presented more center of mass (COM) sway in the anterior-posterior (CSM: 2.87 vs. C: 0.74cm; p=.023) and right-left (CSM: 5.16 vs. C: 2.51cm; p=.003) directions and head sway (anterior-posterior – CSM: 2.17 vs. C: 0.82cm; p=.010 and right-left – CSM: 3.66 vs. C: 1.69cm; p=.044) and more COM (CSM: 44.72cm vs. HC: 19.26cm, p=.001) and head (Pre: 37.87cm vs. C: 19.93cm, p=.001) total sway in comparison to the healthy controls. CSM patients expended statistically significantly more muscle activity to maintain static standing, as manifest by increased muscle activity in their Multifidus (CSM: 22.25mV vs. HC: 12.39mV, p=.038), Erector Spinae (CSM: 26.76mV vs. HC: 14.41mV, p=.044), Rectus Femoris (CSM: 29.05mV vs. HC: 16.07mV, p=.037), and Tibialis Anterior(CSM: 23.06mV vs. HC: 14.48mV, p=.048) muscles during one minute standing in comparison to healthy control. CONCLUSIONS In symptomatic CSM patients, COM and head total sway were significantly greater than controls. Individuals with CSM exhibit more trunk and lower extremity muscle activity, and thus expend more energy to maintain a balanced, static standing posture. While most of the balance research in patients with spinal disorders is done based on static x-rays and mostly focused on sagittal spinal alignment, this study is the first effort to evaluate global balance as a dynamic process.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P60. The effect of physical therapy on gait and balance in patients follow lumbar artificial disc replacement: a preliminary study

BACKGROUND CONTEXT Lumbar disc replacement (LDR) is used primarily to treat lumbar degenerative disc disease (DDD) resulting with back pain and/or leg pain in the absence of nerve root compression due to its advantages over fusion, including reduction of adjacent segment disease and reoperations as well as spinal motion preservation. A key factor of clinical success is rehabilitation. Physical therapy (PT) is often used to improve flexibility, strength and stability as well as balance and coordination, areas commonly deficient after surgery. Studies on PT and LDR are scarce. The impact of PT intervention on the neuromuscular, biomechanical, and self-reported outcomes of LDR patients’ gait and balance have not yet been explored. PURPOSE To evaluate the effect of PT on the biomechanics of the lower extremities and spine during gait and balance in patients with DDD after LDR surgical intervention. STUDY DESIGN/SETTING A prospective concurrent control cohort study. PATIENT SAMPLE Eight LDR patients. OUTCOME MEASURES Gait spatiotemporal parameters and center of mass (COM) and head sway during functional balance test along with VAS and ODI. METHODS After LDR surgery, gait and functional balance analyses were performed the week before PT (pre) and after completion of 6-8 weeks PT (post). PT consisted of manual therapy, therapeutic exercises and activities as well as neuromuscular education per LDR protocol, which focused on improved mobility, stability and strength as well as balance in accordance with appropriate precautions or restrictions. No modalities, except for cold packs, were used. Spatiotemporal parameters (ie, gait speed, cadence, stride length, width and time, etc.) were calculated during the gait evaluation. The functional balance test was similar to a Romberg's test. COM and head displacements in the sagittal and coronal planes and total sway amount were calculated. ODI and VAS were collected on the day of each testing. RESULTS ODI score was reduced from 29.3±22.8 to 15.5±2.5. VAS leg (pre: 3.3±2.3vs. post: 0.6±0.5), and lower back (pre: 3.6±2.9vs. post: 1.4±0.3) scores were reduce as well. Patients presented with less COM say in the forward–backward direction (pre: 1.27±1.11vs. post: 0.21±0.87 cm), less external oblique muscle (pre: 0.028±0.020vs. post: 0.009±0.003 mV) but more rectus femoris (pre: 0.009±0.004vs. post: 0.012±0.005 mV) and tibialis anterior (pre: 0.009±0.002vs. post: 0.012±0.001 mV) muscle activity after completion of PT in comparison to their pre-PT state. Gait spatiotemporal parameters did not significantly change completion of PT. This may be due to the small sample size we have. CONCLUSIONS This is the first study to explore the effect of PT treatment on function in patients with DDD after LDR surgery. Minimal information is available on the effect of PT and LDR. PT after LDR surgery may positively affect the COM sway and improved muscle recruitment of the tibialis anterior and rectus femoris during balance resulting with a more stable, efficient, and normal balance pattern. Gait appears intact after LDR. More research and standardization of PT care is needed for optimal LDR benefits.

A method to quantify the "cone of economy".

A non-randomized, prospective, concurrent control cohort study. The purpose of this study is to develop and evaluate a method to quantify the dimensions of the cone of economy (COE) and the energy expenditure associated with maintaining a balanced posture within the COE, scoliosis patients and compare them to matched non-scoliotic controls in a group of adult degenerative. Balance is defined as the ability of the human body to maintain its center of mass (COM) within the base of support with minimal postural sway. The cone of economy refers to the stable region of upright standing posture. The underlying assumption is that deviating outside one's individual cone challenges the balance mechanisms. Adult degenerative scoliosis (ADS) patients exhibit a variety of postural changes within their COE, involving the spine, pelvis and lower extremities, in their effort to compensate for the altered posture. Ten ADS patients and ten non-scoliotic volunteers performed a series of functional balance tests. The dimensions of the COE and the energy expenditure related to maintaining balance within the COE were measured using a human motion video capture system and dynamic surface electromyography. ADS patients presented more COM sway in the sagittal (ADS: 1.59 cm vs. H: 0.61 cm; p = 0.049) and coronal (ADS: 2.84 cm vs. H: 1.72 cm; p = 0.046) directions in comparison to the non-scoliotic control. ADS patients presented with more COM (ADS: 33.30 cm vs. H: 19.13 cm; p = 0.039) and head (ADS: 31.06 cm vs. H: 19.13 cm; p = 0.013) displacements in comparison to the non-scoliotic controls. Scoliosis patients expended more muscle activity to maintain static standing, as manifest by increased muscle activity in their erector spinae (ADS: 37.16mV vs. H: 20.31mV; p=0.050), and gluteus maximus (ADS: 33.12mV vs. H: 12.09mV; p=0.001) muscles. We were able to develop and evaluate a method that quantifies the COE boundaries, COM displacement, and amount of sway within the COE along with the energy expenditure for a specific patient. This method of COE measurement will enable spine care practitioners to objectively evaluate their patients in an effort to determine the most appropriate treatment options, and in objectively documenting the effectiveness of their intervention.

GAIT SYMMETRY AFTER STROKE: DO CEREBRAL HEMISPHERES INFLUENCE EQUALLY?

Stroke responds to a high death rate and is the world major impairment cause. The risk of going through this condition increases 22% after the age of 55 years and increases further 13% every 5 years. The brain damage brings loss of selective muscle control and primitive locomotor patterns may arise to reinforce stability. This adaptation causes asymmetry and is related to the constant postural balance compensation need. It is known that the cerebral hemispheres have different motor tasks. The right one is responsible for the motor control while the left one controls the spacial orientation. The aim of this cross-sectional 3D gait analysis study was to assess stride width and gait speed symmetry among stroke survivors (SS), using the Symmetry Index (SI), and compare those with left (LBD) from those with right brain damage (RBD). A sample of 32 SS (47yo±17,32) and 32 able-bodied (25,09yo±3,77) were divided in three groups: LBD (16, 43,87yo±17,90), RBD (18, 49,76yo±16,83) and Able-bodied (32). Results showed less stride width symmetry and slower gait (0,5m/s±0,2) at RBD while LBD symmetry was not different from Able-bodied (p=0,074). The LBD group showed better recovery and motor compensation bringing their symmetry next to those able-bodied. Less stride width asymmetry leads to less center of mass sway and benefits dynamic postural balance. The more asymmetrical LBD group showed a slower gait as a compensation. Differences in symmetry bring diferente level of stability challenges. It is important to keep that in mind when managing stroke survivors in rehabilitation programmes.

Exergaming in Older People Living with HIV Improves Balance, Mobility and Ameliorates Some Aspects of Frailty

Approximately 1.2 million people in the United States live with HIV infection. Medical advancements have increased the life expectancy and this cohort is aging. HIV-positive individuals have a high incidence of frailty (~20%) characterized by depression and sedentary behavior. Exercise would be healthy, but due to the frail status of many HIV-positive individuals, conventional exercise is too taxing. The aim of this study was to evaluate the effectiveness and acceptability of a novel game-based training program (exergame) in ameliorating some aspects of frailty in HIV-infected individuals. Ten older people living with HIV were enrolled in an exergame intervention. Patients performed balance exercises such as weight shifting, ankle reaching, and obstacle crossing. Real-time visual/audio lower-extremity joint motion feedback was provided using wearable sensors to assist feedback and encourage subjects to accurately execute each exercise task. Patients trained twice a week for 45 min for 6 weeks. Changes in balance, gait, psychosocial parameters and quality of life parameters were assessed at the beginning, midterm and at conclusion of the training program. Ten patients completed the study and their results analyzed. The mean age was 57.2 ± 9.2 years. The participants showed a significant reduction in center of mass sway (78.2%, p = .045) during the semi-tandem balance stance with eyes closed and showed a significant increase in gait speed during a dual task motor-cognitive assessment (9.3%, p = .048) with an increase in stride velocity of over 0.1 m/sec. A significant reduction in reported pain occurred (43.5%, p = .041). Preliminary results of this exergame intervention show promise in improving balance and mobility while requiring older people living with HIV to be more active. The exergame can be continued at home and may have long term as well as short-term benefits for ameliorating frailty associated with HIV infection.

Exergaming in Older People Living with HIV Improves Balance, Mobility and Ameliorates Some Aspects of Frailty.

Approximately 1.2 million people in the United States live with HIV infection. Medical advancements have increased the life expectancy and this cohort is aging. HIV-positive individuals have a high incidence of frailty (~20%) characterized by depression and sedentary behavior. Exercise would be healthy, but due to the frail status of many HIV-positive individuals, conventional exercise is too taxing. The aim of this study was to evaluate the effectiveness and acceptability of a novel game-based training program (exergame) in ameliorating some aspects of frailty in HIV-infected individuals. Ten older people living with HIV were enrolled in an exergame intervention. Patients performed balance exercises such as weight shifting, ankle reaching, and obstacle crossing. Real-time visual/audio lower-extremity joint motion feedback was provided using wearable sensors to assist feedback and encourage subjects to accurately execute each exercise task. Patients trained twice a week for 45 min for 6 weeks. Changes in balance, gait, psychosocial parameters and quality of life parameters were assessed at the beginning, midterm and at conclusion of the training program. Ten patients completed the study and their results analyzed. The mean age was 57.2 ± 9.2 years. The participants showed a significant reduction in center of mass sway (78.2%, p = .045) during the semi-tandem balance stance with eyes closed and showed a significant increase in gait speed during a dual task motor-cognitive assessment (9.3%, p = .048) with an increase in stride velocity of over 0.1 m/sec. A significant reduction in reported pain occurred (43.5%, p = .041). Preliminary results of this exergame intervention show promise in improving balance and mobility while requiring older people living with HIV to be more active. The exergame can be continued at home and may have long term as well as short-term benefits for ameliorating frailty associated with HIV infection.