Publications by authors named "Tanvi Bhatt"

88 Publications

Perturbation-Induced Protective Arm Responses: Effect of Age, Perturbation-Intensity, and Relationship with Stepping Stability: A Pilot Study.

Brain Sci 2022 Jul 20;12(7). Epub 2022 Jul 20.

Department of Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Baltimore, MD 21201, USA.

During balance recovery from slip perturbations, forward flexion (elevation) of the arms serves to counterbalance the posteriorly displaced center of mass (CoM). We aimed to investigate whether aging affects modulation of arm responses to various intensities of unpredictable slip perturbations and whether arm responses are related to compensatory stepping stability. Ten healthy young adults and ten healthy older adults participated. Participants were asked to react naturally to three randomly administered levels of slip-like surface perturbations (intensity 1 (7.75 m/s), intensity 2 (12.00 m/s) and intensity 3 (16.75 m/s), which occurred by means of forward acceleration of the treadmill belt while standing. Kinematic data were collected using a motion capture system. Outcomes included arm elevation displacement, velocity, and margin of stability (MoS) of compensatory stepping. The results reveal no modulation of arm elevation velocity in older adults from perturbation intensity 1 to 2, whereas younger adults demonstrated progressive increases from intensity 1 to 2 to 3. At intensity 3, older adults demonstrated reduced maximal arm elevation velocity compared to younger adults ( = 0.02). The results in both groups combined reveal a positive correlation between maximal arm elevation velocity and first compensatory step MoS at intensity 3 ( = 0.01). Together, these findings indicate age-related decreases in arm response modulation and the association of arm elevation response with protective stepping stability, suggesting that fall prevention interventions may benefit from an emphasis on arm elevation velocity control in response to greater perturbation intensities.
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http://dx.doi.org/10.3390/brainsci12070953DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9313371PMC
July 2022

Association of balance control mechanisms with brain structural integrity in older adults with mild cognitive impairment.

Neurosci Lett 2022 07 30;783:136699. Epub 2022 May 30.

Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, USA.

Background: Older adults with mild cognitive impairment (OAwMCI) exhibit subtle balance control and gait deficits which are predominantly associated with structural brain pathologies such as impaired white matter integrity and reduced gray matter volume. However, the relationship between balance recovery mechanisms and neural substrates in OAwMCI remains unknown. This study thus aimed to explore the associations of volitional (self-initiated) and reactive balance (in response to an external perturbation) control with structural brain integrity.

Methods: Ten OAwMCI (MoCA 18-25/30; greater than 55 years) were examined on the limits of stability test (volitional balance via Equitest), stance perturbation test (reactive balance via ActiveStep treadmill) and underwent magnetic resonance imaging. Forward movement (frequently performed functional activity of daily living) was quantified by maximum excursion (maximum ability to shift one's center of gravity toward the theoretical limit [MXE-%])and directional control (amount of movement exhibited towards the target proportional to the movement away from the target [DCL-%]) on the limits of stability test. Slip-like (prevalent type of accidental falls) perturbations were quantified by postural stability (shortest distance of the COM motion state, i.e., its position and velocity, to the theoretical boundary) on the ActiveStep treadmill. White matter integrity was quantified by fractional anisotropy (FA, movement of water molecules directionality) and gray matter volume measured in mm.

Results: For volitional balance control, reduced forward MXE was significantly (p < 0.05) associated with lower FA in left (R = 0.56) and right (R = 0.60) corticospinal tract, left (R = 0.49) and right (R = 0.51) corticothalamic tract, left (R = 0.70) and right (R = 0.57) frontopontine tract, right (R = 0.67) cingulum, anterior commissure (R = 0.82), and corpus callosum (R = 0.62). Reduced forward DCL was significantly (p < 0.05) associated with reduced gray matter volume in the left (R = 0.75) and right (R = 0.81) cerebellum, brainstem (R = 0.64), right (R = 0.49) thalamus. For reactive balance control, reduced postural stability (p < 0.05) was significantly associated with reduced FA in the left (R = 0.75) and right (R = 0.64) corticospinal tract, left (R = 0.67) and right (R = 0.65) frontopontine tract. Reduced postural stability was significantly (p < 0.05) associated with reduced gray matter volume in the brainstem (R = 0.72) and right cerebellum (R = 0.70).

Conclusion: Our results indicate that structural brain integrity influences stability control in OAwMCI for both volitional and reactive balance tasks, which may share some common cortico-subcortical motor pathways and relay centers. Results also show that the integrity of descending pathways from cortical attentional centers could influence stability control for both tasks.
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http://dx.doi.org/10.1016/j.neulet.2022.136699DOI Listing
July 2022

Near-Fall Detection in Unexpected Slips during Over-Ground Locomotion with Body-Worn Sensors among Older Adults.

Sensors (Basel) 2022 Apr 27;22(9). Epub 2022 Apr 27.

Department of Physical Therapy, University of Illinois at Chicago, Chicago, IL 60612, USA.

Slip-induced falls are a growing health concern for older adults, and near-fall events are associated with an increased risk of falling. To detect older adults at a high risk of slip-related falls, this study aimed to develop models for near-fall event detection based on accelerometry data collected by body-fixed sensors. Thirty-four healthy older adults who experienced 24 laboratory-induced slips were included. The slip outcomes were first identified as loss of balance (LOB) and no LOB (NLOB), and then the kinematic measures were compared between these two outcomes. Next, all the slip trials were split into a training set (90%) and a test set (10%) at sample level. The training set was used to train both machine learning models ( = 2) and deep learning models ( = 2), and the test set was used to evaluate the performance of each model. Our results indicated that the deep learning models showed higher accuracy for both LOB (>64%) and NLOB (>90%) classifications than the machine learning models. Among all the models, the Inception model showed the highest classification accuracy (87.5%) and the largest area under the receiver operating characteristic curve (AUC), indicating that the model is an effective method for near-fall (LOB) detection. Our approach can be helpful in identifying individuals at the risk of slip-related falls before they experience an actual fall.
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http://dx.doi.org/10.3390/s22093334DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9102890PMC
April 2022

Gait Slip-Induced Fall-Type Assessment Based on Regular Gait Characteristics in Older Adults.

J Appl Biomech 2022 Apr 28:1-7. Epub 2022 Apr 28.

Department of Physical Therapy, University of Illinois at Chicago, Chicago, IL,USA.

Older adults could experience split falls or feet-forward falls following an unexpected slip in gait due to different neuromuscular vulnerabilities, and different intervention strategies would be required for each type of faller. Thus, this study aimed to investigate the key factors affecting the fall types based on regular gait pattern. A total of 105 healthy older adults who experienced a laboratory-induced slip and fall were included. Their natural walking trial immediately prior to the novel slip trial was analyzed. To identify the factors related to fall type, gait characteristics and demographic factors were determined using univariate logistic regression, and then stepwise logistic regression was conducted to assess the slip-induced fall type based on these factors. The best fall-type prediction model involves gait speed and recovery foot angular velocity, which could predict 70.5% of feet-forward falls and 86.9% of split falls. Body mass index was also a crucial fall-type prediction with an overall prediction accuracy of 70.5%. Along with gait parameters, 84.1% of feet-forward falls and 78.7% of split falls could be predicted. The findings in this study revealed the determinators related to fall types, which enhances our knowledge of the mechanism associated to slip-induced fall and would be helpful for the development of tailored interventions for slip-induced fall prevention.
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http://dx.doi.org/10.1123/jab.2021-0337DOI Listing
April 2022

Can a single session of treadmill-based slip training reduce daily life falls in community-dwelling older adults? A randomized controlled trial.

Aging Clin Exp Res 2022 Jul 2;34(7):1593-1602. Epub 2022 Mar 2.

Department of Physical Therapy, College of Applied Health and Sciences, University of Illinois at Chicago, Chicago, IL, 60612, USA.

Background: Task-specific training with single-session overground slip simulation has shown to reduce real-life falls in older adults.

Aims: The purpose of this study was to determine if fall-resisting behavior acquired from a single-session treadmill-based gait slip training could be retained to reduce older adults' falls in everyday living over a 6-month follow-up period.

Methods: 143 community-dwelling older adults (≥ 65 years old) were randomly assigned to either the treadmill-based gait slip training group (N = 73), in which participants were exposed to 40 unpredictable treadmill slips, or the control group (N = 70), in which participants walked on a treadmill at their comfortable speed. Participants reported their falls from the preceding year (through self-report history) and over the following 6 months (through fall diaries and monitored with phone calls).

Results: There was no main effect of time (retrospective vs. prospective fall) and training (treadmill training vs. control) on fall reduction (p > 0.05 for both). The survival distributions of event of all-cause falls or slip falls were comparable between groups (p > 0.05 for both).

Discussion: Unlike overground slip training where a single training session could significantly reduce everyday falls in a 6-month follow-up period, the results indicated that one treadmill-based gait slip training session by itself was unable to produce similar effects.

Conclusion: Further modification of the training protocol by increasing training dosage (e.g., number of sessions or perturbation intensity) may be necessary to enhance transfer to daily living. This study (NCT02126488) was registered on April 30, 2014.
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http://dx.doi.org/10.1007/s40520-022-02090-3DOI Listing
July 2022

Can prior exposure to repeated non-paretic slips improve reactive responses on novel paretic slips among people with chronic stroke?

Exp Brain Res 2022 Apr 1;240(4):1069-1080. Epub 2022 Feb 1.

Department of Physical Therapy, College of Applied Health Sciences, University of Illinois, Chicago, IL, 60612, USA.

This study examined if people with chronic stroke (PwCS) could adapt following non-paretic overground gait-slips and whether such prior exposure to non-paretic slips could improve reactive responses on novel paretic slip. Forty-nine PwCS were randomly assigned to either adaptation group, which received eight unexpected, overground, nonparetic-side gait-slips followed by two paretic-side slips or a control group, which received two paretic-side slips. Slip outcome, recovery strategies, center of mass (CoM) state stability, post-slip stride length and slipping kinematics were analyzed. The adaptation group demonstrated fall-reduction from first to eighth non-paretic slips, along with improved stability, stride length and slipping kinematics (p < 0.05). Within the adaptation group, on comparing novel slips, paretic-side demonstrated comparable pre-slip stability (p > 0.05); however, lower post-slip stability, increased slip velocity and falls was noted (p < 0.05). There was no difference in any variables between the novel paretic slips of adaptation and control group (p > 0.01). However, there was a rapid improvement on the 2nd slip such that adaptation group demonstrated improved performance from the first to second paretic slip compared to that in the control group (p < 0.01). PwCS demonstrated immediate proactive and reactive adaptation with overground, nonparetic-side gait-slips. However, PwCS did not demonstrate any inter-limb performance gain on the paretic-side after prior nonparetic-side adaptation when exposed to a novel paretic-side slip; but they did show significant positive gains with single slip priming on the paretic-side compared to controls without prior adaptation.Clinical registry number: NCT03205527.
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http://dx.doi.org/10.1007/s00221-021-06300-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9290783PMC
April 2022

Dance-based exergaming on postural stability and kinematics in people with chronic stroke - A preliminary study.

Physiother Theory Pract 2021 Dec 2:1-13. Epub 2021 Dec 2.

Department of Physical Therapy, University of Illinois at Chicago, Chicago, IL.

Introduction: The study evaluated the feasibility, and compliance of a dance-based exergaming (DBExG) on postural stability (PS) and lower extremity (LE) kinematics, along with post-intervention changes in gait function and falls self-efficacy in people with chronic stroke (PwCS).

Methods: Fifteen PwCS underwent DBExG for six weeks using Kinect "Just Dance 3." Pre- to post- changes were recorded during DBExG assessment on a fast-paced song (130 bpm) using an 8-camera motion capture system to assess PS (center of mass [CoM] excursions [EXs] in the anterior-posterior [AP] and mediolateral [ML] directions) and LE kinematics (hip, knee, and ankle joint angle EXs). Gait function was also assessed with gait parameters, such as gait speed, cadence, and gait symmetry on an electronic walkway. Falls self-efficacy was recorded with Falls Efficacy Scale (FES).

Results: The AP and ML CoM EXs and paretic joint angle EXs significantly increased pre- to post- DBExG assessment ( < .05). Gait parameters, and falls self-efficacy measures significantly changed pre- to post- DBExG ( < .05).

Conclusions: Results exhibited the feasibility of the proposed DBExG for positively impacting postural stability, and kinematics, along with increasing gait function and falls self-efficacy among PwCS.
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http://dx.doi.org/10.1080/09593985.2021.1994072DOI Listing
December 2021

Application of neuromuscular electrical stimulation on the support limb during reactive balance control in persons with stroke: a pilot study.

Exp Brain Res 2021 Dec 5;239(12):3635-3647. Epub 2021 Oct 5.

Department of Physical Therapy, University of Illinois at Chicago, 1919 W, Taylor Street, Chicago, IL, 60612, USA.

The aim of the present study was to investigate the effect of the application of neuromuscular electrical stimulation to the quadriceps muscle of the paretic limb during externally induced stance perturbations on reactive balance control and on fall outcomes in people with chronic stroke. Ten participants experienced 12 stance treadmill perturbation trails, 6 forward balance perturbation trials and 6 backward balance perturbation trials. For each perturbation condition, three perturbation trials were delivered synchronized with neuromuscular electrical stimulation applied to the quadriceps of the paretic limb and three perturbation trials were delivered without stimulation. Behavioral outcome measures, such as incidence of laboratory falls and number of compensatory steps, kinematic outcome measures, such as margin of stability and minimum hip high values after the perturbation, step initiation time, step execution time and step length of the stepping leg were analyzed. The application of neuromuscular electrical stimulation on the paretic quadriceps between the range of 50 and 500 ms after stance forward and backward perturbations reduced the laboratory falls incidence (p < 0.05), improved stability values (p < 0.05) and reduced the hip height descent (p < 0.05) compared to the experimental condition in which participants were exposed to stance perturbations without neuromuscular electrical stimulation. Additionally, step initiation time of the recovery step was lower in neuromuscular electrical stimulation condition during the forward balance perturbation protocol. Our results showed that the application of neuromuscular electrical stimulation on the knee extensor muscles of the paretic limb reduces the incidence of laboratory falls, enhances reactive stability control and reduces vertical limb collapse after stance forward and backward perturbations in people with chronic stroke.
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http://dx.doi.org/10.1007/s00221-021-06209-2DOI Listing
December 2021

Perturbation-based balance assessment: Examining reactive balance control in older adults with mild cognitive impairments.

Physiol Int 2021 Sep 16;108(3):353-370. Epub 2021 Sep 16.

Department of Physical Therapy, The University of Illinois at Chicago, Chicago, Illinois, USA.

Background: Older adults with mild cognitive impairment (OAwMCI) present subtle balance and gait deficits along with subjective memory decline. Although these presentations might not affect activities of daily living (ADLs), they attribute to a two-folded increase in falls. While changes occurring in volitional balance control during ADLs have been extensively examined among OAwMCI, reactive balance control, required to recover from external perturbations, has received little attention. Therefore, this study examined reactive balance control in OAwMCI compared to their healthy counterparts.

Methods: Fifteen older adults with mild cognitive impairment (OAwMCI), fifteen cognitively intact older adults (CIOA) (>55 years), and fifteen young adults (18-30 years) were exposed to stance perturbations at three different intensities. Behavioral outcomes postural COM state stability, step length, step initiation, and step execution were computed.

Results: Postural COM state stability was the lowest in OAwMCI compared to CIOA and young adults, and it deteriorated at higher perturbation intensities (P < 0.001). Step length was the lowest among OAwMCI and was significantly different from young adults (P < 0.001) but not from CIOA. Unlike OAwMCI, CIOA and young adults increased their step length at higher perturbation intensities (P < 0.001). OAwMCI showed longer recovery step initiation times and shorter execution times compared to CIOA and young adults at higher perturbation intensities (P < 0.001).

Conclusion: OAwMCI exhibit exacerbated reactive instability and are unable to modulate their responses as the threat to balance control altered. Thus, they are at a significantly higher risk of falls than their healthy counterparts.
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http://dx.doi.org/10.1556/2060.2021.00181DOI Listing
September 2021

Perturbation Training for Fall-Risk Reduction in Healthy Older Adults: Interference and Generalization to Opposing Novel Perturbations Post Intervention.

Front Sports Act Living 2021 16;3:697169. Epub 2021 Aug 16.

Department of Physical Therapy, College of Applied Health and Sciences, University of Illinois at Chicago, Chicago, IL, United States.

This study examined the effects of perturbation training on the contextual interference and generalization of encountering a novel opposing perturbation. One hundred and sixty-nine community-dwelling healthy older adults (69.6 ± 6.4 years) were randomly assigned to one of the three groups: slip-perturbation training (St, = 67) group received 24 slips, trip-perturbation training (Tt, = 67) group received 24 trips, and control (Ctrl: = 31) group received only non-perturbed walking trials (ClinicalTrials.gov NCT03199729; https://clinicaltrials.gov/ct2/show/NCT03199729). After training, all groups had 30 min of rest and three post-training non-perturbed walking trials, followed by a reslip and a novel trip trial for St, a retrip and a novel slip trial for Tt, and randomized novel slip and trip trials for Ctrl. The margin of stability (MOS), step length, and toe clearance of post-training walking trials were compared among three groups to examine interferences in proactive adjustment. Falls, MOS at the instant of recovery foot touchdown, and hip height of post-training perturbation trials were investigated to detect interferences and generalization in reactive responses. Results indicated that prior adaptation to slip perturbation training, resulting in walking with a greater MOS (more anterior) and a shorter step length ( < 0.01) than that of the Ctrl group, would be associated with a greater likelihood to forward balance loss if encountered with a trip. The trip adaptation training mainly induced a higher toe clearance during walking ( < 0.01) than the Ctrl group, which could lead to reduced effectiveness of the reactive response when encountered with a novel slip. However, there was no difference in the reactive MOS, limb support, and falls between the control group and the slip and trip training groups on their respective opposing novel perturbation post-training (MOS, limb support, and falls for novel slip: Tt = Ctrl; for the novel trip: St = Ctrl, both > 0.05). Current findings suggested that, although perturbation training results in proactive adjustments that could worsen the reactive response (interference) when exposed to an unexpected opposing perturbation, older adults demonstrated the ability to immediately generalize the training-induced adaptive reactive control to maintain MOS, to preserve limb support control, and to reduce fall risk.
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http://dx.doi.org/10.3389/fspor.2021.697169DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8418084PMC
August 2021

Effect of robotic-assisted ankle training on gait in stroke participants: A case series study.

Physiother Theory Pract 2021 Aug 23:1-10. Epub 2021 Aug 23.

Department of Physical Therapy. University of Illinois at Chicago. Chicago, IL United States.

Background: Robotic rehabilitation therapy has grown rapidly during the last two decades allowing researchers and clinicians to deliver high-intensity training to persons with sensorimotor disorders caused by neurological injuries and diseases.

Methods: This case series reports the effect of robot-assisted, impairment-oriented training for persons recovering from stroke on impairment of the paretic ankle as well as on the kinematic and spatiotemporal parameters of gait. Five persons with chronic stroke (>6 months post-stroke) participated in a 10-week training protocol, receiving three, 30-min sessions per week of a robot-assisted therapy. The robot-assisted intervention cyclically induced dorsiflexion and plantarflexion to the ankle at 5 degrees/s through ±15 degrees while the participants assisted with the imposed movement. Concurrently, participants received visual feedback of their active, assistive torque as well as targeted mechanical vibration of the ankle tendons when lengthened by the applied motion. Walking speed, cadence, step length of the non-paretic leg, percentage of paretic single limb support during the gait cycle, and ankle strength were assessed just before training began (baseline), after the last training session (post-training), and 3 months post-training (follow-up).

Discussion: Robot-assisted training that provided assisted movement, biofeedback, and proprioceptive stimulation reduced ankle impairment and improved kinematic and spatiotemporal gait parameters, suggesting that impairment-oriented therapy applied to the paretic ankle may provide a valuable adjunct to locomotor therapies in persons with chronic gait disorders due to stroke.
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http://dx.doi.org/10.1080/09593985.2021.1964658DOI Listing
August 2021

Effect of Multisession Progressive Gait-Slip Training on Fall-Resisting Skills of People with Chronic Stroke: Examining Motor Adaptation in Reactive Stability.

Brain Sci 2021 Jul 7;11(7). Epub 2021 Jul 7.

Department of Physical Therapy, College of Applied Health Sciences, University of Illinois, Chicago, IL 60612, USA.

Background: This study examined whether a multisession gait-slip training could enhance reactive balance control and fall-resisting skills of people with chronic stroke (PwCS).

Methods: A total of 11 PwCS underwent a four-week treadmill-based gait-slip training (four sessions). Pre- and post-training assessment was performed on six intensities of gait-slips (levels 1-6). Training consisted of 10 blocks of each progressively increasing intensity (four trials per block) until participants fell at >2 trials per block (fall threshold). In the next session, training began at a sub-fall threshold and progressed further. Fall outcome and threshold, number of compensatory steps, multiple stepping threshold, progression to higher intensities, pre- and post-slip center of mass (CoM), state stability, clinical measures, and treadmill walking speed were analyzed.

Results: Post-training, PwCS demonstrated a reduction in falls and compensatory steps on levels 5 and 6 ( < 0.05) compared to pre-training. While an increase in pre-slip stability was limited to level 6 ( < 0.05), improvement in post-slip stability at lift-off was noted on levels 2, 3, and 5 ( < 0.05) along with improved post-slip minimum stability on levels 5 and 6 ( < 0.05). Post-training demonstrated improved fall ( < 0.05) and multiple stepping thresholds ( = 0.05). While most participants could progress to level 4 between the first and last training sessions, more participants progressed to level 6 ( < 0.05). Participants' treadmill walking speed increased ( < 0.05); however, clinical measures remained unchanged ( > 0.05).

Conclusions: Multisession, progressively increasing intensity of treadmill-based gait-slip training appears to induce significant adaptive improvement in falls, compensatory stepping, and postural stability among PwCS.
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http://dx.doi.org/10.3390/brainsci11070894DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8303184PMC
July 2021

Muscle synergy differences between voluntary and reactive backward stepping.

Sci Rep 2021 07 29;11(1):15462. Epub 2021 Jul 29.

Department of Physical Therapy, University of Illinois at Chicago, 1919 W Taylor St (M/C 898), Chicago, IL, 60612, USA.

Reactive stepping responses are essential to prevent falls after a loss of balance. It has previously been well described that both voluntary and reactive step training could improve the efficacy of reactive stepping in different populations. However, the effect of aging on neuromuscular control during voluntary and reactive stepping remains unclear. Electromyography (EMG) signals during both backward voluntary stepping in response to an auditory cue and backward reactive stepping elicited by a forward slip-like treadmill perturbation during stance were recorded in ten healthy young adults and ten healthy older adults. Using muscle synergy analysis, we extracted the muscle synergies for both voluntary and reactive stepping. Our results showed that fewer muscle synergies were used during reactive stepping than during voluntary stepping in both young and older adults. Minor differences in the synergy structure were observed for both voluntary and reactive stepping between age groups. Our results indicate that there is a low similarity of muscle synergies between voluntary stepping and reactive stepping and that aging had a limited effect on the structure of muscle synergies. This study enhances our understanding of the neuromuscular basis of both voluntary and reactive stepping as well as the potential effect of aging on neuromuscular control during balance tasks.
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http://dx.doi.org/10.1038/s41598-021-94699-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8322057PMC
July 2021

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

J Dance Med Sci 2021 Sep 3;25(3):200-213. Epub 2021 Jun 3.

University of Illinois at Chicago, Department of Physical Therapy, Chicago, Illionois;, Email:

Background: 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.
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.
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.
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).
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.
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http://dx.doi.org/10.12678/1089-313X.091521eDOI Listing
September 2021

Validity of Inertial Sensors for Assessing Balance Kinematics and Mobility during Treadmill-Based Perturbation and Dance Training.

Sensors (Basel) 2021 Apr 28;21(9). Epub 2021 Apr 28.

Department of Physical Therapy, University of Illinois at Chicago, Chicago, IL 60612, USA.

Inertial sensors (IS) enable the kinematic analysis of human motion with fewer logistical limitations than the silver standard optoelectronic motion capture (MOCAP) system. However, there are no data on the validity of IS for perturbation training and during the performance of dance. The aim of this present study was to determine the concurrent validity of IS in the analysis of kinematic data during slip and trip-like perturbations and during the performance of dance. Seven IS and the MOCAP system were simultaneously used to capture the reactive response and dance movements of fifteen healthy young participants (Age: 18-35 years). Bland Altman (BA) plots, root mean square errors (RMSE), Pearson's correlation coefficients (R), and intraclass correlation coefficients (ICC) were used to compare kinematic variables of interest between the two systems for absolute equivalency and accuracy. Limits of agreements (LOA) of the BA plots ranged from -0.23 to 0.56 and -0.21 to 0.43 for slip and trip stability variables, respectively. The RMSE for slip and trip stabilities were from 0.11 to 0.20 and 0.11 to 0.16, respectively. For the joint mobility in dance, LOA varied from -6.98-18.54, while RMSE ranged from 1.90 to 13.06. Comparison of IS and optoelectronic MOCAP system for reactive balance and body segmental kinematics revealed that R varied from 0.59 to 0.81 and from 0.47 to 0.85 while ICC was from 0.50 to 0.72 and 0.45 to 0.84 respectively for slip-trip perturbations and dance. Results of moderate to high concurrent validity of IS and MOCAP systems. These results were consistent with results from similar studies. This suggests that IS are valid tools to quantitatively analyze reactive balance and mobility kinematics during slip-trip perturbation and the performance of dance at any location outside, including the laboratory, clinical and home settings.
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http://dx.doi.org/10.3390/s21093065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8125244PMC
April 2021

Kinematic synergies in over-ground slip recovery outcomes: Distinct strategies or a single strategy?

Gait Posture 2022 06 17;95:270-276. Epub 2021 Feb 17.

Department of Physical Therapy, University of Illinois at Chicago, Chicago, IL, 60612, United States. Electronic address:

Background: After experiencing an unexpected slip perturbation, individuals' behavioral performance can be classified into three categories: recovery, feet-forward fall, and split fall. Researchers are uncertain whether these differences in slip outcomes are due to distinct strategies or part of a single strategy.

Research Question: Whether older adults with different behavioral outcomes during their novel slip have different kinematic synergies?

Methods: The kinematic synergies were extracted from segment angles in 87 participants using principal component analysis (PCA). The first two principal components (PC1 and PC2) in pre-slip, early-reactive, and late-reactive phases were compared across different slip outcomes.

Results: Results showed that the kinematic synergies in pre-slip and early-reactive phases are highly consistent among the three outcomes (recovery, split fall, and feet-forward fall). For the late-reactive phase, both split falls and feet-forward falls showed different kinematics synergies from recoveries.

Significance: Our findings indicated that a single strategy might be used for different slip outcomes in the pre-slip and early-reactive phases, while distinct strategies were used by fallers compared to recovered individuals. Specifically, larger trunk flexion in pre-slip phase, larger knee flexion and plantar flexion of the slipping limb in both early-reactive and late-reactive phase, and larger knee extension of the recovery limb in late-reactive phase would lower the fall risk. This study would help to assess the vulnerabilities in control strategy, according to which individualized treatment could be provided to reduce predisposition to specific types of falls.
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http://dx.doi.org/10.1016/j.gaitpost.2021.01.025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8368075PMC
June 2022

Does stroke-induced sensorimotor impairment and perturbation intensity affect gait-slip outcomes?

J Biomech 2021 03 17;118:110255. Epub 2021 Jan 17.

Department of Physical Therapy, College of Applied Health Sciences, University of Illinois, Chicago, IL 60612, USA. Electronic address:

People with chronic stroke (PwCS) demonstrate similar gait-slip fall-risk on both paretic and non-paretic side. Compensatory stepping and slipping limb control are crucial to reduce gait-slip fall-risk. Given the unpredictable intensities of real-life perturbations, this study aimed to determine whether recovery from paretic or non-paretic slips vary as a function of perturbation intensity among PwCS. Forty-four PwCS were assigned to non-paretic low intensity slip, non-paretic high intensity slip, paretic low intensity slip, or paretic high intensity slip group. Participants were subjected to a novel overground gait-slip with a distance of 24 cm (low) or 45 cm (high), under either limb. Recovery strategies, center of mass (CoM) state stability and slipping kinematics were analyzed. Both non-paretic high and low intensity groups demonstrated similar percentage of aborted and recovery stepping, however, paretic high intensity group demonstrated greater aborted stepping (p > 0.05). Both high and low intensity paretic slip groups demonstrated reduced post-slip CoM stability relative to the non-paretic slip groups (p < 0.05). Slip displacement was greater in paretic high group compared with non-paretic high group (p < 0.05). Greater slip displacement at higher intensity was noted only in paretic slip group (p < 0.05). The slip velocity was faster in paretic groups compared to non-paretic slip groups (p < 0.05). Paretic slips showed lower stability at both intensities associated with difficulty in modulating slipping kinematics and resorting to an increased aborted stepping strategy compared to non-paretic slip. These findings are suggestive of developing balance interventions for improving both compensatory non-paretic limb stepping and reactive control of slipping paretic limb for fall-risk reduction.
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http://dx.doi.org/10.1016/j.jbiomech.2021.110255DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8278392PMC
March 2021

Kinematic Gait Adjustments to Virtual Environments on Different Surface Conditions: Do Treadmill and Over-Ground Walking Exhibit Different Adaptations to Passive Virtual Immersion?

Rehabil Res Pract 2020 19;2020:8901973. Epub 2020 Dec 19.

Department of Physical Therapy, University of Illinois at Chicago, Chicago IL, USA.

Background: The aim of this study was to examine the kinematic gait adjustments performed in response to passive and photorealistic virtual reality environment (VRE) demands during over-ground and treadmill walking conditions and determine whether the surface presentation order affects the gait adjustments in response to different VREs.

Methods: Twenty young participants divided into two groups performed two virtual reality (VR) walking protocols which included two different VREs (snowy and crowded conditions). Group A performed the VR over-ground protocol (four natural walking (NW), seven VR snowy, and seven VR crowded trials) followed by the VR treadmill protocol (four NW, one VR snowy, and one VR crowded trials); Group B performed the VR treadmill protocol (four NW, seven VR snowy, and seven VR crowded trials) followed by the VR over-ground protocol (four NW, one VR snowy, and one VR crowded trials). Center of mass (COM) excursion angles and mediolateral (ML) COM excursions were analyzed and used as outcome measures.

Results: Group A showed higher COM excursion angles and ML-COM excursion on over-ground VR trials compared to NW trials ( < 0.05), while Group B only showed kinematic changes for the crowded VRE compared to NW trials during the treadmill walking protocol ( < 0.05). Post over-ground exposure, Group A showed greater COM excursion angle and ML-COM excursions on VR trials compared to NW trials during the treadmill walking protocol ( < 0.05). Post treadmill exposure, Group B only showed higher COM excursion angles for the snowy VRE compared to NW trials during the over-ground walking protocol ( < 0.01).

Conclusion: Results showed that higher kinematic gait adjustments in response to VRE demands were observed during over-ground walking. Additionally, higher sensorimotor responses to VRE demands were observed when the VR protocol was first performed on the over-ground surface and followed by the treadmill walking condition (Group A) compared to the opposite (Group B).
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http://dx.doi.org/10.1155/2020/8901973DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7769665PMC
December 2020

Does Exercise-Based Conventional Training Improve Reactive Balance Control among People with Chronic Stroke?

Brain Sci 2020 Dec 22;11(1). Epub 2020 Dec 22.

Department of Community Health Sciences, School of Public Health, University of Illinois at Chicago, Chicago, IL 60608, USA.

Background: Exercise-based conventional training has predominantly benefited fall-associated volitional balance control domain; however, the effect on reactive balance control is under-examined. Therefore, the purpose of this study was to examine the effect of exercise-based conventional training on reactive balance control.

Methods: Eleven people with chronic stroke (PwCS) underwent multi-component training for six weeks (20 sessions) in a tapering manner. Training focused on four constructs-stretching, functional strengthening, balance, and endurance. Volitional balance was measured via movement velocity on the Limits of Stability (LOS) test and reactive balance via center of mass (COM) state stability on the Stance Perturbation Test (SPT). Additionally, behavioral outcomes (fall incidence and/or number of steps taken) were recorded.

Results: Movement velocity significantly increased on the LOS test ( < 0.05) post-intervention with a significant decrease in fall incidence ( < 0.05). However, no significant changes were observed in the COM state stability, fall incidence and number of recovery steps on the SPT post-intervention.

Conclusion: Although volitional and reactive balance control may share some neurophysiological and biomechanical components, training based on volitional movements might not significantly improve reactive balance control for recovery from large-magnitude perturbations due to its task-specificity.
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http://dx.doi.org/10.3390/brainsci11010002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7821930PMC
December 2020

Can Smartphone-Derived Step Data Predict Laboratory-Induced Real-Life Like Fall-Risk in Community- Dwelling Older Adults?

Front Sports Act Living 2020 10;2:73. Epub 2020 Jul 10.

Department of Physical Therapy, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, IL, United States.

As age progresses, decline in physical function predisposes older adults to high fall-risk, especially on exposure to environmental perturbations such as slips and trips. However, there is limited evidence of association between daily community ambulation, an easily modifiable factor of physical activity (PA), and fall-risk. Smartphones, equipped with accelerometers, can quantify, and display daily ambulation-related PA simplistically in terms of number of steps. If any association between daily steps and fall-risks is established, smartphones due to its convenience and prevalence could provide health professionals with a meaningful outcome measure, in addition to existing clinical measurements, to identify older adults at high fall-risk. This study aimed to explore whether smartphone-derived step data during older adults' community ambulation alone or together with commonly used clinical fall-risk measurements could predict falls following laboratory-induced real-life like slips and trips. Relationship between step data and PA questionnaire and clinical fall-risk assessments were examined as well. Forty-nine community-dwelling older adults (age 60-90 years) completed Berg Balance Scale (BBS), Activities-specific Balance Confidence scale (ABC), Timed Up-and-Go (TUG), and Physical Activity Scale for the Elderly (PASE). One-week and 1-month smartphone steps data were retrieved. Participants' 1-year fall history was noted. All participants' fall outcomes to laboratory-induced slip-and-trip perturbations were recorded. Logistic regression was performed to identify a model that best predicts laboratory falls. Pearson correlations examined relationships between study variables. A model including age, TUG, and fall history significantly predicted laboratory falls with a sensitivity of 94.3%, specificity of 58.3%, and an overall accuracy of 85.1%. Neither 1-week nor 1-month steps data could predict laboratory falls. One-month steps data significantly positively correlated with BBS ( = 0.386, = 0.006) and ABC ( = 0.369, = 0.012), and negatively correlated with fall history ( = -0.293, = 0.041). Older participants with fall history and higher TUG scores were more likely to fall in the laboratory. No association between smartphone steps data and laboratory fall-risk was established in our study population of healthy community-dwelling older adults which calls for further studies on varied populations. Although modest, results do reveal a relationship between steps data and functional balance deficits and fear of falls.
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http://dx.doi.org/10.3389/fspor.2020.00073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7739785PMC
July 2020

Motor adaptation to real-life external environments using immersive virtual reality: A pilot study.

J Bodyw Mov Ther 2020 Oct 30;24(4):152-158. Epub 2020 Jul 30.

Department of Physical Therapy, University of Illinois at Chicago, Chicago, IL, 60612, United States. Electronic address:

Introduction: Virtual reality (VR) has been described as an emerging therapeutic strategy to promote motor adaptation in different populations. The aim of this study was to investigate the effect of virtual environment demands, provided by an immersive VR system, on kinematic and spatio-temporal gait parameters in healthy young participants.

Methods: Fifteen healthy young participants participated in this experimental study performing, in sequence, a baseline natural walking (NW) block, two different virtual environment walking blocks (snowy and crowded conditions), and a mixed walking block (including NW, snowy, and crowded conditions). Participants' Center-of-Mass (COM) excursion angle, medio-lateral (ML) COM excursion, step length, and walking speed were analyzed for each trial.

Results: COM excursion angle and ML-COM excursion increased significantly during the first snowy and crowded VR trials compared to NW trials, while walking speed and step length decreased only for the snowy conditions. COM excursion angle and ML-COM excursion increased significantly from the first to the fourth VR snowy trial and decreased from the first to the fourth VR crowded trial. Participants retained the acquired motor adaptations even after the mixed block.

Conclusion: This study showed that kinematic and spatio-temporal gait parameters of young participants changed according to the virtual environment demands provided for each virtual scenario. In addition, all participants showed a consistent gait adaptation process to each virtual environment across the VR trials. The present findings highlight the impact of VR for gait adaptation, suggesting that VR training could modify motor behavior and enhance the motor adaptation process in healthy young participants.
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http://dx.doi.org/10.1016/j.jbmt.2020.06.031DOI Listing
October 2020

The retention of fall-resisting behavior derived from treadmill slip-perturbation training in community-dwelling older adults.

Geroscience 2021 04 25;43(2):913-926. Epub 2020 Sep 25.

Department of Physical Therapy, University of Illinois at Chicago, 1919 W. Taylor Street, Fourth Floor, Chicago, IL, 60612, USA.

The purpose of this study was to determine whether and to what extent the immediate generalization of treadmill slip-perturbation training could be retained over 6 months to resist overground slip-induced falls. Four protocols (Tc: treadmill control; Tt: treadmill slip-perturbation training; Oc: overground control; Ot: overground slip-perturbation training) from two randomized controlled trials were compared in which two training protocols were executed with single-session repeated slip-perturbation training on the treadmill or overground context, while two control protocols were executed without repeated training. A total of 152 community-dwelling older adults (≥ 65 years) who were trained by one of the four protocols and tested by an overground slip in the initial session attended a retest session 6 months later. Falls were detected by a load cell. Data collected from motion analysis system and force plates were used to calculate stability. Tt group had no significant change in fall incidence from initial post-training test to retest. Tt group had significantly lower fall incidence (p < 0.05) and higher reactive stability (p < 0.05) than Tc group in retest. Tt group had significantly higher fall incidence (p < 0.05) and lower reactive stability (p < 0.01) than Ot group. The generalization of a single session of treadmill slip-perturbation training to overground slip resulted in inferior outcomes compared with overground slip-perturbation training (absolute retention), although the training generalization could be retained over 6 months (relative retention). Thus, treadmill slip-perturbation training could be more convenient to use if future dose-response studies indicate better or equal efficacy to overground slip-perturbation training.
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http://dx.doi.org/10.1007/s11357-020-00270-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8110680PMC
April 2021

Determining the optimal dose of reactive balance training after stroke: study protocol for a pilot randomised controlled trial.

BMJ Open 2020 08 26;10(8):e038073. Epub 2020 Aug 26.

Toronto Rehabilitation Institute - University Health Network, Toronto, Ontario, Canada.

Introduction: Falls risk poststroke is highest soon after discharge from rehabilitation. Reactive balance training (RBT) aims to improve control of reactions to prevent falling after a loss of balance. In healthy older adults, a single RBT session can lead to lasting improvements in reactive balance control and prevent falls in daily life. While increasing the dose of RBT does not appear to lead to additional benefit for healthy older adults, stroke survivors, who have more severely impaired balance control, may benefit from a higher RBT dose. Our long-term goal is to determine the optimal dose of RBT in people with subacute stroke. This assessor-blinded pilot randomised controlled trial aims to inform the design of a larger trial to address this long-term goal.

Methods And Analysis: Participants (n=36) will be attending out-patient stroke rehabilitation, and will be randomly allocated to one of three groups: one, three or six RBT sessions. RBT will replace a portion of participants' regular physiotherapy so that the total physical rehabilitation time will be the same for the three groups. Balance and balance confidence will be assessed at: (1) study enrolment; (2) out-patient rehabilitation discharge; and (3) 6 months postdischarge. Participants will report falls and physical activity for 6 months postdischarge. Pilot data will be used to plan the larger trial (ie, sample size estimate using fall rates, and which groups should be included based on between-group trends in pre-to-post training effect sizes for reactive balance control measures). Pilot data will also be used to assess the feasibility of the larger trial (ie, based on the accrual rate, outcome completion rate and feasibility of prescribing specific training doses).

Ethics And Dissemination: Institutional research ethics approval has been received. Study participants will receive a lay summary of results. We will also publish our findings in a peer-reviewed journal.

Trial Registration Number: NCT04219696; Pre results.
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http://dx.doi.org/10.1136/bmjopen-2020-038073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7451480PMC
August 2020

Can Treadmill Slip-Perturbation Training Reduce Longer-Term Fall Risk Upon Overground Slip Exposure?

J Appl Biomech 2020 Aug 25:1-9. Epub 2020 Aug 25.

University of Illinois at Chicago.

The purpose was to examine and compare the longer-term generalization between 2 different practice dosages for a single-session treadmill slip-perturbation training when reexposed to an overground slip 6 months later. A total of 45 older adults were conveniently assigned to either 24 or 40 slip-like treadmill perturbation trials or a third control group. Overground slips were given immediately after initial training, and at 6 months after initial training in order to examine immediate and longer-term effects. The performance (center of mass stability and vertical limb support) and fall percentage from the laboratory-induced overground slips (at initial posttraining and at 6 mo) were measured and compared between groups. Both treadmill slip-perturbation groups showed immediate generalization at the initial posttraining test and longer-term generalization at the 6-month retest. The higher-practice-dosage group performed significantly better than the control group (P < .05), with no difference between the lower-practice-dosage and the control groups at the 6-month retest (P > .05). A single session of treadmill slip-perturbation training showed a positive effect for reducing older adults' fall risk for laboratory-induced overground slips. A higher-practice dosage of treadmill slip perturbations could be more beneficial for further reducing fall risk.
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http://dx.doi.org/10.1123/jab.2019-0211DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8344091PMC
August 2020

Slip-Fall Predictors in Community-Dwelling, Ambulatory Stroke Survivors: A Cross-sectional Study.

J Neurol Phys Ther 2020 10;44(4):248-255

MS Program in Rehabilitation Sciences, Department of Physical Therapy, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, Illinois (R.G.); PhD Program in Rehabilitation Sciences, Department of Physical Therapy, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, Illinois (S.D., L.K.); Department of Physical Therapy, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, Illinois (S.W., E.W., T.B.); and School of Physical and Occupational Therapy, McGill University, Montreal, Quebec, Canada (J.F.).

Background And Purpose: Considering the multifactorial nature and the often-grave consequences of falls in people with chronic stroke (PwCS), determining measurements that best predict fall risk is essential for identifying those who are at high risk. We aimed to determine measures from the domains of the International Classification of Functioning, Disability and Health (ICF) that can predict laboratory-induced slip-related fall risk among PwCS.

Methods: Fifty-six PwCS participated in the experiment in which they were subjected to an unannounced slip of the paretic leg while walking on an overground walkway. Prior to the slip, they were given a battery of tests to assess fall risk factors. Balance was assessed using performance-based tests and instrumented measures. Other fall risk factors assessed were severity of sensorimotor impairment, muscle strength, physical activity level, and psychosocial factors. Logistic regression analysis was performed for all variables. The accuracy of each measure was examined based on its sensitivity and specificity for fall risk prediction.

Results: Of the 56 participants, 24 (43%) fell upon slipping while 32 (57%) recovered their balance. The multivariate logistic regression analysis model identified dynamic gait stability, hip extensor strength, and the Timed Up and Go (TUG) score as significant laboratory-induced slip-fall predictors with a combined sensitivity of 75%, a specificity of 79.2%, and an overall accuracy of 77.3%.

Discussion And Conclusions: The results indicate that fall risk measures within the ICF domains-body, structure, and function (dynamic gait stability and hip extensor strength) and activity limitation (TUG)-could provide a sensitive laboratory-induced slip-fall prediction model in PwCS.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A323).
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http://dx.doi.org/10.1097/NPT.0000000000000331DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8291756PMC
October 2020

Effect of an Exergaming-Based Dance Training Paradigm on Autonomic Nervous System Modulation in Healthy Older Adults: A Randomized Controlled Trial.

J Aging Phys Act 2021 02 22;29(1):1-9. Epub 2020 Jul 22.

The purpose of this study was to determine if an exergaming-based dance training protocol can improve heart rate variability (HRV) in healthy older adults. A total of 20 healthy older adults (≥65 years old) were randomly assigned to two groups. The intervention group received an exergaming-based dance aerobic training for 6 weeks, while the control group received a 1-hr education on conventional physical exercises. Data obtained from HRV analysis pre- (Week 0) and postintervention (Week 7) consisted of high-frequency power, low- and high-frequency ratio, and root mean square of differences and percentage of adjacent RR intervals with a difference of duration greater than 50 ms values. HRV was assessed during rest and during a 6-min walk test. In addition, the YMCA submaximal cycle ergometer test was used to acquire estimated maximal O2 consumption pre- and postintervention. After the training, the intervention group showed significant improvement in HRV high-frequency power, root mean square of differences, and percentage of adjacent RR intervals with a difference of duration greater than 50 ms values in both rest and 6-min walk test conditions compared with the control group. Similarly, the intervention group showed higher maximal O2 consumption compared with the control group after the training. Our results support the effectiveness of an exergaming-based dance aerobic training on improving cardiac autonomic control in aging.
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http://dx.doi.org/10.1123/japa.2019-0452DOI Listing
February 2021

Aging, Vestibular Function, and Balance: Proceedings of a National Institute on Aging/National Institute on Deafness and Other Communication Disorders Workshop.

J Gerontol A Biol Sci Med Sci 2020 11;75(12):2471-2480

Division of Gerontology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts.

Balance impairment and falls are among the most prevalent and morbid conditions affecting older adults. A critical contributor to balance and gait function is the vestibular system; however, there remain substantial knowledge gaps regarding age-related vestibular loss and its contribution to balance impairment and falls in older adults. Given these knowledge gaps, the National Institute on Aging and the National Institute on Deafness and Other Communication Disorders convened a multidisciplinary workshop in April 2019 that brought together experts from a wide array of disciplines, such as vestibular physiology, neuroscience, movement science, rehabilitation, and geriatrics. The goal of the workshop was to identify key knowledge gaps on vestibular function and balance control in older adults and develop a research agenda to make substantial advancements in the field. This article provides a report of the proceedings of this workshop. Three key questions emerged from the workshop, specifically: (i) How does aging impact vestibular function?; (ii) How do we know what is the contribution of age-related vestibular impairment to an older adult's balance problem?; and more broadly, (iii) Can we develop a nosology of balance impairments in older adults that can guide clinical practice? For each of these key questions, the current knowledge is reviewed, and the critical knowledge gaps and research strategies to address them are discussed. This document outlines an ambitious 5- to 10-year research agenda for increasing knowledge related to vestibular impairment and balance control in older adults, with the ultimate goal of linking this knowledge to more effective treatment.
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http://dx.doi.org/10.1093/gerona/glaa097DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7662183PMC
November 2020

Effect of Mental Fatigue on Postural Sway in Healthy Older Adults and Stroke Populations.

Brain Sci 2020 Jun 19;10(6). Epub 2020 Jun 19.

Department of Physical Therapy, University of Illinois at Chicago, Chicago, IL 60612, USA.

The aim of this study was to examine the effect of mental fatigue on postural sway under different sensory conditions in healthy older adults and in persons with chronic stroke (PwCS). Thirty healthy older adults (> 60 years old), randomly separated into experimental and control groups, as well as 15 PwCS participated in this study. Experimental groups were asked to stand on a force platform wearing seven inertial sensors while performing the Sensory Organization Test (SOT) under two cognitive conditions (single- and dual-task) before and after a mental fatigue task (stop-signal task for 60 min). The control group performed the same protocol before and after watching a movie for 60 min. Changes in subjective fatigue was assessed by the NASA Task Load Index and psychophysiological workload was assessed by heart rate variability (HRV). Postural sway was assessed by calculating the Jerk and root mean square (RMS) of center of mass (COM). Higher Jerk and RMS of COM ( < 0.05) were observed after the mental fatigue task in both healthy older adults and PwCS during SOT, which was not observed in the control group ( > 0.05). Additionally, postural sway increased in the three groups as the SOT conditions became more challenging. Our results indicate that mental fatigue, induced by sustained cognitive activity, can impair balance during SOT in older adult and stroke populations.
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http://dx.doi.org/10.3390/brainsci10060388DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7349503PMC
June 2020

Which Are the Key Kinematic and Kinetic Components to Distinguish Recovery Strategies for Overground Slips Among Community-Dwelling Older Adults?

J Appl Biomech 2020 Jun 3:1-11. Epub 2020 Jun 3.

University of Illinois at Chicago.

Slip outcomes are categorized as either a backward loss of balance (LOB) or a no loss of balance (no-LOB) in which an individual does not take a backward step to regain their stability. LOB includes falls and nonfalls, while no-LOB includes skate overs and walkovers. Researchers are uncertain about which factors determine slip outcomes and at which critical instants they do so. The purpose of the study was to investigate factors affecting slip outcomes in proactive and early reactive phases by analyzing 136 slip trials from 68 participants (age: 72.2 [5.3] y, female: 22). Segment angles and average joint moments in the sagittal plane of the slipping limb were compared for different slip outcomes. The results showed that knee flexor, hip extensor, and plantar flexor moments were significantly larger for no-LOB than for LOB in the midproactive phase, leading to smaller shank-ground and foot-ground angles at the slip onset, based on forward dynamics. In the early reactive phase, the hip extensor and plantar flexor moments were larger for no-LOB than for LOB, and all segment angles were smaller for no-LOB. Our findings indicate that the shank angle and knee moment were the major determinants of slip outcomes in both proactive and reactive phases.
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http://dx.doi.org/10.1123/jab.2019-0285DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8344101PMC
June 2020

Mixed slip-trip perturbation training for improving reactive responses in people with chronic stroke.

J Neurophysiol 2020 07 13;124(1):20-31. Epub 2020 May 13.

Department of Physical Therapy, College of Applied Health Sciences, University of Illinois, Chicago, Illinois.

This study determined the effect of mixed (slip- and trip-like stance perturbation) training on reactive responses in people with chronic stroke (PwCS) and examined modulation of their reactive responses on higher intensity perturbations posttraining (scaling). Twelve PwCS were exposed to consecutive blocks of treadmill-based slip-like and trip-like perturbations and mixed-stance perturbations. A higher intensity trial was provided postblock and postmixed training. Postural stability [center-of-mass position (CoMP) and velocity (CoMV)], compensatory step length, step count, and trunk angle were examined. PwCS demonstrated an anterior positioning of the CoM, increased step length, and reduced compensatory step count with slip-like block training ( < 0.05). Trip-like block training resulted in reductions in step count, step length, and trunk angle ( < 0.05); however, CoMP remained unchanged ( > 0.05). With mixed training, there was a decrease rather than an increase in step length for slip-like perturbations but a continued decrease in step length and trunk angle was seen on trip-like perturbations ( < 0.05); however, CoMP and step count remained unchanged for both. For both perturbations, the higher intensity trials demonstrated no change from the last block trial. Postmixed block, the higher intensity trial demonstrated an increase only in step count on trip-like perturbation. Between postblock and postmixed higher intensity trials, an increase in step count and decrease in step length was noted only for slip-like perturbations. Block training with slip- and trip-like stance perturbations can enhance reactive responses among PwCS. Although mixed perturbation training continued to improve trip-induced adaptation, prior slip-induced adaptive changes were not maintained and further slip-adaptation was not seen. PwCS demonstrated partial scaling of reactive responses postblock and postmixed training. Block perturbation training led to development of favorable reactive responses to counteract treadmill-based, slip-like and trip-like stance perturbations among people with chronic stroke. During mixed block, previously acquired adaptive changes in reactive responses from slip-block training were not maintained, probably due to interference offered by trip block. Instead, on trip-like perturbations, trip block-induced adaptation was maintained and continued to show further improvement. Our findings might provide future direction for designing effective mixed perturbation training paradigms to counteract both opposing perturbation types.
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http://dx.doi.org/10.1152/jn.00671.2019DOI Listing
July 2020
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