Retention of Adaptive Control Over Varying Intervals: Prevention of Slip- Induced Backward Balance Loss During Gait

2006 ◽  
Vol 95 (5) ◽  
pp. 2913-2922 ◽  
Author(s):  
T. Bhatt ◽  
E. Wang ◽  
Y.-C. Pai
Keyword(s):  
Center Of Mass ◽  
Acquisition Session ◽  
Contralateral Limb ◽  
Gait Stability ◽  
Rapid Acquisition ◽  
Shortest Distance ◽  
State Position ◽  
Young Subjects ◽  
Balance Loss

Stability improvements made in a single acquisition session with merely five slips in walking are sufficient to prevent backward balance loss (BLOB) at the end of session, but not after 12 mo. The purpose of this study was to determine whether the effect of an enhanced single acquisition session would be retainable if tested sooner, at intervals of ≤4 mo. Twenty-four young subjects were exposed to blocks of slip, nonslip, and both types of trials during walking at their preferred speed in the acquisition session. In each of the four follow-up sessions around 1 wk, 2 wk, 1 mo, and 4 mo later, these same subjects experienced only a single slip after eight to 13 unperturbed walking trials in an otherwise identical setup. Gait stability was obtained as the shortest distance between the measured center of mass (COM) state (position and velocity) and the mathematically predicted threshold for BLOB at pre- and postslip, corresponding to the instants of touchdown of the slipping limb and liftoff of the contralateral limb, respectively. During the acquisition session, pre- and postslip stability improved significantly, resulting in a reduction of BLOB from 100% in the first slip (S1) to 0% in the last slip (S24), with improvements converging to a steady state, that enabled all of the subjects to avoid BLOB, regardless of whether a slip occurred. During retest sessions, subjects' preslip stability was not different from that in S24, but was greater than that in S1. Their postslip stability was also greater than that in S1 but less than that in S24, resulting in BLOB at a 40% level. No difference was found in any of these aspects between each follow-up session. These adaptive changes were associated with a range of individual differences, varying from no detectable deterioration in all aspects ( n = 8) to a consistent BLOB in all follow-ups ( n = 3). Our findings demonstrated the extent of plasticity of the CNS, characterized by rapid acquisition of a stable COM state under unpredictable slip conditions and retention of such improvements for months, resulting in a reduced occurrence of unintended backward falling.

Long-Term Retention of Gait Stability Improvements

2005 ◽  
Vol 94 (3) ◽  
pp. 1971-1979 ◽  
Author(s):  
T. Bhatt ◽  
Y.-C. Pai
Keyword(s):  
Control System ◽  
Feedforward Control ◽  
Balance Control ◽  
Center Of Mass ◽  
Internal Representation ◽  
Acquisition Session ◽  
Gait Stability ◽  
Balance Loss

Evidence of long-term modification of behavior—in particular, gait alterations in response to repeated exposure to slips—within the locomotor-balance control system is limited. The purpose of this study was to examine whether improvements in fall-resisting behavior as reflected by improvements in gait stability could be retained on a long-term basis. Eight healthy young subjects were exposed to a block of repeated slip trials during a single acquisition session consisting of five repeated slip exposures; the same subjects were then re-tested using the same protocol at a minimum of 12 mo later. Pre- and postslip gait stability for all slip trials was measured at touchdown (slipping limb) and liftoff (contralateral limb) based on the center of mass state (i.e., its instantaneous position and velocity) relative to the base of support (BOS) and the predicted thresholds for backward loss of balance. In the acquisition session, subjects were able to increase pre- and postslip stability, which significantly correlated with a decrease in the incidence of balance loss from 100% (1st slip) to 0% (5th slip). All subjects exhibited a similar balance loss on the first slip of the follow-up session. Nonetheless, subjects were able to retain the acquired preslip stability with feedforward control on the first slip but not the postslip stability related to the reactive response. Also, the subjects demonstrated a faster re-acquisition, with only one balance loss on the second slip of the follow-up session, as compared with seven balance losses on the acquisition session. Such rapid improvements were achieved by the significantly greater increase in post- compared with preslip stability; this increase was for the most part, a consequence of reductions in slip intensity (i.e., the peak BOS velocity). We concluded that a single acquisition session could only produce limited long-term retainable effects within the locomotor-balance control system. It appeared, however, that the CNS was still primed to more rapidly update its internal representation of gait stability during re-acquisition.

scholarly journals Can Observational Training Substitute Motor Training in Preventing Backward Balance Loss After an Unexpected Slip During Walking?

2008 ◽  
Vol 99 (2) ◽  
pp. 843-852 ◽  
Author(s):  
T. Bhatt ◽  
Y.-C. Pai
Keyword(s):  
Training Group ◽  
Gait Pattern ◽  
Motor Training ◽  
Perceptual Knowledge ◽  
Internal Representations ◽  
Gait Stability ◽  
Slip Displacement ◽  
Young Subjects ◽  
Stability Limits ◽  
Balance Loss

A person's awareness of potential slippery walking conditions induces a cautious gait pattern. The purposes of this study were to determine whether neuromechanical changes associated with such cognitive conditioning are sufficient to alter the outcome of a slip and whether the effects of such conditioning are comparable to those of motor training. Prior to their own first slip exposure, 18 young subjects watched videos and slides demonstrating where and how the slip would occur and how people adapted to repeated-slip exposure (observe). The outcomes of the first slip exposure experienced by another 16 subjects who did not receive any such information were used as controls (naïve). The latter subjects subsequently experienced an additional 23 slips and thus served in a dual-role as the motor training group (motor). Gait stability as measured against backward loss of balance (BLOB) was obtained for pre- and postslip instances. A protective step landing posterior to the slipping-limb identified each BLOB outcome. The observe group had a greater postslip stability and lower slip displacement and velocity than the naïve group. However, such effects were insufficient to prevent balance loss (100% BLOB). The motor group showed significantly better performance on the last training slip (0% BLOB) than did the observe group. The results indicated that updating the cognitive centers of the CNS with awareness and perceptual knowledge through observational training can yield tangible benefits. Nonetheless observation could not replace the task-specific motor training that adaptively updated the internal representations of stability limits for prevention of BLOB.

Time-To-Contact Analysis of Gait Stability in the Swing Phase of Walking in People With Multiple Sclerosis

Motor Control ◽  
2015 ◽  
Vol 19 (4) ◽  
pp. 289-311 ◽  
Author(s):  
Jebb G. Remelius ◽  
Richard E.A. van Emmerik
Keyword(s):  
Multiple Sclerosis ◽  
Center Of Mass ◽  
Swing Phase ◽  
The Body ◽  
Head Movements ◽  
Gait Stability ◽  
Time To Contact ◽  
Prospective Control ◽  
Body Center ◽  
All Speeds

This study investigated timing and coordination during the swing phase of swing leg, body center of mass (CoM) and head during walking people with multiple sclerosis (MS; n = 19) and controls (n = 19). The MS group showed differences in swing phase timing at all speeds. At imposed but not preferred speeds, the MS group had less time to prepare for entry into the unstable equilibrium, as the CoM entered this phase of swing earlier. Time-to-contact coupling, quantifying the coordination between the CoM and the swing foot, was not different between groups. The projection of head motion on the ground occurred earlier after toeoff and was positioned closer to the body in the MS group, illustrating increased reliance on visual exproprioception in which vision of the body in relation to the surface of support is established. Finally, prospective control, linking head movements to the swing foot time-to-contact and next step landing area, was impaired in the MS group at higher gait speeds.

Individual limb work does not explain the greater metabolic cost of walking in elderly adults

2007 ◽  
Vol 102 (6) ◽  
pp. 2266-2273 ◽  
Author(s):  
Justus D. Ortega ◽  
Claire T. Farley
Keyword(s):  
Young Adults ◽  
Mechanical Energy ◽  
Center Of Mass ◽  
Reaction Force ◽  
Metabolic Cost ◽  
Metabolic Energy ◽  
Elderly Subjects ◽  
Similar Amount ◽  
Elderly Adults ◽  
Young Subjects

Elderly adults consume more metabolic energy during walking than young adults. Our study tested the hypothesis that elderly adults consume more metabolic energy during walking than young adults because they perform more individual limb work on the center of mass. Thus we compared how much individual limb work young and elderly adults performed on the center of mass during walking. We measured metabolic rate and ground reaction force while 10 elderly and 10 young subjects walked at 5 speeds between 0.7 and 1.8 m/s. Compared with young subjects, elderly subjects consumed an average of 20% more metabolic energy ( P = 0.010), whereas they performed an average of 10% less individual limb work during walking over the range of speeds ( P = 0.028). During the single-support phase, elderly and young subjects both conserved ∼80% of the center of mass mechanical energy by inverted pendulum energy exchange and performed a similar amount of individual limb work ( P = 0.473). However, during double support, elderly subjects performed an average of 17% less individual limb work than young subjects ( P = 0.007) because their forward speed fluctuated less ( P = 0.006). We conclude that the greater metabolic cost of walking in elderly adults cannot be explained by a difference in individual limb work. Future studies should examine whether a greater metabolic cost of stabilization, reduced muscle efficiency, greater antagonist cocontraction, and/or a greater cost of generating muscle force cause the elevated metabolic cost of walking in elderly adults.

scholarly journals Cervical Epidural Spinal Analgesia for Acute Management of Severe Unilateral Forelimb Lameness: Case Report

2021 ◽  
Vol 8 ◽  
Author(s):  
Amanda R. Watkins ◽  
Klaus Hopster ◽  
David Levine ◽  
Samuel D. Hurcombe
Keyword(s):  
Epidural Catheter ◽  
Epidural Morphine ◽  
Cervical Vertebrae ◽  
Insertion Site ◽  
Spinal Analgesia ◽  
Flexor Muscle ◽  
Contralateral Limb ◽  
Epidural Catheter Placement ◽  
Pain Scores

A 20-year-old Quarter Horse gelding was presented with severe right forelimb lameness (5/5 AAEP Lameness Scale) due to a tear of the superficial digital flexor muscle which was diagnosed via palpation of swelling and ultrasonography revealing major muscle fiber disruption and hematoma formation. When traditional systemic therapy (non-Steroidal anti-inflammatories) did not restore clinically acceptable comfort and the risk of supporting limb laminitis became a reasonable concern, a cervical epidural catheter was placed between the first and second cervical vertebrae in the standing, sedated patient using ultrasound guidance. The gelding was treated with epidural morphine (0.1 mg/kg every 24 h then decreased to 0.05 mg/kg every 12 h) and was pain-scored serially following treatment. Spinal analgesia was provided for 3 days. Pain scores significantly decreased following each treatment with morphine, and the gelding was successfully managed through the acutely painful period without any adverse effects associated with the C1-C2 epidural catheter placement technique, the epidural morphine, or contralateral limb laminitis. At the 2-month follow-up, the gelding was walking sound with no complications seen at the catheter insertion site. In this case, spinal analgesia using epidural morphine administered via a cervical epidural catheter was an effective and technically achievable option for pain management associated with severe forelimb muscle injury in a horse.

Traumatic Coxofemoral Luxation in Dysplastic Dogs Managed with a Triple Pelvic Osteotomy: Results in four Dogs

1997 ◽  
Vol 10 (03) ◽  
pp. 136-140 ◽  
Author(s):  
D. D. Lewis ◽  
S. C. Kerwin ◽  
S. T. Murphy
Keyword(s):  
Femoral Head ◽  
Hip Dysplasia ◽  
External Rotation ◽  
Pelvic Osteotomy ◽  
Degenerative Joint Disease ◽  
Joint Disease ◽  
Contralateral Limb ◽  
Norberg Angle

SummaryTriple pelvic osteotomy (TPO) was used in the treatment for traumatic coxofemoral luxations in four adult, large breed dogs with hip dysplasia. Initial closed reductions failed in three and one dog had an initial closed reduction and subsequent open reduction of the coxofemoral luxation that failed. Hip dysplasia was thought to be a prominent factor contributing to the reluxation. TPO successfully maintained reduction of the coxofemoral luxation in all of the dogs. An increase in dorsal acetabular coverage of the femoral head following TPO was demonstrated by an increased Norberg angle. The improved congruency was thought to maintain reduction of the femoral head in the acetabulum and decrease stresses on the joint capsule, allowing healing to occur. Long-term (median: 343, mean ± SD: 406 ± 226 days follow-up) function of the affected limb was comparable to the contralateral limb. Three of the four dogs did not have radiographic progression of coxofemoral degenerative joint disease of the affected joint and differences in the progression of degenerative joint disease were not evident between the affected and the contralateral coxofemoral joint. A decrease in abduction and external rotation and an increase in internal rotation following TPO was noted in the affected coxofemoral joint. Our results establish the utility of this procedure in dysplastic dogs with traumatic coxofemoral luxations.Triple pelvic osteotomy used in the treatment for traumatic coxofemoral luxation in four adult, large breed dogs with hip dysplasia successfully maintained reduction and resulted in satisfactory limb function in all patients.

Outcomes in Patients with a Calipered Kinematically Aligned TKA That Already Had a Contralateral Mechanically Aligned TKA

2019 ◽  
Vol 34 (01) ◽  
pp. 087-093 ◽  
Author(s):  
Trevor J. Shelton ◽  
Manpreet Gill ◽  
Gurbir Athwal ◽  
Stephen M. Howell ◽  
Maury L. Hull
Keyword(s):  
Total Knee Arthroplasty ◽  
Retrospective Study ◽  
Outcome Measures ◽  
Knee Arthroplasty ◽  
Contralateral Limb ◽  
Primary Tkas ◽  
Clinical Benefits ◽  
History Of ◽  
Total Knee

AbstractPrior studies suggest kinematically aligned (KA) total knee arthroplasty (TKA) provides some clinical benefits. There are no reports of self-reported outcome measures in patients treated with a calipered KA TKA that already had a contralateral mechanically aligned (MA) TKA. We performed a retrospective study and asked the following questions: (1) Were you satisfied with your MA TKA when you were treated with the KA TKA? (2) What are the Forgotten Joint Scores (FJS) and Oxford Knee Scores (OKS) in each of your knees? (3) Do you favor one knee? and (4) Did one knee recover faster? From January 2013 to January 2017, 2,378 consecutive primary TKAs were performed of which all were treated with calipered KA that uses serial verification checks incorporating measurements of bone resections and positions to restore the prearthritic or native joint lines accurately. A records review identified patients with a prior primary MA TKA in the contralateral limb. Excluded were those with a history of fracture, osteotomy, infection, or revision knee surgery in either limb. In September 2018, 78 patients (57 females) with a mean age of 73 years (range, 50–91 years) completed a follow-up evaluation consisting of the FJS and OKS questionnaires and three anchor questions. A total of 83% of patients were satisfied with the MA TKA and 92% were satisfied with the KA TKA. The KA TKA had a 15 point higher median FJS and a comparable OKS to that of the MA TKA. Also, 56% of patients favored the KA TKA, and 8% favored the MA TKA. Seventy four percent of patients favored the recovery of the KA TKA, and 6% favored the recovery of the MA TKA. Accordingly, a patient considering a contralateral KA TKA can expect that more often than not the KA TKA will have a higher FJS, a similar OKS, be their favorite knee, and recover faster. Present study is therapeutic and reflects level IV evidence.

scholarly journals Assessing Gait Stability before and after Cochlear Implantation

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Katarzyna Kaczmarczyk ◽  
Michalina Błażkiewicz ◽  
Ida Wiszomirska ◽  
Katarzyna Pietrasik ◽  
Agnieszka Zdrodowska ◽  
...  
Keyword(s):  
Cochlear Implantation ◽  
Research Question ◽  
Center Of Mass ◽  
Strong Stability ◽  
Control Group ◽  
Gait Stability ◽  
Risk Of Falls ◽  
Single Support Phase ◽  
Experimental Group ◽  
Support Phase

Background. It is known that cochlear implantation may alter the inner ear and induce vestibular disorders. Research Question. How does cochlear implantation influence gait stability? Material and Methods. An experimental group of twenty-one subjects scheduled for cochlear implantation underwent gait testing twice, on the day before cochlear implantation (BCI) and three months after cochlear implantation (ACI), using a motion capture system. A control group of 30 age-matched healthy individuals were also tested. Results. In the experimental group, the gait stability ratio (GSR) was found to improve in 17 subjects after implantation, by an average of 6%. Certain other parameters also showed statistically significant improvement between the two experimental group tests: step time (p<0.001), single-support phase walking speed (p<0.05), and center of mass (CoM) (p<0.05). Using the CoM results of the control group, we devised a stability classification system and applied it to the pre- and postimplantation subjects. After implantation, increases were seen in the number of subjects classified in interval II (strong stability) and III (weak stability). The number of subjects in interval I (perfect stability) decreased by 1 and in interval IV (no stability) by 4. Significance. (1) Although cochlear implantation intervenes in the vestibular area, we found evidence that gait stability improves in most subjects after the surgery, reducing the risk of falls. (2) We found statistically significant improvements in individual parameters (such as single-support phase time), in GSR, and in CoM. (3) Based on CoM results, we proposed a new rule-of-thumb way of classifying patients into gait stability intervals, for use in rehabilitation planning and monitoring.

scholarly journals Relationship between total cholesterol level and tuberculosis risk in a nationwide longitudinal cohort

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yong Suk Jo ◽  
Kyungdo Han ◽  
Dahye Kim ◽  
Jung Eun Yoo ◽  
Yuji Kim ◽  
...  
Keyword(s):  
Total Cholesterol ◽  
Cholesterol Level ◽  
Total Cholesterol Level ◽  
Inverse Association ◽  
Significant Inverse Association ◽  
Cholesterol Levels ◽  
Increased Risk ◽  
Korean National Health Insurance ◽  
Young Subjects

AbstractThe association between the total cholesterol level and tuberculosis (TB) risk has been controversial. Our study aimed to evaluate whether total cholesterol level can predict the risk of TB. Data from 5,000,566 subjects who participated in a health screening exam in 2009 were investigated using the Korean National Health Insurance Service database (2009–2018). Cox hazard regression analyses were used to evaluate TB risk according to the quartile of total cholesterol levels. During an average of 8.2 years of follow-up, 32,078 cases of TB occurred. There was a significant inverse association between the total cholesterol level and TB risk. Compared with subjects in the highest quartile, those in the lowest quartile had a 1.35-fold increased TB risk (95% confidence interval = 1.31–1.39). The association between total cholesterol level and TB risk was more apparent in young subjects (age < 65 years), those without diabetes mellitus (DM), and those without obesity (p for interaction < 0.001 for age group, DM, and body mass index). Although there was a significant inverse association between total cholesterol level and TB risk in subjects who did not use a statin, no significant association was observed between the total cholesterol level and TB risk in subjects who used a statin. A low total cholesterol level was significantly associated with an increased risk of TB, even after adjusting for confounders, especially in patients younger than 65 years, those without DM or obesity, and those who did not use a statin.

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