Toward more reliable stability measurements in stance: recommendations for number of measurements, foot position and feedback——a cross-sectional study among servicemen

Background:In the military,insufficient postural stability is a risk factor for developing lower extremity injuries.Postural stability training programs are effective in preventing these injuries.However,an objective method for the measurement of postural stability in servicemen is lacking.The primary objective of this study was to assess the influence of the number of repetitions,different foot positions and real-time visual feedback on postural stability,as well as their effects on the intrasession reliability of postural stability measurements in servicemen.The secondary objective was to assess the concurrent validity of the measurements.Methods:Twenty healthy servicemen between 20 and 50 years of age and in active duty were eligible for this quantitative,cross-sectional study.The measurements took place on a force plate,measuring the mean velocity of the center of pressure.The participants were asked to stand as still as possible in three different foot positions(wide stance,small stance,and on one leg),five times each for 45 s each time,and the measurements were performed with and without real-time visual feedback.Results:We observed a significant main effect of foot position(P<0.001),but not of visual feedback(P=0.119)or repetition number(P=0.915).Postural stability decreased in the more challenging foot positions.The ICC estimates varied from 0.809(one repetition in wide stance)to 0.985(five repetitions on one leg).The common variance(R2)between different foot positions without feedback varied between 0.008(wide stance)and 0.412.Conclusions:To yield reliable data,wide-stance measurements should be conducted three times,and small-stance measurements and measurements on one leg should be conducted two times.The scores of a measurement in a particular foot position cannot predict the scores of measurements in other foot positions.

On-demand sedation with propofol for colonoscopy—A prospective pilot study of the influence on short-term memory, psychomotor function and postural stability

Background: After sedated colonoscopy, patients are discharged on the basis of their subjective judgment that they have recovered, corroborated by the nursing staff. The aim of this study was to assess objectively whether patients were in fact fully recovered at the time of discharge, and to demonstrate whether the methods of testing applied could detect any influence of sedation on short-term memory, psychomotor function and postural stability. Methods: Twenty-two patients were investigated. At the beginning of the procedure, a defined bolus of propofol/alfentanil was given intravenously. During the procedure, an additional bolus was injected one or more times as requested by the patient. After colonoscopy, the patients stayed in the recovery room until the patients judged that they had recovered completely, which was also the judgement of the nursing staff at that time. Before colonoscopy and again before discharge, tests were performed of short-term memory, psychomotor function and postural stability (balance). Results: A positive correlation was found between the duration of colonoscopy and the amount of sedative given (p that they have recovered fully, some patients are still affected by the sedative at the time of discharge, as demonstrated by tests of short-term memory, reaction time and postural stability.

Posture Control of Legged Locomotion Based on Virtual Pivot Point Concept

This paper presents a novel control approach for achieving robust posture control in legged locomotion,specifically for SLIP-like bipedal running and quadrupedal bounding with trunk stabilization.The approach is based on the virtual pendulum concept observed in human and animal locomotion experiments,which redirects ground reaction forces to a virtual support point called the Virtual Pivot Point(VPP)during the stance phase.Using the hybrid averaging theorem,we prove the upright posture stability of bipedal running with a fixed VPP position and propose a VPP angle feedback controller for online VPP adjustment to improve performance and convergence speed.Additionally,we present the first application of the VPP concept to quadrupedal posture control and design a VPP position feedback control law to enhance robustness in quadrupedal bounding.We evaluate the effectiveness of the proposed VPP-based controllers through various simulations,demonstrating their effectiveness in posture control of both bipedal running and quadrupedal bounding.The performance of the VPP-based control approach is further validated through experimental validation on a quadruped robot,SCIT Dog,for stable bounding motion generation at different forward speeds.

Athletes who train on unstable compared to stable surfaces exhibit unique postural control strategies in response to balance perturbations

Background:Athletes have been shown to exhibit better balance compared to non-athletes(NON).However,few studies have investigated how the surface on which athletes train affects the strategies adopted to maintain balance.Two distinct athlete groups who experience different types of sport-specific balance training are stable surface athletes(SSA) such as basketball players and those who train on unstable surfaces(USA) such as surfers.The purpose of this study was to investigate the effects of training surface on dynamic balance in athletes compared to NON.Methods:Eight NON,eight SSA,and eight USA performed five 20-s trials in each of five experimental conditions including a static condition and four dynamic conditions in which the support surface translated in the anteroposterior(AP) or mediolateral(ML) planes using positive or negative feedback paradigms.Approximate entropy(Ap En) and root mean square distance(RMS) of the center of pressure(Co P) were calculated for the AP and ML directions.Four 3 × 5(group × condition) repeated measures ANOVAs were used to determine significant effects of group and condition on variables of interest.Results:USA exhibited smaller Ap En values than SSA in the AP signals while no significant differences were observed in the ML Co P signals.Generally,the negative feedback conditions were associated with significantly greater RMS values than the positive feedback conditions.Conclusion:USA exhibit unique postural strategies compared to SSA.These unique strategies seemingly exhibit a direction-specific attribute and may be associated with divergent motor control strategies.

Evidence of a conservative gait strategy in athletes with a history of concussions

Background：A history of 3 or more concussions is frequently associated with numerous short-and long-term neuropathologies.Impairments in postural control are a known acute consequence of concussion;however,limited evidence exists on the effects of multiple concussions on gait.The purpose of this study was to assess gait stepping characteristics in collegiate aged student-athletes based on concussion history.Methods：There were 63 participants divided into 3 even groups based on concussion history：≥3 concussions,1–2 concussions,and 0 concussion.All participants completed 10 trials of gait on a 4.9 m instrumented walkway.The dependent variables of interest included both gait stepping characteristics（step velocity,length,and width,double support time,and the percentage of the gait cycle in stance） and coefficien of variability（CoV） measures（step length,time,and width）.The gait stepping characteristics were compared firs with a MANOVA with follow-up 1-way ANOVAs and Tukey post hoc tests as appropriate.The Co V measures were compared with 1-way ANOVAs and Tukey post hoc tests.Results：There were main effects for group for step velocity,length,width,and double support time.Overall,the 0 concussion group displayed typical healthy young gait parameters and performed significant y better than either concussion group.The 0 concussion group had a significant y greater step length Co V,but there were no differences in the step time or width Co V.Conclusion：This findin provides evidence of subtle impairments in postural control during gait among individuals with prior history of concussion which could be an early indicator of future neurological deficiencies The limited difference in the variability measures is consistent with prior static stance studies and could suggest the individuals constrain their motor systems to reduce variability.Taken together,these findi gs suggest a conservative gait strategy which is adopted by individuals with a history of concussions.

The diagnostic and prognostic utility of the dual-task tandem gait test for pediatric concussion

Background:The tandem gait test has gained interest recently for assessment of concussion recovery.The purpose of our study was to determine the prognostic and diagnostic use of the single-and dual-task tandem gait test,alongside other clinical measures,within 10 days of pediatric concussion.Methods:We assessed 126 patients post-concussion(6.3§2.3 days post-injury,mean§SD)at a pediatric sports medicine clinic and compared them to 58 healthy controls(age:15.6§1.3 years;43%female).We also compared the 31 patients with concussion who developed persistent post-concussion symptoms(PPCS)(age=14.9§2.0 years;48%female)to the 81 patients with concussion who did not develop PPCS following the initial assessment(age:14.1§3.0 years;41%female).All subjects completed a test battery,and concussion patients were monitored until they experienced concussion-symptom resolution.The test battery included tandem gait(single-task,dual-task(performing tandem gait while concurrently completing a cognitive test)conditions),modified Balance Error Scoring System(mBESS),and concussion symptom assessment(Health and Behavior Inventory).We defined PPCS as symptom resolution time>28 days post-concussion for the concussion group.Measurement outcomes included tandem gait time(single-and dual-task),dual-task cognitive accuracy,mBESS errors(single/double/tandem stances),and symptom severity.Results:The concussion group completed the single-task(mean difference=9.1 s,95%confidential interval(95%CI):6.1-12.1)and dual-task(mean difference=12.7 s,95%CI:8.716.8)tandem gait test more slowly than the control group.Compared to those who recovered within 28 days of concussion,the PPCS group had slower dual-task tandem gait test times(mean difference=7.9 s,95%CI:2.0-13.9),made more tandem-stance mBESS errors(mean difference=1.3 errors,95%CI:0.2-2.3),and reported more severe symptoms(mean difference=26.6 Health and Behavior Inventory rating,95%CI:21.1-32.6).Conclusion:Worse dual-task tandem gait test time and mBESS tandem stance performance predicted PPCS in pediatric patients evaluated within 10 days of concussion.Tandem gait assessments may provide valuable information augmenting common clinical practices for concussion management.

Association between improved trunk stability and walking capacity using ankle-foot orthosis in hemiparetic patients with stroke： evidence from three-dimensional gait analysis

Background Restoration of both normal movement of the pelvis and centre of mass is a primary goal of walking rehabilitation in post-stroke patients because these movements are essential components of effective gait. The aim of this study is to quantitatively analyze the effect of ankle-foot orthosis on walking ability, and to investigate the correlation between improvements in trunk motion and walking capacity.

Does weight loss affect the center of pressure of children with obesity: a follow-up study

Background:Children with obesity were found to show the greater postural instability compared to the normal-weighted children.However,it’s still unclear if their altered postural control ability would recover towards normal pat-tern after weight loss.The purpose of this study was to investigate the effect of weight loss on the center of pressure(COP)for obese children.Method:Totally 147 children were conducted a follow-up study in three years.A total number of 22 participants aged 7-13 years were recruited for their remission of obesity problem after 36 months.Their dynamic plantar pressure data were collected by Footscan pressure plate.The normalized time of four sub-phases,displacements and velocities of COP in anterior-posterior(AP)and medial-lateral(ML)directions were calculated to perform the Kolmogorov-Smirnov test and paired sample t test for statistical analyses.Results:After weight loss,children’s normalized time of forefoot contact phase(FFCP)increased significantly,and their duration of flat foot phase(FFP)decreased significantly.They also exhibited the more medial and posterior ori-entated COP path after weight loss.In ML-direction,the COP displacement during FFP and FFPOP increased,and the COP velocity during FFPOP increased.In AP-direction,COP velocity during FFP and FFPOP increased.Conclusions:The findings indicated that weight loss would have effects on the COP characteristics and postural stability for obese children.COP trajectory can provide essential information for evaluating foot function.The findings may be useful for obese children,medical staff,and healthcare physician.