Weight Transfer Time Research Articles

Characteristics of sit-to-stand movement are associated with trunk and lower extremity selective control in children with cerebral palsy: a cross-sectional study.

Even though the effect of several factors on sit-to-stand (STS) performance of children with CP has been previously explored, the potential role of lower extremity selective control, trunk control and sitting function on the performance of STS has not been examined. This study aimed to investigate the association of trunk control and lower extremity selective motor control with STS performance in children with CP. We recruited 28 children with CP aged between 4 and 10 years whose Gross Motor Function Classification System levels were I and II and 32 age-matched typically developing (TP) children. Trunk control, sitting function, selective control of the lower extremities and STS were evaluated with Trunk Control Measurement Scale (TCMS), sitting section of Gross Motor Function Measure-88 (GMFM-88), Selective Control Assessment of the Lower Extremity (SCALE) and the STS outcomes of a force platform [weight transfer time, rising index, and center of gravity (COG) sway velocity], respectively. In all evaluations, children with CP demonstrated lower scores than TD children. A moderate correlation was found between total scores of TCMS, GMFM-88 sitting section scores and COG sway velocity during STS and a fair correlation between SCALE total scores and COG sway velocity in the CP group ( r = -0.51, r = -0.52, r = -0.39, respectively). A fair correlation was found between SCALE total scores and the weight transfer time during STS in children with CP ( r = -0.39). Based on these results, improving trunk and lower extremity selective control may enhance STS performance in children with CP.

Effect of optokinetic virtual reality scenes on a sitting-to-stand movement.

Visual perception plays a role in balance control while performing a sit-to-stand movement (STS). The dynamic virtual environment could reduce effective neuromuscular regulation and instability. Nevertheless, virtual reality (VR) on the STS movement was not explored in any research. This study's aim was to investigate the effect of the VR of an optokinetic drum on the STS movement by using optokinetic drum VR scenes. This study used a repeated measurement research design. Ninety healthy subjects aged 18-23years with no experience in virtual reality were recruited. Each participant was asked to stand as quickly as possible from a height-adjustable chair three times under five conditions: with eyes-open (EO), eyes-closed (EC), and three VR scenes: a limited field view of an optokinetic scene, a black and white striped scene, moving in horizontal direction (VRhori), vertical direction (VRvert), and roll (VRroll). VR scenes were generated using a mobile phone in a head-mounted display. The rising index (the upward force produced by the legs as a proportion of body weight), sway velocity, and weight transfer time were measured using a NeuroCom Balance Master. Only VRvert condition significantly reduced weight transfer time as compared to EO and the other two VR conditions. All three VR scenes significantly reduced the rising index as compared to EO. VRvert condition significantly increased sway velocity as compared to all conditions. These findings suggest that optokinetic environment scenes in virtual reality could be used as an alternative method to increase the challenge of maintaining the balance during STS.

The Relationship Between Fat Tissue & Lean Body Mass and Sit to Stand Task in Obese Individuals

Objective: Obesity, currently one of the important health issues, can be defined through Fat Tissue Mass (FTM) and Lean Body Mass (LBM). The study aimed to investigate to what extent do FTM and LBM are associated with movement strategies of Sit-to-Stand (STS) task in individuals with obesity. Methods: Forty-nine obese individuals (52,83 ± 7,39) with no diagnosis of any health condition included in the study. The Balance Master System was used to evaluate the STS movement. STS task was analyzed by means of Weight Transfer Time (WTT) (second), Rising Index (RI) (force exerted by legs-%Body Weight), the Center of Gravity (COG) sway velocity (degrees per second). The FTM and LBM were regressed against each STS parameter including age as a covariate. Results: The regression models could explain 10-21% of the variabilities in STS parameters: RI (21%), COG sway velocity (11%), WTT (10%). FTM significantly related to RI (β: – 0.287, p=0.040), but not with COG sway velocity (β: 0.270, p=0.073) and WTT (β: – 0.038, p=0.802). LBM was significantly associated with RI (β: 0.435, p=0.003); yet, not with COG sway velocity (β: – 0.100, p=0.066), WTT (β: – 0.092, p=0.549). Conclusion: This study revealed that FTM and LBM can explain the significant percent of the variation in RI during STS task, meaning a decrease in FTM and an increase in LBM provided support to rise during STS task. Moreover, an increase in FTM deteriorated postural stability. Improving LBM and decreasing FTM would be an effective strategy to improve STS in the obese population to increase their agility and could encourage physical activity participation.

Relationship Between Posturography, Clinical Balance and Executive Function in Parkinson´s Disease

ABSTRACTThis study aimed to evaluate the relationship between posturography, clinical balance, and executive function tests in Parkinson´s disease (PD). Seventy-one people participated in the study. Static posturography evaluated the center of pressure fluctuations in quiet standing and dynamic posturography assessed sit-to-stand, tandem walk, and step over an obstacle. Functional balance was evaluated by Berg Balance Scale, MiniBESTest, and Timed Up and Go test. Executive function was assessed by Trail Making Test (TMT) and semantic verbal fluency test. Step over obstacle measures (percentage of body weight transfer and movement time) were moderately correlated to Timed Up and Go, part B of TMT and semantic verbal fluency (r > 0.40; p < 0.05 in all relationships). Stepping over an obstacle assesses the responses to internal perturbations. Participants with shorter movement times and higher percentage of body weight transfer (higher lift up index) on this task were also faster in Timed Up and Go, part B of TMT, and semantic verbal fluency. All these tasks require executive function (problem solving, sequencing, shifting attention), which is affected by PD and contribute to postural assessment.

Whole-body vibration training improves balance control and sit-to-stand performance among middle-aged and older adults: a pilot randomized controlled trial

BackgroundAging is associated with decreased balance, which increases falling risk. The objective of the current study was to determine the feasibility and effects of whole-body vibration (WBV) training on knee extensor muscle power, limits of stability, and sit-to-stand performance among community-dwelling middle-aged and older adults in the United States.MethodsA randomized pilot study with participant blinding was conducted. Feasibility outcomes included recruitment and compliance rate. Twenty-nine community-dwelling older adults were randomly assigned to perform body-weight exercises with either an individualized vibration frequency and amplitude, a fixed vibration frequency and amplitude, or no vibration. Isokinetic knee extensor power, limits of stability, and sit-to-stand tests were conducted before beginning the exercises (baseline) and after 8 weeks of training.ResultsWith a favorable recruitment rate (58%) and compliance rates (attrition 9%; adherence 85%), the intervention was deemed feasible. The limits of stability endpoint excursion score for the individualized frequency–amplitude group was increased by 8.8 (12.9%; P = 0.025) after training, and that group’s maximum excursion score was increased by 9.2 (11.5%; P = 0.006) after training. The average weight transfer time score was significantly decreased by 0.2 s in the fixed group. The participants in the individualized group demonstrated a significant increase (3.2%) in weight rising index score after 8 weeks of WBV training.ConclusionsWBV training is feasible for use with elderly people, and this study achieved good recruitment and compliance. The present paper suggests that 8 weeks of WBV training improves limits of stability and sit-to-stand performance. Future studies must determine whether WBV training improves other factors that affect posture control.Trial registrationThis study was registered at the Texas Woman’s University Institutional Review Board [TWU IRB 17632] on the 3rd of November 2014.

Wearable Gait Lab System providing quantitative statistical support for human balance tests

Abstract Sensory devices have the potential to improve monitoring balance tests and providing quantitative supports for activity analysis. The Wearable Gait Lab system is proposed to monitor activities of feet and legs during balance tests. In this system, a wearable underfoot force sensing unit is used to record foot motions and plantar pressure data; a joint angular and EMG sensing unit is used to record leg motions and muscular data; and an android application is implemented to control all units, monitor the data recording process, and upload recorded data to cloud server, which allows health professionals to review it remotely. The system provides adequate data for balance ability analysis and simplifies the scoring processes in balance tests. The proposed system is evaluated with standard balance tests (Limits of Stability, Sit-To-Stand, and Rhythmic Weight Shift), whereas the data collected are analyzed with data mining techniques to verify the reliability of the designated process. Certain parameters are computed such as Center of Gravity (COG), weight transfer time, and sway velocities. The results show that the system is informational and reliable in the process of determining balance status during tests with additional advantages in high portability and efficient review communications.

Evaluation of postural stability in children with hemiplegic cerebral palsy.

[Purpose] Postural stability is the ability of to maintain the position of the body within the support area. This function is affected in cerebral palsy. The aim of the present study was to compare static and dynamic postural stability between children with hemiplegic cerebral palsy and healthy controls. [Subjects and Methods] Thirty-seven children between the ages of 5 and 14 diagnosed with hemiplegic cerebral palsy (19 right, 18 left) and 23 healthy gender- and age-matched controls were included in the study. Postural stability was evaluated in both of the groups using a Neurocom Balance. Sway velocity was measured both with the eyes open and closed. Sit to stand and turning abilities were also assessed. [Results] The sway velocities with the eyes open and closed were significantly different between the groups. The weight transfer time in the Sit to Stand test was also significantly slower in children with cerebral palsy. Children with cerebral palsy also showed slower turning times and greater sway velocities during the Step and Quick Turn test on a force plate compared with their healthy counterparts. [Conclusion] Both static and dynamic postural stability parameters are affected in hemiplegic cerebral palsy. Further research is needed to define rehabilitation interventions to improve these parameters in patients.

The effects of vision on sit-to-stand movement.

[Purpose] It is well known that vision is an important factor contributing to postural control. However, there has been little discussion about the effect of vision on sit-to-stand movement. The purpose of this study was to evaluate the effect of constrained vision on sit-to-stand movement. [Subjects and Methods] Twenty-three healthy subjects (11 males, 12 females) aged 18–23 years with normal body mass indices were recruited for this study. Each participant was asked to stand as quickly as possible from a height-adjustable chair 3 times under 2 conditions: with eyes closed (EC) and eyes open (EO). The weight transfer time, rising index, and center of gravity sway velocity were measured using a NeuroCom Balance Master. [Results] The results show there were significant differences between the EC and EO conditions in the weight transfer time and the centre of gravity sway velocity. No significant difference was found between the EC and EO conditions in the rising index. These findings suggest that visual perception may play a role in balance control while performing sit-to-stand movement.

Balance analysis during the sit-to-stand movement of chronic hemiparetic individuals based upon their functional levels.

Introduction: Balance deficits are frequently observed in individuals with hemiparesis and lead to disabilities in daily activities, such as the ability to walk. The sit-to-stand movement is essential for independent gait, and balance is one of the main requirements for its performance. Objective: To analyse the balance parameters during the sit-to-stand movement in individuals with chronic hemiparesis, stratified according to the level of functional performance. Method: Individuals above 20 years of age with a time since the onset of the stroke of at least six months were divided into three functional groups, according to their walking speeds: Household ambulation (&lt;0.4 m/s), limited community ambulation (0.4 to 0.8 m/s), and complete community ambulation (&gt;0.8 m/s). The following balance parameters were assessed by the sit-to-stand test of the Balance Master System: (1) weight transfer time, (2) rising index, and (3) the centre of gravity sway velocity. It was considered a significance level of α&lt;0.05. Results: Eight-six individuals (56±13 years) participated. Statistically significant differences regarding weight transfer time were observed only between the household group and the others (limited community ambulation and complete community ambulation (F=4.42;p=0.01). Similarly, regarding the rising index, significant differences were observed only for the household ambulation group (F=8.46;p&lt;0.01). Conclusion: Individuals with chronic hemiparesis, who had lower functional performance levels (household ambulation) spent more time to perform the sit-to-stand movement with less weight transfer to the lower limbs. These findings suggest that within clinical contexts when balance training is carried out to improve mobility and gait performance in individuals with household ambulation, parameters related to the transfer time and rising index should be emphasized.

Effects of rehabilitative horse riding on the Sit-to-Stand action of the adolescent with brain lesions.

The purpose of this study was to investigate the balance abilities of the adolescent girl with brain lesions by Sit-to-Stand (STS) action analysis before and after the rehabilitative horse riding of 16 week program. The subject aged 16 yr old who had the disabilities of spasticity and hemiplegia was recruited with the consent approval. The equilibrium abilities of the subject were tested by Sit-to-Stand examination with Weight Transfer Time (WTT), Mean Rising Index (MRI), Mean Weight Asymmetry (MWA), Max Trunk Flexion Velocity (MTFV), and Max Trunk Extension Velocity (MTEV). Research was designed by AB single subject study with baseline of 3 times of measurement and rehabilitative horse riding treatments. In the results, the enhancement of the subject’s equilibrium ability was shown from the comparisons between baseline and treatment by the STS test that WTT was 2.37 sec faster, MRI was 6.64 N/kg higher, and MWA was 8.12% lower, and MTFV was 0.57°/sec larger than all those means of baseline. It suggested that the subject showed her enhanced balance ability while in sitting and standing after the rehabilitative horse riding treatments.

Altered movement strategies in sit-to-stand task in persons with transtibial amputation

Sit-to-stand movement is an essential function for participation in many activities of daily living. Although this movement is one of the most important functional tasks, there is limited research investigating strategies of sit-to-stand movement in transtibial amputees. To examine movement strategies of the sit-to-stand task in persons with transtibial amputation and healthy non-amputated individuals. Cross-sectional study. A total of 12 male unilateral transtibial amputees and 19 healthy male subjects participated in this study. Sit-to-stand movement was evaluated in terms of weight transfer time, weight-bearing symmetry, sway velocity, and rising index by using Balance Master System. Participants in both groups exhibited similar weight-bearing transfer time (p > 0.05). Transtibial amputees demonstrated significantly greater weight-bearing asymmetry, higher sway velocity, and lower rising index than healthy subjects during the sit-to-stand transfer movement (p < 0.05). Transtibial amputees were unable to use the same movement strategies during a sit-to-stand task as healthy individuals; therefore, they had to develop new strategies to perform this task. Little is known about the altered movement strategies during sit-to-stand task in transtibial amputees. The results of the study might provide some new insight into the motor components of the sit-to-stand movement in persons with transtibial amputation for both clinicians and researchers.

12주간 승마 운동이 초·중학생들의 Sit-to-Stand 동작 시 신체 이동 및 평형성 그리고 몸통의 굴신 운동에 미치는 영향

The purpose of this study was to analyze the 12-week horse riding exercise effect on the locomotion of a body and bilateral balance and flexion/extension of trunk during the sit-to-stand(STS) in elementary and middle school students. One-hundred eleven participants were divided into three groups. Each group was subject to a different horse riding exercise: control group(n =3 6), 1 time/week group(n=37), and 3 times/week group(n=38). Two-way repeated ANOVA was used to compare weight transfer time(WTT), trunk flexion velocity(TFV), trunk extension velocity(TEV), mean rising index(MRI), mean weight asymme- try(MWA) among the groups, and STS changes in before and after 12 weeks. There was a group interaction in WTT, TFV, TEV, MRI, and MWA with different responses to horse riding exercise participation. There was a significant increase in 1 time/week group and 3 times/week group of WTT, TFV, TEV, and MRI. Additionally, MWA(an index of a capacity for bilateral balance) in lower extremity was decreased in 3 times/week group. It seems that horse riding exercise positively affected musculoskeletal function of the trunk and lower extremity by accelerating locomotion and bilateral balance.

Lighting for improving balance in older adults with and without risk for falls

SIR—The visual system acquires sensory information about self-position and location of objects in the environment and, together with sensory input from the vestibular and somatosensory systems, helps maintain balance. The dependence on visual information for the maintenance of postural stability and control increases with age due to age-related changes that occur in the vestibular and somatosensory systems [1–10]. Lighting that enhances veridical visual information about the environment for older adults could be a practical and effective intervention to reduce falls risk. Figueiro et al. [11] showed that, in healthy, non-faller older adults, a wall-plug nightlight (NL) was associated with significantly greater sway in the early phase of the sit-to-stand (STS) test than was found with a novel NL system providing low-level ambient illumination and enhanced horizontal and vertical (H/V) visual information. The present study aimed to extend these findings by testing the effectiveness of a similar NL system on another measure, the weight transfer time (WTT), in two groups of older adults, those with and without fall risks. A longer WTT should be associated with more difficulty in getting up [12–14]. It was hypothesised that compared with wall-plug NLs, WTT in the STS test would be better with the novel NL system for both groups, and that the effect would be larger for fallers than for non-fallers. It was also hypothesised that a high contrast (black on white versus white on white) veridical stimulus would be better for postural stability and control than a low contrast stimulus.

Measurement of Paretic–Lower-Extremity Loading and Weight Transfer After Stroke

Weight bearing through, or "loading" of, the paretic lower extremity and transfer of weight from one lower extremity to the other are important impairment-level goals of stroke rehabilitation. Improvements in these limb-loading and weight-transfer abilities have been shown to relate to improved performance of many functional activities. Unfortunately, valid and practical clinical measures of paretic-lower-extremity loading and weight transfer have not been identified. The purpose of this study was to assess convergent validity of the Step Test (ST) and the knee extension component of the Upright Motor Control Test (UMCe) as measures of paretic-limb loading and of the Repetitive Reach Test (RR) as a measure of weight transfer in the first 6 months after stroke. This was a prospective cohort study of 33 adults with lower-extremity motor impairment following unilateral, noncerebellar stroke. Participants were tested one time per month from 1 to 6 months poststroke. Scores on the ST (performed with the nonparetic leg as the stepping leg) and UMCe were positively correlated with peak vertical ground reaction forces (GRFs) beneath the paretic limb during functional tasks (R(2)=.35-.76 for the ST, pseudo R(2)=.21-.34 for the UMCe). Scores on the RR were positively correlated with change in vertical GRF beneath the paretic limb during the diagonal reach task (R(2)=.45) and with weight-transfer time during stepping with the nonparetic limb (R(2)=.15). The ST, performed with the nonparetic leg as the stepping leg, is a valid measure of paretic-limb loading during stroke recovery. Of the clinical measures tested, the ST correlated most strongly with the force platform measures.

Kinematics of the threshold of balance recovery are not affected by instructions limiting the number of steps in younger adults

To our knowledge, the effect of instructions limiting the number of steps on the threshold of balance recovery has not been quantified, which could make comparisons between studies difficult. We determined the maximum forward lean angles from which 28 younger adults could be suddenly released and still recover balance using: (i) only a single step, (ii) no more than two steps and (iii) no limit on the number of steps. Results showed that instructions limiting the number of steps significantly affected the maximum lean angle but only by a maximum of 1°. At the maximum lean angles, they also significantly affected reaction time, first weight transfer time, first stride velocity, first stride length and second stride velocity but only by 8% on average. However, they did not affect muscular latencies, first stride time, first stride height, first stride width or other second step variables. Moreover, at lean angles larger than their maximum, participants were able to respect the instructions but unable to recover balance without safety harness assistance. Given that the effect was too small to be pertinent, we can state that, between the three limits on the number of steps, not only were the maximum lean angles similar but the first steps were nearly identical and the additional steps did not help to increase the maximum lean angle. Therefore, we have demonstrated that instructions limiting or not limiting the number of steps appear to be equally valid to study the threshold of balance recovery in younger adults.

Visual guidance of landing behaviour when stepping down to a new level

When stepping down from one level to another, the leading limb has to arrest downward momentum of the body and subsequently receive and safely support bodyweight before level walking can begin. Such step downs are performed over a wide range of heights and predicting when and where contact between the landing limb and the lower level will be made is likely a critical factor. To determine if visual feedback obtained after movement initiation is habitually used in guiding landing behaviour, the present study determined whether pre-landing kinematics and the mechanics of landing would be modulated according to the type of visual feedback available during the stepping down phase. Ten healthy participants (32.3 +/- 7.9 years) stepped, from a standing position, down from three different heights onto a forceplatform, either coming immediately to rest or proceeding directly to walking across the laboratory. Repeated trials were undertaken under habitual vision conditions or with vision blurred or occluded 2-3 s prior to movement initiation. Pre-landing kinematics were assessed by determining, for the instant of landing, lead-limb knee and ankle angle, stepping distance, forwards positioning of the body CM within the base of support and the forwards and downwards body CM velocity. Landing mechanics for the initial contact period were characterized using lead limb vertical loading and stiffness, and trail limb un-weighting. When vision was occluded movement time, ankle plantarflexion and knee flexion were significantly increased compared to that determined for habitual vision, whereas forwards body CM positioning and velocity, vertical loading and stiffness, and trail limb un-weighting, were significantly reduced (p < 0.05). Similar adaptations were observed under blurred conditions, although to a lesser extent. Most variables were significantly affected by stepping task and step height. Subjects likely reduced forwards CM position and velocity at instant of landing, in order to keep the CM well away from the anterior border of the base of support, presumably to ensure boundary margins of safety were high should landing occur sooner or later than expected. The accompanying increase in ankle plantarflexion at instant of landing, and increase in single limb support time, suggests that subjects tended to probe for the ground with their lead limb under modified vision conditions. They also had more bodyweight on the trail limb at the end of the initial contact period and as a consequence had a prolonged weight transfer time. These findings indicate that under blurred or occluded vision conditions subjects adopted a cautious strategy where by they 'sat back' on their trail limb and used their lead limb to probe for the ground. Hence, they did not fully commit to weight transfer until somatosensory feedback from the lead limb confirmed they had safely made contact. The effect of blurring vision was not identical to occluding vision, and led to several important differences between these conditions consistent with the use of impoverished visual information on depth. These findings indicate that online vision is customarily used to regulate landing behaviour when stepping down.

Age differences in using a rapid step to regain balance during a forward fall.

Earlier studies showed that healthy old adults have substantially reduced abilities to develop joint torques rapidly. We hypothesized that this age decline would reduce abilities to regain balance once a forward fall is underway. The present study examined whether aging in fact reduces ability to regain balance by taking a single, rapid step upon release from a forward lean. Ten young (mean age 24.3 yr) and ten old (72.8 yr) healthy males were released from a forward-leaning position and instructed to regain standing balance by taking a single step forward. Lean angle was successively increased until a subject failed to regain balance as instructed. Lower extremity motions and foot-floor reactions were measured during the responses. Total response time was divided into reaction, weight transfer, and step times. At small lean angles, responses of old subjects were similar to those of the young. However, the mean maximum lean angle from which old could regain balance as instructed was significantly smaller than that for young (23.9 vs 32.5 deg, p < .0005). Within each age group, maximum lean angle correlated strongly with weight transfer time and step velocity. Substantial age-related declines in the ability to regain balance by taking a rapid step exist among healthy adults when the time available for recovery is short. The source of the decline seems largely to lie in the decrease with age of maximum response execution speed rather than in the sensory or motor programming processes involved in response initiation.

Age-related changes in balance control system: initiation of stepping

The balance control system of a group of healthy and fit, young and elderly subjects was studied during the initiation of stepping in one of three directions: forward, sideways, and backwards in response to a light cue. The performance of these movements requires shifting support from two to one foot, moving the centre of mass outside the initial base of support and creating a new support configuration. By recording and analysing the vertical ground reaction force beneath the subject's stepping foot, we were able to examine the two phases prior to limb lift-off for stepping: reaction time and weight transfer time. Both reaction time and weight transfer time increased with age: The elderly subjects had a proportionately larger increase in weight transfer time compared to the reaction time. The peak force generated showed an age by stepping direction effect: the elderly had a significantly lower peak force for the forwards stepping compared to the younger subjects. The larger increase in weight transfer results in a slower stepping response. Since a stepping task is often recruited to avoid a fall, the increase in response execution time can have undesirable consequences.