How Does Standing Anteroposterior Stability Limits Correlate to Foot/ankle Functions in Bilateral Spastic Cerebral Palsy?

PURPOSE: To determine whether foot and ankle functions are correlated with the limits of stability (LoS) while standing in individuals with bilateral spastic cerebral palsy (BSCP). METHODS: Eighteen people who could walk and with BSCP and 18 people without disability participated. Anteroposterior LoS was measured using a force platform. To quantify ankle and foot functions, spasticity, isometric muscle strength, passive range of motion, and plantar light touch-pressure sensation were assessed. RESULTS: In the BSCP group, anteroposterior LoS was significantly decreased, and anterior LoS reduction was correlated with decreases in plantar flexor and toe flexor strength and in sensitivity of the forefoot to light touch-pressure sensation, whereas the posterior LoS reduction was correlated with reduced dorsiflexor strength. CONCLUSIONS: The present findings suggest that improvement in these foot and ankle functions in BSCP may increase LoS while standing.

An increase in relative contribution of compensatory postural adjustments during voluntary movement while standing in adolescents and young adults with bilateral spastic cerebral palsy.

Previous studies have revealed several deficits in anticipatory postural adjustments (APAs) during voluntary movements while standing in individuals with bilateral spastic cerebral palsy (BSCP). However, it remains unclear whether compensatory postural adjustments (CPAs) during movement increase to compensate for APA deficits. We investigated the anticipatory and compensatory activities of postural muscles during voluntary movement while standing in adolescents and young adults with BSCP. The study included seven participants with BSCP with level II on the Gross Motor Function Classification System (GMFCS), seven with BSCP with level III on the GMFCS, and fourteen healthy controls. The participants stood on a force platform and lifted a load under two weight conditions (light and heavy). The electromyographic activities of postural muscles were analyzed at time intervals typical for APAs and CPAs. The percentage of muscle activity in the CPA time epoch against the total muscle activity during the APA and CPA time epochs was higher in the two BSCP groups than in the control group. In the control group, a load-related modulation was observed only in the APA time epoch, whereas in the BSCP-II group, the load-related increase was observed in both the APA and CPA time epochs. No load-related modulations were observed in the BSCP-III group. These findings suggest that adolescents and young adults with BSCP exhibit an increase in the relative contribution of CPAs during voluntary movement and that there exist severity-related differences in the modulation of APAs and CPAs.

Peroneus longus muscle exhibits pre-programmed anticipatory activity before unilateral abduction of the lower limb while standing: a pilot study.

[Purpose] This study aimed to develop a method for assessing anticipatory postural adjustments associated with voluntary movements in individuals with functional ankle instability. We examined whether the peroneus longus muscle exhibits anticipatory activation before unilateral abduction of the lower limb in individuals without disability. [Participants and Methods] Twelve healthy young adults participated in this study. Participants maintained a standing posture with 95 ± 2.5% of their weight on the left side and with the thenar of their right foot in contact with a small wooden board fixed to a force platform. Thereafter, they abducted their right lower limb by approximately 35° at maximum speed; during this time, electromyographic activities of the focal and postural muscles were recorded. [Results] The peroneus longus, external oblique, and erector spinae muscles on the left side of the body were activated before the right gluteus medius muscle, which is a focal muscle of abduction of the right lower limb. The activation timing of the left peroneus longus was the fastest among these postural muscles. [Conclusion] These findings suggest that the peroneus longus muscle plays an important role in anticipatory postural adjustments associated with unilateral abduction of the lower limb and that an ankle strategy is adopted in anticipatory postural adjustments during this task.

Use of the sit-to-stand task to evaluate motor function of older adults using telemetry.

BACKGROUND: Physical exercises are widely used in community programs, but not all older adults are willing to participate. Information and communication technology may solve this problem by allowing older people to participate in fitness programs at home. Use of remote instruction will facilitate physical exercise classes without requiring that participants gather at one place. The aim of this study was to examine use of a sit-to-stand task in evaluating motor function using conventional video communication in a telemetry system to enable real-time monitoring, and evaluation in physical performance of older adults at home. METHODS: The participants were 59 older individuals and 81 university students. Three physical exercise batteries were used: arm curl, figure-of-eight walk test, and functional reach. The knee extension maximum angular velocity (KEMAV) and the iliac elevation maximum velocity (IEMV) during standing up from a chair and the heel rise frequency were used in the motion-capture measurements. The results were assessed using multi-group structural equation modeling (SEM) for the young and older groups. RESULTS: Young participants consistently performed better than their older counterparts on all items. Analyses with multi-group SEM based on correlations between items yielded a good model-fit for the data. Among all path diagrams for IEMV and KEMAV in the older and young groups, paths from muscular strength to skillfulness showed significant effects. The path from the IEMV to muscular strength was also significant in the older group. CONCLUSIONS: Multi-group SEM suggested that video-based measurements of IEMV during sit-to-stand motion can estimate muscular strength, which suggests that remote monitoring of physical performance can support wellness of community-dwelling older adults.

Quiet standing and anteroposterior limits of stability in adolescents and young adults with bilateral spastic cerebral palsy.

Stance stability in individuals with bilateral spastic cerebral palsy (BSCP) in various standing postures including the quiet standing (QS) and limits of stability (LoS) has been widely studied. However, the relationships between the QS and LoS remain unclear. This study aimed to determine the relationships between the positions and postural sway in the QS and anteroposterior LoS in individuals with BSCP. It included 27 adolescents and young adults with BSCP (BSCP group) and 27 adolescents and young adults without disability (control group). The position of center of pressure in the anteroposterior direction (CoPy position) and the path length of center of pressure (CoP path length) during the QS and the anterior and posterior LoS (A-LoS and P-LoS, respectively) were measured using a force platform. The CoPy positions in the A-LoS and P-LoS in the BSCP group were limited compared with those in the control group. In the BSCP group, the more anterior the CoPy position in the QS, the more anterior (i.e., limited) it was in the P-LoS. Although the CoP path length in the QS was larger in the BSCP group, those in the A-LoS and P-LoS were larger in the control group. The BSCP group also showed that the more anterior the CoPy position or the longer the CoP path length in the QS, the more decreased the anteroposterior LoS range was. Therefore, assessing various standing postures, including QS and anteroposterior LoS, is important to manage balance impairments in individuals with BSCP.

A coactivation strategy in anticipatory postural adjustments during voluntary unilateral arm movement while standing in individuals with bilateral spastic cerebral palsy.

Individuals with bilateral spastic cerebral palsy (BSCP) reportedly has problems with anticipatory postural adjustments (APAs) while standing. However, the use of coactivation strategy in APAs in individuals with BSCP has conflicting evidence. Hence, this study aimed to investigate postural muscle activities in BSCP during unilateral arm flexion task in which postural perturbations occur in the sagittal, frontal, and horizontal planes. We included 10 individuals with BSCP with level II on the Gross Motor Function Classification System (BSCP group) and 10 individuals without disability (control group). The participants stood on a force platform and rapidly flexed a shoulder from 0° to 90° at their own timing. Surface electromyograms were recorded from the rectus femoris, medial hamstring, tibialis anterior, and medial gastrocnemius. The control group showed a mixture of anticipatory activation and inhibition of postural muscles, whereas the BSCP group predominantly exhibited anticipatory activation with slight anticipatory inhibition. Compared with the control group, the BSCP group tended to activate the ipsilateral and contralateral postural muscles and the agonist-antagonist muscle pairs. The BSCP group had a larger disturbance in postural equilibrium, quantified by the peak displacement of center of pressure during the unilateral arm flexion, than those without disability. Individuals with BSCP may use coactivation strategy, mainly the anticipatory activation of postural muscle activity, during a task that requires a selective postural muscle activity to maintain stable posture.

Fingertip light touch contact increases anteroposterior limits of stability in healthy young and older adults.

BACKGROUND: The limit of stability (LoS), an index of stance balance ability, is reduced in older adults. Although contacting an earth-fixed external surface through fingertips' light touch improves older adults' stance balance control, its effects on the LoS in this population are unclear. RESEARCH QUESTION: Does light touch increase the LoS and reduce postural sway in the LoS? METHODS: This study included 20 young adults (11 women and 9 men, mean age = 20.6 years) and 15 community-dwelling older adults (8 women and 7 men, mean age = 74.5 years). The position and path length of the center of pressure (CoP) during quiet standing (QS) and the anterior and posterior LoS (A-LoS and P-LoS, respectively) were measured using a force platform under two touch conditions (no-touch condition and light-touch condition). In light-touch condition, participants placed the tip of their dominant index finger on a load cell, which had an applied force of <1 N. RESULTS: In both touch conditions, the older group had a more limited CoP position in the anteroposterior LoS and a longer CoP path length in the QS and LoS than the younger group. In both participant groups, the light-touch condition showed a wider CoP position in the anteroposterior LoS and a shorter CoP path length in the QS and LoS than the no-touch condition. SIGNIFICANCE: Light touch increases the anteroposterior LoS and decreases postural sway in the LoS. Therefore, contacting an external object by fingertips' light touch may be an effective training protocol to increase the LoS in older adults.

Deficits in anticipatory inhibition of postural muscle activity associated with load release while standing in individuals with spastic diplegic cerebral palsy.

This study aimed to determine whether individuals with spastic diplegic cerebral palsy (SDCP) have deficits in anticipatory inhibition of postural muscle activity. Nine individuals with SDCP (SDCP group, 3 female and 6 male, 13-24 yr of age) and nine age- and sex-matched individuals without disability (control group) participated in this study. Participants stood on a force platform, which was used to measure the position of the center of pressure (CoP), while holding a light or heavy load in front of their bodies. They then released the load by abducting both shoulders. Surface electromyograms were recorded from the rectus abdominis, erector spinae (ES), rectus femoris (RF), medial hamstring (MH), tibialis anterior (TA), and gastrocnemius (GcM) muscles. In the control group, anticipatory inhibition before load release and load-related modulation of the inhibition were observed in all the dorsal muscles recorded (ES, MH, and GcM). In the SDCP group, similar results were obtained in the trunk muscle (ES) but not in the lower limb muscles (MH and GcM), although individual differences were seen, especially in MH. Anticipatory activation of the ventral lower limb muscles (RF and TA) and load-related modulation of the activation were observed in both participant groups. CoP path length during load release was longer in the SDCP group than in the control group. The present findings suggest that individuals with SDCP exhibit deficits in anticipatory inhibition of postural muscles at the dorsal part of the lower limbs, which is likely to result in a larger disturbance of postural equilibrium.

Exploring the factors associated with decreased dynamic balance ability in older patients with heart failure.

BACKGROUND: Older patients with heart failure (HF) have a higher prevalence of frailty and poorer dynamic balance ability than other community-dwelling older adults. However, the association of frailty and other clinical characteristics with dynamic balance ability in these patients remains unclear. OBJECTIVES: We aimed to determine the clinical characteristics associated with decreased dynamic balance ability in older patients with HF. METHODS: This observational study included patients aged ≥65 years who could walk independently and were admitted to our university hospitals to undergo a cardiac rehabilitation. The timed up and go test (TUG) was used to evaluate dynamic balance ability. Pearson's and Spearman's correlation analyses were performed to determine the relationships between TUG scores and clinical characteristics. A multiple regression model based on the forced entry method was used to determine independent predictors of TUG scores. RESULTS: Of the 183 participants in this study (94 women; mean age, 82.5 ± 8.1 years), 116 (61.7%) had frailty. Pearson's and Spearman's correlation analyses revealed that age, frailty, sex, knee extensor muscle strength, maximum calf circumference, and Mini-Mental State Examination-Japanese version (MMSE-J) score were significantly correlated with TUG score (p < 0.001). Further, multiple regression analysis showed that age (p < 0.001), frailty (p = 0.041), knee extensor muscle strength (p = 0.002), and MMSE-J score (p = 0.048) were independent predictors of TUG scores. CONCLUSION: Multiple factors, including age, frailty, knee extensor muscle weakness, and cognitive function impairment are independently associated with decreased dynamic balance ability in older patients with HF.

Three-dimensional gait analysis of lower extremity gait parameters in Japanese children aged 6 to 12 years.

We aimed to develop gait standards for gait parameters in school-aged Japanese children and assess age-related differences in gait patterns and parameters. Children aged 6-12 years (n = 424) were recruited from two elementary schools. An instrumented three-dimensional gait analysis system was used to record each child's gait kinematics, kinetics, and spatiotemporal parameters. Participants were subdivided into three age groups (Group A, 6-8 years; Group B, 9-10 years; and Group C, 11-12 years). LMS Chartmaker, version 2.54, was used to create a developmental chart for the gait pattern. The non-normalized step and stride lengths were significantly longer, and the cadence was lower in older children; however, the opposite outcome occurred when analyzing normalized data. Ankle moment differed significantly by age, and the maximum ankle moment was higher in older children than that in younger children. Furthermore, the hip and knee flexion angles during gait and the normalized spatiotemporal parameters of Japanese children aged 6-12 years differed by age and from those of children from other countries. The centile chart of the gait pattern is a useful tool for clinicians to assess developmental changes in the gait pattern and detect gait abnormalities in children.

Deficits in task-specific modulation of anticipatory postural adjustments in individuals with spastic diplegic cerebral palsy.

We examined whether individuals with spastic diplegic cerebral palsy (SDCP) have the ability to utilize lower leg muscles in anticipatory postural adjustments (APAs) associated with voluntary arm movement while standing, as well as the ability to modulate APAs with changes in the degree of postural perturbation caused by arm movement. Seven individuals with spastic diplegia (SDCP group, 12-22 yr of age) and seven age- and sex-matched individuals without disability (control group) participated in this study. Participants flexed both shoulders and lifted a load under two different load conditions, during which electromyographic activities of focal and postural muscles were recorded. Although the timing of anticipatory activation of the erector spinae and medial hamstring (MH) muscles was similar in the two participant groups, that of the gastrocnemius (GcM) muscle was significantly later in the SDCP group than in the control group. An increase in anticipatory postural muscle activity with an increase in load was observed in MH and GcM in the control group but not in GcM in the SDCP group. The degree of modulation in MH was significantly smaller in the SDCP group than in the control group. An additional experiment confirmed that these differences in APAs between the two participant groups were unlikely to be attributable to their differences in initial standing posture before load lift. The present findings suggest that lower leg muscles play a minor role in APAs in individuals with spastic diplegia. In addition, it is likely that these individuals have difficulty modulating anticipatory postural muscle activity with changes in the degree of postural perturbation.

Limits of Stability and Functional Base of Support While Standing in Community-Dwelling Older Adults.

This study aimed to determine, among community-dwelling older adults, effects of aging on limits of stability in various directions and total area of functional base of support (FBoS) while standing. Forty-three older adults and 43 young adults maintained limits of stability in eight directions. FBoS was defined as the octagon formed by the corners made by the positions of center of pressure in the eight stability limits. FBoS area was smaller in older adults (36.6% ± 7.6% of base of support) than in young adults (47.2% ± 6.4%). Although the reduction in limits of stability in older adults can occur in all directions, the degree of the reduction varies in a direction-specific manner.

Body alignment and postural muscle activity at quiet standing and anteroposterior stability limits in children with spastic diplegic cerebral palsy.

PURPOSE: We investigated body alignment and muscle activity at quiet standing and anteroposterior stability limits in children with spastic diplegic cerebral palsy (SDCP). METHOD: Body alignment and electromyographic (EMG) activity of ventral and dorsal lower limb muscles at three different standing positions were compared between seven children with SDCP (SDCP(group)) and seven controls [typically developing (TD(group))]. We also compared these measurements in a child with SDCP before and after a 3-week training in which the child leant forward and maintained the forward-leaning posture with the help of a physiotherapist who manually held her lower limbs fixed in position. RESULTS: In TD(group), EMG activity of the dorsal muscles increased at the extreme forward-leaning position, whereas that of the ventral muscles increased at the extreme backward-leaning position. In SDCP(group), such direction-specific increases were observed in lower leg muscles but not in thigh muscles. As a result of training, direction-specific activity in the dorsal muscles improved, and crouch posture was also improved. CONCLUSIONS: Our findings suggest that children with SDCP have difficulty modulating muscle activity while standing and that the quadriceps plays a critical role in maintaining couch posture. In addition, crouch posture may be improved by the training which focuses on control of the dorsal muscles.

Correction: Association between Gait Deviation Index and Physical Function in Children with Bilateral Spastic Cerebral Palsy: A Cross-Sectional Study. J. Clin. Med. 2020, 9, 28.

The authors wish to make the following corrections to this paper [...].

Effects of neck flexion on contingent negative variation and anticipatory postural control during arm movement while standing.

We investigated the effects of neck flexion on contingent negative variation (CNV) and anticipatory postural control using an arm flexion task in standing. CNV was adopted to evaluate the state of activation of brain areas related to anticipatory postural control. Subjects were required to flex the arms in response to a sound stimulus preceded by a warning sound stimulus. Two different intervals (2.0 and 3.5s) between these two stimuli were used in neck position in quiet standing (neck resting) and neck position at 80% angle of maximal neck flexion. The mean amplitude of CNV 100-ms before the response stimulus, recorded from a Cz electrode, was calculated. Onset timing of activation of the postural muscles (lumbar paraspinal, biceps femoris and gastrocnemius) with respect to the anterior deltoid was analyzed. Reaction time at the anterior deltoid was significantly shorter in the 2.0s period than in the 3.5s period, and in the neck flexion than in the neck resting in both periods. In the 2.0s, but not in the 3.5s period, neck flexion resulted in an increased CNV amplitude and an increased duration of preceding activation of the postural muscles, and the correlation between these increases was significant.

Association between Gait Deviation Index and Physical Function in Children with Bilateral Spastic Cerebral Palsy: A Cross-Sectional Study.

This study examined the association between Gait Deviation Index (GDI) and the five-times-sit-to-stand test (FTSST) or gait speed results, which represent mobility and muscle strength of the lower extremities in ambulatory children with Gross Motor Function Classification System (GMFCS) level I and II spastic cerebral palsy. In this cross-sectional, observational study, three-dimensional gait analysis data were obtained during gait trials to evaluate the GDI in 35 children (age 5-16 years) with spastic palsy. Motor function was evaluated using FTSST and gait speed. Gross motor function was evaluated using GMFCS. Children with GMFCS level II spastic cerebral palsy demonstrated lower GDI (p < 0.001) and poorer FTSST (p = 0.031) than those with GMFCS level I spastic cerebral palsy. Correlation analysis showed that FTSST results were significantly correlated with GDI (r = -0.624; p < 0.001). Motor function may be important for the maintenance of gait quality in patients with GMFCS level I and II spastic cerebral palsy and should not be ignored. In conclusion, reduction in gait impairment may affect the values of FTSST and GDI in patients with spastic cerebral palsy who can ambulate without an assistive device.

Effects of allocation of visuo-spatial attention to visual stimuli triggering unilateral arm abduction on anticipatory postural control.

OBJECTIVE: We investigated the effects of allocation of visuo-spatial attention to visual stimuli triggering arm movement on anticipatory postural control. METHODS: Fourteen healthy right-handed subjects participated in the study. Visual stimuli were randomly presented to the left or right visual field on a screen. An attention-directing cue or a non-directional cue was presented at 1000ms before visual stimulus onset. Subjects focused or divided visuo-spatial attention (focused- and divided-attention conditions, respectively) based on types of cues, and abducted the left or right arm rapidly in response to target stimuli (with 30% probability of visual stimuli) according to the side of presentation. Peak-to-peak amplitude of P1 and N1 components of event-related potentials (P1-N1 amplitude) elicited by visual stimuli and activation timing of postural muscles with respect to the middle deltoid were measured. RESULTS: Compared with divided-attention condition, in focused-attention condition P1-N1 amplitude at occipital electrodes was enhanced and activation of the left hip abductors during right arm abduction was hastened. A significant correlation was observed between the attention-related changes in these two measurements. CONCLUSIONS: Anticipatory postural control during right arm abduction was influenced by attention-related modulation of sensory-perceptual processing. SIGNIFICANCE: These findings are important for understanding of the effects of visuo-spatial attention on anticipatory postural control.

Changes in the activity of the cerebral cortex relate to postural response modification when warned of a perturbation.

OBJECTIVE: To determine whether the cerebral cortex contributes to modifying upcoming postural responses to external perturbations when provided with prior warning of the perturbation. METHODS: Electroencephalographic (EEG) potentials were recorded from 12 healthy human subjects (21-32 years of age) before perturbing their balance with backward translations of a platform under their feet. The subjects responded with and without a visual cue that warned them 2s before the perturbation (the Cue and No Cue conditions, respectively). RESULTS: Contingent negative variation (CNV) was evident before perturbation onset in only the Cue condition. In the Cue condition, the subjects also produced smaller center of pressure (CoP) displacements than in the No Cue condition. The cue-related difference in the subjects' CNV potentials correlated with the cue-related difference in their CoP displacements. No significant associations existed among the CNV potentials and any cue-related postural adjustments made before the perturbation. CONCLUSIONS: Cortical activity before an externally triggered perturbation associates with modifications of the ensuing postural response. SIGNIFICANCE: This is the first study to demonstrate a cortical correlate for changes in central postural set that modify externally triggered postural responses based on anticipation.

Postural movement pattern and muscle action sequence associated with self-paced bilateral arm flexion during standing.

Investigated were postural movement pattern and action sequence of postural muscles while subjects rapidly flexed both arms during standing. The arm movement was started at the subject's own pace. Subjects were healthy individuals; 48 men and 53 women. Postural movement pattern was classified based on the movement angles of foot-leg (ankle joint) and leg-trunk (hip joint). Electromyograms were recorded from the anterior deltoid, biceps femoris, and erector spinae. The time difference between action onsets of the latter two muscles and the anterior deltoid was analyzed. Movement angles of the ankle and hip for both sexes were distributed on a similar linear regression line (y = -2.092x - 2.552 (r = -.71). The postural movement pattern was categorized based on the distribution into three types: hip flexion (in the 2nd quadrant), backward leaning (the 3rd), and hip extension (the 4th). The proportion of subjects was 26% in the hip flexion type, 55% in backward leaning type, and 19% in hip extension type. The action of biceps femoris and erector spinae significantly preceded that of anterior deltoid in the backward leaning and hip extension types but did not in the hip flexion type.

Effects of severity of gross motor disability on anticipatory postural adjustments while standing in individuals with bilateral spastic cerebral palsy.

BACKGROUND: Although individuals with bilateral spastic cerebral palsy (BSCP) exhibit several deficits in anticipatory postural adjustments (APAs) while standing, effects of severity of motor disability on their APAs are unclear. AIMS: To determine whether individuals with BSCP exhibit severity-dependent deficits in APAs. METHODS AND PROCEDURES: Seven individuals with level II BSCP (BSCP-II group) and seven with level III BSCP (BSCP-III group) according to the Gross Motor Function Classification System and seven healthy controls lifted a load under two different load conditions. OUTCOMES AND RESULTS: Anticipatory activities of the erector spinae (ES), medial hamstring (MH), and gastrocnemius (GCM) were smaller in the two BSCP groups than in the control group. Although the anticipatory GCM activity was similar between the BSCP groups, the ES and MH activities were larger in the BSCP-II group than in the BSCP-III group. In the BSCP-II group, an increase in anticipatory activity with an increase in load was observed in the MH, but not in the GCM. In the BSCP-III group, load-related modulation was not found in the MH or GCM. CONCLUSIONS AND IMPLICATIONS: The present findings suggest that in individuals with BSCP with severe motor disability, APA deficits extend to more proximal parts of the body.