Characteristics Of Anticipatory Postural Adjustments Research Articles

Analysis of the characteristics of anticipatory postural adjustments in older adults using smartphones: Association between cognitive and balance functions

ObjectivesUsing smartphones, we aimed to clarify the characteristics of anticipatory postural adjustments (APA) in older adults and examine the relationship between cognitive and balance functions. MethodsThe study participants were 10 young and 13 older adults. An accelerometer built into a smartphone was attached to the lower back (L5) of the participant, and acceleration in the mediolateral direction was measured using a one-leg stance (OLS). As APA features, we analyzed the time to the peak value in the stance direction (peak latency [PL]) and the amount of displacement to the peak value in the stance direction (peak magnitude [PM]). Additionally, the measured PL was divided by PM for each group to obtain the APA ratio (APAr). We investigated the relationship between the APAr and Mini-BESTest subitems. ResultsOlder adults showed delayed PL and decreased PM levels (p < 0.01). While in the Mini-BESTest sub-items, deductions were most common in the order of dual-task and single-leg standing, and most participants with low APAr scores were degraded in APA of sub-items. The correlation was observed between APAr and both TUG and dual-task cost (DTC) (r= −0.56, r= −0.67). According to the receiver operating characteristic curve, the APAr value was 1.71 in the older age group. ConclusionsOlder adults showed delayed PL and decreased PM, and APAr was associated with cognitive and locomotor functions. By evaluating the APAr at the initiation of movement, it may be possible to distinguish the APA of the older adluts from the possible to the impossible of OLS movement.

Development of temporal and spatial characteristics of anticipatory postural adjustments during gait initiation in children aged 3-10years.

This study aimed to analyze the development of direction specificities of temporal and spatial control and the coordination pattern of anticipatory postural adjustment (APA) along the anteroposterior (AP) and mediolateral (ML) directions during gait initiation (GI) in children aged 3-10years. This study included 72 healthy children aged 3-10years and 14 young adults. The child population was divided into four groups by age: 3-4, 5-6, 7-8, and 9-10years. The GI task included GI using the dominant limb. The peak center of feet pressure (COP) shifts during APAs (APApeak), initiation time of COP shifts (APAonset), and the COP vectors in the horizontal plane were calculated to evaluate the direction specificity of spatial, temporal, and coordination control, respectively. A difference in direction specificity development was found for the APApeak. The APApeak in the mediolateral axis, but not in the anteroposterior axis, was significantly higher in the 7-8years age group than in other groups. Although APAonset was not found for direction specificity, a significant difference between the adult and children groups (5-6years, 7-8years, and 9-10years) was observed in the direction of the COP vector. In conclusion, the developmental process of the spatial, temporal, and coordination control of APAs during GI varied with age. Furthermore, the spatial control and coordination pattern of APAs was found to be direction specific. All components of APAs, namely temporal and spatial control, coordination pattern, and direction specificities, should be analyzed to capture the developmental process of anticipatory postural control.

Anticipatory Postural Adjustments in Dart Throwing

The aim of this study was to explore the effects of accuracy constraints on the characteristics of anticipatory postural adjustments (APA) in a task that involves a movement consisting of a controlled phase and a ballistic phase. It was hypothesized that APA scaling with task parameters (target size) would be preserved even when the task is performed by muscles that have no direct effects on APA. Sixteen healthy right handed subjects participated in the study. All participants had no prior experience in dart throwing. Subjects' average age was 24.1 ± 1.9 years. A force platform and a motion capture system were used to register kinetics of the body and kinematics of the throwing arm and throwing accuracy. The experiment consisted of six series of twenty consecutive dart throws to a specified target. Target sizes (T2-T6) were set at 25%, 50%, 75%, 125% and 150% of target 1 (T1) initially set as the spread of the last 20 throws in a 50 throw training session. This allowed to distinguish six indexes of difficulty (ID's) ranging from 2,9 to 5,9. A one-way ANOVA for repeated measures was used for statistical analysis. Results of ANOVA showed a significant effect of target size at Constant Error but no effect at APA time. There were also no significant differences between hit and miss throws. From a control perspective, it can be stated that changes in central commands did not lead to changes in APA time in the analyzed motor task.

Evidence for a common process in gait initiation and stepping on to a new level to reach gait velocity

The aim of this study was to examine the adaptability of the gait initiation process when confronted with stepping on (SO) to a new level. Eight young adults performed gait initiation at two different speed conditions in a level walking (LW) situation and in a SO situation aimed at walking on an elevated (16 cm) level surface. As in a previous study using a single step, we found in SO a contradiction between the characteristics of anticipatory postural adjustments (APA) and gait velocity, i.e. the peak of anteroposterior velocity of the body's centre of gravity (CG) reached at the end of the first step. In normal and fast gaits, gait velocity was similar in both situations, whereas the duration and amplitude of the APA were smaller in SO than in LW. The reduction of APA in SO allowed the forward velocity of CG at the time of foot contact of the stepping limb to be lower than in LW. This is explained by the fact that the majority of body lift, beginning at this time, required a greater increase in forward velocity than in LW. Thus, with lower APA in SO, the gait velocity could be similar in both situations. From LW to SO, the spatio-temporal patterns in the forward velocity of CG varied within characteristic phases of the movement, but in a predictable way as gait velocity changed. These results gave evidence of an adaptation of the gait initiation process for the new constraints, despite the contradiction between APA and gait velocity. The spatio-temporal parameters of the anticipation phase in SO were pre-set according to the new requirements of the task: reaching gait velocity with a body lift. Furthermore, the time for reaching gait velocity was independent of both the amplitude of this velocity and the situation. This expressed the capacity of the subjects to use in SO the same optimal conditions to reach gait velocity as in LW, i.e. essentially in a ballistic manner.

Caractérisation des ajustements posturaux lors d'une initiation de la marche déclenchée par un stimulus sonore et autocommandée chez 20 sujets sains

Objective. – Preparation of upper-limb movements differs between self-paced and triggered conditions. This study analyzed the anticipatory postural adjustments (APAs) of gait initiation in normal subjects in 2 conditions: self-generated and triggered by a “beep” sound. Methods. – We recorded kinematic, spatiotemporal parameters of the first two steps by means of video motion analysis (6 infrared cameras), and kinetic parameters (using a force platform and the optoelectronic system) in 20 normal subjects. Two conditions: 1) self-generated initiation; and 2) initiation triggered by a “beep” sound were studied to evaluate the APA phase, by recording kinetic data (duration of the APAs, trajectory of the center of pressure, speed and trajectory of the center of mass). Kinematic data (first and second step speed, length and duration) were also recorded. Results. – First step speed and length were increased in self-paced gait initiation compared to triggered gait initiation in controls. We found no difference between the 2 conditions in terms of second step kinematic data. It was caused by a significant difference between the 2 conditions for the temporal characteristics of anticipatory postural adjustments (APAs) in the initiation of the first step, which was longer when normal subjects performed self-generated gait initiation. The trajectory of center of pressure and center of mass remained the same in the 2 conditions. Conclusion. – APAs of gait initiation process are delayed under self-paced condition, although they do not differ qualitatively between reaction time and self-paced condition. Neuphysiological support of self-generated movement could explain these differences.

Study of Anticipatory Postural Adjustments in an Air Pistol-Shooting Task

A segmental teleokinetic movement performed from an upright standing position is usually preceded by a sequence of postural movements having the goal of counteracting the imbalance which will be caused by the forthcoming movement. This study had two aims, (1) to verify whether the postural component was programmed in the same way as that of the teleokinetic component and (2) to verify whether the postural component was specific to the direction and speed of the movement. 12 participants performed a pistol-shooting task involving a rapid arm-raising movement. Three directions, two time deadlines, and three types of cue were manipulated. This study showed that the postural component was sensitive to the cue effects, the characteristics of anticipatory postural adjustments were specific to the direction of the movement, and the characteristics of the postural muscle EMG burst were the same whether the participants programmed or deprogrammed and reprogrammed their movements for a given direction. The speed parameter did not seem to have any significant influence on the characteristics of the anticipatory postural adjustments.

STUDY OF ANTICIPATORY POSTURAL ADJUSTMENTS IN AN AIR PISTOL-SHOOTING TASK

A segmental teleokinetic movement performed from an upright standing position is usually preceded by a sequence of postural movements having the goal of counteracting the imbalance which will be caused by the forthcoming movement. This study had two aims, (1) to verify whether the postural component was programmed in the same way as that of the teleokinetic component and (2) to verify whether the postural component was specific to the direction and speed of the movement. 12 participants performed a pistol-shooting task involving a rapid arm-raising movement. Three directions, two time deadlines, and three types of cue were manipulated. This study showed that the postural component was sensitive to the cue effects, the characteristics of anticipatory postural adjustments were specific to the direction of the movement, and the characteristics of the postural muscle EMG burst were the same whether the participants programmed or deprogrammed and reprogrammed their movements for a given direction. The speed parameter did not seem to have any significant influence on the characteristics of the anticipatory postural adjustments.