scholarly journals Anticipatory Postural Adjustments and kinematic arm features when postural stability is manipulated

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4309 ◽  
Author(s):  
Bianca Callegari ◽  
Ghislain Saunier ◽  
Manuela Brito Duarte ◽  
Gizele Cristina da Silva Almeida ◽  
Cesar Ferreira Amorim ◽  
...  
Keyword(s):  
Upper Limb ◽  
Postural Stability ◽  
Motor Planning ◽  
Anticipatory Postural Adjustments ◽  
The Body ◽  
Postural Adjustments ◽  
Pointing Task ◽  
Standing Up ◽  
Degree Of Stability

Beyond the classical paradigm that presents the Anticipatory Postural Adjustments (APAs) as a manner to create forces that counteract disturbances arising from the moving segment during a pointing task, there is a controversial discussion about the role APAs to facilitate the movement and perform a task accurately. In addition, arm kinematics features are classically used to infer the content of motor planning for the execution and the control of arm movements. The present study aimed to disentangle the conflicting role of APAs during an arm-pointing task in which the subjects reach a central diode that suddenly turns on, while their postural stability was manipulated. Three postures were applied: Standing (Up), Sit without feet support (SitUnsup) and Sit with feet support (SitSup). We found that challenging postural stability induced an increase of the reaction time and movement duration (observed for the SitUnsup compared to SitSUp and Up) as well as modified the upper-limb velocity profile. Indeed, a greater max velocity and a shorter deceleration time were observed under the highest stability (SitSup). Thus, these Kinematics features reflect less challenging task and simple motor plan when the body is stabilized. Concerning the APAs, we observed the presence of them independently of the postural stability. Such a result strongly suggests that APAs act to facilitate the limb movement and to counteract perturbation forces. In conclusion, the degree of stability seems particularly tuned to the motor planning of the upper-limb during a pointing task whereas the postural chain (sitting vs. standing) was also determinant for APAs.

scholarly journals Anticipatory Postural Adjustments in the Frail Older Adults When Postural Stability is Manipulated

2020 ◽  
Author(s):  
Bianca Callegari ◽  
Alexandre Kubicki ◽  
Ghislain Saunier ◽  
Manuela Brito Duarte ◽  
Gizele Cristina da Silva Almeida ◽  
...  
Keyword(s):  
Older Adults ◽  
Postural Stability ◽  
Motor Planning ◽  
Functional Independence ◽  
Anticipatory Postural Adjustments ◽  
The Body ◽  
Upright Posture ◽  
Postural Adjustments ◽  
Frail Older Adults ◽  
The Impact

Abstract Background: Anticipatory Postural Adjustments (APAs) are importantly affected by age and may represent restrictions for functional independence. Previous studies have already highlighted some delayed APAs during self-generated rapid arm movements in aged adults, as well as in cases of non-optimal aging, such as in frail older adults. In young (Y) adults, it was also previously demonstrated that changing the postural stability (i.e. seated vs. upright posture) affects the motor planning and APAs. Considering the clinical relevance of these balance tasks in the functional independence in frail older adults (FOA), and the lack of literature about this task, the present study aimed to investigate the impact of these different conditions of postural stability on APAs in FOA. Methods: In this paper, participants executed an arm-pointing task to reach a diode immediately after it turned on, under different conditions of stability (seated with and without feet support and in upright posture). Results: The main finding of this study is that the adopted posture and body stabilization in FOA did not reflect differences in APAs or kinematic features. In addition, they did not present an optimal APA, since postural muscles are recruited simultaneously with the deltoid. Conclusion: Thus, FOA seem to use a single non-optimal motor plan to assist the task performance and counterbalance perturbation forces, in which they present similar APAs and do not modify their kinematics features according to the body stabilization (i.e. less challenging task present greater finger velocity).

Modification of postural responses and step initiation: evidence for goal-directed postural interactions

1994 ◽  
Vol 72 (6) ◽  
pp. 2892-2902 ◽  
Author(s):  
A. L. Burleigh ◽  
F. B. Horak ◽  
F. Malouin
Keyword(s):  
External Perturbation ◽  
Anticipatory Postural Adjustments ◽  
The Body ◽  
Original Position ◽  
Foot Pressure ◽  
Postural Adjustments ◽  
Step Initiation ◽  
Postural Responses ◽  
Surface Translation ◽  
Automatic Postural Responses

1. In this study, the interaction between anticipatory postural adjustments for step initiation and automatic postural responses to an external perturbation were investigated by having subjects initiate a voluntary forward step while perturbed by a backward surface translation, which caused forward sway of the body. The postural adjustments for step initiation act to move the body center of mass (COM) forward, whereas the automatic postural responses act to move the COM backward to restore stance equilibrium. Because the postural behaviors are in opposition, we asked whether a temporal hierarchy exists in which automatic postural responses are executed to restore equilibrium and followed by stereotypic postural adjustments for step initiation, or whether the interaction between these two postural behaviors is more dynamic. 2. Lower extremity electromyographs (EMGs), ground reaction forces, and kinematics were recorded from 10 subjects during three conditions: to quantify the anticipatory postural adjustments for step initiation, subjects stepped forward as soon as they felt a proprioceptive cue; to quantify the automatic postural responses to perturbation, subjects maintained stance equilibrium in response to a backward surface translation under both feet; and to quantify the interaction between the postural adjustments for the voluntary step and the automatic responses to the perturbation, subjects were exposed to a backward surface translation and instructed to step forward as soon as they felt the platform begin to move. 3. The anticipatory adjustments for step initiation included tibialis activation [stance limb = 163 +/- 28 (SE) ms; swing limb = 173 +/- 33 ms] and soleus inhibition resulting in center of foot pressure (COP) moving backward and lateral toward the swing limb to propel the COM forward over the stance limb. Subsequently, activation of the swing limb gastrocnemius resulted in heel-off. In contrast, the automatic postural adjustments for maintenance of stance equilibrium during a backward surface translation included activation of soleus and gastrocnemius (104 +/- 23 ms and 115 +/- 14 ms, respectively) resulting in a symmetrical forward displacement of the COP that moved the COM back to its original position with respect to the feet. 4. When a forward step was initiated in response to the translation, the automatic postural responses were reduced in amplitude bilaterally in soleus and in the stance limb gastrocnemius. When present the postural response occurred at the same latency when the goal was to initiate a step as when the goal was to maintain standing.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Anticipatory Postural Adjustments in Dart Throwing

2013 ◽  
Vol 37 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Grzegorz Juras ◽  
Kajetan Słomka
Keyword(s):  
Repeated Measures ◽  
Training Session ◽  
Motor Task ◽  
Anticipatory Postural Adjustments ◽  
The Body ◽  
Target Size ◽  
Postural Adjustments ◽  
Dart Throwing ◽  
Task Parameters ◽  
Kinetics Of

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.

scholarly journals Overview of the Cerebellar Function in Anticipatory Postural Adjustments and of the Compensatory Mechanisms Developing in Neural Dysfunctions

2020 ◽  
Vol 10 (15) ◽  
pp. 5088
Author(s):  
Silvia Maria Marchese ◽  
Veronica Farinelli ◽  
Francesco Bolzoni ◽  
Roberto Esposti ◽  
Paolo Cavallari
Keyword(s):  
Motor Performance ◽  
Center Of Mass ◽  
Anticipatory Postural Adjustments ◽  
Brain Lesions ◽  
Whole Body ◽  
Compensatory Mechanisms ◽  
Postural Adjustments ◽  
Cerebellar Function ◽  
Neural Dysfunctions

This review aims to highlight the important contribution of the cerebellum in the Anticipatory Postural Adjustments (APAs). These are unconscious muscular activities, accompanying every voluntary movement, which are crucial for optimizing motor performance by contrasting any destabilization of the whole body and of each single segment. Moreover, APAs are deeply involved in initiating the displacement of the center of mass in whole-body reaching movements or when starting gait. Here we present literature that illustrates how the peculiar abilities of the cerebellum i) to predict, and contrast in advance, the upcoming mechanical events; ii) to adapt motor outputs to the mechanical context, and iii) to control the temporal relationship between task-relevant events, are all exploited in the APA control. Moreover, recent papers are discussed which underline the key role of cerebellum ontogenesis in the correct maturation of APAs. Finally, on the basis of a survey of animal and human studies about cortical and subcortical compensatory processes that follow brain lesions, we propose a candidate neural network that could compensate for cerebellar deficits and suggest how to verify such a hypothesis.

scholarly journals Role of the premotor cortex in leg selection and anticipatory postural adjustments associated with a rapid stepping task in patients with stroke

2010 ◽  
Vol 32 (4) ◽  
pp. 487-493 ◽  
Author(s):  
Wen-Hsing Chang ◽  
Pei-Fang Tang ◽  
Yao-Hung Wang ◽  
Kwan-Hwa Lin ◽  
Ming-Jang Chiu ◽  
...  
Keyword(s):  
Premotor Cortex ◽  
Anticipatory Postural Adjustments ◽  
Postural Adjustments
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