Constraints of Load and Posture on Coordination Variability and Marksmanship Performance

Motor Control ◽  
2020 ◽  
Vol 24 (3) ◽  
pp. 435-456
Author(s):  
Christopher J. Palmer ◽  
Richard E.A. van Emmerik
Keyword(s):  
Postural Control ◽  
Task Performance ◽  
Upper Extremity ◽  
Center Of Pressure ◽  
Head Extension ◽  
Speed And Accuracy ◽  
Insight Into

The purpose of this study was to assess the establishment of dynamic marksmanship performance under different load and postural configurations. Participants quickly established two postures (forward and high targets) under head, trunk, and extremity loads during marksmanship performance. With the dynamic establishment of posture, load disrupted coordinative dynamics, resulting in reduced speed and accuracy on target. Specifically, torso loads increased segmental variability while establishing posture, and smaller head and upper extremity loads extended quieting time before firing. Increased head extension at the high target further destabilized posture, with reduced accuracy across all loads. Large torso loads reduced the adaptability to modulate postural fluctuations at the foot center of pressure while establishing postures for marksmanship, as evidenced by reductions in center of pressure variability. This study expands traditional static marksmanship research, providing insight into relations between task performance, coordinative variability, and postural control while dynamically establishing precision postures.

scholarly journals Immediate Impact of Extremity Manipulation on Dual Task Performance: A Randomized, Crossover Study

2020 ◽  
Author(s):  
Christopher Alexander Malaya ◽  
Joshua Haworth ◽  
Katherine A. Pohlman ◽  
Dean L. Smith
Keyword(s):  
Lower Extremity ◽  
Task Performance ◽  
Upper Extremity ◽  
Dual Task ◽  
Center Of Pressure ◽  
Frontal Plane ◽  
Main Effect ◽  
Dual Task Performance ◽  
Eyes Open ◽  
Suprapostural Task

Abstract Background: Previous research demonstrated that manipulation of the extremities was associated with changes in multisegmental postural sway as well as improvement in a lower extremity balancing task. We were interested if these effects would extend to an upper extremity task. Our aim in this study was to investigate whether extremity manipulation could influence dual task performance where the explicit suprapostural task was balancing a water filled tube in the frontal plane.Methods: Participants were healthy volunteers (aged 21-32 years). Upper- or lower-extremity manipulations were delivered in a participant and assessor blinded, randomized crossover, clinical trial. Postural (center of pressure) and suprapostural (tube motion) measurements in the frontal plane were made pre-post manipulation under eyes open and eyes closed conditions using a BTrackS™ force plate and a Shimmer inertial measurement unit, respectively. Pathlength, range, root mean square and sample entropy were calculated to describe each signal during the dual task performance.Results: There was no main effect of manipulation or vision for the suprapostural task (tube motion). However, follow-up to interaction effects indicates that roll pathlength, range and root means square of tube motion all decreased (improvement) following lower extremity manipulation with eyes open. Regarding the postural task, there was a main effect of manipulation on mediolateral center of pressure such that pathlength reduced with both upper and lower extremity manipulation with larger decreases in pathlength values following upper extremity manipulation. Conclusion: Our findings show that manipulation of the extremities enhanced stability (e.g. tube stabilization and standing balance) on performance of a dual task. This furthers the argument that site-specific manipulations influence context specific motor behavior/coordination.Trial Registration: Clinicaltrials.gov, NCT03877367, Registered 15 March 2019, https://clinicaltrials.gov/ct2/show/NCT03877367?term=NCT03877367&draw=2&rank=1

Ski Boots Do Not Impair Standing Balance by Restricting Ankle-Joint Mobility

2018 ◽  
Vol 61 (2) ◽  
pp. 214-224
Author(s):  
Frédéric Noé ◽  
Xavier García-Massó ◽  
Damien Ledez ◽  
Thierry Paillard
Keyword(s):  
Control System ◽  
Postural Control ◽  
Center Of Pressure ◽  
Frontal Plane ◽  
Emg Activity ◽  
Hip Joints ◽  
Postural Control System ◽  
Postural Tasks ◽  
Ankle Movement ◽  
Insight Into

Objective: This study was undertaken in order to provide new insight into sensorimotor control of posture when wearing high-shaft (HS) boots as ski boots. Background: Previous studies into the effects of HS boots on postural control have produced controversial results. Some studies reported postural control impairments with ski boots in bipedal postural tasks due to ankle movement restrictions without quantifying the actual restrictive effect of these boots and specifying the adaptations of the postural control system. Method: Eighteen young healthy subjects took part in the experiment. Bilateral postural control was assessed on stable and unstable surfaces, while standing barefoot or wearing ski boots. Center of pressure (COP) parameters, ankle, knee, and hip joints movements were calculated and EMG activity from main postural muscles was recorded. Results: Ski boots did not restrict the amplitude of ankle angular movements and largely impacted COP parameters and EMG activity on stable ground. In conditions of mediolateral instability, COP data illustrated an enhanced postural control in the frontal plane when wearing ski boots. Conclusions: Ski boots do not affect bipedal postural balance by restricting the ankle angular motions but induce complex adaptations of the postural control system which combine factors of a mechanical, motor, and sensorial nature. They impede postural control mainly when standing on stable ground without producing similar deleterious effects on unstable surfaces. Application: Our results show that HS boots as ski boots can improve lateral balance on unstable surfaces, which can contribute to prevent fall risk and ankle sprain.

“Going Backward”: Effects of age and fatigue on posterior-directed falls in Parkinson disease

2021 ◽  
pp. 1-9
Author(s):  
Evan V. Papa ◽  
Rita M. Patterson ◽  
Nicoleta Bugnariu
Keyword(s):  
Postural Control ◽  
Parkinson Disease ◽  
Repeated Measures ◽  
Center Of Pressure ◽  
Angular Displacement ◽  
Reaction Times ◽  
Older Individuals ◽  
Peak Knee ◽  
Significant Difference ◽  
Fatiguing Exercise

BACKGROUND: Nearly half of persons with Parkinson disease (PD) report fatigue as a factor in their fall history. However, it is unknown whether these self-reported falls are caused by a sensation of fatigue or performance fatigue. OBJECTIVE: We sought to investigate the influences of performance fatigue and age on postural control in persons with PD. METHODS: Individuals with PD (n = 14) underwent postural control assessments before (T0) and immediately after (T1) fatiguing exercise. Biomechanical data were gathered on participants completing a treadmill-induced, posterior-directed fall. Performance fatigue was produced using lower extremity resistance exercise on an isokinetic ergometer. Repeated measures ANCOVAs were used with age as a covariate to determine the effects of performance fatigue on biomechanical variables. RESULTS: After adjustment for age, there was a statistically significant difference in peak center of pressure (COP) latency during the support phase of recovery. Pairwise comparisons demonstrated a decrease in peak ankle displacement from T0 to T1. Age was also found to be significantly related to reaction time and peak knee displacement while participants were fatigued. CONCLUSIONS: The decreased peak COP latency, along with decreased ankle angular displacement, suggest that persons with PD adopt a stiffening strategy in response to backward directed falls. Postural stiffening is not uncommon in persons with PD and could be a risk factor for falls. Older individuals with PD demonstrate slower mobility scores and decreased reaction times in the setting of fatigue, suggesting a combined effect of the aging and fatigue processes.

scholarly journals Postural Control Disturbances Induced by Virtual Reality in Stroke Patients

2021 ◽  
Vol 11 (4) ◽  
pp. 1510
Author(s):  
Charles Morizio ◽  
Maxime Billot ◽  
Jean-Christophe Daviet ◽  
Stéphane Baudry ◽  
Christophe Barbanchon ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Postural Control ◽  
Virtual Environments ◽  
Center Of Pressure ◽  
Dynamic Condition ◽  
Static Condition ◽  
Stroke Patients ◽  
Post Stroke ◽  
Subacute Stroke

People who survive a stroke are often left with long-term neurologic deficits that induce, among other impairments, balance disorders. While virtual reality (VR) is growing in popularity for postural control rehabilitation in post-stroke patients, studies on the effect of challenging virtual environments, simulating common daily situations on postural control in post-stroke patients, are scarce. This study is a first step to document the postural response of stroke patients to different challenging virtual environments. Five subacute stroke patients and fifteen age-matched healthy adults were included. All participants underwent posturographic tests in control conditions (open and closed eyes) and virtual environment without (one static condition) and with avatars (four dynamic conditions) using a head-mounted device for VR. In dynamic environments, we modulated the density of the virtual crowd (dense and light crowd) and the avoidance space with the avatars (near or far). Center of pressure velocity was collected by trial throughout randomized 30-s periods. Results showed that more challenging conditions (dynamic condition) induced greater postural disturbances in stroke patients than in healthy counterparts. Our study suggests that virtual reality environments should be adjusted in light of obtaining more or less challenging conditions.

scholarly journals The Effects of Abdominal Hypopressive Training on Postural Control and Deep Trunk Muscle Activation: A Randomized Controlled Trial

2021 ◽  
Vol 18 (5) ◽  
pp. 2741
Author(s):  
María del Mar Moreno-Muñoz ◽  
Fidel Hita-Contreras ◽  
María Dolores Estudillo-Martínez ◽  
Agustín Aibar-Almazán ◽  
Yolanda Castellote-Caballero ◽  
...  
Keyword(s):  
Postural Control ◽  
Muscle Activation ◽  
Center Of Pressure ◽  
Controlled Trial ◽  
Trunk Muscle ◽  
Posture Control ◽  
Trunk Muscles ◽  
Control Group ◽  
Female Population ◽  
Imaging Results

Background: Abdominal Hypopressive Training (AHT) provides postural improvement, and enhances deep trunk muscle activation. However, until recently, there was a lack of scientific literature supporting these statements. The major purpose of this study was to investigate the effect of AHT on posture control and deep trunk muscle function. Methods: 125 female participants aged 18–60 were randomly allocated to the Experimental Group (EG), consisting of two sessions of 30 min per week for 8 weeks of AHT, or the Control Group (CG), who did not receive any treatment. Postural control was measured with a stabilometric platform to assess the static balance and the activation of deep trunk muscles (specifically the Transverse Abdominal muscle (TrA)), which was measured by real-time ultrasound imaging. Results: The groups were homogeneous at baseline. Statistical differences were identified between both groups after intervention in the Surface of the Center of Pressure (CoP) Open-Eyes (S-OE) (p = 0.001, Cohen’s d = 0.60) and the Velocity of CoP under both conditions; Open-Eyes (V-OE) (p = 0.001, Cohen´s d = 0.63) and Close-Eyes (V-CE) (p = 0.016, Cohen´s d = 0.016), with the EG achieving substantial improvements. Likewise, there were statistically significant differences between measurements over time for the EG on S-OE (p < 0.001, Cohen´s d = 0.99); V-OE (p = 0.038, Cohen´s d = 0.27); V-CE (p = 0.006, Cohen´s d = 0.39), anteroposterior movements of CoP with Open-Eyes (RMSY-OE) (p = 0.038, Cohen´s d = 0.60) and activity of TrA under contraction conditions (p < 0.001, Cohen´s d = 0.53). Conclusions: The application of eight weeks of AHT leads to positive outcomes in posture control, as well as an improvement in the deep trunk muscle contraction in the female population.

scholarly journals Habitual Physical Activity as a Determinant of the Effect of Moderate Physical Exercise on Postural Control in Older Men

2012 ◽  
Vol 7 (1) ◽  
pp. 58-65 ◽  
Author(s):  
Rafał Stemplewski ◽  
Janusz Maciaszek ◽  
Maciej Tomczak ◽  
Robert Szeklicki ◽  
Dorota Sadowska ◽  
...  
Keyword(s):  
Physical Activity ◽  
Postural Control ◽  
Sagittal Plane ◽  
Center Of Pressure ◽  
Force Plate ◽  
Frontal Plane ◽  
Habitual Physical Activity ◽  
Similar Reaction ◽  
Mean Velocity ◽  
Ergometer Exercise

The aim of the study was to compare the effect of exercise on postural control (PC) among the elderly with lower or higher level of habitual physical activity (HPA). The study involved 17 elderly men (mean age 72.9 ± 4.79 years). Mean velocity of the center of pressure (COP) displacements was measured using a force plate both before and after cycle ergometer exercise. A significantly higher increase in mean velocity of COP displacements and its component in the sagittal plane were observed in the group with lower level of HPA in comparison with the group with higher HPA level. Simultaneously, a relatively similar reaction to the exercise in the frontal plane was observed in both groups, possibly connected to the specific type of used exercise, which mainly activated the sagittal muscles.

Test-Retest Reliability of Center of Pressure Measures for Postural Control Assessment in Older Cardiac Patients

2021 ◽  
Author(s):  
Jeanette Dobberke ◽  
Omar Baritello ◽  
Miralem Hadzic ◽  
Heinz Völler ◽  
Sarah Eichler ◽  
...  
Keyword(s):  
Postural Control ◽  
Center Of Pressure ◽  
Cardiac Patients ◽  
Retest Reliability ◽  
Test Retest Reliability

Surface height effects on postural control: A hypothesis for a stiffness strategy for stance*

1999 ◽  
Vol 9 (4) ◽  
pp. 277-286 ◽  
Author(s):  
Mark G. Carpenter ◽  
James S. Frank ◽  
Cathy P. Silcher
Keyword(s):  
Postural Control ◽  
Center Of Pressure ◽  
High Surface ◽  
Quiet Standing ◽  
Vestibular Input ◽  
Mean Power ◽  
Mean Power Frequency ◽  
Balance Confidence ◽  
Eyes Closed ◽  
Ankle Stiffness

One possible factor influencing the control of upright stance is the perceived threat to one's personal safety, i.e. balance confidence. We explored this factor by examining the control of stationary stance when standing on an elevated platform under various conditions of reduced visual and vestibular inputs. Twenty-eight adults (14 male and 14 female, mean age = 23.5 years) participated in the experiment. Postural control was examined by recording the amplitude variability (RMS) and mean power frequency (MPF) of center of pressure excursions (COP) over a 2-minute interval while participants stood in a normal stance on a low (0.19 m) and a high (0.81 m) platform with toes positioned either at or away from the edge of the platform. Vision was manipulated through eyes open and eyes closed trials. Vestibular input was reduced by tilting the head into extension [1]. Anterior-posterior RMS and MPF of COP were significantly influenced by an interaction between surface height and vision. When vision was available, a significant decrease in RMS was observed during quiet standing on a high surface compared to a low surface independent of step restriction. When vision was available MPF increased when subjects were raised from a low to a high surface. The mean position of the COP was significantly influenced by an interaction between height and step restriction. Differences in RMS and MPF responses to height manipulation were observed between genders in eyes closed conditions. Vestibular input influenced postural control at both low and high levels with significant increases in RMS when vestibular input was reduced. The reciprocal changes observed in RMS and MPF suggest modifications to postural control through changes in ankle stiffness. Vision appears to play a role in increasing ankle stiffness when balance confidence is compromised.

scholarly journals Lower Extremity Neuromuscular Control Immediately After Fatiguing Hip-Abduction Exercise

2011 ◽  
Vol 46 (6) ◽  
pp. 607-614 ◽  
Author(s):  
Kelly L. McMullen ◽  
Nicole L. Cosby ◽  
Jay Hertel ◽  
Christopher D. Ingersoll ◽  
Joseph M. Hart
Keyword(s):  
Lower Extremity ◽  
Postural Control ◽  
Center Of Pressure ◽  
Neuromuscular Control ◽  
Lower Extremity Injury ◽  
Median Frequency ◽  
Men And Women ◽  
Hip Abduction ◽  
Quality Of Movement

Context: Fatigue of the gluteus medius (GMed) muscle might be associated with decreases in postural control due to insufficient pelvic stabilization. Men and women might have different muscular recruitment patterns in response to GMed fatigue. Objective: To compare postural control and quality of movement between men and women after a fatiguing hip-abduction exercise. Design: Descriptive laboratory study. Setting: Controlled laboratory. Patients or Other Participants: Eighteen men (age = 22 ± 3.64 years, height = 183.37 ± 8.30 cm, mass = 87.02 ±12.53 kg) and 18 women (age = 22 ± 3.14, height = 167.65 ± 5.80 cm, mass = 66.64 ± 10.49 kg) with no history of low back or lower extremity injury participated in our study. Intervention(s): Participants followed a fatiguing protocol that involved a side-lying hip-abduction exercise performed until a 15% shift in electromyographic median frequency of the GMed was reached. Main Outcome Measure(s): Baseline and postfatigue measurements of single-leg static balance, dynamic balance, and quality of movement assessed with center-of-pressure measurements, the Star Excursion Balance Test, and lateral step-down test, respectively, were recorded for the dominant lower extremity (as identified by the participant). Results: We observed no differences in balance deficits between sexes (P &gt; .05); however, we found main effects for time with all of our postfatigue outcome measures (P ≤ .05). Conclusions: Our findings suggest that postural control and quality of movement were affected negatively after a GMed-fatiguing exercise. At similar levels of local muscle fatigue, men and women had similar measurements of postural control.

scholarly journals Added body mass alters plantar shear stresses, postural control, and gait kinetics: Implications for obesity

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246605
Author(s):  
Hwigeum Jeong ◽  
A. Wayne Johnson ◽  
J. Brent Feland ◽  
Spencer R. Petersen ◽  
Jared M. Staten ◽  
...  
Keyword(s):  
Postural Control ◽  
Body Mass ◽  
Mass Distribution ◽  
Repeated Measures ◽  
Center Of Pressure ◽  
Health Concern ◽  
Shear Stresses ◽  
Clinical Role ◽  
Body Distribution ◽  
Weighted Vest

Context Obesity is a growing global health concern. The increased body mass and altered mass distribution associated with obesity may be related to increases in plantar shear that putatively leads to physical functional deficits. Therefore, measurement of plantar shear may provide unique insights on the effects of body mass and body distribution on physical function or performance. Purpose 1) To investigate the effects of body mass and distribution on plantar shear. 2) To examine how altered plantar shear influences postural control and gait kinetics. Hypothesis 1) a weighted vest forward distributed (FV) would shift the center of pressure (CoP) location forward during standing compared with a weighted vest evenly distributed (EV), 2) FV would increase plantar shear spreading forces more than EV during standing, 3) FV would increase postural sway during standing while EV would not, and 4) FV would elicit greater compensatory changes during walking than EV. Methods Twenty healthy young males participated in four different tests: 1) static test (for measuring plantar shear and CoP location without acceleration, 2) bilateral-foot standing postural control test, 3) single-foot standing postural test, and 4) walking test. All tests were executed in three different weight conditions: 1) unweighted (NV), 2) EV with 20% added body mass, and 3) FV, also with 20% added body mass. Plantar shear stresses were measured using a pressure/shear device, and several shear and postural control metrics were extracted. Repeated measures ANOVAs with Holms post hoc test were used to compare each metric among the three conditions (α = 0.05). Results FV and EV increased both AP and ML plantar shear forces compared to NV. FV shifted CoP forward in single-foot trials. FV and EV showed decreased CoP range and velocity and increased Time-to-Boundary (TTB) during postural control compared to NV. EV and FV showed increased breaking impulse and propulsive impulse compared to NV. In addition, EV showed even greater impulses than FV. While EV increased ML plantar shear spreading force, FV increased AP plantar shear spreading force during walking. Conclusion Added body mass increases plantar shear spreading forces. Body mass distribution had greater effects during dynamic tasks. In addition, healthy young individuals seem to quickly adapt to external stimuli to control postural stability. However, as this is a first step study, follow-up studies are necessary to further support the clinical role of plantar shear in other populations such as elderly and individuals with obesity or diabetes.

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