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A comparison of the stability of standing shooting stance in expert and novice mountain infantry shooters

Ratajczyk Mariusz, Homańczuk Arkadiusz, Pacześny Sławomir, Sobera Małgorzata

Scientific Journal of the Military University of Land Forces

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2023

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Vol. 55, No. 1(207)

33--42

EN

This study compares balance control in standing shooting stance in expert and novice military shooters among mountain infantry soldiers. Balance control was assessed using AccuSway (AMTI, USA) force platforms in terms of the range of the centre of pressure (COP) displacements in the mediolateral (RANGE(ML)) and anteroposterior direction (RANGE(AP)), the standard deviation of COP displacements in the mediolateral (SD(ML)) and anteroposterior direction (SD(AP)), the sway area of COP displacements (ELLIPSE), the average velocity of COP displacements (AVG VEL) and the COP path length (LENGTH). The participants (expert shooters, N=10; novice shooters, N=15) adopted tactical standing shooting stance wearing the field uniform, with a rifle on force platforms (one for each lower limb), over a period of 10 seconds, with sampling frequency of 100Hz. The statistical analysis using the Mann-Whitney U test revealed a significant difference between the studied groups, taking into account the ELLIPSE and the AVG VEL variables values for the dominant leg only. It was concluded that the expert shooters showed better stability than novice shooters. This study presents implications regarding biomechanical aspects of standing shooting stance stability.

PL

Celem pracy jest porównanie jakości procesu kontroli równowagi w postawie strzeleckiej stojąc doświadczonych i początkujących strzelców piechoty górskiej. Kontrolę równowagi oceniono za pomocą platform sił AccuSway (AMTI, USA) pod względem wartości miar stabilności obliczonych na podstawie przebiegu punktu przyłożenia wypadkowej siły reakcji na podłoże – COP (ang. Center of Pressure), w tym: zakresu przemieszczeń w kierunku przyśrodkowo-bocznym (RANGE(ML)) i przednio-tylnym (RANGE(AP)), odchylenia standardowego przemieszczeń COP w kierunku przyśrodkowo-bocznym (SD(ML)) i przednio-tylnym (SD(AP)), pola elipsy przemieszczeń COP (ELLIPSE), średniej prędkości przemieszczeń COP (AVG VEL) oraz długości ścieżki COP (LENGTH). Uczestnicy (doświadczeni strzelcy, N=10, początkujący strzelcy, N=15) przyjęli taktyczną postawę strzelecką stojąc w umundurowaniu polowym z karabinkiem Beryl wz. 96 na platformach sił (po jednej dla każdej kończyny dolnej) przez okres 10 sekund, z częstotliwością próbkowania ustawioną na 100Hz. Analiza statystyczna przeprowadzona za pomocą testu U Manna-Whitneya wykazała istotną różnicę pomiędzy badanymi grupami w wartościach wskaźnika pola elipsy (ELLIPSE) oraz średniej prędkości przemieszczeń COP (AVG VEL) jedynie dla dominującej kończyny dolnej. Stwierdzono, że doświadczeni strzelcy charakteryzują się większą stabilnością przyjętej postawy strzeleckiej niż początkujący strzelcy. W pracy przedstawiono implikacje dotyczące biomechanicznych aspektów stabilności postawy strzeleckiej stojąc.

2

EEG based cortical investigation for the limit of stability analysis in transfemoral amputees: A comparison with able-bodied individuals

Khajuria Aayushi, Joshi Deepak

Biocybernetics and Biomedical Engineering

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2022

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Vol. 42, no. 1

362--374

EN

Background: The evidences for demonstrating the contributions of the cerebral cortex in human postural control is increasing. However, there remain little insights about the cortical correlates of balance control in lower-limb amputees. The present study aimed to investigate the cortical activity and balance performance of transfemoral amputees in comparison to healthy individuals during a continuous balance task (CBT). Methods: The postural stability of the participants was defined with limit of stability parameter. Electroencephalography (EEG) data were recorded in synchronization with the center of pressure (CoP) data from eighteen individuals (including eight unilateral transfemoral amputees). We anticipated that, due to the limb loss, the postural demand of transfemoral amputees increases which significantly modulates the spectral power of intrinsic cortical oscillations. Findings: Using the independent components from the sensorimotor areas and supplementary motor area (SMA), our results present a well-pronounced drop of alpha spectral power at sensorimotor area contralateral to sound limb of amputees in comparison to SMA and the sensorimotor area contralateral to prosthetic limb. Following this, we found significantly higher (p < 0.05) limit of stability (LOS) at their sound limb than at the prosthetic limb. Healthy individuals have similar contribution from both the limbs and the EEG alpha spectral power was similar across the three regions of the cortex during the balance control task as expected. Overall, a decent correlation was found between the LOS and alpha spectral power in both amputee and healthy individuals (Pearson’s correlation coefficient > 0.5). Interpretation: By externally stimulating the highlighted cortical regions, neuroplasticity might be promoted which helps to reduce the training time for the efficient rehabilitation of amputees. Additionally, this new knowledge might benefit in the designing and development of innovative interventions to prevent falls due to lower limb amputation.

3

Immediate after-effects of shapes of clothing worn on tandem gait performance

Oshita Kazushige

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 3

79--85

EN

Purpose: This study investigated the immediate after-effects of clothing shape on tandem gait performance. Methods: Nineteen healthy men (21.8 ± 1.8 years) performed tandem gait tests while blindfolded under three clothing conditions: only half or short tights, a cotton cloth wrapped around the waist and draped to the middle point of the lower leg (DC), and tracksuit bottoms (TS). Participants performed pre- and post-gait tests at their fastest possible speed while wearing tights. Between the pre- and post-tests, participants practiced the same tandem gait, but at their own chosen speed while wearing DC or TS. Results: The practice with the DC increased gait speed and decreased lateral shift during the post-gait test compared to the pre-gait test. The practice while wearing the TS also reduced lateral shift but did not increase gait speed. Conclusions: These results suggest that some clothing shapes are more effective for motor learning of balance control during tandem gait by enhancing the feedback for body orientation. Clothing that has a certain amount of space between the material and the body and that makes contact with the body as it moves may be more effective.

4

Gender differences of the improvement in balance control based on the real-time visual feedback system with smart wearable devices

Wang I-Lin, Wang Li-I, Xue Shi-Jie, Hu Rui, Jian Rong-Jiun, Ho Chun-Sheng

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 1

163--171

EN

Purpose: The body maintains stability by integrating inputs from the central nervous system of vision, hearing, proprioception, and multiple senses. With the development of smart wearable devices, smart wearable devices can provide real-time center of pressure position-assisted balance control, which is beneficial to maintain physical balance. Methods: Forty healthy college students (20 male, 20 female) participated in this study, and the posture balance actions of left-leg stance non-visual feedback, left-leg stance visual feedback, right-leg stance non-visual feedback, and right-leg stance visual feedback were performed. Visual feedback provided smart insoles matching Podoon APP on a tablet computer with the COP position displayed by a dot as real-time visual feedback. Results: The experimental results show that the displacement, velocity, radius, and area of the COP decreased significantly in the left-leg stance visual feedback/right-leg stance visual feedback, the test compared the parameters in the left-leg stance non-visual feedback/right-leg stance nonvisual feedback (P < 0.05). Providing visual feedback through intelligent insoles can reduce the movement of the center of mass and maintain physical stability for healthy young people of different genders. In the one leg visual/non-visual in standing, the COP maximum anteroposterior displacement, COP anteroposterior velocity, COP radius, and COP area in women are significantly smaller than in men (P < 0.05). Women have better real-time balance control ability than men with smart insoles. Conclusions: The simple intelligent wearable assisted devices can immediately increase the control ability in static stance of men and women, and women have better real-time balance control ability than men.

5

Disparity of a Seat Cushion and Its Influence on Postural Control

Nag P.K., Nag A., Vyas H., Shah P.

International Journal of Occupational Safety and Ergonomics

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2013

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Vol. 19, No. 4

573--581

EN

Properties of supporting surfaces of a seat have an influence on postural control. Centre of pressure (COP) displacement parameters reflect both the balance controlling process and movements of the centre of a mass of entire body. The subjects of the study were 9 healthy men. A seat cushion was examined with a 2-force platform setup. Force exertion at a seat pan and feet and COP displacement at a seat pan were measured to analyse postural control. Analysis of variance determined the differences in postural control depending on a cushion type among the subjects. Significant differences in COP displacement parameters were in COP trajectory length, medio-lateral COP displacement and COP velocity. The results of the study showed that foam cushion ensures better postural control.