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The effect of a light finger touch on the signal complexity during quiet standing

Brachman Anna, Sawicka Anna, Bednarz Bartłomiej, Akbas Anna, Słomka Kajetan J.

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 3

91--97

EN

The purpose of the study was to investigate the influence of additional tactile information (light fingertip touch) on the postural sway and regularity of center-of-pressure (COP) fluctuations. Thirty-two young, healthy participants performed a quiet standing task (30 s) on a force platform with and without light fingertip touch. COP time-series were analyzed using standard postural sway measures (range, root mean square error, velocity), COP regularity was measured with Sample entropy. Participants demonstrated significantly smaller postural sway with a light touch, but only in the anteroposterior direction. The amount of sway with additional tactile information in the sagittal plane reached the level of sway in the frontal plane without this information. Similarly, COP fluctuations were more irregular during light touch condition only in the anteroposterior direction, as evidenced by significantly higher Sample entropy. Furthermore, COP regularity decreased in the sagittal plane and reached level in the frontal plane without light touch. These results suggest that postural sway is mostly controlled in the sagittal plane and that in the mediolateral direction the control is mostly automated. In conclusion, our results support the notion that the light touch provides additional information which enhances postural stabilization. Our results expand the relation between COP regularity and the attention invested in posture in the touch domain and prove that light touch, as an attentional demanding task, leads to increased COP irregularity. Nonlinear measures of signal regularity (i.e., SampEn) provide surplus insight into human postural control and can be used as an additional useful tool to traditional balance measures.

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Influence of force-time parameters of hip abductors on maintaining balance in frontal plane in young healthy females

Bugalska Aneta, Hadamus Anna, Wójtowicz Sebastian, Daniluk Anna, Wiaderna Karolina, Grabowicz Marta

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 1

4--8

EN

The aim of this study was to determine the impact of isometric and isokinetic hip abductor muscle strength on the quality of maintaining static balance in healthy subjects. Methods: The study enrolled 51 healthy women aged 18–25. Balance assessment was carried out according to the M-CTSIB protocol and Single Leg Stance Test (with eyes open and closed) using the Biodex Balance System. An isokinetic evaluation conducted at 30 °/s and an isometric evaluation of the hip abductors were performed with the Humac Norm system. Results: Regression analysis for Sway Index (SW) and Stability Index (ST) in bipedal standing showed a significant importance of the presence of visual feedback (RSW EO = –0.922; p < 0.0001; RST EO = –0.613; p = 0.0493), and unstable surface (RSW US = 1.253; p < 0.0001; RSW US = 2.547; p < 0.0001). Regression analysis for single-leg stance showed correlations between the following indices: overall sway index (OR) in single-leg stance, the antero-posterior (AP) sway index and the medio-lateral (ML) sway index on the one hand and isometric abduction time to peak torque (R OR TPT = 0.769; p = 0.0005; R AP TPT = 0.565; p = 0.008; R ML TPT = –1.74; p < 0.05, respectively) as well as the test conditions on the other. Conclusions: Physiological activation of the hip abductors may be important for physiological maintenance of postural balance in young people, in both leg standing as well as in single-leg stance. The present results warrant prospective, randomized studies of larger groups that are diversified with regard to age and gender of the participants.

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Quiet standing postural sway of 10- to 13-year-old, national-level, female acrobatic gymnasts

Opala-Berdzik A., Głowacka M., Wilusz K., Kołacz P., Szydło K., Juras G.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 2

117--123

EN

Purpose: The aim of the study was to determine whether 10- to 13-year-old, national-level, female acrobatic gymnasts present a different quiet standing postural control (with and without visual cues) than untrained female peers. Methods: The mean velocity of the center of pressure (in anterior-posterior and medial-lateral directions) was computed from 60-s long quiet-standing trials on a stationary force plate in fifteen 10- to 13-year-old female acrobatic gymnasts and thirteen sex- and age-matched non-athletes. A two-way repeated measures ANOVA (acrobatic gymnasts vs. non-athletes and eyes open vs. eyes closed) was used for the anterior-posterior and mediallateral COP mean velocity. The relation between subjects’ body mass and COP mean velocity was tested with the used Spearman’s Rank Correlation Coefficient. Results: Postural sway (represented by COP mean velocity) was not significantly different between the acrobatic gymnasts and the non-athletes ( p > 0.05), except for the faster medial-lateral sway in eyes-open conditions in the acrobatic gymnasts ( p < 0.05). The gymnasts’ body mass negatively correlated with their anterior-posterior sway velocity in both visual conditions (eyes open: r = –0.7; eyes closed: r = –0.6) and with medial-lateral sway velocity during eyes-closed trials (r = –0.5; p < 0.05). Conclusions: Results of the study indicate that in quiet standing postural control 10- to 13-year-old acrobatic gymnasts did not make use of their trained abilities. Heavier gymnasts might have been more stable than lighter ones during quiet standing.

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A longitudinal assessment of myoelectric activity, postural sway, and low-back pain during pregnancy

Moreira L. S., Elias L. A., Gomide A. B., Vieira M. F., Do Amaral W. N.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 3

77--83

EN

The present study aimed at investigating the control of upright quiet standing in pregnant women throughout pregnancy, and whether low-back pain exerts influence on this motor task. Methods: Myoelectric signals from postural muscles and stabilometric data were collected from 15 non-pregnant and 15 pregnant women during upright quiet standing. Electromyogram envelopes and center of pressure metrics were evaluated in the control group, as well as in pregnant women in their first and third trimester of pregnancy. A correlation analysis was performed between the measured variables and a low-back pain disability index. Results: Pregnant women exhibited a decreased maximum voluntary isometric activity for all postural muscles evaluated. Additionally, the activity of lumbar muscles during the postural task was significantly higher in the pregnant women in comparison to the non-pregnant controls. The soleus muscle maintained its activity at the same level as the gestation progressed. Higher postural oscillations were observed in the anteroposterior direction while mediolateral sway was reduced in the third trimester of pregnancy. No correlation was detected between the lowback pain disability index and neuromechanical variables. Conclusion: This study provides additional data regarding the functioning and adaptations of the postural control system during pregnancy. Also, we provide further evidence that postural control during quiet standing cannot be used to predict the occurrence of low-back pain. We hypothesize that the modifications in the neural drive to the muscles, as well as in postural sway may be related to changes in the biomechanics and hormonal levels experienced by the pregnant women.