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Using nonlinear measures to evaluate postural control in healthy adults during bipedal standing on an unstable surface

Kędziorek Justyna, Błażkiewicz Michalina, Kaczmarczyk Katarzyna

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 1

9--17

EN

This study examined the use of nonlinear measures – sample entropy (SampEn), fractal dimension (FD), and the Lyapunov exponent (LyE) – to evaluate postural control in adults during standing on an unstable surface, with and without visual feedback. Methods: 14 healthy young adults (24.07 ± 7.32 years) completed bipedal standing trials on an unstable-plate Biodex Balance System (BBS) connected to a Vicon system, with eyes open and closed. Each trial lasted 20 sec. Analysis was performed based on the center of mass (CoM), for which the three nonlinear measures were calculated. Results: Excluding visual feedback was found to cause a significant increase in linear and nonlinear parameters. Moreover, SampEn and FD values were found to be significantly higher in the PD direction, compared to AP or ML, whereas LyE values in this direction were minimal. Conclusions: Results show that the three nonlinear measures provide a useful way of evaluating postural control in healthy adults. Moreover, it seems that introducing an unstable surface meant that the projection of the CoM was not perpendicular to the surface, but rather set at a certain continually changing angle, forcing the whole system to adapt to chaotic and unpredictable conditions. Such refined changes in conditions can be evaluated in a precise way only by using nonlinear measures.

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The influence of three different test positions and thigh asymmetry on measurements of isometric hip flexion strength in men and women

Mańka Jacek, Bobowik Patrycja, Jaskulski Karol, Wiszomirska Ida, Kaczmarczyk Katarzyna

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 4

49--56

EN

The aim of this study was to compare muscle strength at 90° hip and knee flexion as measured in three different positions and to investigate whether an internal or external deficit in the range of rotation in the hip joint affects flexor muscle strength. Methods: We measured the peak muscle torque of rotation in the hip joint, using isometric torquemeter, and hip ROM in healthy participants N = 40, aged 21.6 ± 1.9, in three different measurement positions. We tested for differences between the positions, and for the potential influence of participant’s sex and ROM asymmetry. Results: The measured peak muscle torque was affected not only by sex and the value of hip flexion affect, but also by the position in which it is measured. Subjects with restricted external rotation of the hip joint (CERD) had significantly higher flexor peak muscle torque compared to subjects with restricted internal rotation (CIRD), in all but the supine position. For CERD, the results were: Supine (SuP) 1.02 ± 0.26; Sitting (StP) 1.32 ± 0.58; Standing (SP) 1.53 ± 0.47; and for CIRD, the results were: Supine (SuP) 1.05 ± 0.17; Sitting (StP) 1.05 ± 0.40; Standing (SP) 1.47 ± 0.53. Conclusions: Overall, measurement position and passive ROM significantly influence the peak muscle torque in isometric conditions. Moreover, an imbalance in thigh rotation movement significantly determines the magnitude of muscle torque of the hip flexion movement. Individuals with increased internal-toexternal rotation achieved significantly higher values for flexor muscle torque force moments. Overall, these findings are of importance for interpreting or comparing any reported values for muscle torque force moments.

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Kinetic analysis of gait in adults with asymptomatic flatfoot

Tomasiak Edyta, Wychowański Michał, Kaczmarczyk Katarzyna, Gajewski Jan

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 1

59--66

EN

The aim of our study was to assess the influence of asymptomatic flatfoot on the kinetic parameters of the lower limb during gait. Methods: Individuals of both sexes were studied: 15 women [age 25 ± 5 years] and 19 men [age 25 ± 4 years] with bilateral asymptomatic flatfoot, as well as 16 women [age 26 ± 4 years] and 14 men [age 24 ± 3 years] with normal feet on both sides. A threedimensional VICON motion analysis system coupled with KISTLER dynamometric platforms was used to perform kinetic gait analysis. Results: Women with flatfoot showed significantly lower maximal relative moments in the ankle in the sagittal plane ( p < 0.05) and significantly lower maximal relative moments in the knee in the sagittal plane in the Terminal Stance ( p < 0.001). In men, a significant difference was found in terms of hip rotation moment in the transverse plane in the Mid Stance ( p < 0.01): men with normal feet showed moments of external rotation, while men with flatfoot generated internal rotational moments. Moreover, men with flatfoot showed significantly lower ( p < 0.01) maximal relative moments in the knee in the transverse plane in the Mid Stance. Conclusions: Women with flatfoot have a weakened lower limb propulsion mechanism, whereas, in men with flatfoot, there is a change in the mechanics of the lower limb in the transverse plane. Our findings cast some doubt on flatfoot as a putative risk factor for stress injuries and degenerative changes in lower-limb structures, and suggest that gender differentiation should be taken into account in the analysis and therapy of flatfoot.

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Hip joint mobility in relation to measurement position, gender and limb dominance

Bobowik Patrycja Żaneta, Mańka Jacek, Jaskulski Karol, Kaczmarczyk Katarzyna

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 2

65--73

EN

The purpose of this study was to determine whether three different measurement position yield divergent results in ROM using a goniometer, and how is it affected by anthropometrical factors. Methods: We measured the range of rotation in the hip joint in healthy participants aged 21.6 ± 1.88, seeking to determine how the distribution of internal vs. external rotation (RI) within the total range of mobility (TR) was influenced by the measurement position used, the gender of the participant, and the dominant lower limb. Results: We found that not only gender and limb dominance, but also the body position in which hip joint’s range of motion is measured significantly affects the values of TR and RI. We found that TR achieves the highest values in the prone position – PrP (males: 95.35 ± 12.44 and 93.15 ± 12.49; females: 103.75 ± 14.87 and 106.25 ± 15.56) and the lowest values in supine position – SuP (male: 62.65 ± 8.51 and 57.85 ± 9.60; female: 59.5 ± 12.27 and 55.85 ± 8.54). The analysis shows that CERD occurs <0.42 RI in females (PrP) and <0.88 RI in men (PrP and sitting position – StP), and CIRD >1.72 RI in women (StP), and >2.08 RI in men (PrP). Conclusions: Due to the similarities between asymmetry of internal/external rotation in the hip joint and asymmetry in the rotation of the shoulder found in Glenohumeral Internal Rotation Deficit (GIRD), we propose the concepts of Coxal Internal Rotation Deficit (CIRD) and Coxal External Rotation Deficit (CERD) as tools to indicate the possibility for injury to the hip joint, and propose threshold rotation index values serving as indicators of these deficits.