Papers by michalina błażkiewicz
Frontiers in Sports and Active Living
Synergy analysis via dimensionality reduction is a standard approach in biomechanics to capture t... more Synergy analysis via dimensionality reduction is a standard approach in biomechanics to capture the dominant features of limb kinematics or muscle activation signals, which can be called “coarse synergies.” Here we demonstrate that the less dominant features of these signals, which are often explicitly disregarded or considered noise, can nevertheless exhibit “fine synergies” that reveal subtle, yet functionally important, adaptations. To find the coarse synergies, we applied non-negative matrix factorization (NMF) to unilateral EMG data from eight muscles of the involved leg in ten people with drop-foot (DF), and of the right leg of 16 unimpaired (control) participants. We then extracted the fine synergies for each group by removing the coarse synergies (i.e., first two factors explaining ≥85% of variance) from the data and applying Principal Component Analysis (PCA) to those residuals. Surprisingly, the time histories and structure of the coarse EMG synergies showed few difference...
Acta of Bioengineering and Biomechanics
Purpose: This study examined the use of nonlinear measures – sample entropy (SampEn), fractal dim... more Purpose: 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. ...
Journal of Clinical Medicine
Tissue flossing is an increasingly popular method in physiotherapy and sports. There is a belief ... more Tissue flossing is an increasingly popular method in physiotherapy and sports. There is a belief that tissue flossing can improve range of motion and muscle strength, shorten muscle recovery time, and reduce the risk of injury. The aim of this study was to analyse the effectiveness of tissue flossing for immediately improving muscle strength in recreational athletes when it is performed during warm-up. All participants were randomly assigned to either an experimental group (n = 36) or a control group (n = 34) using a random number generator. The experimental group (n = 36) performed an intervention comprising exercises with muscle tissue flossing and exercises without flossing. The control group (n = 30) performed the same protocol without a floss band. Muscle strength was measured for knee flexion end extension at three speeds (60, 120, and 180 °/s) 3 times. Analysed parameters include peak torque, work, and power related to body weight, flexors–extensors ratio, and time to peak to...
Entropy
Background: Human motor systems contain nonlinear features. The purpose of this study was to eval... more Background: Human motor systems contain nonlinear features. The purpose of this study was to evaluate the geometric structure of attractors and analyze recurrence in two different pirouettes (jazz and classic) performed by 15 professional dancers. Methods: The kinematics of the body’s center of mass (CoM) and knee of the supporting leg (LKNE) during the pirouette were measured using the Vicon system. A time series of selected points were resampled, normalized, and randomly reordered. Then, every second time series was flipped to be combined with other time series and make a long time series out of the repetitions of a single task. The attractors were reconstructed, and the convex hull volumes (CHV) were counted for the CoM and LKNE for each pirouette in each direction. Recurrence quantification analysis (RQA) was used to extract additional information. Results: The CHVs calculated for the LKNE were significantly lower for the jazz pirouette. All RQA measures had the highest values f...
Journal of Clinical Medicine
Total knee replacement (TKR) is the treatment of choice for advanced stages of osteoarthritis but... more Total knee replacement (TKR) is the treatment of choice for advanced stages of osteoarthritis but it requires good postoperative rehabilitation. This study aimed to assess the effectiveness of exercises using virtual reality to improve gait parameters in patients after TKR. Fifty-nine patients 7–14 days after TKR surgery were divided into a study group (VRG, n = 38) and a control group (CG, n = 21). Both groups underwent the same 4-week rehabilitation protocol. The VRG group had 12 additional nonimmersive virtual reality game sessions on the Virtual Balance Clinic prototype system at 30 min each, focusing on gait and balance improvement. Spatiotemporal, force and foot plantar pressure parameters were collected on an instrumented treadmill during a 30 s walk. The most significant improvement was in the symmetry indices of forefoot force, maximum forefoot force, loading response time, and preswing time (p < 0.05) in both groups. Gait speed increased by 31.25% and 44% in the VRG and...
Diagnostics
Primary osteoarthritis treatments such as a total hip (THR) or knee (TKR) replacement lead to pos... more Primary osteoarthritis treatments such as a total hip (THR) or knee (TKR) replacement lead to postural control changes reinforced by age. Balance tests such as standing with eyes open (EO) or closed (EC) give a possibility to calculate both linear and nonlinear indicators. This study aimed to find the group of linear and/or nonlinear measures that can differentiate healthy people and patients with TKR or THR from each other. This study enrolled 49 THR patients, 53 TKR patients, and 16 healthy controls. The center of pressure (CoP) path length, sample entropy (SampEn), fractal dimension (FD), and the largest Lyapunov exponent (LyE) were calculated separately for AP and ML directions from standing with EO/EC. Cluster analysis did not result in correct allocation to the groups according to all variables. The discriminant model included LyE (ML-EO, ML-EC, AP-EC), FD (AP-EO, ML-EC, AP-EC), CoP-path AP-EC, and SampEn AP-EC. Regression analysis showed that all nonlinear variables depend on...
Purpose: Sabre is one of the three disciplines in fencing, characterised by the use of a lightwei... more Purpose: Sabre is one of the three disciplines in fencing, characterised by the use of a lightweight cutting weapon to score hits on an opponent while maneuvering for position with dynamic footwork. The aim of this study is concerned with the estimation of the load applied to the lower extremities during a step-forward lunge. Methods: The study group comprised sixteen subjects from ASA club. Examinations of kinetic parameters of analyzed movement were carried out using Vicon system, Kistler plates and the equipment designed to measure joint torques in isometric conditions. Results: Maximal value of the vertical component of the ground-reaction-force generated by the lead leg is significantly higher than the one recorded in the rear leg. The maximal value of hip flexion torque of lead leg in dynamic conditions significantly exceeds the value for this joint recorded in isometric conditions. The maximal value of knee flexion of rear leg in dynamic conditions significantly exceeds the value obtained in the isometric conditions. In general, the sequence of the joint loading from the highest to the lowest is as follows: hip, knee, ankle. Conclusions: The comparative analysis of the torques generated by the muscles in isometric and dynamic conditions provides an adequate tool for the assessment of the characteristics of the muscle effort. Therefore, it defines the structure of movement patterns in saber, from the kinetics' point of view, in the process of improving fencing footwork.
Backward walking (BW) is a common technique employed in the treatment of a variety of orthopedic ... more Backward walking (BW) is a common technique employed in the treatment of a variety of orthopedic and neurological diseases. BW training may offer some benefits especially in balance and motor control ability beyond those experienced through forward walking (FW). The purpose of this study was to determine whether BW represented a simple reversal of FW and, hence muscle force distribution is the same. The study involved one male healthy student of physical education (22 years, h = 185 cm, m = 80 kg). Measurements of spatial-temporal gait parameters were conducted using eight Vicon system cameras, and Kistler plates. Noraxon EMG was used to obtain muscles activity. OpenSim software was used to compute muscle force distribution during both types of gait. During FW and BW there is small difference for force curves produced by m. gluteus maximus (RMS = 0.04), m. biceps femoris short head (RMS = 0.19) and m. tibialis anterior (RMS = 0.16). Good validation by EMG signal was obtained for m. rectus femoris, m. biceps femoris short head, m. tibialis posterior during FW and BW. For m. iliacus, only during BW good validation was achived.
Advances in Rehabilitation, 2021
Hallux valgus (HV) and hallux rigidus (HR) are common foot conditions that lead to deterioration ... more Hallux valgus (HV) and hallux rigidus (HR) are common foot conditions that lead to deterioration of health status. This review aims to summarize and update information on the currently published research explicitly related to the influence of HV and HR surgeries on lower extremity gait biomechanics. A review of papers published from 1999 to 2020 has been conducted. The databases searched included Science Direct, PubMed Central, PubMed and EBSCO. After HV surgeries, most of patients’ spatio-temporal parameters remain the same as they were before them. Changes in plantar pressure parameters of the hallux region are inconclusive and depend on a study. In patients after HR surgeries, such as cheilectomy and Ist metatarsophalangeal joint (MTP I) arthrodesis, they do not affect knee or hip kinematics. The influence of MTP I arthrodesis on ankle joint kinematics is unclear. Cheilectomy in most cases increases MTP I motion in the sagittal plane. The HV angle and the intermetatarsal angle ha...
Symmetry, 2021
Background: Gait deviations may negatively affect the articular surfaces of the lower extremity j... more Background: Gait deviations may negatively affect the articular surfaces of the lower extremity joints and lead to some minor degenerative changes. The simplest method for gait evaluation is to assess the symmetry of its parameters, assuming that each undisturbed gait should be symmetrical. This study aims to quantify the degree of asymmetry of kinematic and kinetic parameters caused by the presence of different ankle orthosis settings using Dynamic Time Warping (DTW). Methods: Barefoot gait and gait with four different walker settings were investigated in eighteen healthy persons. Kinematic and kinetic parameters were measured using the Vicon system and Kistler plates. Symmetry was assessed using the DTW method. Results: It was shown that the presence of different ankle orthosis settings significantly disturbs the symmetry of all lower limb kinematic parameters and only knee and hip torques. The highest values of asymmetry were noted for the walker set at 15° of dorsiflexion (15DF)...
Entropy, 2021
Exercises in virtual reality (VR) have recently become a popular form of rehabilitation and are r... more Exercises in virtual reality (VR) have recently become a popular form of rehabilitation and are reported to be more effective than a standard rehabilitation protocol alone. The aim of this study was to assess the efficacy of adjunct VR training in improving postural control in patients after total knee replacement surgery (TKR). Forty-two patients within 7–14 days of TKR were enrolled and divided into a VR group and a control group (C). The C group underwent standard postoperative rehabilitation. The VR group additionally attended twelve 30-min exercise sessions using the Virtual Balance Clinic prototype system. Balance was assessed on the AMTI plate in bipedal standing with and without visual feedback before and after the four-week rehabilitation. Linear measures and sample entropy of CoP data were analyzed. After four weeks of rehabilitation, a significant reduction in parameters in the sagittal plane and ellipse area was noted while the eyes remained open. Regression analysis sho...
Acta of Bioengineering and Biomechanics, 2020
Purpose: Yoga is known as a type of exercise that combines physical, mental and spiritual aspects... more Purpose: Yoga is known as a type of exercise that combines physical, mental and spiritual aspects. There has not been much research on the postural control in various yoga poses. The aim of this study was to examine CoP regularity in both yoga instructors and novices during the performance of four yoga poses, and to verify the sensitivity of linear and nonlinear methods for assessing postural stability. Methods: The dynamic characteristics of CoP fluctuations were examined using linear and nonlinear methods on a group of 22 yoga instructors (Y) and 18 age-matched non-practitioners of yoga (NY). The study involved maintaining a balance for 20 seconds while performing four yoga poses. Results: Conventional analysis of CoP trajectories showed that NY and Y exhibited similar control of postural sway, as indicated by similar CoP path-length and area values observed in both groups. These results suggest that the special balance yoga training received by Y may not have an impact on less ch...
Acta of Bioengineering and Biomechanics, 2021
Purpose: The objective of this study was to analyze the muscle force distribution and lower limb ... more Purpose: The objective of this study was to analyze the muscle force distribution and lower limb joint loading during two types of pirouettes and check which muscle in which pirouette generates the highest force and which joint is the most loaded. Methods: Skilled dancers (n = 16) performed single-turn pirouettes in jazz and classic styles. Kinematic and kinetic data were collected using the Vicon system and Kistler plates. The joint reaction forces and muscle forces were calculated using a musculoskeletal model in the AnyBody Modeling System. Results: No statistically significant differences were found for the duration of the turn in both pirouettes. The range of motion in all joints of supporting leg in sagittal plane and in hip joint in frontal plane for non-supporting leg were significantly higher in classic pirouette. The ankle joint was the most loaded joint in both pirouettes and its maximal value was significantly higher in classic pirouette. The force generated by ankle pla...
Advances in Rehabilitation, 2021
Introduction: Postural control is a complex system that combines many subcomponents. The central ... more Introduction: Postural control is a complex system that combines many subcomponents. The central nervous system's connection with the muscular system allows to execute the voluntary movements and provides appropriate tonus and contractions of postural muscles. The aim of this study was to assess the effect of voluntary muscle contraction on the stability of standing posture. Material and methods: Seventeen young adults (24.11 ± 3.05 years) completed 4 bipedal standing attempts lasting 20 seconds each. Measurements were performed on AMTI plate and involved maintaining balance while standing barefoot on both feet with eyes open and closed. Two additional tests with provoked isometric voluntary muscle contraction were performed under the same visual conditions. Results: For examined healthy subjects, the lack of visual feedback in combination with increased muscle tension caused a significant increase in the peak of sway in the anteriorposterior (AP) and medio-lateral (ML) direction. On the other hand, the values of the center of pressure (CoP) path length and its velocity due to the increased muscle contraction did not significantly decrease their values for trials with eyes open and closed. Conclusions: This study indicates that voluntary muscle contraction can influence the standing posture mainly in combination with a lack of visual feedback, causing its deterioration.
Biomedical Human Kinetics, 2021
Study aim: To investigate the effect of wearing ski boots on kinematic and kinetic parameters of ... more Study aim: To investigate the effect of wearing ski boots on kinematic and kinetic parameters of lower limbs during gait. Furthermore, loads in lower limb joints were assessed using the musculoskeletal model. Material and methods: The study examined 10 healthy women with shoe size 40 (EUR). Kinematic and kinetic data of walking in ski boots and barefoot were collected using a Vicon system and Kistler plates. A musculoskeletal model derived from AnyBody Modeling System was used to calculate joint reaction forces. Results: Wearing ski boots caused the range of motion in the knee joint to be significantly smaller and the hip joint to be significantly larger. Muscle torques were significantly greater in walking in ski boots for the knee and hip joints. Wearing ski boots reduced the reaction forces in the lower limb joints by 18% for the ankle, 16% for the knee, and 39% for the hip. Conclusions: Ski boot causes changes in the ranges of angles in the lower limb joints and increases muscle...
Entropy, 2021
Osteoporosis is a prevalent health concern among older adults and is associated with an increased... more Osteoporosis is a prevalent health concern among older adults and is associated with an increased risk of falls that may result in fracture, injury, or even death. Identifying the risk factors for falls and assessing the complexity of postural control within this population is essential for developing effective regimes for fall prevention. The aim of this study was to assess postural control in individuals recovering from osteoporotic vertebral fractures while performing various stability tasks. Seventeen individuals with type II osteoporosis and 17 healthy subjects participated in this study. The study involved maintaining balance while standing barefoot on both feet for 20 s on an Advanced Mechanical Technology Inc. (AMTI) plate, with eyes open, eyes closed, and eyes closed in conjunction with a dual-task. Another three trials lasting 10 s each were undertaken during a single-leg stance under the same conditions. Fall risk was assessed using the Biodex Balance platform. Nonlinear ...
Entropy, 2020
Conventional biomechanical analyses of human movement have been generally derived from linear mat... more Conventional biomechanical analyses of human movement have been generally derived from linear mathematics. While these methods can be useful in many situations, they fail to describe the behavior of the human body systems that are predominately nonlinear. For this reason, nonlinear analyses have become more prevalent in recent literature. These analytical techniques are typically investigated using concepts related to variability, stability, complexity, and adaptability. This review aims to investigate the application of nonlinear metrics to assess postural stability. A systematic review was conducted of papers published from 2009 to 2019. Databases searched were PubMed, Google Scholar, Science-Direct and EBSCO. The main inclusion consisted of: Sample entropy, fractal dimension, Lyapunov exponent used as nonlinear measures, and assessment of the variability of the center of pressure during standing using force plate. Following screening, 43 articles out of the initial 1100 were revi...
Applied Sciences
Postural control is a term used to describe how the central nervous system regulates sensory info... more Postural control is a term used to describe how the central nervous system regulates sensory information from other systems to produce adequate motor output to maintain a controlled, upright posture. Emotions (fear, anxiety) and thus personality type can affect the strategy of body control. This study aimed to evaluate the impact of personality on postural control. Thirty-three healthy individuals participated in this study. The big-five model was used to examine personality traits. Each participant performed four different standing tasks (one and both legs standing with eyes open (eo) and closed (ec): 2eo, 2ec, 1eo, 1ec). We showed that the dominant personality traits in the study group were extraversion and agreeableness. There were significantly low negative associations between nonlinear parameters and personality traits. A moderate correlation was noted for the 1eo trial between Openness and the Lyapunov exponent. In conclusion, nonlinear measures provide a possible link betwee...
Niepełnosprawność - zagadnienia, problemy, rozwiązania, 2018
Seeking a method to evaluate and monitor the performance of the shot put, discus and javelin thro... more Seeking a method to evaluate and monitor the performance of the shot put, discus and javelin throw, we analyzed the transfer of mechanical energy between body segments. Methods: The study was conducted on groups consisting of elite throwers on the Polish National Team for each of the aforementioned sport disciplines. The movements of each throw were recorded using Vicon system and Kistler plates. The power and energy fluctuations were computed for the final acceleration phase of each throw. Results: In all three disciplines studied, we found an average energy loss of 1.63 J/kg generated from shoulder to wrist. The value of generated energy from ankle to torso initially increased in all disciplines, followed by a descent-with the exception of the javelin throw, where there was an average 27% decrease in both hip joints. We found strong correlations between relative amplitude values of energy and the athlete's personal performance records:-0.8226 (shot put), 0.6008 (discus) and 0.7273 (javelin). Conclusions: Measuring the transfer of mechanical energy between body segments offers a useful method for evaluating the technique of ballistic movements and for monitoring training progress.
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Papers by michalina błażkiewicz