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External torque as a factor to modify load in abdominal curl-up exercises

100%
Rutkowska-Kucharska A., Szpala A.
Biomedical Human Kinetics
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2015
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vol. 7
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issue 1
EN
Study aim: the aim of our study was to evaluate electromyography (EMG) activity in exercises where the load to the muscles is determined by the external torque. In a part of the exercises, we changed the value of the external force, while in the other we modified the length of the lever arm at which the force was applied. Material and methods: the study was carried out on a group of 12 subjects (21 ± 2 years, 61 ± 4.8 mass, 172 ± 5 cm height). Electromyographic activity of the rectus abdominis (RA) muscle was evaluated by recording the EMG signal. The length of the lever arm of the external force was changed by using four different positions of the upper limbs, whereas the magnitude of the external force was changed through adding the weights of 0.5, 1.0, and 1.5 kg. The data recorded were normalized with respect to EMG activity measured under maximum voluntary contraction (MVC) conditions. Results: it was found that the change of the lever arm at which the force was applied (any change in the position of the upper limbs) causes a change in EMG activity in each part of the RA muscle from ca. 50% to ca. 100% MVC (p < 0.001). Further, the change in the external load changes statistically significantly the EMG activity only in the left upper part of the RA muscle (p < 0.05). Conclusions: activity in the RA muscle that increased for longer lever arms of the external force, offers opportunities for changing the load used during the exercise in a manner that is safe for the vertebral column.
2
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Muscle torque of the hip joint flexors and extensors in physically active and inactive amputees

100%
Kowal M., Rutkowska-Kucharska A.
Biomedical Human Kinetics
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2014
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vol. 6
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issue 1
EN
Study aim: The aim of this study was to assess proportion and symmetry between torque in muscles that affect the hip joint in the non-amputated and the amputated limb in persons both engaged in and not engaged in sports. Material and methods: Study participants comprised 12 persons with above-knee leg amputation. The group of participants was divided into two subgroups: persons engaged in sports and physically inactive persons. The strength and the speed capacity of hip joint flexors and hip joint extensors were measured using a Biodex System 4 dynamometer. The measurement was conducted at two angular velocities (60°/s and 120°/s) and during isometric activity of the non-amputated and the amputated limb. Results: Maximal torque of hip joint flexors in the amputated limb of physically active persons constituted 65.3% of the corresponding value in persons without amputation and was higher than in physically inactive persons (55.9%). Similar values were obtained for extensors. The time to reach maximal muscle torque in the amputated limb during the extension of the hip joint at 60°/s equalled 400 ms in physically active persons and 900 ms in physically inactive persons and during flexion, equalled 400 ms and 600 ms, respectively. Conclusions: Physically active persons showed greater dynamics in generating maximal muscle torque, especially during the extension of the hip joint. Physical activity benefits the strength and speed capacity of muscles that affect the hip joint in persons with above-knee amputation, thus decreasing asymmetry and disproportion between limbs.
3
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Step Aerobics and Rhythm of Movement of the Upper and Lower Limbs

81%
Milewska J., Jaroszczuk S., Rutkowska-Kucharska A.
Human Movement
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2013
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vol. 14
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issue 1
70-75
EN
Purpose. The aim of this investigation was to look for relationships between the repeatability of forces generated during the movement rhythm present in step aerobics and the movement to a rhythm by the upper and lower limbs alone. As step aerobics requires the symmetric involvement of both the upper and lower limbs, it appears to be important to examine whether a relationship exists between repeatability of a rhythm and a repeatability of forces generated when moving to a rhythm. As step aerobics is considered an endurance activity, the repeatability of the force reproduced by the lower limb muscles may be important in the prevention of injury. Methods. The study involved using a mock step bench which consisted of two Kistler force plates. The 29 female subjects of the study executed two motor tasks. The first task was hitting the plate with the dominant and the non-dominant upper and lower limb to a musical rhythm. The second task consisted in performing the basic step of step aerobics on the bench. The rhythm in both tasks was dictated by the beat of a metronome. Results. No statistically significant differences were found between respectability of producing a rhythm by the dominant and non-dominant upper and lower limbs. No correlation was found between the rhythm reproduction error of the limbs and the accuracy of moving to a rhythm during the step aerobics task. This second task was characterized by a high repeatability of the generated forces and a high variability in following a musical rhythm. Conclusions. Body mass does not influence the force generated during rhythm reproduction with the upper and lower limbs. During step walking, the study participants were characterized with a high repeatability of generated force and also by a high variability in following a musical rhythm.
4
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Choosing the Right Body Position for Assessing Trunk Flexors and Extensors Torque Output

81%
Szpala A., Rutkowska-Kucharska A., Drapała J., Brzostowski K.
Human Movement
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2011
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vol. 12
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issue 1
57-64
EN
Purpose. The sitting position is generally adopted when measuring the torques produced by flexors and extensors of the trunk. Results of such measurements are influenced by the strength of both abdominal muscles and flexors of the hip joint. In order to assess the effect of exercises used to strengthen the abdominal muscles it was necessary to find such a measuring position which engaged mainly the abdominal muscles. The objective of the study was an assessment of EMG activity of abdominal and spinal muscles during the measurements of muscle torques in the sitting position, as well as in the lying position. Basic procedures. Thirteen female students of the University School of Physical Education in Wrocław participated in the study. The methods of measuring muscle torques and surface electromyography (sEMG) were used under static conditions. The torques were measured on a multifunctional chair in the lying and sitting positions. The surface EMG electrodes were placed on the right and left hand sides of m. rectus abdominis (RA) and m. erector spinae (ES). Signals from both muscles were sampled at 1000 Hz. Main findings. The maximal torques of trunk flexors in the sitting position and in the lying position were similar: 130.6 ± 31.7 Nm and 129.8 ± 37.9 Nm, respectively. By contrast, the torque of trunk extensors was significantly larger when the measurement was carried out in the sitting position (228.1 ± 76.4 Nm) as compared with the lying position (148.8 ± 25.3 Nm). The ratio of the maximal torques of flexors and extensors of the trunk in the women examined was 0.572 in the sitting position and 0.872 in the lying position. Both RA and ES showed higher EMG activity in the lying position than in the sitting position. Conclusions. The higher EMG activity of the RA muscle in the lying position at the same values of the trunk flexors torque in both positions may suggest that in the sitting position flexors of the hip joint are more engaged than abdominal muscles. That is why, in order to assess the effects of abdominal muscles training, measurements of the trunk flexors torque should be performed in the lying position.
5
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The assessment of specific physical fitness of children aged 8 and 9 years participating in tennis classes using the Jindrich Hoehm test

81%
Szpala A., Rutkowska-Kucharska A., Syrewicz P.
Biomedical Human Kinetics
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2014
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vol. 6
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issue 1
EN
Study aim: The purpose of the study was to use the Jindrich Hoehm test to evaluate physical fitness in boys and girls aged 8 and 9 years participating in tennis classes. Material and methods: A total of 40 children divided into four sample groups participated in the study. The J. Hoehm test consisting of seven components was used to measure and assess the physical fitness of the research participants. This test is used in child and adolescent tennis training to assess specific physical fitness. Results: The actual data showed significant differences between 8-year-old boys and girls that were established based on the test components assessing lower extremity strength capacity and the agility assessment test. In the group of children aged 9, the differences between boys and girls emerged in the test assessing lower extremity strength capacity as well as the test component assessing the forehand and backhand footwork movement technique. Inasmuch as the test component assessing lower extremity strength capacity showed differences between 8- and 9-year-old boys, no test demonstrated statistically significant differences between 8- and 9-year-old girls. Based on the normalized data, 8-year-old girls are physically fitter than 8-year-old boys. In the group of 9-year-old children, the relation is reversed. The children participating in the study display a low level of physical fitness. Conclusion: The J. Hoehm test can be a useful tool for assessing the performance of tennis coaches.
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