Differences in Velocities of Crucial Body Segments while Executing Roundhouse Kicks for Both Sides.

Lower limb kinematics of the roundhouse kick is a well-known topic studied by many researchers. However, there is a lack of data about the velocity of the core and upper limbs during the execution of this technique. The aim of this study was to evaluate the differences in velocities of all crucial body segments while executing roundhouse kicks for both sides of the body. Thirteen elite taekwon-do athletes participated in this study. They performed kicks to a table tennis ball three times using each leg. The spatial-temporal data of markers placed on toes, knees, hips, shoulders, elbows, hands, and sternum were captured with the use of the Human Motion Lab equipment composed of 10 infrared cameras NIR Vicon MX-T40. There were statistical differences in the maximal velocity of the sternum and opposite shoulder. There were different correlations between the time of acquiring maximal velocities of specific body segments and the maximal velocity of the toe marker for each kicking side. Higher correlations were observed for the left kick despite the participant's declaration of their preference for the right leg. The obtained results facilitate the conclusion that small non-resistant targets require different motor control depending on the kicking side, despite not revealing significant differences between maximal velocity. While such an indicator could be perceived as a suitable benchmark of an athlete's performance, more detailed analysis seems to be required for a better understanding of martial arts techniques.

Feeling of Meaningfulness and Anxiety of Taekwon-Do Fighters in a Salutogenic Notion.

This study aimed to examine the relation between the feeling of meaningfulness and also the characteristics of engaged participation (namely, the frequency of participation in voluntary groupings) and the level of anxiety among those who train a group of elite taekwon-do fighters. The research encompassed 58 people, all of whom were taekwon-do ITF (International Taekwon-do Federation) athletes at an elite level. The Questionnaire of Life Orientation (SOC-29) and the Inventory of the State and Features of Anxiety were used. The data were supplemented by the authors' own questions referring to activities in the field of taekwon-do. The group of taekwon-do fighters chosen was internally divided with regard to the level of the state of anxiety and the feeling of meaningfulness (p < 0.01). It was found that, together with the growth in the values stipulated in the accepted model, the frequency of taekwon-do groupings (ß = -0.38), as well as the feeling of meaningfulness (ß = -0.31), the value of the level of intensification of the state of anxiety dropped. The data revealed that, together with age, the level of anxiety decreased and the feeling of meaningfulness increased. The difference in the levels of anxiety between women and men was statistically non-significant (p > 0.05). The research findings illustrate that the feeling of meaningfulness and participation in groupings constitute a differentiating factor in terms of the intensification of the average level of anxiety in the elite taekwon-do group. More frequent participation in training goes hand-in-hand with the greater feeling of meaningfulness; perhaps, this is associated with the specific training, which, among other factors, favours adaptation to challenges and actions under pressure.

Morphological differences in scoliosis curvatures as a cause of difficulties in its early detection based on angle of trunk inclination.

INTRODUCTION: The three dimensional deformation of the spine in scoliosis is specific for a given child with regard to the number and length of curvatures, their degree of rotation and the size of the curvature angle. Early diagnosis of scoliosis in a clinical examination according to the Adams test depends on the correlation between the angle of trunk inclination (ATI) and the Cobb angle and the adopted diagnosis criterion. The aim of the study was to demonstrate the need to adopt different diagnostic criteria for ATI depending on the age and location of scoliosis. Moreover, the observed differences in the ATI/Cobb correlation became the basis for the proposal to introduce the concept of low, medium and high-rotated of curvature to the clinical description of scoliosis. MATERIALS AND METHODS: The group consisted of 229 children who were first examined, aged 6 to 17 years, with an average age of -11.57 years (SD ± 3.26), with symptoms of idiopathic scoliosis. The correlation of the criteria for the diagnosis of scoliosis in the ATI 7° clinical trial with a Cobb angle of 10° three dimensional in the X-ray image was used to distinguish three types of curvature/scoliosis, i.e., low, medium and high rotation. The frequencies of each type were compiled for three age groups and three scoliosis locations. Moreover, the degree of vertebral rotation according to the Perdriolli (AVR) of curvature was correlated with the Cobb angle and ATI. A one-way logistic regression model was used to assess the effectiveness of scoliosis detection in children based on the measurement of the ATI angle alone and the measurement of both ATI and Cobb angles. RESULTS: Low-rotated curves were most often found in the age groups of 6-9 and 10-12 years in 65.6% and 71.4% of patients, respectively (p < 0.05). Medium-rotated curvatures were most common in the age group of 13-17 years - 51.6%. With regard to the localization of scoliosis, the low-rotated curvatures were significantly more frequently (p < 0.05) found in the lumbar and thoracolumbar spine. Moreover, the univariate regression model for ATI showed that we could detect scoliosis best by taking the cut-off point of 5° and the mathematically determined Cobb angle was 9.5°. Patients with ATI ≥ 7° had significantly higher AVR values ​​than those with ATI < 7°, and the ATI/AVR correlation was of average strength. CONCLUSION: The specific morphology of the scoliotic curvature of the child's spine may be manifested by the difference in the ATI/Cobb correlation depending on the location of the scoliosis and change with age. The curvatures of the scoliosis that form can be low, medium and high-rotated, and the low-rotated curvatures were most often found in the 6-9- and 10-12-year-old groups and in the lumbar and thoracolumbar section. To increase the rate of early diagnosis of scoliosis, the results suggest the need to adopt two ATI criteria for the diagnosis of scoliosis at screening, 5° for age of 6-12 years, and when asymmetry affects the lumbar and thoracolumbar section, and 7° for the remaining children.

Kinematic Effects of the Target on the Velocity of Taekwon-Do Roundhouse Kicks.

The phenomena of target kinematic effects under different striking conditions and applying different techniques constitute one of the fields of research for sports biomechanics. However, the influence of some kinematic variables which change under different strike conditions for specific parts of the lower limb remains unknown. The aim of this study was to extend the knowledge on how targets of different shapes or the lack of a physical target would affect maximal velocity registered by a marker placed on the foot, knee and hip during the execution of a roundhouse kick. In total, 15 adult males were included in this study. All participants were taekwon-do elite athletes. The displacement of markers placed on the lateral side of the foot, knee and hip during movement execution was registered by a stereophotogrammetry apparatus. Participants performed taekwon-do roundhouse kicks for three target types (into the air, a table tennis ball and a training shield) applying either a sport or a traditional style. The highest maximal velocity was obtained for kicking into the training shield. When applying the sport style, the highest maximal velocity of foot markers for the executed kicks was registered. Kicking into air resulted in higher velocities for proximal body parts than kicking into a tennis ball, but the effect was reversed for the foot marker. In conclusion, a large resistance target is suitable for athletes' motor preparation as it allows the highest maximum velocity to be reached. Small non-resistant targets are recommended for technical training.

The Effects of Repeated Thermal Stress on the Physiological Parameters of Young Physically Active Men Who Regularly Use the Sauna: A Multifactorial Assessment.

The aim of this study was to determine the effects of thermal stress (TS) on changes in blood biochemical parameters and fluid electrolyte levels in young adult men with moderate and high levels of physical activity. Thirty men (22.67 ± 2.02 years) were exposed to four 12-min sauna sessions (temperature: 90-91 °C; relative humidity: 14-16%) with four 6-min cool-down breaks. The evaluated variables were anthropometric, physiological, and hematological characteristics. The mean values of HRavg (102.5 bpm) were within the easy effort range, whereas HRpeak (143.3 bpm) values were within the very difficult effort range. A significant increase was noted in pO2 (p < 0.001), total cholesterol (p < 0.008), HDL (p < 0.006) and LDL cholesterol (p < 0.007). Significant decreases were observed in the SBP (by 9.7 mmHg), DBP (by 6.9 mmHg) (p < 0.001), pH (p < 0.001), aHCO3- (p < 0.005), sHCO3- (p < 0.003), BE (ecf) (p < 0.022), BE (B), ctCO2 (for both p < 0.005), glucose (p < 0.001), and LA (p < 0.036). High 72-min TS did not induce significant changes in the physiological parameters of young and physically active men who regularly use the sauna, excluding significant loss of body mass. We can assume that relatively long sauna sessions do not disturb homeostasis and are safe for the health of properly prepared males.

Social Support and Dietary Habits as Anxiety Level Predictors of Students during the COVID-19 Pandemic.

The COVID-19 pandemic is a public health emergency concern and a challenge to students' mental health due to changes in education and social isolation. The aim of this research was to expand knowledge about the relations that shape the level of anxiety amongst men and women who are studying during the pandemic in terms of the relations towards their sense of social support and their nutritional behaviors. A State-Trait Anxiety Inventory was used to measure anxiety level, alongside supplementary questions such as the feeling of support from close ones, concentration of attention on nutrition during the pandemic and externally derived factors (university, specialization). Analysis of the regression was applied to the examination of the dependency between the anxiety level (in both forms of its occurrence-as state-anxiety and as trait-anxiety). We observed that the pandemic situation affected a level of state-anxiety above average (mean value of 46-48 points) even when students felt social support. Nutrition habits and chosen education type are associated with trait-anxiety level, which was also elevated (mean values of 49-50 points). Chosen factors had a partial influence on the anxiety level of students, therefore their mental health should concern shaping positive nutrition habits and social support.

Stereophotogrammetry measurement of kinematic target effect as speed accuracy benchmark indicator for kicking performance in martial arts.

PURPOSE: The development of a motion capture system leads to fast and accessible ways of precise testing of athletes and their motor abilities. The striking performance in martial arts and combat sports requires measuring velocity in the context of successful contact with the target. The aim of this study was to present the novel kinematic target effect coefficient and its possible use as a speed accuracy benchmark of performance based on the example of taekwon-do roundhouse and frontal kicks. METHODS: The stereophotogrammetry motion capture setup consists of 10 infrared cameras (NIR Vicon MX-T40). Analysis includes 180 kicks (roundhouse and frontal kicks) performed by 15 adult participants on a master level in taekwon-do. The kinematic target effect comparison includes two targets - a training shield and a table tennis ball hanging from the ceiling. Markers were placed on the lower extremities of participants. Spatial-temporal variables were registered for both kicking legs, techniques, and target types. RESULTS: Both roundhouse and frontal kicks revealed target and marker dependent differences during its execution. The kinematic target effect coefficient values differ for the specific marker and kick type. CONCLUSION: The wireless motion capture systems could be helpful in the training process and an athlete's evaluation before sports competitions.

Determinants of anxiety levels among young males in a threat of experiencing military conflict-Applying a machine-learning algorithm in a psychosociological study.

BACKGROUND: Anxiety could be felt even in objectively peaceful situations, but a vision of conflict could result in increased stress levels. In this article, we aimed to identify hidden patterns of mental conditions and create male profiles to illustrate the different subgroups as well as determinants of anxiety levels among them in accordance with proximity to a possibility of direct exposure to military action. METHODS: A sample of Ukrainian males, in duty as conscripts to military service (n = 392, M±SD = 22.1±5.3) participated in a survey. We used the 36-Item Short Form Health Survey, and State-Trait Anxiety Inventory. In addition to psychological indices, social-demographic data were collected. To discover the number of clusters, the k-means algorithm was used, the optimal number of clusters was found by the elbow algorithm. For validation of the model and its use for further prediction, the random forest machine-learning algorithm, was used. RESULTS: By performing k-means cluster analyses, 3 subgroups were identified. High values of psychological indices dominated in Subgroup 2, while lowest values dominated in Subgroup 3. Subgroup 1 showed a more even distribution among the indices. The strength of the relevance and main determinants of the prediction of the presented model mostly consisted of mental qualities, while socio-demographic data were slightly significant. CONCLUSIONS: There is no clear relevance between proximity or even the experience of military actions and anxiety levels. Other factors, mostly subjective feelings about mental conditions, are crucial determinants of feeling anxiety.

The influence of gender, dominant lower limb and type of target on the velocity of taekwon-do front kick.

PURPOSE: The current study aimed to quantify the main influences and the interactions (joint effects) of gender, leg and type of target on the biomechanics of front kick quality. Through the quantification, we tried to identify the relevant factors related to the kick accuracy and maximum velocity for coaching practice. METHODS: A ten-camera NIR VICON MX40 motion capture system (250 Hz) was used to determine the kicking foot maximum velocity from two well-trained subject groups (8 males and 6 females). Each subject performed both left and right front kicks in a lateral standing position into the air (without a physical target), to a board, to a table tennis ball and to a training shield. The target were set on a height corresponding to a height of solar plexus of each participant. RESULTS: The results showed that all the three factors (gender, leg and type of target) have significant influences on kicking speed ( p < 0.001) and significant interaction (joint effect) was only found between gender and target ( p < 0.001). Further analysis revealed that the males' kicking maximum velocity was affected more by board, while females' one was affected by the size of the target. CONCLUSIONS: The results would seem to suggest that, for males, kick-to-a-board may be the more effective method for increasing kick quality, compared to other type of target. For females, kick-to-a-small-ball appears to be effective method for increasing kick maximum velocity.