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A sedentary lifestyle, characterised by a lack of physical activity, negatively influences Body Mass Index (BMI). BMI may be related to the prevalence of flat feet. This study aims to observe the occurrence of flat feet in young children and determine its association with BMI. Additionally, it aims to analyse foot loading in the forefoot, midfoot and rearfoot. Dynamographic records of children (N = 142; age = 10.3 ± 0.21 years) were collected during walking, and foot-type evaluations were conducted using a force plate. A normal foot type was observed in 44% of children (BMI 16.0 ± 2.3 kg/m2). Flat feet were observed in 54% of children (BMI 18.4 ± 4.3 kg/m2). A high foot arch was observed in only 2% of children (BMI 16.0 ± 1.3 kg/m2). Children with flat feet had higher BMI values than those with normal feet. The contact time and maximal vertical force in the forefoot and rearfoot were similar in children with normal and flat feet. Significantly higher pressure values were observed in the midfoot zone of children with flat feet. Regression analysis results showed that in children with flat feet, there is a decrease in forefoot loading and an increase in midfoot loading with increasing BMI. This trend was not observed in children with normal feet. We recommend incorporating exercise interventions at this age to prevent pain and promote willingness to engage in physical activity. Higher BMI values indicate an increased risk for the prevalence of flat feet.
- MeSH
- chůze fyziologie MeSH
- dítě MeSH
- index tělesné hmotnosti * MeSH
- lidé MeSH
- noha (od hlezna dolů) fyziologie anatomie a histologie MeSH
- plochá noha * epidemiologie MeSH
- sedavý životní styl MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: The interaction between joint kinematics and kinetics is usually assessed by linear correlation analysis, which does not imply causality. Understanding the causal links between these variables may help develop landing interventions to improve technique and create joint-specific strengthening programs to reduce reaction forces and injury risk. OBJECTIVE: Therefore, the aim of this study was to analyze the causal interaction between lower limb sagittal kinematics and vertical ground reaction force (VGRF) during single-leg jump landing in children who are jumpers (volleyball and gymnastics) and non-jumpers, using the causal empirical decomposition method. Our hypothesis is that children who participate in jumping sports, compared to those who do not, employ a different joint strategy to regulate ground reaction forces during landing, particularly at the ankle level. METHODS: Two groups were compared: the jumpers group (n = 14) and the non-jumpers (control group, n = 11). The causal interaction between sagittal kinematics and VGRF was assessed using ensemble empirical mode decomposition (EEMD) and time series instantaneous phase dependence in bi-directional causality. The relative causal strength (RCS) between the time series was quantified as the relative ratio of absolute cause strength between kinematics and VGRF. RESULTS: A significant interaction between joint and group was found for RCS (p = 0.035, η2p = 0.14). The post-hoc analysis showed the jumpers group had higher ankle-to-VGRF RCS than the control group (p = 0.017, d = 1.03), while in the control group the hip-to-VGRF RCS was higher than the ankle-to-VGRF RCS (p = 0.004, d = 0.91). CONCLUSION: Based on the causal decomposition approach, our results indicate that practicing jumping sports increases the causal effect of ankle kinematics on ground reaction forces in children. While non-jumper children rely more on the hip to modulate reaction forces, jumper children differ from non-jumpers by their greater use of the ankle joint. These findings could be used to develop specific training programs to improve landing techniques according to practice level, potentially helping to reduce the risk of injury in both athletes and non-athletes.
- MeSH
- biomechanika fyziologie MeSH
- dítě MeSH
- dolní končetina fyziologie MeSH
- gymnastika * fyziologie MeSH
- hlezenní kloub fyziologie MeSH
- lidé MeSH
- volejbal fyziologie MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Relationship of bioelectrical properties of human body and vertical jump performance is still unexplored, especially in non-athletic population. The aim of this study is to evaluate association of bioelectrical impedance results with mean force and power of the lower limbs in non-athletic young adults, and to evaluate differences between sexes in both bioelectrical impedance results and vertical jump performance. The cross-sectional study included 75 healthy non-athletic college students (40 women and 35 men aged 19-24 years). Whole-body bioelectrical impedance analysis was performed for phase angle and body composition. Force and power of lower limbs were assessed by vertical jump test. There is difference between sexes in both body composition and vertical jump performance. Along to higher content of muscles (47.5% vs 40.5%) and lower content of fat in the body (19.25% vs 28.19%), men also had higher mean force (3691.75 N vs 2351.44 N) and explosive power of the lower limbs (5627.19 W vs 2752.21 W) compared to women. Leg force and power are in correlation with body composition and with phase angle obtained by bioelectrical impedance analysis. Difference between sexes in force and power of the legs persists even after adjustment for body composition.
Vertical drop jump consists two landings of which the first one is the most frequently analysed one. Aim of this paper was to compare kinetic patterns between first and second landings and dominant and non-dominant leg between landings by analysing force-time curves and their variability across landings. 44 top level female handball players (N = 25) and volleyball players (N = 19) of average age 24 ± 4 y, height 181.1 ± 7.8 cm and weight 72.4 ± 8.0 kg agreed to participate in this study. Each subject completed 4 successful drop jumps from an initial height of 30 cm on two parallel ground reaction force platforms. Force-time curve analysis revealed significant differences (p < .05) in certain parts of the cycle between the two landings for each leg. Moreover, significant differences (p < .05) were found between dominant and non-dominant leg solely in the second landing. Second landings were shown to be significantly more variable (p < .001) than the first ones. Results of the current study confirm previous findings of different neuromuscular pathways used in two landings thus indicating a possible increased risk of ACL injury which highlights the importance of second landing analysis in drop vertical jump.
The aim of the present study was to examine the effects of attentional focus instructions on acute changes in the transverse relaxation time (T2) of the femorotibial cartilage and in cartilage volume during repeated drop-jump landings. Ten healthy females (Mage = 20.4 ± 0.8 years) performed a drop landing task from a 50 cm high box over the course of 3 days (50 repetitions each day) across three attentional focus conditions: external focus (EF: focus on landing as soft as possible), internal focus (IF: focus on bending your knees when you land), and control (CON: no-focus instruction), which was counterbalanced across focus conditions. T2 mapping and the volume of femorotibial cartilage were determined from magnetic resonance imaging scans at 1.5 T for the dominant knee before and after completing the drop landings in each attentional focus condition per day. Results indicated a smaller change in cartilage T2 relaxation time and volumetry in the central load-bearing lateral cartilage under the EF, compared to IF and CON. Moreover, the change in T2 and cartilage volume was greater for lateral tibial cartilage as compared to femoral cartilage and was independent of attentional focus instructions. No significant acute quantitative changes were observed in the medial compartment. The peak vertical ground reaction force was found to be the lowest under the EF, compared to IF and CON. These findings suggest that external focus of attention may reduce cartilage load, potentially aiding in the control or management of cartilage injuries during landing in female athletes.
- MeSH
- biomechanika MeSH
- kloubní chrupavka * fyziologie diagnostické zobrazování MeSH
- kolenní kloub fyziologie MeSH
- lidé MeSH
- magnetická rezonanční tomografie * MeSH
- mladý dospělý MeSH
- plyometrická cvičení MeSH
- pozornost * fyziologie MeSH
- tibie fyziologie diagnostické zobrazování MeSH
- zatížení muskuloskeletálního systému * fyziologie MeSH
- Check Tag
- lidé MeSH
- mladý dospělý MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
PURPOSE: Subretinal (SR) injection in porcine models is a promising avenue for preclinical evaluation of cell and gene therapies. Targeting of the subretinal fluid compartment (bleb) is critical to the procedure, especially if treatment of the cone-rich area centralis is required (i.e., visual streak [VS] in pigs). To our knowledge, this study is the first to investigate the influence of injection site placement on VS involvement in the pig eye. METHODS: We performed 23-gauge pars plana vitrectomy followed by SR injection in 41 eyes of 21 animals (Sus scrofa domesticus). In 27 eyes (65.9%), the injection site was placed superior to the VS, and in 14 eyes (34.1%) it was placed inferior to it. Using intraoperative imaging, blebs were classified based on their propagation behavior relative to the VS. RESULTS: In 79% of cases, blebs from inferior injection sites developed away from the VS, exhibiting a mean ± SEM vertical anisotropy (AP) of 0.67 ± 0.11. In contrast, blebs from superior injection sites tended to develop toward the VS with an AP of 1.27 ± 0.18 (P = 0.0070). Blebs developed away from the VS in only 41% of injections (P = 0.0212). Inferior blebs were orientated close to 0° (horizontal), whereas superior blebs displayed varied orientations with a mean angle of 56° (P = 0.0008). CONCLUSIONS: Bleb propagation was anisotropic (i.e., directionally biased) and dependent on injection site placement. Superior injection sites led to superior VS detachment. Morphological analysis suggested increased adhesion forces at the VS and superior vascular arcades. This study will aid the planning of surgeries for targeted subretinal delivery in pig models.
BACKGROUND: High-velocity concentric actions can be negatively impacted by cumulative fatigue during plyometric training. Reducing vertical ground reaction forces (GRF) upon landing could decrease eccentric demands, potentially minimizing fatigue, maintaining concentric performance, and benefiting concentric training adaptations. Therefore, this study examined the effect of intentionally higher and lower landing vertical GRF on the ability to sustain concentric jumping performance. METHODS: Twenty men (25.2±3.5 years) performed 30 maximal effort jumps over a 50 cm hurdle (high-landing GRF) and onto a 50 cm box (low-landing GRF), on two separate occasions in a counter-balanced order. Jumps were measured using two force platforms (one for takeoff and one for landing) and a linear position transducer. The 30 jumps were divided into 5 groups of 6 repetitions, and the mean value for each group was analyzed. RESULTS: There was no significant condition × repetition group interaction for any parameters, indicating that the greater landing GRF during hurdle jumps did not negatively affect concentric jump performance throughout the 30 jumps. Concentric velocities and jump height were significantly greater during box jumps compared to hurdle jumps. CONCLUSIONS: Thirty maximal-effort jumps did not cause fatigue-related decrease of performance, independent of jump type (i.e., the magnitude of landing GRF). Although, reduced vertical GRF upon landing appears to have a neutral-to-positive effect on concentric jumping performance. Therefore, reducing landing GRF, such as by using BJs, could acutely augment jumping performance and help to reduce cumulative training load.
- MeSH
- biomechanika MeSH
- dospělí MeSH
- lidé MeSH
- mladý dospělý MeSH
- plyometrická cvičení * MeSH
- sportovní výkon * fyziologie MeSH
- svalová únava fyziologie MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
The aim of this study was to examine the effect of attentional focus instructions on the biomechanical variables associated with the risk of anterior cruciate ligament injury of the knee joint during a drop landing task using a time series analysis. Ten female volleyball players (age: 20.4 ± 0.8 years, height: 169.7 ± 7.1 cm, mass: 57.6 ± 3.1 kg, experience: 6.3 ± 0.8 years) performed landings from a 50 cm height under three different attentional focus conditions: (1) external focus (focus on landing as soft as possible), (2) internal focus (focus on bending your knees when you land), and (3) control (no-focus instruction). Statistical parameter mapping in the sagittal plane during the crucial first 30% of landing time showed a significant effect of attentional focus instructions. Despite the similarity in landing performance across foci instructions, adopting an external focus instruction promoted reduced vertical ground reaction force and lower sagittal flexion moment during the first 30% of execution time compared to internal focus, suggesting reduced knee loading. Therefore, adopting an external focus of attention was suggested to reduce most biomechanical risk variables in the sagittal plane associated with anterior cruciate ligament injuries, compared to internal focus and control condition. No significant differences were found in the frontal and horizontal planes between the conditions during this crucial interval.
- MeSH
- biomechanika fyziologie MeSH
- kolenní kloub * fyziologie MeSH
- lidé MeSH
- mladý dospělý MeSH
- poranění předního zkříženého vazu patofyziologie MeSH
- pozornost * fyziologie MeSH
- volejbal * fyziologie MeSH
- Check Tag
- lidé MeSH
- mladý dospělý MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Guanine quadruplex (GQ) is a noncanonical nucleic acid structure formed by guanine-rich DNA and RNA sequences. Folding of GQs is a complex process, where several aspects remain elusive, despite being important for understanding structure formation and biological functions of GQs. Pulling experiments are a common tool for acquiring insights into the folding landscape of GQs. Herein, we applied a computational pulling strategy─steered molecular dynamics (SMD) simulations─in combination with standard molecular dynamics (MD) simulations to explore the unfolding landscapes of tetrameric parallel GQs. We identified anisotropic properties of elastic conformational changes, unfolding transitions, and GQ mechanical stabilities. Using a special set of structural parameters, we found that the vertical component of pulling force (perpendicular to the average G-quartet plane) plays a significant role in disrupting GQ structures and weakening their mechanical stabilities. We demonstrated that the magnitude of the vertical force component depends on the pulling anchor positions and the number of G-quartets. Typical unfolding transitions for tetrameric parallel GQs involve base unzipping, opening of the G-stem, strand slippage, and rotation to cross-like structures. The unzipping was detected as the first and dominant unfolding event, and it usually started at the 3'-end. Furthermore, results from both SMD and standard MD simulations indicate that partial spiral conformations serve as a transient ensemble during the (un)folding of GQs.
The genus Acomys is of growing importance to many research fields. Previous research has shown that individuals differ when exploring new environments and that these behavioural strategies are consistent in time. In this study, we subjected 60 commensal Acomys cahirinus (37 males, 23 females) to a series of seven tests (free exploration, forced exploration under bright illumination, forced exploration under low illumination, hole board test, vertical activity test, elevated plus maze, and voluntary wheel running) to acquire independent behavioural traits and investigate whether and how personality develops in spiny mice. The full series of experiments was performed twice during ontogeny: once in the sub-adult stage (tested at 62-72 days of age) and once in the adult stage (102-112 days of age). We found that behaviour of the animals was repeatable both within (range of R values from 0.155 to 0.726) and across the two life-stages (0.238 to 0.563). While the structure of behaviour in adults was rather clear, it had not been fully crystalized in sub-adults, suggesting personality changes during maturation, even though some individual traits might be repeatable across ontogeny. Notably, the most consistent behavioural traits across the different tests were jumping and rearing, which are not commonly reported.
- MeSH
- kognice MeSH
- Murinae MeSH
- osobnost MeSH
- pátrací chování * MeSH
- pohybová aktivita * MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
