Experimental characterization and constitutive modeling of the mechanical behavior of the human trachea

BACKGROUND AND AIMS

Cartilage and smooth muscle constitute the main structural components of the human central airways, their mechanical properties affect the flow in the trachea and contribute to the biological function of the respiratory system. The aim of this work is to find out the mechanical passive response of the principal constituents of the human trachea under static tensile conditions and to propose constitutive models to describe their behavior.

METHODS

Histological analyses to characterize the tissues and mechanical tests have been made on three human trachea specimens obtained from autopsies. Uniaxial tensile tests on cartilaginous rings and smooth muscle were performed. Tracheal cartilage was considered an elastic material and its Young's modulus and Poisson's coefficient were determined fitting the experimental curves using a Neo-Hookean model. The smooth muscle was proved to behave as a reinforced hyperelastic material with two families of collagen fibers, and its non-linearity was investigated using the Holzapfel strain-energy density function for two families of fibers to fit the experimental data obtained from longitudinal and transversal cuts.

RESULTS

For cartilage, fitting the experimental curves to an elastic model, a Young's modulus of 3.33 MPa and nu=0.49 were obtained. For smooth muscle, several parameters of the Holzapfel function were found out (C(10)=0.877 kPa, k(1)=0.154 kPa, k(2)=34.157, k(3)=0.347 kPa and k(4)=13.889) and demonstrated that the tracheal muscle was stiffer in the longitudinal direction.

CONCLUSION

The better understanding of how these tissues mechanically behave is essential for a correct modeling of the human trachea, a better simulation of its response under different loading conditions, and the development of strategies for the design of new endotracheal prostheses.

Patient-specific models of human trachea to predict mechanical consequences of endoprosthesis implantation

Nowadays, interventions associated with the implantation of tracheal prostheses in patients with airway pathologies are very common. This surgery may promote problems such as migration of the prosthesis, development of granulation tissue at the edges of the stent with overgrowth of the tracheal lumen or accumulation of secretions inside the prosthesis. Among the movements that the trachea carries out, swallowing seems to have harmful consequences for the tracheal tissues surrounding the prosthesis. In this work, a finite-element-based tool is presented to construct patient-specific tracheal models, introducing the endotracheal prosthesis and analysing the mechanical consequences of this surgery during swallowing. A complete description of a patient-specific tracheal model is given, and a fully experimental characterization of the tracheal tissues is presented. To construct patient-specific grids, a mesh adaptation algorithm has been developed and the implantation of a tracheal prosthesis is simulated. The ascending deglutition movement of the trachea is recorded using real data from each specific patient from fluoroscopic images before and after implantation. The overall behaviour of the trachea is modified when a prosthesis is introduced. The presented tool has been particularized for two different patients (patient A and patient B), allowing prediction of the consequences of this kind of surgery. In particular, patient A had a decrease of almost 30 per cent in his ability to swallow, and an increase in stresses that were three times higher after prosthesis implantation. In contrast, patient B, who had a shorter trachea and who seemed to undergo more damaging effects, did not have a significant reduction in his ability to swallow and did not present an increase in stress in the tissues. In both cases, there are clinical studies that validate our results: namely, patient A underwent a further intervention whereas the outcome of patient B's surgery was completely successful. Notwithstanding the fact that there are a lot of uncertainties relating to the implantation of endotracheal prostheses, the present work gives a new insight into these procedures, predicting their mechanical consequences. This tool could be used in the future as pre-operative planning software to help thoracic surgeons in deciding the optimal prosthesis as well as its size and positioning.

Distance Motor Learning during the COVID-19 Induced Confinement: Video Feedback with a Pedagogical Activity Improves the Snatch Technique in Young Athletes

The purpose of the present study was to investigate which of two strategies, Video Feedback with Pedagogical Activity (VF-PA) or Video Feedback (VF), would be more beneficial for the remote error correction of the snatch weightlifting technique during the confinement period. Thirty-five school aged children with at least three months of weightlifting experience were randomized to one of three training conditions: VF-PA, VF or the Control group (CONT). Subjects underwent test sessions one week before (T0) and one day after (T1) a six-session training period and a retention test session a week later (T2). During each test session, the Kinovea version 0.8.15 software measured the kinematic parameters of the snatch performance. Following distance learning sessions (T1), the VF-PA improved various kinematic parameters (i.e., barbell horizontal displacements, maximum height, looping and symmetry) compared with T0 (p < 0.5; Cohen's d = 0.58-1.1). Most of these improvements were maintained during the retention test (T2) (p<0.01, Cohen's d = 1.2-1.3) when compared withT0. However, the VF group improved only twoparameters (i.e., barbell symmetry and horizontal displacement) at T1 (p < 0.05; Cohen's d = 0.9), which were not maintained at T2. Better horizontal displacement and looping values were registered during the retention test in the VF-PA group compared with theCONT group (p < 0.05, Cohen's d = 1.49-1.52). The present findings suggest combining video feedback with pedagogical activity during the pandemic induced online coaching or physical education to improve movement learning in school aged children.

Working Memory in Overweight Boys during Physical Education Classes

This study examined the effect of small-sided football games (SSFG) and small-sided Ultimate Frisbee games (SSUFG) on working memory, response times, and feeling mood of boys with overweight. Twenty-eight boys (age 12.23 ± 1.58 years) participated in two trials during physical education lessons (20-min SSFG and 20-min SSUFG) in a counterbalanced, randomized crossover design. The response times and feeling mood were measured for all participants post-exercise through the Sternberg paradigm and feeling scale. For the response times, the paired samples t-test revealed a significantly better reaction time after SSUFG at the "One item level" of the Sternberg paradigm (p = 0.014, Hedges' g = 0.27, small effect) and (p = 0.010, Hedges' g = 0.74, medium effect), at "Three item level" (p = 0.000106, Hedges' g = 1.88, very large effect). The SSFG also showed vigor at the "Five item level" (p = 0.047, Hedges' g = 0.61, medium effect). For the feeling mood, the feeling score was significantly higher after the SSUFG session than the SSFG session and the increase in feeling scores observed after switching from SSFG to SSUFG was significantly different (p < 0.001) from the decrease observed in feeling scores after switching from SSUFG to SSFG. Therefore, the results of the study allow the teacher to introduce new sports and reflect on the motor tasks he or she proposes for boys with overweight during physical education classes.

Information Processing and Technical Knowledge Contribute to Self-Controlled Video Feedback for Children Learning the Snatch Movement in Weightlifting

Our aim in this study was to examine, via technical performance analysis and speed of execution, whether information processing and technical knowledge help explain learning benefits of self-controlled video feedback in children's weightlifting performance. We randomized 24 children (aged 10 to 12 years) into self-controlled (SC) and yoked (YK) feedback groups. Learners underwent test sessions one week before (pre-test) and one day after (post-test) six weightlifting training sessions. During each test session, we recorded kinematic parameters of snatch performance using Kinovea version 0.8.15 software. After the learning sessions, the SC group improved on most kinematic parameters (e.g., the horizontal displacement of the bar between the first and the second pulls [M_DXV = 25.42%, SD = 18.96, p = 0.003) and the maximum height reached by the bar (M_HMV = 5.51%, SD = 7.71, p < 0.05)], while the YK group improved only on the DxV (M_DXV = 19.08%, SD = 24.68, p < 0.05). In addition, the SC group showed a more advanced phase of cognitive processing compared to the YK group, and the SC group showed a superior improvement in their technical knowledge level (p < 0.001) compared to the YK group (p < 0.05). Thus, key elements to correcting motor errors in children's weightlifting through self-controlled feedback were improvements in information processing and technical knowledge.

Enhancing Time Reading and Recording Skills in First-Grade Children with Learning Difficulties Using the "Clock Motor Game"

This study aimed to explore the effect of the motor game, "Clock Motor Games", on the improvement of "Reading and Recording of Time" (RRT) in children with Grade 1 mathematical learning difficulties (MLDs). A within-school cluster-randomized intervention study was conducted with 232 children (aged 6-7 years) with limited physical education experience (0.7 ± 0.3 years). The participants were divided into two groups: a control group, which received conventional teaching on time without any additional motor activities, and an experimental group, which incorporated the concept of time with the "Clock Motor Game", for 3 weeks. The Clock-Reading Test was administered before the intervention (T0), immediately after each session (T1), and five weeks after the intervention (T2) in both groups. The results demonstrated that the experimental group exhibited significantly greater improvements in RRT performance compared to the control group (U = 4416.5; p < 0.001; r = 0.3; medium effect). Additionally, the experimental group was more likely to show progress and less likely to experience regression or stagnation compared to the control group (25% vs. 38.4%). The findings suggest that practicing "Clock Motor Games" can positively contribute to the RRT ability in children with Grade 1 MLD.

The Feeling of Pleasure for Overweight Children during Different Types of Physical Activity

The feeling of pleasure during physical education (PE) could increase with physical activity participation and adherence for overweight children. While traditional games are known to have positive benefits on motor skill development, especially for children with poorer motor skills, and on the body mass of children, little is known about overweight children's feelings of enjoyment when playing these games. To identify a program of physical activity appreciated by overweight children, we tested the effect of different activities, namely soccer (SO), shot put (SP), and traditional motor games (TMGs), on the feelings of pleasure for 28 overweight male children (aged 12.11 ± 0.63 years, BMI 26.89 ± 0.15 kg·m-2) participating in a 3-month cross-over study. To measure affective responses to exercises, we applied a validated feeling scale. The data were collected during eight PE lessons, which were organized for each cycle taught. Post hoc pairwise comparisons revealed a significant difference (Z = -3.195, p < 0.01) between the mean feeling score reported after the SO cycle (2.48 ± 0.41) and that after the TMGs (3.04 ± 0.32). A similar significant difference (Z = -3.304, p < 0.01) was found between the mean feeling scores reported after the SP cycle (2.27 ± 0.32) and the TMGs (3.04 ± 0.32). There was no significant difference between the mean feeling scores reported after the SO (2.48 ± 0.41) and SP cycles (2.27 ± 0.32). In conclusion, the findings of the present study suggest that TMGs may have beneficial effects on the feelings of pleasure for overweight children. Therefore, TMGs might potentially be considered as an alternative to conventional physical activities.

The Impact of Exercise Training Intensity on Physiological Adaptations and Insulin Resistance in Women with Abdominal Obesity

Abdominal obesity has emerged globally as a major public health issue due to its high prevalence and morbidity. The benefits of physical exercise among the obese population are well documented. However, the optimal exercise intensity for reducing body fat and preventing insulin resistance and metabolic disorders is still under debate. This study aimed to examine the effects of three different intensities of combined endurance and strength training programs on anthropometric variables, physiological and muscular adaptations, and insulin sensitivity. Forty-three obese young women (age 26.4 ± 4.7 years, BMI 33.1 ± 2.5 kg/m2) were randomly assigned to one of four groups: a control group (G0), a moderate-intensity training group (G50, exercising brisk walking at 50% heart rate reserve HRR), a high-intensity training group (G75, exercise jogging at 75% HRR), and an alternated-intensity training group (G50/75, exercise brisk-walking/jogging at 50−75% HRR) with additional strength training once a week for each group. Body composition, waist circumference (WC), fasting blood glucose, insulin sensitivity and resistance (Homa-IR), resting heart rate (RHR), 6-min walk distance (6MWD), 1-repetition maximum (1-RM), and time to exhaustion (TTE) at 45% and 75% maximal voluntary contraction (MVC) for both the flexor and extensor muscle groups of the knees, were recorded before and after three months of exercise training. All training groups showed significant decreases in body mass, BMI, total body fat, body fat percentage, WC, abdominal and visceral mass (p < 0.001), with a greater reduction of body mass and BMI in G75 (p < 0.05). Lean mass increased significantly only in G50/75 (p < 0.05). The insulin sensitivity and Homa-IR decreased in the three training groups (p < 0.01), with greater enhanced resistance in G50 compared to G75 and G50/75 (p < 0.05). In contrast, there were no pre-post changes in all groups for fasting blood glucose (p > 0.05). 1-RM and TTE of the knee flexor and extensor muscles were improved in the three groups (p < 0.01), with greater improvement in G50/75 for 1RM and G75 in most of the TTE parameters (p < 0.05). RHR decreased and 6MWD increased significantly in the three training groups (p < 0.01), with greater 6MWD improvement in G75 (p < 0.05). In conclusion, the three training intensities seem to generate benefits in terms of body composition, physiological and muscular adaptations, and insulin resistance. High training intensity resulted in greater improvements in body mass, BMI, and endurance and strength, whereas moderate training intensity resulted in greater improvements of insulin resistance and homo-IR. Following alternate-intensity training, greater improvements were observed in lean mass and maximal strength performance.

Listening to Music and Playing Activities during Recreation between Lessons Regenerate Children's Cognitive Performance at Different Times of Day

The interruption of learning processes by breaks filled with diverse activities is common in everyday life. The purpose of this study was to investigate the effects of the time of day (TOD) of playing with or without music during recess on cognitive performance regeneration among students aged between 11 and 12. Twenty-seven volunteer children (aged 12 ± 0.6 years) completed four trials at 09h45, 10h15, 14h45, and 15h15. Each test session was separated by recreation between classroom lessons with different conditions: music only (MSC), playing only (PAY), music and playing (MSC-PAY), and without music and playing (NON). During each session, oral temperature, reaction time (RT), and constant attention (CA) were measured. For all parameters, the ANOVA revealed a significant effect of the type of activity. However, no significant effect of the TOD and no significant interaction of type of activity × TOD were reported. The Bonferroni post hoc test revealed that Δ-core temperature was significantly higher during PAY and MSC-PAY compared to NON (p < 0.05). Δ-attention was higher during MSC, PAY, and MSC-PAY compared to NON (p < 0.001). Δ-attention was lower during MSC (p < 0.05), PAY (p < 0.05), and MSC-PAY (p < 0.01) compared to NON. Therefore, playing, listening to music, and playing while listening to music at recess improve the child’s ability to regenerate cognitive performance regardless of the TOD.

Peer-to-peer online video feedback with pedagogical activity improves the snatch learning during the COVID-19-induced confinement in young weightlifting athletes

The lack of training caused by the COVID-19 pandemic could have significant consequences on the performance and health of athletes. The aim of the present study was to test the effects of two innovative distance education methods on improving motor skills in weightlifting. We randomized 35 children (aged 10 to 12) into groups of peer-to-peer online video feedback with a pedagogical activity (P-VF-PA), peer-to-peer online video feedback only (P-VF), and control group (CONT). Learners underwent a test one week before (T0) and one day after (T1) an eight-session training intervention and a retention test session a week later (T2). Kinovea was used to measure the kinematic parameters of the snatch performance. After the distance learning sessions, the training with the P-VF-PA method improved most of the kinematic parameters compared to the P-VF method, and the advantages derived from its application persisted in the retention test (e.g., the difference between the right side and left side distances of the bar trajectory Diff-Tr (T1 vs. T0: 42.32 ± 41.33%, Hedges’ g = 1.16, p  < 0.01; T2 vs. T0: 37.82 ± 37.57%, Hedges’ g = 1.37, p  < 0.05)). In conclusion, distance motor learning based on the P-VF-PA method improved performance and technical knowledge of the snatch in 10–12 years weightlifters.

Short-Term Total Tamponade with Perfluorocarbon Liquid and Silicone Oil in Complex Rhegmatogenous Retinal Detachment with Severe Proliferative Vitreoretinopathy

Background

To evaluate retinal reattachment, visual functional results, and complications rates after total tamponade (TT) with perfluorocarbon liquid (PFCL) and silicone oil (SO) for 2 days followed by PFCL-SO exchange in complex retinal detachment (RD).

Methods

Retrospective study including 52 consecutive eyes with complex RD and advanced proliferative vitreoretinopathy, who underwent vitrectomy with TT. Patients underwent first surgery by 25-Gauge vitrectomy and partial PFCL-SO exchange (approximately 60% PFCL 40% SO fill) followed by second surgery with extraction of the PFCL and complete SO fill.

Results

After a mean follow-up period of 25.15 ± 6.6 months, the retina remained reattached in 48/52 eyes (92.3%) including 28 eyes (58.3%) without SO and 20 eyes (41.7%) with prolonged SO tamponade. Visual acuity improved in 45 eyes (86.6%) (P<0.001), remained stable in 4 eyes (7.7%) and decreased in 3 eyes (5.7%). Complications consisted in mild anterior chamber inflammation in 10 eyes, ocular hypertension in 12 eyes, and cataract in 10 eyes.

Conclusion

Two-day TT with PFCL and SO may be considered in complex RD with advanced proliferative vitreoretinopathy especially in monocular patients. Further studies with longer follow-up period and retinal electrophysiologic assessment may be needed.

The effect of blended learning on tacking technique improvement in preteen sailing

This study investigates the effects of two blended learning strategies on improving tacking technique in Optimist sailing among children aged 11-13. Specifically, it compares video feedback with online written instructions (BLIV) and online written instructions only (BLI). Thirty-one children aged 11-13 years old were randomly divided into three groups with different learning strategies: BLIV, BLI, and a control group (CONT). Each participant completed a pre-test (T0) and a post-test (T1) following a four-session learning unit. Evaluations focused on (i) tacking technique, rated by three sailing coaches, (ii) execution time measured using Kinovea software, and (iii) theoretical knowledge, assessed through a test involving error detection in a novice's video. Statistical analyses revealed that the BLIV group demonstrated significant improvements at T1 in technical performance (p < 0.001, Hedges' g = 2.71), execution time (p = 0.006, Hedges' g = 1.14), and theoretical knowledge (p < 0.001, Hedges' g = 1.98), outperforming the BLI and CONT groups in tacking performance. These findings underscore the effectiveness of the BLIV strategy in enhancing learning outcomes in environments with high levels of sensory distractions. By facilitating a deeper understanding of technique and error correction, this technology-enhanced instructional approach shows promise as a valuable tool for teaching complex motor skills in sports. The research findings suggest that BLIV demonstrates significant improvements in sailing skills, execution time, and theoretical understanding among young sailors compared to other methods. The study advocates for the integration of blended learning approaches that combine in-class activities with delayed video-based feedback delivered online to enhance skill acquisition young sailors.

Exploring the impact of verbal encouragement on strength, endurance, and psychophysiological responses: enhancing teaching strategies in sports science education

Introduction

This study investigates the effects of teacher verbal encouragement (VE) on strength, endurance, and psychophysiological responses, aiming to enhance teaching strategies in sports science education.

Methods

Forty-eight sports science students, aged 21.3 ± 0.5 years, participated in this study. The sample was randomly divided into two groups, and a counterbalancing procedure was implemented. Participants completed strength and endurance testing sessions under normal conditions in the first week and repeated similar sessions in the second week with teacher VE. Strength was assessed using the 1RM bench press, squat, and deadlift tests, while endurance was evaluated through 8-minute time trials (8MTT: burpees, box jumps, hand-release push-ups, and sit-ups). Perceived exertion and physical activity enjoyment were investigated using self-reporting instruments.

Results

The key findings showed that participants lifted greater weights in the 1RM bench press (p < 0.01; r   = 0.45, medium to large effect), squat (p < 0.001; Hedges' g = 1.36, large effect), and deadlift tests (p < 0.001; r = 0.79, large effect) and completed a greater number of repetitions in the 8MTT (p < 0.001; r = 0.87, large effect) under VE. Perceived exertion was found to be lower under normal conditions (p < 0.05; r = 0.29, small effect), yet physical activity enjoyment significantly increased under VE (p < 0.05; r = 0.81, large effect).

Discussion

In conclusion, implementing teacher VE in sports science education can contribute to improved strength and endurance training outcomes and student psychophysiological response.

The Good Behaviour Game: Maintaining students' physical distancing in physical education classes during the COVID-19 pandemic

Background

Maintaining physical distancing is one of the most important steps to enforce in educational institutions to reduce the risk of transmission of COVID-19. However, close proximity and physical contact between students are often considered 'normal' during physical education (PE) classes, making it challenging for PE teachers to ensure physical distancing.

Objectives

The aim of this study was to assess the effect of the implementation of the Good Behaviour Game (GBG) in maintaining physical distancing in PE settings in times of the COVID-19 pandemic.

Method

In a quasi-experimental design, two groups were separately designated as an experimental group (20 classes involving 220 students) and a control group (20 classes involving 231 students). They were all enrolled in the eighth grade of the Tunisian education system. In the experimental group, the PE teacher managed physical distancing by administering the GBG. Physical distancing was evaluated by direct observation of videos of filmed PE sessions using a code grid. It was measured twice for the two groups using Kinovea software.

Results

Quantitative data analyses showed that the level of maintaining physical distancing increased after the GBG intervention in the experimental group (p < .001). Furthermore, greater percent changes between pre- and post-intervention were identified in the experimental group compared to the control group (120% vs 1%, respectively).

Conclusion

The GBG was effective in ensuring students' physical distancing when implemented in PE settings.

Verbal encouragement during strength and endurance assessments: The gender of the encourager can matter

Research supports using verbal encouragement (VE) to improve performance in strength and endurance exercises. However, there is still a gap in understanding how the gender of the coach or teacher affects the efficacy of VE. This study examines whether the teacher's gender influences performance in strength and endurance assessments among male and female student-athletes. In a crossover randomized controlled design, 16 male and 16 female student-athletes (mean age 20.9 ± 0.9 years) completed one-repetition maximum (1RM) tests in Squat, Deadlift, and Bench press, as well as 8-min time trials (8MTT), under normal conditions and with VE-first from a male teacher and then from a female teacher. A counterbalancing procedure over eight weeks controlled for confounding factors related to exposure order (without and with VE), test order (1RM and 8MTT), and time of day (morning and afternoon). Male student-athletes showed significant improvements nearly across all tests (p < 0.01 to p < 0.001) under VE from both male and female teachers, with no significant interaction "Condition × Teacher Gender" effect (p > 0.05). Female student-athletes also demonstrated significant improvements (p < 0.05 to p < 0.001), with an interaction effect favoring VE from the female teacher (p < 0.05 to p < 0.01) in all tests except the squat. In conclusion, female student-athletes demonstrated statistically significant performance improvements with female teacher VE. Male student-athletes also showed improvements, though not statistically significant, with female teacher VE. It is therefore recommended that stakeholders in athletic clubs and educational institutions take into account gender when assigning coaches/teachers to mixed-gender groups, particularly for strength and endurance training, in order to optimize the efficacy of VE. This research provides novel data supporting the increased representation of women in coaching and physical education, specifically in relation to VE efficacy.

[Left paraduodenal internal hernia. A new case report]

OBJECTIVE

Remind the clinical and radiological features of the internal left para duodenal hernia.

MATERIALS AND METHOD

We report the case of a left para duodenal hernia in a 30 years old woman who suffers of an acute abdominal pain explored by ultra sonography, barium upper gastro intestinal radiography, computed tomography and MRI.

RESULTS

CT shows a well limited intra abdominal mass composed of small bowel wrapped in a bag of peritoneum, and moving to the left the mesenteric axis

CONCLUSION

Left internal para duodenal hernia is a rare phenomenon and is frequently non diagnosed. Spiral computed tomography allows us now, to make the diagnostic with a good sensitivity in the majority of cases.