Tamás Horváth

Background: The breathing cycle consists of abdominal breathing (AB), for which the diaphragm is responsible, and thoracic breathing (TB), generated by the intercostal muscles. Contraction of the two portions of the diaphragm accounts for 80% percent of inspiration. While bilateral diaphragmatic paralysis causes severe shortness of breath, hemidiaphragm paralysis (HDP) gives fewer symptoms at rest, making it difficult to recognize and diagnose. Because this condition is rare, little is known regarding its consequences on breathing efficiency. Hypothesis: Based on previous studies, we hypothesized that body positions substantially affect the efficiency of breathing in a patient with unilateral hemidiaphragm paralysis and the corresponding physiological parameters. Aims: To measure and compare the amplitudes of abdominal and chest movements in different body positions in an individual with HDP and measure parameters indicating breathing efficiency. Patient and Methods: The patient had HDP due to iatrogenic phrenic nerve injury. Changes in the circumference of the abdomen and chest were measured during inhalation and exhalation with respiratory plethysmography belts (placed on standardized reproducible positions on the chest and abdomen) in different body positions: sitting (SI), standing (ST), lying (SU) and prone (PR). Breathing frequency was calculated, and blood oxygen saturation (SpO₂) was measured with a pulse oximeter. Results: The percentage (%) contributions of abdominal breathing were SI: 16.0; ST: 50.3; SU: −53.5; PR: 1.1. A negative sign shows paradoxical breathing. Blood oxygen saturation (SpO₂) in the four positions was SI: 93%; ST: 93%; SU: 82%; and PR: 82%, whereas the respiratory rate (1/min) was SI:19.4; ST: 15.0; SU: 37.5; PR: 35.9. Conclusions: Body position markedly influences the relative contributions of abdominal and thoracic breathing and overall respiratory efficiency in patients with hemidiaphragm paralysis; abdominal breathing in the supine and prone positions is greatly reduced leading to decreased blood oxygen saturation, a compensatory increase in respiratory rate, and severe dyspnea even at rest.

Background: In patients with severe atherosclerotic internal carotid artery stenosis (ICAS), the capacity of cerebral vasoreactivity (CVR)—an independent risk factor for cerebral ischemia—is reduced, and dysregulation of arterial blood pressure (ABP) may also be present. Thus, this study assessed the relationship between changes in cerebral blood flow velocity (BFV) in response to vasoactive stimuli (as measured by transcranial Doppler (TCD)), characterizing CVR and cardiovascular autonomic nervous system (CANS) function. Methods: Common carotid artery compression (CCC n = 26), hyperventilation (HV) and breath-holding (BH) tests (n = 31), and the Valsalva maneuver (VM n = 34) were used to assess CVR in patients with ICAS. In the middle cerebral arteries, BFV was monitored by TCD, whereas ABP was registered non-invasively. For statistical analysis, validated indices describing CANS function—namely, sympathetic index (SI), pressure recovery time (PRT), and Valsalva heart rate ratio (VHRR)—were selected based on the VM response. Several parameters were defined in order to evaluate CVR responses, including cerebral arterial resistance (CAR = ABP/BFV), which was correlated with the CVR indices using Spearman’s pairwise correlation and canonical correlation. Results: A significant correlation was found between several CVR indices of the HV-BH and VM tests and CANS indices of VM using Spearman’s pairwise correlation test. Regarding the HV-BH CVR and CANS indices of VM, a significant correlation was found between CAR values until it reached its maximum on the to-be-operated side (CAR_{timetomaxICAop}) and VHRR (p = 0.041). A significant correlation was also found between the time elapsed until the CAR minimum value (CAR_{timetominICAop}) and SI (p = 0.019). Concerning the CVR and CANS indices of the VM, a significant correlation was found between cerebrovascular Valsalva ratio on the to-be-operated side (CVAR_ICAop) and PRT (p = 0.002). Canonical correlation analysis confirmed that impairments of CANS and CVR may be associated. Conclusions: In patients with severe ICAS, the potentially concomitant dysregulation of cerebrovascular reactivity and the cardiovascular autonomic nervous system can further increase cerebral ischemic risk.

Background: Myocarditis in children is strongly related to earlier viral infections. SARS Cov-2 virus (COVID-19) infection is often associated with myocarditis in adults. Athletes are more prone to develop severe myocarditis in relation to viral infections due to the increased cardiac load required by sport activities. It is also known that certain SARS Cov-2 virus vaccines increase the incidence of myocarditis among young athletes. Aim: Thus, the aim of the present study was to retrospectively assess the cardiovascular status of non-vaccinated, young, competitive athletes recovering from COVID-19 disease. Methods and Study sample: Data from 108, competitive young athletes (13–17 years old, 50 girls, 58 boys) participating in examinations prior returning to regular sports activity were collected. All participant has documented COVID-19 infection with varying disease severity. The cardiovascular diagnostic evaluation consisted of oscillometric blood pressure measurements, 12-lead electrocardiograms, transthoracic echocardiography, and measuring plasma high-sensitive troponin-I levels. Results: Systolic and pulse pressures were ∼10 mmHg higher in boys compared to girls (systolic pressures: 120.8 ± 10.8 vs. 111.6 ± 10 mmHg, pulse pressures: 49.8 ± 11.8 vs. 41.8 ± 10.7 mmHg), whereas diastolic and mean blood pressures were not different between sexes. 3 asymptomatic subjects (1 girl and 2 boys) had slightly elevated plasma levels of troponin-I (187, 122, 62 ng L ⁻¹ ). The diagnostic modalities used did not detect any cardiac pathological changes. Cardiac MRI examinations in the 3 cases did not show signs of myocarditis. In all three cases troponin-I elevations spontaneously returned to normal range at the follow-up. Mild post-Covid symptoms were present in 24% of the sample. Conclusions: The data of the present study suggest that 1) confirmed myocarditis after recovering from COVID-19 disease in non-vaccinated young competitive athletes was not present, 2) the elevated troponin-I levels in three athletes were unlikely due to COVID-19 infection. Thus, based on the findings of the present study and data from other studies, we conclude that prevalence of myocarditis related to COVID-19 virus infection does not differ substantially from that of other (non-Covid) viral infections thus the return to sport activity testing protocols should be similarly applied.

Heart rate (HR) monitoring is a practical method for assessing internal load (IL). However, it remains unclear for which age group HR would be an appropriate predictor of IL considering the relationship with external load (EL). Thus, this study aims to evaluate the relevance and applicability of HR monitoring by exploring the relationship between EL and IL among U16 soccer players. EL was measured using global positioning system (GPS) data, while IL was assessed through training impulse (TRIMP), Edward’s TRIMP, HR exertion, rate of perceived exertion (RPE), and session-RPE (s-RPE). Nineteen (N = 19) male footballers from an elite football academy participated, with data collected from 50 training sessions and 11 matches. In the analysis of the training sessions, TRIMP demonstrated a near-perfect correlation with total distance (TD) (p < 0.001), and eTRIMP correlated strongly with TD (r = 0.82) and player load (r = 0.79). HR exertion also correlated significantly with TD, medium-speed running, decelerations, inertial movement analysis (IMA) events, and player load (p < 0.001). In matches, a large correlation was observed between TRIMP and TD (r = 0.73), while the strongest correlation was between RPE and s-RPE with TD and PL (p < 0.001). Furthermore, TD emerged as the best GPS-derived predictor of both TRIMP and HR exertion in training contexts. These findings provide evidence for the validity and usability of heart rate-based and RPE-based measures to indicate IL in U16 soccer players. Future research should focus on contextual factors in exploring the relationship between EL and IL.

Background and Aims: Decreased cerebrovascular reactivity (CVR) in patients with significant internal carotid artery stenosis (ICAS ≥ 70%) is an independent risk factor for cerebral infarction. To evaluate CVR, changes in cerebral perfusion pressure and blood flow velocity (BFV) of the middle cerebral artery (MCA) can be estimated by CO₂- (hyperventilation—HV and breath-holding—BH) and pressure–flow-based (Common Carotid Artery Compression—CCC and Valsalva Maneuver—VM) stimuli. We used a multimodal approach to characterize CVR in patients before carotid endarterectomy (CEA). Methods: HV, BH, CCC, and VM tests were performed on 31, 26, and 34 patients. BFV of MCAs was monitored by transcranial Doppler, and continuous arterial blood pressure was registered non-invasively. CVR was compared between the operated significantly stenotic and the contralateral sides. Results: The extent of HV- and BH-induced CVR was similar, but the time to the lowest HV-induced BFV was shorter on the side with significant ICAS. The response to CCC was sensitive to hemodynamic asymmetry in the transient hyperemic response ratio and in the cumulative change in the (mean arterial blood pressure)/(mean BFV) ratio. In VM, the slope of BFV increased in the ascending (2b) phase, and the time to overshoot correlated with the side of the stenosis. Conclusions: These results suggest that in patients with significant ICAS, in addition to CO₂ reactivity measurements, a more complex estimation of CVR, by using hemodynamic tests (CCC and VM), should also be used to better quantify cerebral ischemic risk.

Heart rate (HR) monitoring is a practical method for assessing internal load (IL). However, it remains unclear that from which age group HR would be appropriate predictor of IL considering the relationship with external load (EL). Thus, this study aims to evaluate the relevance and applicability of HR monitoring by exploring the relationship between EL and IL among U16 soccer players. EL was measured using global positioning system (GPS) data, while IL was assessed through training impulse (TRIMP), Edward's TRIMP, HR exertion, rate of perceived exertion (RPE) and session-RPE (s-RPE). Nineteen (N=19) male footballers from an elite football academy participated, with data collected from 50 training sessions and 11 matches. In the analysis of the training sessions, TRIMP demonstrated a near-perfect correlation with total distance (TD) (p < 0.001) and eTRIMP correlated strongly with TD (r = 0.82) and player load (r = 0.79). HR exertion also correlated significantly with TD, medium-speed running, decelerations, inertial movement analysis (IMA) events, and player load (p < 0.001). In matches, large correlation was observed between TRIMP and TD (r = 0.73), while the strongest correlation was with RPE and s-RPE with TD and PL (p < 0.001). Furthermore, TD emerged as the best GPS-derived predictor of both TRIMP and HR exertion in training contexts. These findings provide evidence for the validity and usability of heart rate-based and RPE-based measures to indicate IL in U16 soccer players. Future research should focus on contextual factors in exploring the relationship between EL and IL.

Background: This study aimed to develop a method to analyze the kinetic and kinematic characteristics of the traditional karate Gyaku Tsuki (reverse punch), focusing on the activation sequence of lower and upper extremities and trunk muscles during execution. Methods: An elite male (N = 1) karate athlete (in kata) performed 20 Gyaku Tsuki punches while equipped with 16 wireless surface EMG sensors integrated with 3-axis accelerometers. The five punches with the highest forearm acceleration were selected for analysis. EMG, accelerometer, and synchronized video data were recorded and processed. Results: A novel visualization technique was developed to represent muscle activation over time, distinguishing a spectrum of 0–25–50–75–100% activation levels. Muscle activation times for arm, leg, and trunk muscles ranged from −0.31 to −0.11 s relative to punch execution, indicating rapid, coordinated muscle engagement. Conclusions: This method enables detailed analysis of muscle activation patterns in karate punches. It offers valuable insights for biomechanics researchers and practical applications for coaches aiming to enhance performance and prevent injuries through better understanding of movement dynamics.

This study aimed to investigate the effect of the FIFA 11+ program on knee instability and motor performance in male youth soccer players. Thirty male youth soccer players were divided into two groups: the experimental group (FIFA+) performed the FIFA 11+ program for 10 weeks, while the control group followed their usual warm-up routine. Dynamic knee valgus (DKV) and squat depth were assessed using a Microsoft Azure Kinect camera and dynaknee software. Maximal isometric muscle force was measured with a dynamometer. The Y Balance test was used to evaluate dynamic balance, while a countermovement jump test assessed lower limb power. The knee range of motion was measured with a goniometer, and the t-test was used to evaluate agility. After the intervention, the FIFA+ group showed a significant decrease in DKV and squat depth (p < 0.05), while the control group showed no significant changes (p > 0.05). Both groups improved in motor performance, with slight progress noted in the FIFA+ group. However, neither group demonstrated significant improvement in dynamic balance (p > 0.05). While the FIFA 11+ program may not substantially enhance overall motor performance or match the effectiveness of other training regimens, it shows potential for addressing biomechanical deficiencies and reducing the risk of injuries, particularly those related to dynamic knee valgus.

Knee injuries are very common in soccer players. High loads on the knee during landing or changes of direction can lead to a valgus shift of the knee, known as Dynamic Knee Valgus (DKV). Many studies have shown that a large shift in DKV is a predisposing factor for knee injuries and disease, such as anterior cruciate ligament injury (ACL), patellofemoral pain syndrome or osteoarthritis. Functional training could be a great tool to reduce DKV. Thus, in this pilot study, nine male youth soccer players (mean age: 16.4 ± 0.2 years) took part in six weeks of functional training program. DKV was measured in pre- and post-measurements during single leg squats using Kinect Azure camera with DynaKnee software. In addition, maximal voluntary muscle contraction (MVC) was measured using a dynamometer and muscle activation amplitude (MAA) was measured using electromyography. Data were analysed using a non-parametric Wilcoxon signed rank test to assess differences in DKV, MAA and MVC at a 5% significance level. Data showed a small improvement of DKV in the dominant leg. MVC increased slightly in all variables. The MAA of the involved muscles in the single-leg squat did not show a higher value, but rather a decreasing trend. However, none of the analyses showed significant changes. The small number of participants and the short duration of the training might have been a limiting factor. Further studies should repeat the procedure with a larger group of participants and a longer training period.

Background/Objectives: The COVID-19 pandemic highlighted that body positions substantially affected the mortality rate. We hypothesized that body position modulates the contribution of abdominal (AB) and thoracic breathing (TB) to the breathing cycle (BC), as well as respiratory rate (RR). In addition, we hypothesized that physical activity level can increase the contribution of abdominal breathing. Methods: Thus, we used plethysmography respiratory belts to measure changes in abdominal (AB) and thoracic (TB) circumferences, their ratio (AB/TB), and respiratory rate (RR) under resting conditions. Measurements were taken in four body positions—standing (St), sitting (Si), supine (Su), and prone (Pr)—for two groups of young adults (aged 21 ± 2 years) with different physical activity levels (low and high PA). Results: The AB/TB ratios significantly differed between the body positions (Si: 45.5/54.5%, St: 40.5/59.5%, Su: 56.8/43.2%, Pr: 52.2/47.8% (p < 0.001)). AB was significantly the highest in Su and lowest in Si and St (p < 0.001). There was a significant difference in respiratory rate (RR) between the four body positions (p = 0.005). RR in the four body positions was the following: Si: 15.1, St: 15.0, Su: 13.7, and Pr: 14.4. RR was the lowest in Su (13.7), where AB was the highest (56.8%), and RR was the highest in Si (15.1) and St (15.0), where TB was higher compared to Su (p < 0.001). PA significantly affected the various body positions’ AB/TB ratio and RR. The high PA group showed a significant difference in the AB/TB ratio between the body positions (p < 0.001). The low PA group showed a significant difference in RR between the body positions (p = 0.025). Conclusions: In young, healthy adults, we found that body position significantly influenced the abdominal/thoracic breathing ratio during the breathing cycle. The supine position showed the highest contribution of abdominal breathing, which correlated with the lowest respiratory rate. Additionally, a higher level of physical activity increased the contribution of abdominal breathing in the Si, Su, and St positions, suggesting a more energy-efficient breathing pattern. These findings suggest the potentials for breathing pattern monitoring and position-based interventions to improve healthcare outcomes and enhance sports performance and recovery.