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Body composition and muscular strength are important for baseball skills and successful performance. Conditioning training programs have the potential to enhance athletic performance via physiological changes. In this single-group interventional study, we investigated the effect of 8 weeks of Pilates training (PT) on contralateral and regional body composition, and isokinetic muscular strength in knee and trunk flexion/extension in adolescent baseball players. In our results, PT increased both right- and left-sided lean mass in the trunk. Following PT, work per repetition and average power showed significant increases in the flexion and extension of the left knee only. PT significantly decreased the peak torque of the trunk flexor and increased the average power of the trunk extensor. In addition, the ratio of the trunk flexion/extension strength of peak torque showed a decreasing trend, whereas that of work and average power did not change significantly following PT. In conclusion, PT evenly improved lean mass on both the right and left sides of the body. Knee and trunk strength increased after PT. Our findings suggest that PT may be a useful strategy for enhancing athletic performance in regard to the muscular strength of adolescent baseball players.

Introduction: High-intensity resistance training may elevate the risk of musculoskeletal injuries and hinder optimal performance execution. Objective: This study compared the effects of low-load resistance training under blood flow restriction (BFR) and hypoxia (HYP) on body composition, strength, and endurance in untrained male college students. Methodology: Forty-five male college students from Ubon Ratchathani Rajabhat University were purposively sampled and matched into three groups (n = 15): 1) high-load resistance training (HLRT), 2) low-load resistance combined with blood flow restriction training (LLBFR), and 3) low-load resistance combined with hypoxic training (LLHYP). All groups trained three times weekly for five weeks. Results: After five weeks of training, all groups showed significant improvements in fat-free mass, skeletal muscle mass and performance outcome (p < 0.05). The LLHYP group also exhibited significantly reduced skinfold thickness and greater arm circumference (p < 0.05). All groups improved strength and endurance, but LLHYP demonstrated significantly greater endurance than HLRT in both exercises (p = 0.021 and 0.003, respectively) and outperformed LLBFR in the dip machine (p = 0.032). Discussion: Findings support that LLBFR and LLHYP can produce similar strength and body composition outcomes as HLRT over a short term. LLHYP, in particular, showed superior benefits in endurance, possibly due to hypoxia-related physiological adaptations. Conclusions: Low-load resistance training with BFR and HYP effectively enhanced body composition, strength, and endurance of the biceps and triceps. This approach may offer a safer alternative for untrained male students. Introducción: El entrenamiento de resistencia de alta intensidad puede aumentar el riesgo de lesiones musculoesqueléticas y dificultar la ejecución óptima del rendimiento. Objetivo: Este estudio comparó los efectos del entrenamiento de baja carga con BFR e hipoxia sobre la composición corporal, fuerza y resistencia en varones universitarios no entrenados. Metodología: Cuarenta y cinco estudiantes varones de la Universidad Rajabhat de Ubon Ratchathani fueron asignados intencionalmente a tres grupos (n = 15): 1) alta carga (HLRT), 2) baja carga con restricción del flujo sanguíneo (LLBFR), y 3) baja carga con hipoxia (LLHYP). Todos entrenaron tres veces por semana durante cinco semanas. Resultados: Después de cinco semanas de entrenamiento, todos los grupos mostraron mejoras significativas en la masa libre de grasa, la masa muscular esquelética y el rendimiento (p < 0.05). El grupo LLHYP también presentó una reducción significativa en el grosor del pliegue cutáneo y un mayor perímetro del brazo (p < 0.05). Todos los grupos mejoraron en fuerza y resistencia, pero el grupo LLHYP demostró una resistencia significativamente mayor que el grupo HLRT en ambos ejercicios (p = 0.021 y 0.003, respectivamente), y superó al grupo LLBFR en la máquina de fondos (p = 0.032). Discusión: Los resultados indican que el LLBFR y el LLHYP pueden igualar al HLRT en fuerza y composición corporal a corto plazo. Además, el LLHYP destacó en resistencia, posiblemente por adaptaciones fisiológicas a la hipoxia. Conclusiones: El entrenamiento de baja carga con BFR e hipoxia mejoró eficazmente la composición corporal, fuerza y resistencia de bíceps y tríceps, siendo una alternativa segura para varones no entrenados. Introdução: O treino de resistência de alta intensidade pode aumentar o risco de lesões musculoesqueléticas e prejudicar o desempenho ideal.Objectivo: Este estudo comparou os efeitos do treino de baixa carga com BFR e hipoxia na composição corporal, força e resistência em estudantes universitários do sexo masculino não treinados.Metodologia: Quarenta e cinco estudantes do sexo masculino da Universidade Rajabhat em Ubon Ratchathani foram intencionalmente divididos em três grupos (n = 15): 1) alta carga (HLRT), 2) baixa carga com restrição do fluxo sanguíneo (LLBFR) e 3) baixa carga com hipoxia (LLHYP). Todos treinaram três vezes por semana, durante cinco semanas.Resultados: Após cinco semanas de treino, todos os grupos apresentaram melhorias significativas na massa livre de gordura, na massa muscular esquelética e no desempenho (p < 0,05). O grupo LLHYP apresentou também uma redução significativa da espessura das pregas cutâneas e um aumento da circunferência do braço (p < 0,05). Todos os grupos apresentaram melhoria na força e resistência, mas o grupo LLHYP demonstrou uma resistência significativamente superior ao grupo HLRT em ambos os exercícios (p = 0,021 e 0,003, respetivamente) e superou o grupo LLBFR no aparelho de mergulho (p = 0,032).Discussão: Os resultados indicam que o LLBFR e o LLHYP podem igualar o HLRT em força e composição corporal a curto prazo. Além disso, o LLHYP destacou-se na resistência, possivelmente devido a adaptações fisiológicas à hipoxia.Conclusões: O treino de baixa carga com BFR e hipoxia melhorou eficazmente a composição corporal, a força e a resistência do bíceps e do tríceps, proporcionando uma alternativa segura para homens não treinados.

To examine the association of health-related physical fitness components and accurate measures of fatness with attention in European adolescents. Cross-sectional study. A sub-sample of 444 adolescents from the HELENA study (14.5±1.2years) from 6 different countries participated in this study. Adolescents underwent evaluations of fitness (20m shuttle run, handgrip strength, standing long jump and 4×10m shuttle run tests), fatness (body mass index, skinfold thicknesses, bioelectrical impedance, Bod Pod and dual-energy X-ray absorptiometry) and attention (d2-test). Higher cardiorespiratory fitness was positively associated with better attention capacity (β=0.1, p=0.03). Body mass index and fat mass index measured by Bod Pod and dual-energy X-ray absorptiometry in a subset were negatively associated with attention (β=−0.11, p=0.02; β=−0.36, p=0.02; β=−0.34, p=0.03; respectively). All models were adjusted for age, sex, family-affluence scale and mother education. When these models were additionally adjusted for cardiorespiratory fitness when fatness was the main predictor and vice versa, the associations were somewhat attenuated and were no longer statistically significant. Muscular strength, speed-agility and body fatness markers measured by bioelectrical impedance and skinfolds were not associated with attention. The fit and non-overweight adolescents presented the highest values of attention capacity whilst their unfit and overweight peers showed the lowest values of attention (47.31±2.34 vs. 33.74±4.39; p<0.01). Our results support that both cardiorespiratory fitness and fatness are associated with attention, yet these associations are not independent. A combined effect was also observed, with fit and non-overweight adolescents showing the highest levels of attention and those unfit and overweight the lowest.

The paper presents the results of study dedicated to the search for effective methods of quantitative evaluation of power loads that allow developing and introducing into the fitness training process safer and simultaneously more effective modes of muscular activity for achieving maximum adaptive reactions in the body of people with different levels of training and functional abilities. To conduct the research we formed a group of 40 trained males aged 20-21 engaged in power fitness for the last three years. The obtained results show that changing at least one index that influence on the conditions of muscular activity in fitness significantly affects not only the choice of the projectile working mass, but also the entire load regime orientation and the training process on the whole. It was found out that while performing partial amplitude exercises (90% of the total), despite the projectile working mass that the athlete can lift will be 5-7% more from the full amplitude of motion mass, which is more characteristic of classical power sports (weightlifting, power lifting). It should be noted that other load regime indicators are identical with the conventional ones. At the same time, when performing a partial amplitude training exercises, the number of repetitions in the set decreases because of appearing the premature muscle fatigue and lack of a fixation phase at the peak point during boom lifting. An empirically developed integral method for estimating the load in power fitness is one of the most important methodological elements necessary to optimize the training activities management process. The use of this method allowed us to clearly define the volumes of exercise used in power fitness in the appropriate quantitative units. Thanks to the development of this method of assessing the power loads, it became possible to avoid sufficiently subjective gradations (small, medium, large) that were previously used by researchers and practitioners in the field of sports physiology, sports theory and practice, and sports medicine. The quantitative values of the indicators provided an opportunity to control the design of the training process in details, depending on the load regime characteristics and the level of person's physical fitness.

This study aimed to determine the relationships between muscle chains from the trunk and those of the upper limbs during certain motive actions. We tested 44 female athletes who were 12 to 16 years old. Eighteen subjects were 12 to 14 years old (right-handers), 16 subjects were 15 to 16 years old (left-handers) and 10 subjects were 12 to 16 years old (left-handers). They were subjected to 13 tests that measure muscle strength at the trunk level, 2 tests that measure the isometric force of the upper limb (of the intra- and extra-rotators muscles with Dynatorq) and 2 tests that measure the isometric force of the upper limbs (flexion and extension with Dynatorq). We calculated 312 correlations between the measured values (in kgf) for the trunk and upper limbs. For the right-handers, the values for r were as follows: intra-extra rotation for the 12 to 14-year-olds (0.12%-0.85%), intra-extra rotation for the 15 to 16-year-olds (0.20%-0.69%), flexion-extension for the 12 to 14 year-olds (0.20%-0.84%), and flexion-extension for the 15 to 16 year-olds (0.12%-0.70%). For subjects with a skilled left arm, we obtained the following values for r: intra-extra rotation for the 12 to 16 year-olds (0.02%-0.77%) and flexion-extension for the 12 to 16 year-olds (0.04%-0.89%). For the subjects from 12 to 14 years old, there were significant correlations between the intra-extra rotation and flexion-extension of the arm, which shows that the entire musculature of the trunk is involved. For the group of 15 to 16-year-olds, we noticed a specialized right arm movement with intra rotation only (specific for throwing the ball). For the extension-flexion actions of the right-handers, there was a certain orientation of forces to the left side of the trunk (good values for the left arm extension and weak values for the flexion of the right arm). This study could be a starting point for improving specific technical training for handball players. These findings should be considered with care because they are specific to this group of subjects.

Lateral ankle sprains (LASs) are among the most common injuries incurred during participation in sport and physical activity, and it is estimated that up to 40% of individuals who experience a first-time LAS will develop chronic ankle instability (CAI). Chronic ankle instability is characterized by a patient's being more than 12 months removed from the initial LAS and exhibiting a propensity for recurrent ankle sprains, frequent episodes or perceptions of the ankle giving way, and persistent symptoms such as pain, swelling, limited motion, weakness, and diminished self-reported function. We present an updated model of CAI that aims to synthesize the current understanding of its causes and serves as a framework for the clinical assessment and rehabilitation of patients with LASs or CAI. Our goal was to describe how primary injury to the lateral ankle ligaments from an acute LAS may lead to a collection of interrelated pathomechanical, sensory-perceptual, and motor-behavioral impairments that influence a patient's clinical outcome. With an underpinning of the biopsychosocial model, the concepts of self-organization and perception-action cycles derived from dynamic systems theory and a patient-specific neurosignature, stemming from the Melzack neuromatrix of pain theory, are used to describe these interrelationships.

Facioscapulohumeral muscular dystrophy (FSHD) is an untreatable disease, characterized by asymmetric progressive weakness of skeletal muscle with fatty infiltration. Although the main genetic defect has been uncovered, the downstream mechanisms causing FSHD are not understood. The objective of this study was to determine natural disease state and progression in muscles of FSHD patients and to establish diagnostic biomarkers by quantitative MRI of fat infiltration and phosphorylated metabolites. MRI was performed at 3T with dedicated coils on legs of 41 patients (28 men/13 women, age 34-76 years), of which eleven were re-examined after four months of usual care. Muscular fat fraction was determined with multi spin-echo and T1 weighted MRI, edema by TIRM and phosphorylated metabolites by 3D (31)P MR spectroscopic imaging. Fat fractions were compared to clinical severity, muscle force, age, edema and phosphocreatine (PCr)/ATP. Longitudinal intramuscular fat fraction variation was analyzed by linear regression. Increased intramuscular fat correlated with age (p<0.05), FSHD severity score (p<0.0001), inversely with muscle strength (p<0.0001), and also occurred sub-clinically. Muscles were nearly dichotomously divided in those with high and with low fat fraction, with only 13% having an intermediate fat fraction. The intramuscular fat fraction along the muscle's length, increased from proximal to distal. This fat gradient was the steepest for intermediate fat infiltrated muscles (0.07±0.01/cm, p<0.001). Leg muscles in this intermediate phase showed a decreased PCr/ATP (p<0.05) and the fastest increase in fatty infiltration over time (0.18±0.15/year, p<0.001), which correlated with initial edema (p<0.01), if present. Thus, in the MR assessment of fat infiltration as biomarker for diseased muscles, the intramuscular fat distribution needs to be taken into account. Our results indicate that healthy individual leg muscles become diseased by entering a progressive phase with distal fat infiltration and altered energy metabolite levels. Fat replacement then relatively rapidly spreads over the whole muscle.

Hand-held dynamometry (HHD) has never previously been used to examine isometric muscle power. Rate of force development (RFD) is often used for muscle power assessment, however no consensus currently exists on the most appropriate method of calculation. The aim of this study was to examine the reliability of different algorithms for RFD calculation and to examine the intra-rater, inter-rater, and inter-device reliability of HHD as well as the concurrent validity of HHD for the assessment of isometric lower limb muscle strength and power. 30 healthy young adults (age: 23±5 yrs, male: 15) were assessed on two sessions. Isometric muscle strength and power were measured using peak force and RFD respectively using two HHDs (Lafayette Model-01165 and Hoggan microFET2) and a criterion-reference KinCom dynamometer. Statistical analysis of reliability and validity comprised intraclass correlation coefficients (ICC), Pearson correlations, concordance correlations, standard error of measurement, and minimal detectable change. Comparison of RFD methods revealed that a peak 200 ms moving window algorithm provided optimal reliability results. Intra-rater, inter-rater, and inter-device reliability analysis of peak force and RFD revealed mostly good to excellent reliability (coefficients ≥ 0.70) for all muscle groups. Concurrent validity analysis showed moderate to excellent relationships between HHD and fixed dynamometry for the hip and knee (ICCs ≥ 0.70) for both peak force and RFD, with mostly poor to good results shown for the ankle muscles (ICCs = 0.31-0.79). Hand-held dynamometry has good to excellent reliability and validity for most measures of isometric lower limb strength and power in a healthy population, particularly for proximal muscle groups. To aid implementation we have created freely available software to extract these variables from data stored on the Lafayette device. Future research should examine the reliability and validity of these variables in clinical populations.

The aim of this study concerns how to use data obtained after evaluating the trunk muscle strength and development of force indicators that can simplify any scientific endeavour made on this line of research. They were evaluated 140 subjects age of 5-18 years, as follows: 27 subjects of 5 years old, 27 subjects of 6 years old, 26 subjects of 7 years old, 15 subjects of 12 years old, 18 subjects of 14 years old, 10 subjects of 16 years old and 17 subjects of 18 years old. It was found in this study, that it appears significant links between muscle strength and weight in the age frame of 14 years-18 years. The highest value belongs to the group of 14 years old (-0.60%) and is gradually decreasing towards 18 years old (-0.40%). The conclusions must be accepted with care, as it concerns only this group of subjects. The study would be complete, if assessed subjects would belong to different age groups and especially as adults.

ResumoIntroduction: Reduced muscle strength is caused by decreased of physical activity and inactive limb due to disease and sedentary lifestyle. Neuro-Muscular Electrical Stimulation (NMES) Russian Protocol and also hybrid training system that provide resistance from antagonist muscle contraction to agonist muscles that contract voluntarily are alternative methods for strengthening exercises to increase muscle strength. This study aimed to analyze the effect of Hybrid modification strengthening exercise and Russian NMES protocol on Quadriceps Femoris muscle strength in healthy untrained subjects. Methods: The subjects of this study were 24 untrained healthy men aged 25-45 years, divided into the Modified Hybrid Training (MHT) Group (n=12) and the Neuro-Muscular Electrical Stimulation (NMES) Group (n=12). Both groups received intervention 3 times per week for 4 weeks (12 sessions). Maximum voluntary isometric contraction (MVIC) of quadriceps muscles measured with surface EMG before and after the intervention. Results: There was significant improvement in the MVIC value of quadriceps muscle in the modified hybrid training group (dominant limb p = 0.001, non-dominant limb p = 0.001). In the NMES group, there were also significant improvement in Maximum Voluntary Isometric Contraction (MVIC) value of the quadriceps muscle (dominant limb p = 0.001, non-dominant limb p < 0.001). There was no significant difference in the change of MVIC (ΔMVIC) of the quadriceps muscle between the Hybrid method and NMES groups on both sides of the leg. Conclusion: Both Modified Hybrid Training (MHT) and the Neuro-Muscular Electrical Stimulation (NMES) are effective in increasing quadriceps muscle MVIC with comparable result.