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Mario Juárez-Ortega,1 Oscar Rojas-Espinosa,1 Raquel Muñiz-Salazar,2 Enrique Becerril-Villanueva,3 Alejandro Hernández-Solís,4 Patricia Arce-Paredes,1 Sergio Islas-Trujillo,1 Raúl Cicero-Sabido4 1Department of Immunology, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico; 2School of Health Sciences, Unidad Ensenada, Universidad Autónoma de Baja California, Ensenada, BC, Mexico; 3Laboratory of Psychoimmunology, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente, Mexico City, Mexico; 4Pneumology Unit, Hospital General de México “Eduardo Liceaga”, UNAM, Mexico City, Mexico Background: Resident alveolar macrophages, dendritic cells, and immigrating neutrophils (NEU) are the first cells to contact Mycobacterium tuberculosis in the lung. These cells, and additional lymphoid cells in the developing granuloma, release a series of components that may concentrate in the serum and affect disease progression. Purpose: The aim of this study was to investigate the effect of the serum from tuberculosis (TB) patients and their household contacts (HHC) on the nuclear morphology of NEU. Materials and methods: NEU from healthy (HLT) people were incubated with sera from patients with active pulmonary TB, their HHC, and unrelated people. Changes in the nuclear morphology of NEU were analyzed by light and electron microscopy. Results: Sera from patients with TB induced changes in the nuclear morphology of NEU that included pyknosis, swelling, apoptosis, and netosis in some cases. Sera from some HHC induced similar changes, while sera from HLT people had no significant effects. Bacteria did not appear to participate in this phenomenon because bacteremia is not a recognized feature of nonmiliary TB, and because sera from patients that induced nuclear changes maintained their effect after filtration through 0.22 µm membranes. Neither anti-mycobacterial antibodies, TNFα, IL-6, IFNγ, or IL-8 participated in the phenomenon. In contrast, soluble mycobacterial antigens were likely candidates, as small quantities of soluble M. tuberculosis antigens added to the sera of HLT people led to the induction of nuclear changes in NEU in a dose-dependent manner. Conclusion: These results might help to detect subclinical TB within HHC, thus leading to a recommendation of prophylactic treatment. Keywords: tuberculosis, serum, neutrophils, pyknosis, apoptosis, netosis

This study investigated simultaneous treatments in contextual interference (blocked and random practice) and their effect on the process of learning four tennis shots. 8 tennis players participated in the research, which was carried out in two phases. The first phase involved a 3-wk. period of 12 sessions with 192 practice tennis shots per session for each tennis player. The second phase comprised 4 retention tests carried out at 48 hr. and 2, 4, and 6 weeks following the learning phase. This phase consisted of evaluating the retention of the skills that had been practiced during the learning phase. The results indicated an improvement in the quality of shots for both practice conditions during the learning phase. Differences in retention appeared relative to differences in the type of practice conditions (random or blocked) in which the skill was learned and also depended on the type of shot and the time that had elapsed since the learning period. DOI 10.2466/PMS.110.2.661-673

Introducción: El tratamiento percutáneo de la enfermedad de múltiples vasos (EMV) en contexto del síndrome coronario agudo (SCA) de acuerdo al estudio COMPLETE, ha demostrado que la revascularización completa tiene mejor pronóstico a corto y largo plazo que la revascularización incompleta. Sin embargo, en mujeres el pronóstico sigue siendo más adverso con mayores complicaciones hospitalarias, menor reperfusión, exhiben mayor mortalidad en el hospital (OR, 1.85) y a un 1 año (OR, 1.6) en comparación con los hombres. Objetivo: Evaluar el pronóstico a 30 días y seis meses en mujeres con SCA y EMV en revascularización completa temprana (grupo I) contra revascularización sólo del vaso culpable (grupo II). Material y métodos: Se incluyeron mujeres con SCA y EMV durante el periodo de agosto 2018 a enero 2021. Se evaluaron las variables de: muerte de origen cardiaco, reinfarto, EVC, revascularización posterior no planeada y rehospitalización por angina a los seis meses posteriores al egreso con tratamiento médico óptimo, así como la supervivencia libre de eventos. resultados: Se incluyeron 35 pacientes, 16 en el grupo I y 19 en el grupo II. La edad promedio fue 64.8 ± 12.55 años. La menopausia y el sedentarismo fueron los principales factores de riesgo (97%), seguido de HAS y diabetes (74.3% y 68.6%, respectivamente). El 65.7% tuvo IAMCEST (grupo I 43.47% vs II 56.5% p = 0.91), IAMSEST el 14.3% (grupo I 12.5% vs II 15.8% p = 0.782) y angina inestable 20% (grupo I 25% vs II 15.8% p = 0.497). En el IAMCEST, la ICP primaria fue la terapia de reperfusión más predominante (45.7%) sin diferencia entre los dos grupos. En los dos grupos el principal acceso vascular fue el radial (68.6%), siendo la nefropatía por contraste la complicación más frecuente (6.8%) del procedimiento seguido de hematoma (5.7%), sin diferencias entre ambos grupos. A los seis meses, la FEVI fue similar entre los dos grupos (42.91% ± 20%). El cumplimiento del tratamiento médico óptimo alta y a los seis meses no tuvo diferencias entre los grupos (91.4%). La mortalidad al egreso hospitalario fue de seis meses, MACE muerte por causa cardiovascular en 11.4%, revascularización posterior 11.4%, angina inestable 17.1%, reinfarto 5.7%, infarto de vaso no culpable57%, trombosis intrastent 5.7%. Supervivencia a seis meses 94.3%. Los pacientes que se someten a revascularización completa presentan reducción en los eventos cardiovasculares mayores, relevancia estadística sólo con reducción de eventos de angina inestable y tendencia a la disminución de la mortalidad en pacientes a 30 días y seguimiento a 6 meses. Se observó menor frecuencia de revascularización posterior no planificada, eventos de angina inestable, reinfarto e infarto de vaso no culpable con diferencia significativa, sin aumento en las complicaciones periprocedimiento. (Tabla T20-1). conclusiones: La revascularización completa en mujeres con SICA y enfermedad de múltiples vasos debe considerarse durante la ICP índice o durante la hospitalización cuando sea factible. [ABSTRACT FROM AUTHOR]

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Objective: to analyze the reliability of the estimated one-repetition maximum (e1RM) through the repetition to fatigue method in four unilateral resistance training exercises performed using weight machines (i.e., leg press, calf raises, leg extension, seated leg curl), and their relationship to gait-related tests., Design: cross-sectional study., Setting: university sports complex., Participants: twenty-four participants with multiple sclerosis completed three testing sessions. They performed three testing sessions that were integrated into a long-term multimodal exercise regime comprising strength, balance, and functional mobility exercises, conducted twice a week in 90-minute sessions., Main Outcome Measures: the first session consisted in the assessment of the gait-related tests [i.e., timed up and go (TUG), timed 25-foot walk (T25FW), 6-minute walk (6MW)]. Two testing sessions were dedicated to the assessment of the e1RM in the aforementioned exercises., Results: intraclass correlation coefficients (ICC 2.1 ) of absolute e1RM ranged from 0.92 to 0.97 and they were slightly higher than those relative to the body mass (0.852.1 <0.96). Typical errors for the four exercises ranged between 2.2 and 4.7 kg (9.3 - 11.6%). The weaker leg e1RM for the calf raises and leg curl exercises were significantly associated with the 6MW (0.654≤r≤0.677), T25FW (-0.555≥r≥-0.557) and TUG (-0.480≥r≥-0.526). Between-leg e1RM asymmetries in these exercises were also correlated to the 6MW (0.420≤r≤0.467), T25FW (0.553≤r≤0.590) and TUG (0.626≤r≤0.627). Unilateral e1RMs during the leg press and leg extension showed no or few significant associations with gait-related tests., Conclusions: the results suggest that e1RM can be safely and reliably performed to quantify single-leg strength and to control the training load in these exercises. Knee flexors and ankle extensors strength, especially of the weaker leg, along with their asymmetry, seem to be the most relevant factors to consider in the strength assessment and training of this population., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interests., (Copyright © 2024. Published by Elsevier Inc.)

Motor variability is an intrinsic feature of human beings that has been associated with the ability for learning and adaptation to specific tasks. The purpose of this review is to examine whether there is a possible direct relationship between individuals' initial variability in their ability for learning and adaptation in motor tasks. Eighteen articles examined the relationship between initial motor variability and the ability for learning or adaptation. Twelve found a direct relationship. In reward-based tasks, greater initial variability was associated with greater learning and adaption improvement when assessed using linear measures of dispersion, however, this association was not observed with temporal structure variability. While in error-based task associations were reported with both greater amount variability and more complexity temporal structure. Nevertheless, bias in initial performance related to the amount of variability was found, so the temporal structure of initial variability seems to be a better indicator of improvement in this type of task. Further research is needed for further research to better understand the potential relationship between initial motor variability and the ability for learning or adaptation in motor tasks., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: The handstand is an essential skill in acrobatic sports. This skill requires the athlete to maintain an inverted upright stance with only the hands supported, which requires a great effort of muscular coordination and motor control. Several factors influence the ability to control the posture, including fatigue, which is a bit studied constraint of handstand performance., Research Question: With the aim to find out whether variability in movement control can be an indicator of fatigue, the present study was carried out., Method: Fourteen male acrobatic gymnasts were required to perform handstands. The time series for analyzing variability were capturing using Force Platforms, which is a traditional laboratory instrument, and Inertial Measurement Units (IMU), which is a more recent and less widely used, but more accessible tool. For this purpose, an analysis of the amount of variability was carried out, using the standard deviation. And analysis of the structure of variability (or complexity), using Detrended Fluctuation Analysis (DFA) and Fuzzy Entropy (FuEn)., Results: Our results reveal that fatigue causes significant increases in the amount of variability in the medio-lateral axis on the force platform, and in the IMU located in the area of the L5 vertebra. These changes are accompanied by increased auto-correlation in the medio-lateral axis of the force platform, and more unpredictable behavior in the L5 IMU., (© 2024. The Author(s).)

Analysis of variability in physiological time series has been shown to be an indicator of the state of the organism. Although there is evidence of the usefulness of analysis of the amount and/or structure of variability (complexity) in cycling actions, there is limited knowledge about its application in resistance exercise. The aim of this study is to find out whether variability in acceleration signals can be an indicator of intensity level in a squat task. For this purpose, an experimental design was developed in which the following participated seventy-two participants (age = 25.7 ± 4.4 years; height = 169.2 ± 9.8 cm; body mass = 67.7 ± 11.2 kg; ratio 1RM/body mass = 1.4 ± 0.3). They performed four repetitions of back squat at loads of 10%, 30%, 50%, 70%, and 90% of 1RM. Acceleration during the exercise was recorded using an inertial measurement unit (IMU) and a force platform. The variability of the movement was then analyzed using Standard Deviation (SD), Detrended Fluctuation Analysis (DFA), Fuzzy Entropy (FuzzyEn), and Sample Entropy (SampEn). For the IMU and for the force platform, significant effects were observed in all variables (p < 0.001). In pairwise comparisons, IMU showed a significant increase in motor complexity with increasing intensity, among most intensities, in DFA, FuzzyEn and SampEn. Differences in force platform were more limited, and only DFA detected differences between most intensities. The results suggest that measures of signal and acceleration variability may be a useful indicator of the relative intensity at which a squat exercise is performed., Competing Interests: The authors have declared that no competing interests exist, (Copyright: © 2024 López-Fernández et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Abstract: Asencio, P, García-Valverde, A, Albaladejo-García, C, Beato, M, Moreno-Hernández, FJ, and Sabido, R. Analysis of concentric and eccentric power in flywheel exercises depending on the subjects' strength level and body mass. J Strength Cond Res 38(8): 1394-1400, 2024-The objective of this study is to describe how flywheel exercise mechanical outputs are affected by the athletes' body mass (BM) and strength level and by the exercise type. Forty-six recreational athletes came to a laboratory 3 times. On the first day, descriptive data, squat (1 repetition maximum: 1RM) and flywheel familiarization were performed. After a second day of familiarization, subjects performed a randomized flywheel exercise-testing protocol of squat and split squat exercises. The variables used for data analysis were peak concentric power and peak eccentric power, eccentric/concentric ratio, and their relationship with 1RM/BM. Subjects were assigned to a stronger or weaker group according to their 1RM/BM ratio. Group differences were found in absolute values of eccentric overload (EOL) ( p < 0.01; effect size [ES] = 0.51) and EOL/BM ( p < 0.01; ES = 0.46) only in the split squat. Absolute power values in the concentric phase showed differences between inertial load ( p < 0.01; ES = 0.41). The stronger group did not present significant differences between inertial loads during squat ( p < 0.01; ES = 0.46), but they showed different ratios with light inertias in comparison with the weaker group ( p < 0.01; ES = 0.46). There were significant differences between groups with light inertias in split squat (nondominant) and squat exercises ( p < 0.05; ES = 0.29) in the eccentric and concentric phases ( p < 0.116; ES = 0.20). Squat and split squat exercises present different profiles depending on the training level. In conclusion, it is recommended that practitioners perform a test to understand the inertial load-power profile (concentric, eccentric, and their ratio) for each exercise and also consider the user's strength level for selection of the inertial load and for the exercise to use in training., (Copyright © 2024 National Strength and Conditioning Association.)

Resistance training programs play a crucial role in optimizing soccer performance. The aim of this study is to compare performance outcomes in sport-specific tasks after implementing two different flywheel resistance training (FRT) programs: variable intensity (VI) and constant intensity (CI). Seventeen ( n = 17) amateur footballers were divided into VI and CI groups with the same training volume. For the VI group, a decrease in inertial load was implemented every four sessions, whereas the CI group maintained a constant load during the entire program. After different familiarization sessions and testing (sprint, change of direction, jump, one-repetition maximum and flywheel strength variables), ten sessions of FRT were performed over 5 weeks. Both groups showed similar improvements in the one-repetition maximum ( p < 0.01) but the CI group had significant improvements in the 10-m sprint ( p = 0.04; ES = 0.72), emphasizing the potential benefits of medium inertial loads to maximize power and specificity in sport tasks. However, no significant differences were observed in the countermovement jump, change of direction and 30-m sprint, possibly attributed to neuromuscular fatigue from a high-volume training schedule and friendly matches. The study highlights the importance of considering training load distribution in FRT programs. The findings emphasize the need for complementary training to maximize the jump and change of direction abilities and caution against high-volume training and friendly match scenarios. In conclusion, FRT programs, whether varying in intensity or not, can yield medium-term performance improvements for soccer players., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Asencio, Moreno, Hernández-Davó and Sabido.)

CrossFit is characterized by being a standardized training program that improves physical performance through the provision of several stimuli regardless of the participant's strength level. This study aimed to compare the acute response in total repetitions as a measurement of performance, jump ability, physiological demand (heart rate and blood lactate), and perceived effort considering the participants' strength level with individualized intensity in CrossFit. Thirty-five participants were assessed and asked to participate on two separate days in a standardized and relative 'As Many Repetitions As Possible' (AMRAP) CrossFit circuit. Both AMRAPs comprised strength, gymnastic and aerobic exercises, although only strength was individualized according to the participant's level. Before the statistical analysis, participants were allocated to higher- or lower-strength groups following the one-repetition maximum-bodyweight ratio in the push press exercise. Results support the existence of a strong relationship between strength level and total repetitions in both AMRAPs. In addition, differences in total repetitions and rate of perceived exertion between strength groups are discarded when AMRAP intensity is individualized while physiological demand and jump ability are maintained. Thus, the higher-strength participants may benefit from similar responses with a lower number of repetitions. Therefore, CrossFit trainers should be encouraged to prescribe strength tasks based on the percentage of 1RM for every training., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Movement control can be an indicator of how challenging a task is for the athlete, and can provide useful information to improve training efficiency and prevent injuries. This study was carried out to determine whether inertial measurement units (IMU) can provide reliable information on motion variability during strength exercises, focusing on the squat. Sixty-six healthy, strength-trained young adults completed a two-day protocol, where the variability in the squat movement was analyzed at two different loads (30% and 70% of one repetition maximum) using inertial measurement units and a force platform. The time series from IMUs and force platforms were analyzed using linear (standard deviation) and non-linear (detrended fluctuation analysis, sample entropy and fuzzy entropy) measures. Reliability was analyzed for both IMU and force platform using the intraclass correlation coefficient and the standard error of measurement. Standard deviation, detrended fluctuation analysis, sample entropy, and fuzzy entropy from the IMUs time series showed moderate to good reliability values (ICC: 0.50-0.85) and an acceptable error. The study concludes that IMUs are reliable tools for analyzing movement variability in strength exercises, providing accessible options for performance monitoring and training optimization. These findings have implications for the design of more effective strength training programs, emphasizing the importance of movement control in enhancing athletic performance and reducing injury risks.

Background: Flywheel resistance training has become more integrated within resistance training programs in a variety of sports due to the neuromuscular, strength, and task-specific enhancements reported with this training., Objective: This paper aimed to present the consensus reached by internationally recognized experts during a meeting on current definitions and guidelines for the implementation of flywheel resistance training technology in sports., Methods: Nineteen experts from different countries took part in the consensus process; 16 of them were present at the consensus meeting (18 May 2023) while three submitted their recommendations by e-mail. Prior to the meeting, evidence summaries were developed relating to areas of priority. This paper discusses the available evidence and consensus process from which recommendations were made regarding the appropriate use of flywheel resistance training technology in sports. The process to gain consensus had five steps: (1) performing a systematic review of systematic reviews, (2) updating the most recent umbrella review published on this topic, (3) first round discussion among a sample of the research group included in this consensus statement, (4) selection of research group members-process of the consensus meeting and formulation of the recommendations, and (5) the consensus process. The systematic analysis of the literature was performed to select the most up-to-date review papers available on the topic, which resulted in nine articles; their methodological quality was assessed according to AMSTAR 2 (Assessing the Methodological Quality of Systematic Review 2) and GRADE (Grading Recommendations Assessment Development and Evaluation). Statements and recommendations scoring 7-9 were considered appropriate., Results: The recommendations were based on the evidence summary and researchers' expertise; the consensus statement included three statements and seven recommendations for the use of flywheel resistance training technology. These statements and recommendations were anonymously voted on and qualitatively analyzed. The three statements reported a score ranging from 8.1 to 8.8, and therefore, all statements included in this consensus were considered appropriate. The recommendations (1-7) had a score ranging from 7.7 to 8.6, and therefore, all recommendations were considered appropriate., Conclusions: Because of the consensus achieved among the experts in this project, it is suggested that practitioners and researchers should adopt the guidelines reported in this consensus statement regarding the use of flywheel resistance technology in sports., (© 2024. The Author(s).)

Purpose: The aim of the present study was to analyze the effect of different eccentric tempos on eccentric kinetics and kinematics and the subsequent concentric performance when performing countermovement jumps against different loads., Methods: After 1-repetition-maximum assessment and 2 familiarization sessions, 13 well-trained participants performed, in randomized order, 12 sets (4 tempos × 3 loads) of 4 repetitions of the loaded countermovement-jump exercise. The eccentric tempos analyzed were 5 and 2 seconds, as fast as possible, and accelerated (ie, without pause between repetitions), while the loads used were 30%, 50%, and 70% of 1-repetition maximum. Several kinetic and kinematic variables during both phases were recorded by linking a linear position transducer to the barbell., Results: The eccentric work was greater in the accelerated condition despite no changes in the eccentric depth. The peak and mean propulsive velocities were greater in the as-fast-as-possible and accelerated conditions. Correlation analysis showed that, compared with the 5-second condition, the increased concentric performance in the accelerated condition was related to the difference in eccentric work performed in the last 100 milliseconds of the eccentric phase (r > .770)., Conclusions: Contrary to current practices, the current study highlights the need for performing the eccentric phase of loaded countermovement jumps, a common exercise performed by athletes for both training and evaluation purposes, as fast as possible. This allows not only a greater eccentric work but also improved concentric performance.

Background: Body tilt changes could affect the intensity/difficulty of core stability exercises, but there is still a lack of knowledge about its impact., Objective: To analyse the trunk muscles activation during prone plank exercises at different body tilts., Methods: Twenty-four young adults who performed recreational gymnastic activities participated in this study. Electromyography activity of the rectus abdominis (RA), external oblique (EO), internal oblique (IO) and erector spinae (ES) was recorded during the performance of six variations of the prone plank exercise (planking with feet supported on the ground [conventional horizontal position] and planking with feet supported on wall bars at five different heights increasing the angle tilt) and an inverted position exercise., Results: The RA, EO and IO activation in all prone plank variations were higher than those observed in the conventional prone plank. In addition, the coefficient of variation of the muscle activation increased with the declination angle, reaching the highest values in the inverted position for the RA and ES muscles., Conclusion: The results seem to indicate that the body tilt variation could be used as an easy and inexpensive strategy for modulating the neuromuscular demands and the motor control challenge during planking exercises.

To assess the influence of age and skill level on handball throwing kinematics and performance, 126 participants were distributed into groups according to their skill level (elite or recreational) and age group (U12, U16 or +18). Each participant performed three sets of 10 throws, aiming to hit a target (40 × 40 cm) located in the right corner of the goal. During testing, kinematic data were recorded and throwing performance (accuracy and velocity) was measured. Results showed greater throwing velocity in the elite compared to recreational groups, whereas no differences were found for throwing accuracy. The elite U16 and +18 groups displayed higher segment velocities (hand, arm and pelvis) than the recreational groups. The participation of proximal segments was higher in older groups, showing the more skilled players (U16 and +18) greater pelvis velocities (1.62-1.75 vs 1.02-1.22 m/s). The increased velocity of the distal joints (hand peak velocity: 13.56 ± 1.65 vs 10.67 ± 1.98 m/s) are responsible for the difference in throwing velocity between the elite and recreational U12 groups. Several correlations were found between joint kinematics and throwing velocity. Coaches could use these results during training, to optimise specific throwing training.

The aim of this study was to assess the influence of the load order used (i. e. incremental, decremental or random loads order) during the bench press throw load-velocity profile on peak velocity achieved against four different loads (20-40-60-80% of one repetition maximum [1RM]). Both intraclass correlation coefficient (ICC) and coefficient of variation (CV) were calculated to assess the reliability of the measures. A repeated measures ANOVA was used to assess differences between protocols. A linear regression analysis was performed to assess the load-velocity relationships among the different protocols. Peak velocity showed good to high ICC values independently of the load used (ICC=0.83-0.92). CV scores showed good reliability (ranging between 2.2 and 6.2%). No significant differences in peak velocity attained at each load were found between the three testing protocols ( p> 0.05). In addition, peak velocity at each load was very large to almost perfect, correlated between protocols ( r= 0.790-0.920). The linear regression model showed a significant relationship between testing protocols ( p< 0.001; R 2 =0.94). In conclusion, due to some ICC scores below 0.9 and R 2 below 0.95, the indistinct use of different load-order protocols to assess load-velocity relationships in the bench press throw exercise is not recommended., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Objectives: The purpose of this study was 1) to determine and compare kinetic parameters during the realization of a countermovement jump (CMJ) between footballers with cerebral palsy (CP) and non-impaired footballers, and 2) to analyze the differences in this action between different players' impairment profiles and a group of non-impaired footballers. Methods: This study involved 154 participants comprising 121 male footballers with CP from 11 national teams and 33 male non-impaired football players recruited as the control group (CG). The footballers with CP were described according to the different impairment profiles (bilateral spasticity = 10; athetosis or ataxia = 16; unilateral spasticity = 77; minimum impairment = 18). All participants performed three CMJs on a force platform to record kinetic parameters during the test. Results: The group of para-footballers presented significantly lower values than the CG in the jump height ( p < 0.01, d = -1.28), peak power ( p < 0.01, d = -0.84), and the net concentric impulse ( p < 0.01, d = -0.86). Concerning the pairwise comparisons between CP profiles and the CG, significant differences were found for the bilateral spasticity, athetosis or ataxia, and unilateral spasticity subgroups compared to the non-impaired players for jump height ( p < 0.01; d = -1.31 to -2.61), power output ( p < 0.05; d = -0.77 to -1.66), and concentric impulse of the CMJ ( p < 0.01; d = -0.86 to -1.97). When comparing the minimum impairment subgroup with the CG, only significant differences were found for jump height ( p = 0.036; d = -0.82). Footballers with minimum impairment presented higher jumping height ( p = 0.002; d = -1.32) and concentric impulse ( p = 0.029; d = -1.08) compared to those with bilateral spasticity. Also, the unilateral spasticity subgroup reports a higher jump height performance than the bilateral group ( p = 0.012; d = -1.12). Conclusion: These results suggest that the variables related to power production during the concentric phase of the jump are crucial for the performance differences between groups with and without impairment. This study provides a more comprehensive understanding of kinetic variables that would differentiate CP and non-impaired footballers. However, more studies are necessary to clarify which parameters better differentiate among different profiles of CP. The findings could help to prescribe effective physical training programs and support the classifier's decision-making for class allocation in this para-sport., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Henríquez, Sabido, Barbado, Roldan, Elvira, Yanci and Reina.)

Background: A main goal of programming is to structure the optimal variations in training factors to optimize athletes' adaptations. Nevertheless, it remains unknown the optimal programming model leading to greater neuromuscular adaptations. Purpose: The aim of the present study was to assess the influence of three different magnitudes of variability within resistance training programs on performance adaptations. Methods: Forty participants were assigned to three different groups differing in the frequency of change in training contents: a weekly model (WM; n = 12), a daily model (DM; n = 14), and a session model (SM; n = 14). The training intervention lasted for six weeks, performing two sessions per week of back-squat exercise. Total training load (volume and intensity) of the six-week intervention was equated for all groups. Maximum dynamic strength (1RM) in the back-squat, countermovement (CMJ) and squat jump (SJ) were measured pre- and post-training intervention. Results: All groups showed significant increases ( p < .05) in 1RM, with the SM showing greater increases than the WM (20.5 vs 13.6%; p = .022). Although not reaching statistical significance, the magnitude of the increases in CMJ tended to be greater for DM and SM group (9.5% and 8.1%, respectively,) than in the WM (4.4%). All groups showed similar increases in the SJ (7.7-9.9%). Conclusions: The results of the present study suggest that the use of more frequent stimuli variations within resistance training programming is a key factor to achieve concomitant increases in strength and jumping performance.

Induced variability by the use of unstable surfaces has been proposed to enhance proprioceptive control to deal with perturbations in the support base better. However, there is a lack of evidence about its benefits facilitating motor adaptions in upper body skills. In this experiment, practice on an unstable surface was applied to analyze the adaptations in an upper limb precision throwing skill. After a pretest, twenty-one participants were randomly allocated into two groups: one group practiced the throwing task on a stable surface and the other group practiced the same task on an unstable support base. Differences in throwing performance between pre- and post-practice were analyzed in accuracy, hand movement kinematics and variability of the throw in both surface conditions. Fuzzy entropy of the horizontal force was calculated to assess the complexity dynamics of postural sway. Participants improved their performance on the stable and the unstable surface. Induced variability using an unstable surface reduced participants' variability and the complexity of postural sway, but it did not facilitate a superior adaptation of the throwing task. The results suggest that the variations induced by unstable surfaces would fall far from the family of specific motor solutions and would not facilitate additional motor performance of the throwing task., Competing Interests: The authors declare there are no competing interests., (©2023 Moreno et al.)