The Effects of Pre-Season and Relationships with Physical, Physiological, Body Composition, and Load Markers: A Case Study Comparing Starters versus Non-Starters from an Elite Female Professional Soccer Team.

Background and Objectives: Research on female soccer players that analyzes playing status is scarce and has previously only examined load monitoring, while other markers, such as physical (i.e., strength, power, and agility), physiological (i.e., maximal oxygen uptake), and body composition (i.e., body fat mass, fat-free mass, body water, and phase angle) markers, warrant further investigation. Thus, the study aims were to (a) compare physical, physiological, body composition, and load markers between starters and non-starters; (b) compare measurements pre- and post-training intervention (five weeks); and (c) analyze any relationships between physical, physiological, body composition, and load markers in an elite female soccer team. Materials and Methods: Fourteen first-team players participated in the study (age 23.29 ± 3.19 years, weight 59.14 ± 6.87 kg, height 1.66 ± 0.08 m). Several physical (n = 15), physiological (n = 1), body composition (n = 11), and load markers (n = 14) were collected. In addition, participants were sub-divided into starters (n = 7) and non-starters (n = 7). Results: No differences were revealed between starters and non-starters in any of the examined variables. Moreover, following the training intervention, a significantly lower value was found for total body water/fat-free mass ratio (p = 0.043; ES = 0.582). In addition, there were several correlations detected between load and physical/physiological markers (n = 28); load and body composition markers (n = 6); physical/physiological and body composition markers (n = 34); and physical and physiological markers (n = 42). Conclusions: In conclusion, only a slight tendency of higher load values for starters than non-starters was observed. In addition, no differences in physical, physiological, and body composition markers were found between starters and non-starters, possibly suggesting that five weeks were not enough to improve such variables. Finally, the present results provide novel information assessing the effects of the pre-season in elite female Portuguese soccer players and contribute to a better understanding of the associations between different types of measurements.

Analysis of individual performance indicators of football goalkeeper

One of the most widely used strategies for performance analysis in different sports is notational analysis through direct observation of technical-tactical actions, which allows to understand the main indicators of sporting performance of the players, both individually and collectively. Football goalkeepers (GKs) are involved in the game differently when compared to the rest of the players in the team and, therefore, they develop different high-level and high-intensity tactical-technical actions. Therefore, the present work aimed to analyse the different performance indicators of football GKs through a search in the following databases: Web of Science (WOS), Scopus (Elsevier), PubMed (NIH) and, SPORTDiscus (EBSCO), until February 2023. The following keywords were used: "Football" or "Soccer", "Goalkeeper" and "Performance analysis". The results show that the main performance indicators are the percentage of avoided goals, the distribution of the ball at the goal kick as well as the number of offensive and defensive actions. Therefore, training sessions should be planned and implemented aimming to improve these skills. (AU)

Una de las estrategias más utilizadas para analizar el rendimiento en diferentes modalidades deportivas, es el análisis notacional a través de la observación directa de las acciones técnico-tácticas, lo que permite conocer los principales indicadores de rendimiento deportivo de los jugadores, tanto individual como colectivamente. Los porteros de fútbol tienen una involucración en el juego diferente comparativamente al resto de los jugadores del equipo, y, por ende, desarrollan diferentes acciones táctico-técnicas de alto nivel y de alta intensidad. Por ello, el objetivo del presente trabajo fui a analizar los diferentes indicadores de rendimiento de los porteros de fútbol mediante una búsqueda en las bases de datos: Web of Science (WOS), Scopus (Elsevier), PubMed (NIH) y SPORTDiscus (EBSCO), hasta febrero del 2023. Para ello, se emplearon las siguientes palabras claves, “Football” o “Soccer”, “Goalkeeper” y “Performance analysis”. Los resultados muestran como los principales indicadores de rendimiento son el porcentaje de goles evitados, la distribución del balón en el saque de portería, así como el número de acciones ofensivas y defensivas. Por tanto, se deben planificar e implementar sesiones de entrenamiento para la mejora de dichas habilidades. (AU)

Oxygen Uptake Kinetics and Time Limit at Maximal Aerobic Workload in Tethered Swimming.

This study aimed to apply an incremental tethered swimming test (ITT) with workloads (WL) based on individual rates of front crawl mean tethered force (Fmean) for the identification of the upper boundary of heavy exercise (by means of respiratory compensation point, RCP), and therefore to describe oxygen uptake kinetics (VO2k) and time limit (tLim) responses to WL corresponding to peak oxygen uptake (WLVO2peak). Sixteen swimmers of both sexes (17.6 ± 3.8 years old, 175.8 ± 9.2 cm, and 68.5 ± 10.6 kg) performed the ITT until exhaustion, attached to a weight-bearing pulley-rope system for the measurements of gas exchange threshold (GET), RCP, and VO2peak. The WL was increased by 5% from 30 to 70% of Fmean at every minute, with Fmean being measured by a load cell attached to the swimmers during an all-out 30 s front crawl bout. The pulmonary gas exchange was sampled breath by breath, and the mathematical description of VO2k used a first-order exponential with time delay (TD) on the average of two rest-to-work transitions at WLVO2peak. The mean VO2peak approached 50.2 ± 6.2 mL·kg-1·min-1 and GET and RCP attained (respectively) 67.4 ± 7.3% and 87.4 ± 3.4% VO2peak. The average tLim was 329.5 ± 63.6 s for both sexes, and all swimmers attained VO2peak (100.4 ± 3.8%) when considering the primary response of VO2 (A1' = 91.8 ± 6.7%VO2peak) associated with the VO2 slow component (SC) of 10.7 ± 6.7% of end-exercise VO2, with time constants of 24.4 ± 9.8 s for A1' and 149.3 ± 29.1 s for SC. Negative correlations were observed for tLim to VO2peak, WLVO2peak, GET, RCP, and EEVO2 (r = -0.55, -0.59, -0.58, -0.53, and -0.50). Thus, the VO2k during tethered swimming at WLVO2peak reproduced the physiological responses corresponding to a severe domain. The findings also demonstrated that tLim was inversely related to aerobic conditioning indexes and to the ability to adjust oxidative metabolism to match target VO2 demand during exercise.

Lower Limb Unilateral and Bilateral Strength Asymmetry in High-Level Male Senior and Professional Football Players.

This study sought to assess the relationship between different jumping asymmetries and associated performance variables in high-level male senior and professional football players. Nineteen football players with at least 12 years of training experience (23.2 ± 3.1 years of age; 75.2 ± 4.8 kg of body mass and 181 ± 0.06 cm of height) participated in this study performing countermovement jump (CMJ), squat jump (SJ), single-leg CMJ and drop jump (DJ), associated performance variable eccentric utilization ratio (EUR), stretch-shortening cycle (SSC), bilateral deficit (BLD), and limb symmetry index (LSI) were determined. High correlations were observed between different methodologies of jump tests and associated performance indicators (SSC, BLD, EUR), except LSI. Moreover, CMJ and SJ results were different (p < 0.05), but no differences were found between interlimb in CMJ (p = 0.19) and DJ (p = 0.14). Between the same limbs and different jumps differences were detected in CMJ and DJ (p < 0.01), and it has also been found that the laterality effect size on strength was small in CMJ (ES = 0.30) and DJ (ES = 0.35). LSI between CMJ and DJ was not different despite higher mean values in CMJ, and although mean BLD was positive (>100%), the results highlight the need for individual evaluation since eight players scored negatively. An in-depth and accurate analysis of performance in preseason screening jump tests should be considered, aiming to detect injury risk, specifically evaluating different jumping test methodologies, and determining jumping associated performance variables for each test, namely EUR, SSC, BLD, and LSI. Specific muscle-strengthening exercises could be implemented based on this study results and outcomes, aiming to reduce injury risks and lower extremity asymmetries and to enhance individual football performance in high-level male senior and professional football players. Sports institutions should pay special attention regarding potential health problems in athletes exposed to daily high training loads.

Documents Publication Evolution (1990-2022) Related to Physical Activity and Healthy Habits, a Bibliometric Review.

This research aims to provide an overview of the growing number of scientific literature publications related to Physical Activity and Healthy Habits. A bibliometric analysis between 1990 and 2022 in the Web of Science was carried out, following the bibliometric analysis law, using Microsoft Excel and VosViewer Software for analysis and data processing. A total of 276 documents (262 primary studies and 14 revisions) related to the topic under study were located. The results reveal an exponential growth of scientific production by 48% between 2006 and 2022. Public Environmental Occupational Health, Kaprio, J., and the USA were the knowledge field, author, and country most productive, respectively. A great thematic diversity was found related to the most used keywords by the authors, such as "physical activity", "health habits", "exercise", and "obesity". Thus, the research related to this theme is really in an exponential phase, with great interest in the importance of physical activity and healthy habits, implying practical decisions in policies to develop programs to promote physical activity and healthy habits.

The effect of the exercise environment and the level of involvement on bone mineral health.

INTRODUCTION: This study aimed to compare athletes practicing exercise in different environments with non-active young and elderly men and women regarding bone mineral density (BMD), hypothesizing that BMD values differ between athletes according to the environment of exercise practice, but those training in a low-gravitational environment have no different stimuli to BMD increasing if compared with healthy peers experiencing reduced exercise involvement, whatever the age group and sex. MATERIALS AND METHODS: 104 participants of both sexes were selected according to the environment of exercise practice [swimmers (N = 26) and judo fighters (N = 26)], and exercise level of involvement [non-active young (N = 26) and older adults (N = 26)]. Dual-energy X-ray absorptiometry provided BMD, lean mass, and fat mass (FM) for the whole body (WB), upper (UL), and lower limbs (LL). RESULTS: For the BMD in WB, UL and LL no effects of group and sex were observed (p > 0.05). Post-hoc analyses detected higher values of BMD in UL for female swimmers compared to non-active older adults (p < 0.05), while judo fighters showed higher BMD in WB, UL, and LL than other participants whatever the sex (p < 0.01). Lower FM was observed for WB, UL, and LL when swimmers and judo fighters were compared to non-active young and older female peers (p < 0.01). CONCLUSION: The findings emphasized that BMD stimuli with swimming are reduced when compared to judo, and despite the stimuli in swimming is not distinguishable from that affecting BMD in WB, UL and LL of non-active young, it is effective in differing BMD in UL among non-active older for women.

The Effect of Resistance Training on Bone Mineral Density in Older Adults: A Systematic Review and Meta-Analysis.

Resistance training (RT) has been considered an intervention with effective stimulus on bone mineral formation and is, therefore, recommended to decrease the rate of bone morpho-functional proprieties loss with aging. Thus, this meta-analysis aimed to analyze the effectiveness of RT protocols in promoting changes in bone mineral density (BMD) in older adults. The systematic reviews and meta-analysis followed the PRISMA guidelines (PROSPERO CRD42020170859). The searches were performed in the electronic databases using descriptors according to the PICO strategy. The methodological quality and risk of bias were assessed with the PEDro scale, and the magnitude of the results was determined by Hedges' g. Seven studies involving 370 elderlies, with the RT planned as a unique exercise mode of intervention, showed designs with four to five exercises for upper- and lower-limbs musculature, two to three sets per exercise, eight to twelve repetitions to failure at 70-90% 1 RM, 60-120 s of rest between sets, and executed three times per week for 12-52 weeks. The RT protocols were classified between good and excellent and evidenced a positive effect on the BMD at the hip (0.64%) and spine (0.62%) but not in the femoral neck (-0.22%) regardless of the intervention length. The narrow range of either positive or negative changes in the BMD after the RT intervention support, at best, a preventive effect against the increasing risk of bone frailty in an older population, which is evident beyond 12 weeks of RT practice engagement.

The Effect of Handlebar Height and Bicycle Frame Length on Muscular Activity during Cycling: A Pilot Study.

The cycling literature is filled with reports of electromyography (EMG) analyses for a better understanding of muscle function during cycling. This research is not just limited to performance, as the cyclist's goal may be rehabilitation, recreation, or competition, so a bicycle that meets the rider's needs is essential for a more efficient muscular activity. Therefore, the purpose of this study was to understand the contribution of the activity of each of the following muscles: TD (trapezius descending), LD (latissimus dorsi), GM (gluteus maximus), and AD (anterior deltoid) in response to different bicycle-rider systems (handlebar height; bicycle frame length) and intensities in a bicycle equipped with a potentiometer. Surface EMG signals from muscles on the right side of the body were measured. A general linear model test was used to analyze the differences between muscle activation in the test conditions. Effect sizes were calculated using a partial Eta2 (η2). The level of significance was set at 0.05. Muscle activation of different muscles differs, depending on the cycling condition (Pillai's trace = 2.487; F (36.69) = 9.300; p < 0.001. η2 = 0.958), mostly during low intensities. In high intensities, one specific pattern emerges, with a greater contribution of GM and TD and weaker participation of LD and AD, enhancing the cycling power output.

Single- and Multi-Joint Maximum Weight Lifting Relationship to Free-Fat Mass in Different Exercises for Upper- and Lower-Limbs in Well-Trained Male Young Adults.

This study aimed to analyze whether the relationship between regional and whole-body fat-free mass (FFM) and strength is related to FFM distribution and area according to limb involvement. Thirty well-trained male young adults underwent one-repetition maximum test (1RM) to assess the strength in arm curl (AC), bench press (BP), seated row (SR), leg press 45° (LP45), knee extension (KE), and leg curl (LC). Dual-energy X-ray absorptiometry was used to evaluate FFM. The values for 1RM in AC, BP, and R correlated to FFM in upper limb (R2 = 0.69, 0.84 and 0.75), without an effect of appendicular mass index (API) or area. For 1RM in KE, the correlation with FFM in lower limb increased with thigh area (R2 = 0.56), whereas 1RM in LC and LP45 correlation to whole-body FFM increased with API (R2 = 0.64 and 0.49). The upper limb's FFM may be reliable for indexing the arms and upper trunk strengths, whereas the relationships between FFM and strength in lower limb improve as muscle mass and thigh area increases between subjects.

Training Load in Different Age Category Soccer Players and Relationship to Different Pitch Size Small-Sided Games.

This study sought to evaluate the training load in different age category soccer players associated with distinct pitch size small-sided games (SSGs). Twenty-four soccer players (eight in each age category: U-12, U-15, and U-23) performed three consecutive 4 vs. 4 ball possession SSGs (SSG1: 16 × 24 m; SSG2: 20 × 30 m; and SSG3: 24 × 36 m) all with 3 min duration and 3 min rest. Subjects carried ultra-wideband-based position-tracking system devices (WIMU PRO, RealTrack System). Total distance covered increased from SSG1 to SSG3 in all age categories and predominantly in running speeds below 12 km·h-1. Moreover, distance covered in 12-18 km·h-1 running speed was different in all performed SSGs and age categories. Residual or null values were observed at 18-21 km·h-1 or above running speed, namely in U-12, the only age category where metabolic power and high metabolic load distance differences occurred throughout the performed SSGs. Edwards' TRIMP differences between age categories was only observed in SSG2 (U-12 < U-15). The design of SSGs must consider that the training load of the players differs according to their age category and metabolic assessment should be considered in parallel to external load evaluation in SSGs. Wearable technology represents a fundamental support in soccer.

Can an Incremental Step Test Be Used for Maximal Lactate Steady State Determination in Swimming? Clues for Practice.

We aimed to compare the velocity, physiological responses, and stroke mechanics between the lactate parameters determined in an incremental step test (IST) and maximal lactate steady state (MLSS). Fourteen well-trained male swimmers (16.8 ± 2.8 years) were timed for 400 m and 200 m (T200). Afterwards, a 7 × 200-m front-crawl IST was performed. Swimming velocity, heart rate (HR), blood lactate concentration (BLC), stroke mechanics, and rate of perceived exertion (RPE) were measured throughout the IST and in the 30-min continuous test (CT) bouts for MLSS determination. Swimming velocities at lactate threshold determined with log-log methodology (1.34 ± 0.06 m∙s-1) and Dmax methodology (1.40 ± 0.06 m∙s-1); and also, the velocity at BLC of 4 mmol∙L-1 (1.36 ± 0.07) were not significantly different from MLSSv, however, Bland-Altman analysis showed wide limits of agreement and the concordance correlation coefficient showed poor strength of agreement between the aforementioned parameters which precludes their interchangeable use. Stroke mechanics, HR, RPE, and BLC in MLSSv were not significantly different from the fourth repetition of IST (85% of T200), which by itself can provide useful support to daily practice of well-trained swimmers. Nevertheless, the determination of MLSSv, based on a CT, remains more accurate for exercise evaluation and prescription.

Evidence for a neural law of effect.

Thorndike's law of effect states that actions that lead to reinforcements tend to be repeated more often. Accordingly, neural activity patterns leading to reinforcement are also reentered more frequently. Reinforcement relies on dopaminergic activity in the ventral tegmental area (VTA), and animals shape their behavior to receive dopaminergic stimulation. Seeking evidence for a neural law of effect, we found that mice learn to reenter more frequently motor cortical activity patterns that trigger optogenetic VTA self-stimulation. Learning was accompanied by gradual shaping of these patterns, with participating neurons progressively increasing and aligning their covariance to that of the target pattern. Motor cortex patterns that lead to phasic dopaminergic VTA activity are progressively reinforced and shaped, suggesting a mechanism by which animals select and shape actions to reliably achieve reinforcement.

Corticostriatal dynamics encode the refinement of specific behavioral variability during skill learning.

Learning to perform a complex motor task requires the optimization of specific behavioral features to cope with task constraints. We show that when mice learn a novel motor paradigm they differentially refine specific behavioral features. Animals trained to perform progressively faster sequences of lever presses to obtain reinforcement reduced variability in sequence frequency, but increased variability in an orthogonal feature (sequence duration). Trial-to-trial variability of the activity of motor cortex and striatal projection neurons was higher early in training and subsequently decreased with learning, without changes in average firing rate. As training progressed, variability in corticostriatal activity became progressively more correlated with behavioral variability, but specifically with variability in frequency. Corticostriatal plasticity was required for the reduction in frequency variability, but not for variability in sequence duration. These data suggest that during motor learning corticostriatal dynamics encode the refinement of specific behavioral features that change the probability of obtaining outcomes.

Dipole moments of isomeric alkoxyalcohols in cyclohexane. Comparison of Hedestrand and Fröhlich procedures with a new formula.

Limiting dipole moments of four isomeric alkoxyalcohols dissolved in cyclohexane at 298.15 K were determined from measurements of the relative permittivity of at least 17 dilute solutions up to solute mole fraction of 0.03. In addition, 5 to 7 data points were obtained up to a mole fraction of 0.1. A stepwise dilution device ensured dielectric measurements to be performed in highly dilute solutions with accurately determined concentrations. Densities of these solutions and refractive indices of the pure liquids were independently measured. Limiting dipole moments were calculated using Hedestrand's equation and an improved method of implementing Fröhlich's equation, which circumvents extrapolation difficulties referred to in the literature. A new formula, based on the one-liquid approach for extending the Onsager-Kirkwood-Fröhlich equation to liquid mixtures, is introduced and shown to yield a reliable and robust procedure for estimating dipole moments of polar molecules dissolved in non-polar solvents. Limiting dipole moment values for 2-tert-butoxyethanol (2.31 D), 1-propoxypropan-2-ol (2.14 D), 2-butoxyethanol (2.14 D) and 2-isobutoxyethanol (2.08 D) are recommended. The relative order of these values appears to determine the order of hydrophilicity of these four alkoxyalcohols as suggested by their recently reported limiting partial molar volumes and isentropic compressions in aqueous solutions.

Stimulation on demand: closing the loop on deep brain stimulation.

High-frequency open-loop deep brain stimulation (DBS) has been used to alleviate Parkinson's symptoms for almost 20 years. In this issue of Neuron, Rosin et al. present a closed-loop real-time approach that improves DBS and shines light on the etiology of motor symptoms in Parkinson's disease.