Corrigendum: Effect of neuromuscular training program on quality of life after COVID-19 lockdown among young healthy participants: A randomized controlled trial.

[This corrects the article DOI: 10.3389/fpsyg.2022.844678.].

The Influence of Transcranial Direct Current Stimulation on Shooting Performance in Elite Deaflympic Athletes: A Case Series.

Transcranial direct current stimulation (tDCS) has been shown to improve motor learning in numerous studies. However, only a few of these studies have been conducted on elite-level performers or in complex motor tasks that have been practiced extensively. The purpose was to determine the influence of tDCS applied to the dorsolateral prefrontal cortex (DLPFC) on motor learning over multiple days on 10-m air rifle shooting performance in elite Deaflympic athletes. Two male and two female elite Deaflympic athletes (World, European, and National medalists) participated in this case series. The study utilized a randomized, double-blind, SHAM-controlled, cross-over design. Anodal tDCS or SHAM stimulation was applied to the left DLPFC for 25 min with a current strength of 2 mA concurrent with three days of standard shooting practice sessions. Shooting performance was quantified as the points and the endpoint error. Separate 2 Condition (DLPFC-tDCS, SHAM) × 3 Day (1,2,3) within-subjects ANOVAs revealed no significant main effects or interactions for either points or endpoint error. These results indicate that DLPFC-tDCS applied over multiple days does not improve shooting performance in elite athletes. Different stimulation parameters or very long-term (weeks/months) application of tDCS may be needed to improve motor learning in elite athletes.

Effect of Neuromuscular Training Program on Quality of Life After COVID-19 Lockdown Among Young Healthy Participants: A Randomized Controlled Trial.

Study in the period of coronavirus disease 2019 (COVID-19) lockdown and the effect of different exercise training programs on the quality of life (QoL) dimension are limited. This randomized control study as a part of which the impact of an 8-week neuromuscular training program on the 90 healthy young individuals' QoL after COVID-19 lockdown was assessed using a short form of the WHOQOL-BREF questionnaire comprising of four domains (physical health, psychological health, social relations, and the environment). The intervention group (NT) (n = 47) took part in a neuromuscular training program consisting of dynamic neuromuscular stabilization and whole-body vibration training. In contrast, the control group (CG) (n = 43) did not participate in any programmed physical activity. From pre- to post-intervention test, the NT group significantly and substantially improved [mean change (95% CI)] all the QoL domains, physical for 12.78 scores (8.89, 16.64), psychological for 13.12 scores (9.51, 16.74), social relationships for 20.57 scores (16.12, 25.02), and environmental for 24.40 scores (21.45, 27.35). These results suggest that the NT program could enhance QoL in young and healthy participants following COVID-19 lockdown.

The effects of daily physical activity intervention on physical fitness in preschool children.

The study aimed to determine the effects of 6 months daily physical activity on physical fitness in preschool children. A total of 72 children (36 boys) and 92 children (47 boys) composed the experimental (EG) and control group (CG), respectively. We used the PREFIT battery access physical fitness. In EG, participants had 45 minutes of organized physical activity 5 days per week. The CG continued their usual routine with 30 minutes of structured physical activity two times per week. The EG improved the mean performance of grip strength (η p2=0.08) and sit-ups in the 30s ( p2=0.16) to a significantly greater extent as compared to the CG. In boys, the improvements of mean performance of handgrip strength (η p2=0.13), 4x10m shuttle run η p2=0.09), standing long jump (η p2=0.05), sit-ups in 30s (η p2=0.17) were significantly greater in EG than in the CG. However, girls in EG only had significant improvements  in the sit-ups in the 30 s test compared to CG (η p2=0.14). Overall, our study shows that after 6 months of daily exercise programme, preschool children improved muscular strength compared to those peers allocated in the control group. No significant differences between groups were found in the remaining fitness components analysed.

Body Composition in Elite Soccer Players from Youth to Senior Squad.

There is a strong relationship between body composition and performance in male soccer players. This study aimed to display an optimal body height and weight, and body composition profile of male soccer players for four competitive age groups. This cross-sectional study included four groups: U-15 (n = 152), U-17 (n = 154), U-19 (n = 61), and seniors (n = 27). Body height and weight were measured under standard conditions, and the bioelectrical impedance analyzer (BIA) analyzed body composition. On average, soccer players in the U-15 group had significantly lower body height, weight, body mass index, skeletal muscle mass, fat-free mass, total body water and basal metabolic rate than U-17, U-19 and seniors, but a higher percentage of body fat than U-17 and U-19, p < 0.05. In addition, the results show significant non-linear increases in body height, weight and body composition as the age of soccer players increases, with the exception of the percentage of body fat mass, which tends to significantly decrease with age. The main findings of this study are that body fat mass remains stable and similar across all age groups, including in the senior squad.

Short-Term Core Strengthening Program Improves Functional Movement Score in Untrained College Students.

Functional movement is an important part of developing athletes' but also untrained individuals' performance. Its monitoring also proved useful in identifying functional limitations and asymmetries, and also in determining the intervention effects. The quasi-experimental pre-test post-test study investigated the effects of core stability training program on the Functional Movement Screen (FMS) score in untrained students after six weeks. The intervention (INT) and control (CG) groups included 73 and 65 male students, respectively. Functional movement patterns were evaluated using the FMS including seven components scores representing seven basic functional patterns. Both groups significantly improved almost all FMS components scores, but the INT increased the mean performance of the hurdle step (partial ŋ2 × 100 = 4%, p = 0.02), in-line lunge (partial ŋ2 × 100 = 3%, p = 0.05), rotatory stability (partial ŋ2 × 100 = 4%, p = 0.02) and total FMS (partial ŋ2 × 100 = 3%, p = 0.04) significantly more than the CG. This justifies that core strengthening can improve FMS in untrained individuals even with the short duration programs.

Anthropometric and Motor Competence Classifiers of Swimming Ability in Preschool Children-A Pilot Study.

Swimming is a form of physical activity and a life-saving skill. However, only a few studies have identified swimming ability classifiers in preschool children. This pilot cross-sectional study aimed to find anthropometric (AM) and motor competence (MC) predictors of swimming ability in preschool children, by building classifiers of swimming ability group (SAG) membership. We recruited 92 children (girls n = 45) aged 5-6 years and took the AM and MC measurements in accordance with the reference manual and using the KTK battery test (motor quotient, MQ), respectively. A linear discriminant analysis tested a classification model of preschoolers' swimming ability (SAG: POOR, GOOD, EXCELLENT) based on gender, age, AM, and MC variables and extracted one significant canonical discriminant function (model fit: 61.2%) that can differentiate (group centroids) POOR (-1.507), GOOD (0.032), and EXCELLENT (1.524). The MQ total was identified as a significant classifier, which absolutely contributed to the discriminant function that classifies children's swimming ability as POOR (standardized canonical coefficient: 1.186), GOOD (1.363), or EXCELLENT (1.535) with an accuracy of 64.1%. Children with higher MQ total ought to be classified into higher SAG; thus, the classification model of SAG based on the MQ total is presented.

Evaluation of Gross Motor Coordination and Physical Fitness in Children: Comparison between Soccer and Multisport Activities.

The early detection and continuous monitoring of children's motor competence levels and physical fitness is very important. The purpose of this study was to determine the differences in motor coordination of children enrolled in soccer and multisport activities. The participants of this study included 147 boys and girls (mean age 7.60 ± 0.85 years). The total sample of subjects was composed of two subgroups: children who were enrolled in organized exercise programs-multisports (n = 77), and children who were engaged in soccer training (n = 70). Motor coordination was evaluated with the Kiphard-Schilling body coordination test (KTK). Physical fitness was assessed with a 20 m shuttle run test, 4 × 10 m shuttle run test, standing long jump, and handgrip strength. The ANCOVA showed significant differences (p < 0.05) with large effect size between groups for tests hopping for height (d = 0.93), total motor quotient (d = 1.31), jumping sideways (d = 1.32), and moving sideways (d = 1.59), after adjusting for age and gender. There were no significant differences between groups in the physical fitness tests. It can be concluded that children enrolled in multisport activities have higher levels of motor coordination than children who are enrolled only in soccer. Therefore, multiple sport training programs should be considered and encouraged by parents, educators, and other training professionals.

The Importance of Reactive Agility Tests in Differentiating Adolescent Soccer Players.

The ability to differentiate the elite from nonelite athletes is not clearly defined. We investigated level differences in speed, change of direction speed (CODS), and reactive agility in a group of trained adolescent soccer players. A total of 75 adolescent male soccer players (aged 14-19 years) were recruited. The players were grouped based on the level of play to elite, sub-elite, and amateur players. Players were tested for 5-, 10- and 20-m sprints, CODS, and reactive agility tests (RAT). Elite players had faster reaction movement time during RAT with live opponent stimuli (p ≤ 0.01) compared to sub-elite and amateur players. Moreover, elite players showed a faster time during light stimuli (p ≤ 0.01) but only compared to amateur players. The times for 5-m and 10-m sprint groups did not differ (p > 0.05). The results demonstrated that the skilled players (elite and sub-elite) performed better in reactive agility tests, speed, and COD speed compared to amateur players. Additionally, we can conclude that total and reaction time in the agility test with live opponent stimuli can be a significant factor that differentiates between adolescent soccer players considering their level.

Eight months of school-based soccer improves physical fitness and reduces aggression in high-school children.

School-based programmes have shown promising results in the reduction of aggressive behaviour, but the effectiveness of physical activity modalities among adolescents remains to be determined. The aim of this study was to determine the effects of a school-based soccer programme on physical fitness and aggression in adolescent students. One hundred and five high school students were randomized to a small-sided soccer training group (SG) or a control group (CG). In addition to the regular physical education classes performed as part of a curriculum, the SG completed eight months of small-sided soccer training twice a week after school. Aerobic fitness (YYIR1), vertical jump (VJ), backward overhead medicine ball throw (BOMBT), and Buss and Perry's aggression questionnaire were evaluated before and after eight months of training. Greater improvements were observed in the SG than in the CG in the BOMBT (%diff=4.3, ŋp 2=.308) and YYIR1 tests (%diff=2.2, ŋp 2=.159), and physical aggression subscale (%diff=-12.1, ŋp 2=.144). Extra, school-based recreational soccer for adolescents was accompanied by a significant improvement in physical fitness, compared to physical education classes only. Moreover, the implementation of recreational soccer into regular physical education classes seems to be a potentially appropriate stimulus for reducing aggression in high-school students.

Validity and Reliability of Isometric-Bench for Knee Isometric Assessment.

There is a strong need for a new, probably cheaper, smaller, and more portable isometric dynamometer. With this aim, we investigated the concurrent validity and reliability of a low-cost portable dynamometer to measure the isometric strength of the lower limb. Seventeen young participants (age 16.47 ± 0.51 years) were randomly assessed on three different days for knee flexion and extension isometric forces with two different devices: a commonly used isokinetic dynamometer (ISOC) and a portable isometric dynamometer prototype (ISOM). No significant differences were observed between the ISOC and the ISOM (all comparisons p > 0.05). Test-retest comparison showed the ISOM to have high reliability (ICC 0.879-0.990). This study showed that measurements with the ISOM could be performed without systematic bias and with high reliability. The ISOM is a device that is able to assess knee isometric strength with excellent concurrent validity and reliability.

Short-Term FIFA 11+ Improves Agility and Jump Performance in Young Soccer Players.

Studies dealing with the effectiveness of the Fédération Internationale de Football Association (FIFA) 11+ prevention program to improve performance outcomes in children aged < 14 years are limited. This study aimed to point out the effects of the application of short-term FIFA 11+ warm-up program on physical performance in young football players. Participants were 36 youth male football players, divided into a FIFA 11+ (n = 19; mean (SD) age: 11.15 (0.79) y) and a control group (CG: n = 17; age: 10.87 (0.8) y) and trained for 4 weeks. Before and after the training period, standing long jump performance, agility, repeated sprint ability, sit and reach, and "30-15" intermittent fitness tests were assessed. A mixed ANOVA showed significant differences between the groups in the standing long jump test (FIFA 11+: 5.6% vs. CG: -1.9%) in favor of FIFA 11+ over CG. Additionally, the FIFA 11+ performance of the Illinois agility test was significantly better compared to the CG performance (FIFA 11+: -1.9% vs. CG: 0.03%). The main findings of this study suggest that just 4 weeks of implementation of the FIFA 11+ improves physical performance compared with traditional warm-up routines in young soccer players.

Correlation between hypermobility score and injury rate in artistic gymnastics.

BACKGROUND: Generalized joint hypermobility (GJH) is suggested as a contributing factor for injuries in young athletes and adults. It is presumed that GJH causes decreased joint stability, thereby increasing the risk of joint and soft tissue injuries during sports activities. The aim of this study was to determine the correlation between the hypermobility score (using the Beighton`s modification of the Carter-Wilkinson criteria of hypermobility) in gymnasts and injury rate, during the period of one year. METHODS: This study observed 24 artistic gymnasts (11-26 years old), members of Qatar National Team in artistic gymnastics. We examined the Beighton joint hypermobility screen and a seasonal injury survey. The gymnasts characteristics (age, gender) and gymnastics characteristics (training per day and number of years in training artistic gymnastics) and their relations to injury rate were also included. RESULTS: The most common injury was the lower back pain injury, followed by knee, shoulder, hip and ankle injuries. We found strong correlation of number of years gymnastics training and injury rate (P<0.001). There is no significant correlation in the numbers of training hours during one week and hypermobility score to numbers of injuries (P>0.05). CONCLUSIONS: According to this study there is no correlation between GJH and injury rate in artistic gymnasts in Qatar. Total training period in gymnastics have greater contribution in injury rate.

Seasonal body composition variations in adolescent soccer players / Variaciones estacionales de composición corporal en jugadores adolescentes de fútbol

The aim of this study was to examine seasonal variations in body composition in adolescent soccer players. A total of 64 young male soccer players (aged 14-18 years) were recruited for this research. Body composition was assessed using the Bioelectric impedance analysis. The variables were body mass, body fat, muscle mass, fat free mass, total body water, BMI, body fat %, basic metabolic rate. Body mass did not change across the three measurement occasions. Body fat mass and body fat % significantly changed between test intervals (p≤0.05). There were no significant differences in other variables between measurements performed during the season. In conclusion, body fat has changed significantly from the start of the season to the end of the competitive period in adolescent soccer players, in accordance with earlier studies.

El objetivo de este estudio fue examinar las variaciones estacionales en la composición corporal en jugadores adolescentes de fútbol. Un total de 64 jóvenes jugadores de fútbol masculino (14-18 años de edad) fueron reclutados para esta investigación. La composición corporal se evaluó mediante el uso del análisis de impedancia bioeléctrica. Las variables fueron masa corporal, grasa corporal, masa muscular, masa libre de grasa, agua corporal total, IMC, porcentaje de grasa corporal, tasa metabólica básica. La masa corporal no cambió en las tres ocasiones de medición. La masa de grasa corporal y el porcentaje de grasa corporal cambiaron significativamente entre los intervalos de prueba (p≤0.05). No hubo diferencias significativas en otras variables entre las mediciones realizadas durante la temporada. En conclusión y de acuerdo a estudios anteriores, la grasa corporal cambió significativamente desde el inicio de la temporada hasta el final del período competitivo en jugadores adolescentes de fútbol.

Calcaneus quantitative ultrasound and body composition in preschool children: physical activity consideration / Ultrasonido cuantitativo de calcáneo y composición corporal en niños preescolares: consideración de actividad física

SUMMARY: The aim of this research was to determine the difference in Calcaneus quantitative ultrasound (QUS) and body composition according to physical activity in preschool children. We recruited 296 healthy children (112 girls and 184 boys) from different kindergartens in Vojvodina, Serbia. Children were evaluated for body composition. Quantitative ultrasound (QUS) measurements of the heel were performed using the Speed of sound, Broadband Ultrasound Attenuation, Quantitative Ultrasound Index and Estimated bone mineral density for further analysis. Furthermore, children were divided into three groups according to physical activity. Apart from the differences in Body fat % and body mass, there were no significant group differences for BMI, waist circumference and abdominal skinfold (p>0.05). The ANOVA showed significant differences (p<0.05) in all QUS measurements between three different intensities of physical activity. The results show that Body Mass and Body fat % were important predictors that discriminate children according to physical activity. Moreover, the results show that beside BMI and Body fat %, all calcaneus QUS measurements showed differences according to physical activity. In conclusion, our study showed differenses in all calcaneus QUS measurements according to physical activity level.

RESUMEN: El objetivo de esta investigación fue determinar la diferencia entre el ultrasonido cuantitativo (USC) de calcáneo y la composición corporal según la actividad física en niños en edad preescolar. Se estudiaron 296 niños sanos (112 niñas y 184 niños) de diferentes jardines infantiles en Vojvodina, Serbia. Se evaluó la composición corporal de los niños. Las medidas de USC del talón se realizaron utilizando la velocidad del sonido, atenuación de ultrasonido de banda ancha, el índice de ultrasonidos cuantitativos y la densidad mineral ósea estimada para un análisis posterior. Los niños se dividieron en tres grupos según actividad física. Además de las diferencias de porcentaje de grasa corporal y masa corporal, no se observaron diferencias significativas de grupo en el índice de masa corporal (IMC), circunferencia de cintura y el pliegue abdominal (p> 0,05). El test de ANOVA mostró diferencias significativas (p <0,05) en todas las mediciones USC entre tres diferentes intensidades de actividad física. Los resultados muestran que la masa corporal y la grasa corporal fueron indicadores importantes que permiten diferenciar a los niños según la actividad física. Por otra parte, los resultados muestran que además del IMC y el porcentaje de grasa corporal, todas las mediciones de USC del calcáneo mostraron diferencias según el nivel de actividad física. En conclusion, nuestro estudio mostró diferencias en el USC de acuerdo al nivel de actividad física.