Acute effect of different doses of caffeinated chewing gum on exercise performance in caffeine-habituated male soccer players.

The ergogenic benefits of caffeine have been well established, but there is scarce research on its chewing gum form. The present research aimed to examine the effects of different doses (100 and 200 mg) of caffeinated chewing gum on muscle strength, vertical jump performance, and ball-kicking speed in trained male soccer players. In a double-blind, randomized counterbalanced, and crossover research design, 14 male soccer players (age = 22 ± 2 y; body mass = 74.2 ± 7.1 kg; height = 180.0 ± 6.8 cm; habitual caffeine intake = 358.9 ± 292.4 mg/day) participated in three experimental trials. In each trial, participants performed isometric handgrip strength, quadriceps and hamstring strength, ball-kicking speed, and 15 s countermovement jump test 10 min after chewing 100 mg (LCAF) or 200 mg (MCAF) of caffeinated gum or placebo (PLA). MCAF improved quadriceps strength (53.77 ± 5.77 kg) compared to LCAF (49.62 ± 8.81 kg, p = 0.048) and PLA (49.20 ± 7.20 kg, p = 0.032). However, neither LCAF nor MCAF had a significant effect on the isometric handgrip and hamstring strength, ball-kicking speed, and 15 s countermovement jump test (all p > 0.05). These findings support chewing gum as an alternative mode of caffeine administration which can be used as a nutritional ergogenic aid for trained soccer players, at least for quadriceps strength.

Effects of plyometric training on kicking performance in soccer players: A systematic review and meta-analysis.

This systematic review and meta-analysis aimed to determine the pooled effect size (ES) of plyometric training (PT) on kicking performance (kicking speed and distance) in soccer players depending upon some related factors (i.e., age, gender, skill level, and intervention duration). This study was carried out according to the PRISMA guidelines. Four electronic databases-EBSCO, PubMed, Scopus, and Web of Science-were searched for relevant studies. A total of n = 16 studies yielding 17 ES with n = 553 participants were finally included in the meta-analysis. A random-effects model was used to calculate Hedge's g with a 95% confidence interval (CI), which showed that plyometric training had a large-sized positive effect on soccer kicking performance (g = 0.979, 95% CI [0.606, 1.353], p < 0.001). Subgroup analyses were performed according to participants' characteristics (i.e., age, gender, skill level) and intervention duration, demonstrating no significant differences between these subgroups. The study pointed out that plyometric training is a generally effective method to improve soccer players' kicking performance, which plays a crucial role in passing and shooting actions during games. As for soccer players and strength and conditioning coaches, the plyometric training aiming to enhance kicking performance has valuable implications in practice. Therefore, besides well-known training methods like power training in the weight room, plyometric training could be incorporated into the overall strength and conditioning programs for soccer players to reach high standards of kicking performance.

Comparación de la aptitud física entre jóvenes futbolistas colombianos / Comparison of physical fitness among young colombian soccer players / Comparação da aptidão física em jovens futebolistas colombianos

El objetivo de este estudio fue comparar la aptitud física entre jóvenes futbolistas colombianos y describirlas según el pico de velocidad de crecimiento. Participaron 58 jugadores de edades comprendidas entre 13,46 y 15,31 años. Se evaluó una antropometría básica y se determinó el pico de velocidad de crecimiento PVC, también se aplicaron seis pruebas físicas relacionadas con fuerza, velocidad y agilidad. Se realizaron gráficas de dispersión de las pruebas físicas según el PVC, múltiples correlaciones entre variables y, finalmente, la población se dividió en tres grupos según el club al que pertenecen los jugadores haciendo una comparación ANOVA entre club A, club B y club C. Aparentemente, el PVC describe las pruebas de fuerza-potencia en mayor medida que las pruebas de agilidad según la apreciación de las gráficas de dispersión. En las múltiples correlaciones se evidencia una gran asociación entre el CMJ con las otras pruebas; en la comparación de clubes, el club A tuvo jugadores más altos, más pesados y con un PVC más adelantado, así mismo presentó mejor rendimiento en las pruebas, principalmente en CMJ F=13,813 P<0,01, Lanzamiento Balón Medicinal F = 11,053 P<0,01, Velocidad de Remate F = 18,916 P<0,01, y Repeated Sprint Ability F=12,950 P<0,01. Se concluye que la influencia de las condiciones antropométricas favorables se relaciona con un mejor desempeño en las pruebas físicas en esta población de jóvenes futbolistas que se encuentran en la época del salto de crecimiento.

The purpose of this study was to compare soccer players' physical fitness and describe them according to Peak Height Velocity (PHV). The participants were 58 young soccer players between 13.46 and 15.31 years old. Basic anthropometry was evaluated, and Peak Height Velocity was determined. Also, six physical tests related to strength, speed, and agility were measured. The physical test was plotted according to PHV, with multiple Pearson correlations among variables. Finally, a sample was compared in an ANOVA, considering the club to which each player belonged to (club A, club B, and club C). It seems that PHV describes strength and speed better than the capacity for agility. The CMJ test had strong correlations with other physical tests, and in ANOVA comparisons, club A had taller, stronger players, with an advanced PHV in comparison to clubs B and C. Likewise, Club A had a better performance in physical tests, mainly in the CMJ F=13.813 P<0.01 medicine ball throw F= 11.053 P<0.01, kicking speed F= 18.916 P<0.01, and repeated sprint Ability F=12.950 P<0.01. In conclusion, favorable anthropometric conditions influence better performance in physical tests in this population of young soccer players in their growth spurt period.

O objetivo deste estudo foi comparar a aptidão física entre jovens futebolistas colombianos e descrever a aptidão de acordo com o pico de velocidade de crescimento. Participaram 58 jogadores com idades entre 13,46-15,31 anos. Foi avaliada uma antropometria básica e determinado o pico de velocidade de crescimento PVC, também foram aplicados seis testes físicos relacionados à força, velocidade e agilidade. Foi usado um gráfico de dispersão para os testes físicos de acordo com o PVC e também múltiplas correlações entre as variáveis, finalmente, os participantes foram divididos em três grupos de acordo com o clube que jogavam, fazendo uma comparação ANOVA entre clube A, B e C. Aparentemente o PVC descreve os testes de força-potência melhor que os testes de agilidade. Nas correlações múltiplas fica evidente uma grande associação entre o CMJ e os demais testes; e na comparação de clubes, o clube A teve jogadores mais altos, mais pesados e com PVC mais avançado, e também apresentou melhor desempenho nos testes, principalmente em CMJ F=13,813 P<0,01 lançamento de bola medicinal F= 11,053 P<0,01, velocidade de remate F= 18,916 P<0,01, e nos sprints repetido F=12,950 P<0,01. Conclui-se que a influência das condições antropométricas está relacionada ao melhor desempenho em testes físicos nesta população de jovens futebolistas colombianos que estão no período de velocidade do crescimento.

Physiological and Anthropometric Determinants of Performance Levels in Professional Futsal.

There is an evident lack of studies examining the pursuit of excellence in futsal. The aims of this study were to evaluate anthropometric and physiological variables that may contribute to distinguishing among performance levels in professional futsal players and to evaluate correlates of those variables. The participants were 75 male professionals (age = 25.1 ± 5.1 years, body height = 182.3 ± 6.2 cm, body mass = 80.8 ± 10.4 kg), who were divided into performance levels using two criteria: (i) starters (first teams) vs. non-starters (substitutes) and (ii) top-level players (members of the national team and players who participated in top-level team competition in Europe) vs. high-level players (team players competing at the highest national competitive rank). Variables included anthropometrics (body height and mass, BMI, body fat percentage), generic tests of physiological capacities [5- and 10-m sprints, countermovement jump, broad jump, 20-yard test, reactive strength index (RSI)], and futsal-specific fitness tests [kicking speed by dominant and non-dominant leg, futsal-specific tests of change of direction speed, and reactive agility (FSRAG) involving/not involving dribbling the ball]. Top-level players outperformed high-level players in RSI, broad jump, kicking speed, and FSRAG involving dribbling. Starters achieved better results than non-starters in fewer variables, including kicking speed and RSI. Body fat percentage negatively influenced FSRAG involving dribbling, and RSI. FSRAG, RSI, and kicking speed were significantly correlated, indicating the similar physiological background of these capacities. The findings suggest that enhanced reactive strength and the ability to rapidly change direction speed in response to external stimulus while executing futsal-specific motor tasks (e.g., dribbling), along with players' ability to kick the ball speedily, can be considered essential qualities required for advanced performance in futsal. Consequently, futsal strength and conditioning training should be targeted toward lowering relative body fat, maximizing lower-body reactive strength and including futsal-specific skills (e.g., dribbling, shooting) in reactive agility drills.