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.

The aim of this study was to examine the acute effects of different levels of hypoxia on maximal strength, muscular endurance, and cognitive function in males and females. In total, 13 males (mean ± SD: age, 23.6 ± 2.8 years; height, 176.6 ± 3.9 cm; body mass, 76.6 ± 2.1 kg) and 13 females (mean ± SD: age, 22.8 ± 1.4 years; height, 166.4 ± 1.9 cm; body mass, 61.6 ± 3.4 kg) volunteered for a randomized, double-blind, crossover study. Participants completed a one repetition strength and muscular endurance test (60% of one repetition maximum to failure) for squat and bench press following four conditions; (i) normoxia (900 m altitude; F_iO₂: 21%); (ii) low dose hypoxia (2000 m altitude; F_iO₂: 16%); (iii) moderate dose hypoxia (3000 m altitude; F_iO₂: 14%); and (iv) high dose hypoxia (4000 m altitude; F_iO₂: 12%). Heart rate, blood lactate, rating of perceived exertion, and cognitive function was also determined during each condition. The one repetition maximum squat (p = 0.33) and bench press (p = 0.68) did not differ between conditions or sexes. Furthermore, squat endurance did not differ between conditions (p = 0.34). There was a significant decrease in bench press endurance following moderate (p = 0.02; p = 0.04) and high (p = 0.01; p = 0.01) doses of hypoxia in both males and females compared to normoxia and low dose hypoxia, respectively. Cognitive function, ratings of perceived exertion, and lactate were also significantly different in high and moderate dose hypoxia conditions compared to normoxia (p < 0.05). Heart rate was not different between the conditions (p = 0.30). In conclusion, high and moderate doses of acute normobaric hypoxia decrease upper body muscular endurance and cognitive performance regardless of sex; however, lower body muscular endurance and maximal strength are not altered.

Post-activation potentiation (PAP) is a phenomenon which can improve force performance executed after a previous conditioning activity. PAP is usually evoked through heavy resistance, but many new methods are being suggested that acutely improve performance in post-activation potentiation protocols. The purpose of this study was to examine the effect of simultaneous application of Smith machine back squats (BS) with electromyostimulation (EMS) on sprint performance. Sixteen male (age = 22.9 ± 2.3 years, body mass = 79.9 ± 13.8 kg, BS one-repetition maximum (1 RM) = 120.5 ± 17.3) amateur football and rugby players volunteered for this study. Participants randomly performed PAP protocols (CON = no load, BS = 3 × 85% of 1 RM BS, EMS = 3 × weightless squat with electric current and BS + EMS = 3 × 85% 1 RM BS with electric current) on four different days with at least 48 h intervals. Participants rested passively for 7 min after preloads and performed the 30 m sprint test. Sprint times for 10 and 30 m were recorded for each condition. As a result, no significant difference was found in the 10 m (p = 0.13) and 30 m (p = 0.10) sprint performance between the preload protocols. The effect size was found to be trivial (ηp²: 0.13 for 10 m; ηp²: 0.11 for 30 m). In individual results, the 10 m sprint performance of five participants and 30 m sprint performance of two participants decreased in BS, EMS, or BS + EMS conditions compared with CON. No PAP effect in other participants was observed. In conclusion, preloads did not affect 10 m and 30 m sprint performance of football and rugby players. It can be said that the applied PAP protocols or physical exertion alone may cause fatigue in some individuals.

The aim of this study is to examine the mental training levels of the athletes and their perceptions of challenge and threat in sports. The participant group consisted of 252 male and 174 female athletes studying at sport sciences in the Southeastern Anatolia region. The personal information form, the Mental Training Inventory in Sports and the Challenge and Threat Scale in Sports were applied. Due to the normal distribution of the data, t-test was used to compare two groups, one-way ANOVA test to compare more than two groups, Tukey multiple comparison test, and Pearson Correlation analysis to determine the relationships between variables. Simple linear regression analysis was used to determine the effect between variables. A significant difference was found in favor of men in the mental performance skills and threat sub-dimension in terms of gender, in favor of professional athletes in the sub-dimension of self-talk in terms of the level of sports, in favor of those who do sports for 10 years or more in the sub-dimensions of mental performance skills and threat according to the sports age variable. A moderately positive relationship was found between mental training levels and the challenge sub-dimension, and a low-level negative relationship was found between the threat sub-dimension. As a result of the regression analysis, it was determined that mental training in sports significantly affects the perception of challenge and threat. As a result, mental training levels of athletes can affect the perception of challenge and threat in sports.

Carbohydrate mouth rinsing (CMR) has been shown to enhance exercise performance. However, the influence of CMR on repetitions to failure with different intensities (40% or 80% of 1 RM) is unknown. Therefore, the purpose of this study was to examine the effects of a 6% CMR solution on muscular endurance assessed at 40% and 80% of 1 RM in resistance-trained males. Sixteen resistance-trained males (age: 25 ± 3 years, height: 182 ± 6 cm, body mass: 86 ± 3 kg, body fat: 16 ± 3%, bench press 1 RM: 106 ± 16 kg, resistance training experience: 5 ± 1 years) completed four conditions in random order. The four conditions consisted of ten seconds of mouth rinsing with 25 mL solutions containing either maltodextrin or placebo (sweetened water) prior to performing a bench press muscular endurance test at either 40% of 1 RM or 80% of 1 RM. Total repetitions, heart rate (HR), ratings of perceived exertion (RPE), glucose (GLU) and felt arousal (FA) were recorded for each condition. There was a significant condition by intensity interaction (p = 0.02). CMR significantly increased total repetitions compared with placebo at the higher intensity (80% of 1 RM; p = 0.04), while there was no effect at the lower intensity (p = 0.20). In addition, HR, RPE, GLU and FA did not differ between conditions or across intensities (p > 0.05). In conclusion, CMR-enhanced muscular endurance performed at higher but not lower intensities.

Warm-up programs in sports education can provide positive developments in motor and technical skills. The objective of this study was to determine the acute effects of ballistic, dynamic, and static warm-up protocols on motor and technical skills in male handball players. Twelve male handball players (mean age: 19.50±3.97 years) from the second league in Turkey participated in this study voluntarily. Warm-up protocols were implemented for the participants at the same time on three different days. At the beginning of the study, the height and body masses of the handball players were measured. After each warm-up protocol, 9-m shot, over-the-block shot, vertical jump, T agility, 20-m sprint, flexibility, and flamingo balance tests were conducted on the participants. The normality level of the data was determined by the Shapiro-Wilk test using the SPSS statistical program. While Repeated Measures ANOVA and the Bonferroni test from post hoc analysis were applied to data with normal distribution, the Friedman test and the Wilcoxon signed-rank test with the Bonferroni correction were used for non-normally distributed data. According to our findings, there was a significant difference between the warm-up protocols in the T agility, flexibility, and over-the-block shooting tests (p < 0.05), while no significant difference was found in the vertical jump, 20-m sprint, balance, or 9-m shooting tests (p > 0.05). The ballistic warm-up protocol applied to male handball players in sports education provided positive improvements in flexibility and over-the-block shooting skills, while the dynamic warm-up protocol yielded positive improvements in agility and flexibility.