Yo-Yo IR1 Research Articles

An Online Training Program Was Effective on Improving Physical Performance and Body Composition in U20 Soccer Players During the COVID-19 Quarantine

Abstract It is recommended for athletes keep training to reduce the negative effects of detraining. This study aimed to verify the effects of a 15-week online training intervention during a pandemic quarantine in body composition and physical capacity of highly trained soccer players. Sixteen male under-20 soccer players were assessed after the first period of COVID-19 quarantine (March 2020 to September 2020; 170 days), and after the second period of COVID-19 quarantine (November 2020 to February 2021, 107 days). Body composition, vertical jump height, hamstring maximum strength and aerobic capacity were assessed. The online training program was performed during the second lockdown. In comparison with first pre assessments, results showed that fat mass (−0.95 ± 1.27), free fat mass (1.22 ± 1.19), squat jump height (5.36 ± 1.99) and counter movement jump (3.19 ± 3.77) were significantly improved (P < 0.05). However, there were no significant changes in total body mass, hamstring eccentric strength, and Yo-Yo IR1 after online training (P > 0.05). In summary, the findings of this study highlight the importance of carrying out a training program during a period of absence from traditional soccer training, in order to maintain the level of physical capacities of youth soccer players.

Performance variables and nutritional status analysis from Moroccan professional and adolescent football players during the competition period: a descriptive study.

Nutrition plays an integral role in optimizing football players' performance during training sessions and matches and maintaining their overall health throughout the season. This study aimed to evaluate how well the dietary practices of professional and adolescent football players in Morocco during the competitive period met international macronutrient recommendations, and to explore the relationship between their nutritional status and aerobic performance, as measured by the Yo-Yo IRL1 test. A total of 277 footballers from Morocco's professional league, "Botola-Pro", were monitored over a seven-day (training microcycle) during the competitive period. The dietary intake was assessed through self-reported methods and 24-hour recalls. Relevant body composition was measured with bioelectrical impedance (BI), and aerobic performance was evaluated using the Yo-Yo IR test. The results indicated significant variations in performance and nutritional status across different categories and age groups. The nutritional status of the players didn't match the UEFA recommendations (p < 0.001). We found that higher intake levels of carbohydrates and proteins were positively correlated with the total distance covered by the players (p < 0.001, r = 0.63, R2 = 0.4 for carbohydrates; p < 0.001, r = 0.59, R2 = 0.35 for proteins). Conversely, a higher proportion of energy derived from fats in the diet was negatively correlated with the distance covered (p < 0.001, r = -0.64, R2 = 0.41). These findings suggest that optimizing carbohydrates and protein intake while managing fat consumption is crucial for enhancing sporting performance. This information is essential for tailoring training programs and nutritional regimens based on the competition level.

An Effective Method of Aerobic Capacity Development: Combined Training with Maximal Aerobic Speed and Small-Sided Games for Amateur Football Players

This study aimed to investigate the effects of combined training with maximal aerobic speed and small-sided games on football players’ aerobic capacity development. Methods: The football players were divided into three groups as a combined training group (n = 20) (Mean ± SD age 23.40 ± 2.92 yrs, BMI was 23.67 ± 1.59 kg/m2, mass: 74.80 ± 5.46 kg, height: 177.73 ± 4.31 cm), maximal aerobic speed group (n = 20) (Mean ± SD age 23.93 ± 2.46 yrs, BMI was 23.32 ± 1.42 kg/m2, mass: 72.66 ± 5.38 kg, height: 176.46 ± 4.99 cm) and regular training group (n = 20) (Mean ± SD age 24.80 ± 5.84 yrs, BMI was 22.87 ± 1.67 kg/m2, mass: 73.06 ± 6.74 kg, height: 178.33 ± 7.98 cm). In addition to regular football training, maximal aerobic speed training with small-sided games was applied to the combined training group (CT) and only maximal aerobic speed training was applied to the maximal aerobic speed group (MAS) twice a week for 12 weeks. The normal training group (NT) continued their routine football training programme. All participants applied the Yo-Yo IR1 test in the pre-test and post-test of the study. As a result of normality tests, it was determined that the data showed normal distribution, and the ANOVA test and Tukey’s multiple comparison test were used in the intergroup evaluation. Results: When the Yo-Yo IR1 Test pre-test and post-test results were analysed, maximal aerobic speed training with small-sided games (CT) and maximal aerobic speed (MAS) groups were significantly higher compared to the normal training (NT) group regarding training load, running distance, and VO2max value among the football players (p = 0.001). There was no difference in the normal training group (p &gt; 0.05). As a result, it was determined that combined training with maximal aerobic speed, small-sided games, and only maximal aerobic speed effectively improved football players’ aerobic capacity and general performance.

Effects of Caffeinated Chewing Gum on Ice Hockey Performance after Jet Lag Intervention: Double-Blind Crossover Trial.

The purpose of this study was to examine the impact of caffeinated chewing gum on the physical performance of elite ice hockey players after a jet lag intervention. Fourteen national-level (age: 25.2 ± 5.4; height: 176.5 ± 5.3; weight: 78.1 ± 13.4) ice hockey players were tested late at night after a full day awake schedule with jet lag. A randomised, double-blind experimental design was employed in which participants either chewed caffeinated gum (CAF) containing 3 mg/kg caffeine or a caffeine-free placebo gum (PLA) for 10 min prior to undertaking a series of on-ice and off-ice tests. The off-ice tests included grip force, the counter-movement jump (CMJ), and the squat jump (SJ). The on-ice tests included a 35 m sprint, the S-Shape agility test, and the Yo-Yo intermittent recovery test (Yo-Yo IR1 test). The CMJ height (CAF: 47.2 ± 4.4; PL: 45.9 ± 3.5; p = 0.035; Cohen's d = 0.32) and SJ height (CAF: 46.7 ± 4.1; PL: 44.9 ± 3.8; p = 0.047; Cohen's d = 0.44) were found to be significantly higher in the CAF than in the PL trial. However, there were no significant differences (p > 0.05) in grip force, as well as in the 35 m sprint, the S-Shape agility test, and the Yo-Yo IR1 test. The present study found that, following a jet lag intervention, although the consumption of caffeinated gum resulted in an increase in vertical jump height, it had no impact on performance in the ice tests. The results of this study may help coaches and athletes consider the need for caffeine supplementation when experiencing jet lag.

The Effects of a 6-Week Plyometric and Sprint Interval Training Intervention on Soccer Player's Physical Performance.

Despite the well-documented benefits of sprint interval training (SIT) and plyometric training (PT) in improving the physical fitness of soccer players, it remains unclear which of these training methods is superior for enhancing players' aerobic and anaerobic performance. Therefore, this study aimed to compare the effects of SIT and PT on physical performance measures of male soccer players. Thirty male soccer players were randomly assigned to PT (n = 10), SIT (n = 10), and an active control group (CON, n = 10). Before and after the training period, participants underwent a battery of tests consisting of vertical jump, Wingate, linear sprint with and without ball dribbling, change of direction, ball kick, and the Yo-Yo intermittent recovery level 1 (Yo-Yo IR1) tests. Both groups exhibited similar improvements in maximal kicking distance (PT, effect size [ES] = 0.68; SIT, ES = 0.92) and measures of aerobic fitness including maximum oxygen uptake (PT, ES = 1.24; SIT, ES = 1.26) and first (PT, ES = 0.85; SIT, ES = 1.08) and second (PT, ES = 0.86; SIT, ES = 0.98) ventilatory thresholds. However, PT intervention resulted in greater changes in vertical jump (ES = 1.72 vs. 0.82, p = 0.001), anaerobic power (peak power, ES = 1.62 vs. 0.97, p = 0.009; mean power, ES = 1.15 vs. 1.20, p = 0.05), linear speed (20-m, ES = -1.58 vs. -0.98, p = 0.038; 20-m with ball, ES = -0.93 vs. 0.71, p = 0.038), and change of direction ability (ES = -2.56 vs. -2.71, p = 0.046) than SIT. In conclusion, both PT and SIT demonstrated effectiveness in enhancing aerobic performance among male soccer players. However, PT yielded superior improvements in anaerobic power, vertical jump, linear speed, and change of direction performance compared to SIT. These findings suggest that PT may offer additional benefits beyond aerobic conditioning.

Anaerobic and Aerobic Metabolic Capacities Contributing to Yo-Yo Intermittent Recovery Level 2 Test Performance in Australian Rules Footballers.

This study aimed to identify the aerobic and anaerobic metabolic performance capacities contributing to Yo-Yo Intermittent Recovery level 2 (Yo-Yo IR2) test performance. Nineteen recreational Australian footballers completed a Yo-Yo IR2 test, and on another day a treadmill peak oxygen uptake (VO2peak) and maximal accumulated oxygen deficit test in a randomised counter-balanced order. The maximal accumulated oxygen deficit (MAOD) procedures included 5 × 5 min sub-maximal continuous runs at progressively higher speeds whilst VO2 was recorded; thereafter, speed was incrementally increased to elicit VO2peak. After 35 min of rest, participants ran at a speed equivalent to 115% of VO2peak until exhaustion, at which point expired air was collected to determine maximal accumulated oxygen deficit. Relationships between variables were assessed using Pearson's correlation and partial correlations. Maximum aerobic speed, relative intensity, and VO2peak were significantly correlated with Yo-Yo IR2 performance. High Yo-Yo IR2 performers also had higher MAS, relative intensity, and VO2peak levels. However, when higher maximum aerobic speed, relative intensity, and VO2peak were controlled for each other and analysed independently, neither maximal aerobic speed nor VO2peak correlated with Yo-Yo IR2 performance. Yo-Yo IR2 performance is the result of a complex interaction between several variables. Training programs should primarily focus on improving VO2peak, maximal aerobic speed, and relative intensity to optimize Yo-Yo IR2 test performance.

Examining the Relationship Between Yo-Yo Intermittent Rest Test Results and Performance in Football Players

The purpose of your study; The aim is to determine the relationship between aerobic endurance and the performance of football players. 30 licensed football players (age 18,33±0,47 years, height 179,5±10,6 cm, body weight 76,6±11,5 kg) playing in the Turkish Football Federation U-19 Development League voluntarily participated in the research. Football players' Yo-Yo IRT1 test was measured twice at eight-week intervals on an artificial football field. During the test, Heart rate (HR) (beats/min) and afterwards Maximal Aerobic Power (VO2max) values were measured and calculated. Paried T-test, one of the parametric tests, was used to determine whether there was a difference in terms of Yo-Yo IRT 1 test, VO2max values and pulse values. All analyzes were processed at the 0.05 significance level. In conclusion; There is no statistically significant difference p&amp;gt;0.005 between the first and last values of the distances traveled by the football players who were subjected to the Yo-Yo IR1 test first and last measurement test, their HR and their measured VO2max values.

Exploring the relationship between caffeine metabolism-related CYP1A2 rs762551 polymorphism and team sport athlete status and training adaptations

BackgroundThis study aimed to achieve a dual objective: to compare the frequencies of CYP1A2 rs762551 genotypes between team sport athletes and a control group, and to determine the association between the rs762551 polymorphism and changes in physical performance after a six-week training program among elite basketball players.MethodsThe study encompassed an analysis of 504 individuals, comprising 320 athletes and 184 controls. For the Turkish cohort, DNA was isolated using the buccal swab method, and genotyping was conducted using the KASP technique. Performance assessments included the Yo-Yo IR2 and 30 m sprint tests. For Russian participants, DNA samples were extracted from peripheral blood, a commercial kit was used for DNA extraction, and genotyping of the rs762551 polymorphism was conducted using DNA microarray.ResultNotably, a statistically significant linear decline in the prevalence of the CC genotype was observed with ascending levels of athletic achievement within team sports (sub-elite: 18.0%, elite: 8.2%, highly elite: 0%; p = 0.001). Additionally, the CA genotype was the most prevalent genotype in the highly elite group compared to controls (80.0% vs. 45.1%, p = 0.048). Furthermore, statistically significant improvements in Yo-Yo IR2 performance were noted exclusively among basketball players harboring the CA genotype (p = 0.048).ConclusionsThe study’s findings indicate that the rs762551 CC genotype is a disadvantage in elite team sports, whereas the CA genotype provides an advantage in basketball performance.

Goldfit Soccer: A Multidimensional Model for Talent Identification of Young Soccer Players

ABSTRACT Studies have provided empirical evidence on the prognostic relevance of test batteries and the “coach’s eye” for talent identification. The aims were 1) to compare objective and subjective assessments as well as a combined soccer-specific potential index between future selected and non-selected players and 2) to evaluate the prognostic validity of a multidimensional model as a tool for talent identification in soccer. The sample was composed by 132 male players (14,5 ± 1,4 years; regional competitive level) from U13 to U17 age groups of a Brazilian soccer talent development program. Athletes completed a multidimensional test battery and were subjectively rated by their coaches for sporting potential. Players’ success was evaluated five years later and was operationalized by achieving under-20 category of the Brazilian Championship or adult professional level (success rate, 15.9%). Confirming univariate prognostic validity, future selected outperformed non-selected players regarding 20-m sprint (p = .009), agility (p = .04), countermovement jump (p = .04), sit-and-reach (p = .001), Yo-Yo IR1 (p = .001), dribbling (p < .001), perceived competence (p = .007), peaking under pressure (p = .01), confidence/motivation (p = .03), coping skills (p = .03), intangibles (p < .001) and player potential (p < .001). A combined index (objective tests, athlete’s assessments and coach’s eye) named Gold Score Soccer (GSS) showed high prognostic validity (p < .001). A binary logistic regression estimated the probability of success (yes/not) with GSS, ambidextrous and predicted age at peak height velocity as predictors. This multidimensional model named GoldFit Soccer showed high prognostic validity (sensitivity = 85.7%; specificity = 83.8%; accuracy = 84.1%; area under the ROC curve = .93 [.87–.98]). Thus, GoldFit Soccer is a valid multidimensional scientific model for talent identification in soccer.

Validity of simple field tests as indicators of elite female field hockey match performance.

Due to the change in field hockey match format, the need exits for research to determine whether current fitness test are still valid indicators of match performance. This study aimed to determine the direct validity of the 5-m multistage shuttle test (5-m MST) and Yo-Yo Intermittent recovery level 1 test (Yo-Yo IR1) by correlating their results with external load measures in international field hockey matches. Nineteen female field hockey players completed the 5-m MST and Yo-Yo IR1 before nine matches. Players covered mean distances of 750.3 m±19.6 m (5-m MST) and 1649.7 m±277.6 m (Yo-Yo IR1). Average relative distance, relative player load, and high-intensity activity during matches were 107.8±16.3 m/min, 10.3±1.4 AU/min, and 10.0±3.0%, respectively. The 5-m MST showed small to moderate significant (P<0.05; r=0.21-0.5) correlations with relative distance and high-intensity activity, while the Yo-Yo IR1 only had a small negative significant (P<0.05; r=-0.27) correlation with high-intensity activity. Strong correlations (r>0.51) were found between the 5-m MST and Yo-Yo IR1. The tests demonstrated low direct validity for current field hockey matches due to weak relationships with relative load and running performance. Additionally, the strong correlation between the Yo-Yo IR1 and 5-m MST suggests that both tests may not be necessary to assess match readiness. Coaches should consider using better-validated fitness tests for this population and sport.

Effects of Sprint Interval Training Surface on Physical Fitness Attributes of Collegiate Female Soccer Players: Identifying Individual Responses to Training on Grass, Sand, and Land Surfaces.

This study aimed to identify the optimal surface for sprint interval training to maximize transfer effects on physical performance measures on the grass pitch. Using a randomized controlled trial design, 40 collegiate female soccer players were equally assigned to three experimental groups performing short sprint interval training (SSIT: 4 sets of 10 repetitions with 5 seconds all-out running, with a 50-second recovery period between each effort and a 3-minute rest interval between sets) on SAND, GRASS, LAND, and a control group. Before and after a 7-week training period, participants underwent a series of field-based tests to evaluate countermovement jump (CMJ), 20-m linear sprint, Illinois change of direction (CoD) speed, Yo-Yo IR1, 2.4 km time trial, and maximal kicking distance (MKD) performance. A two-way analysis of variance with repeated measures was conducted on the data, along with Bonferroni post hoc testing. After the intervention, the control group did not show any changes, while the SAND, GRASS and LAND training groups demonstrated improvements (p = 0.001) in their performance as follows: CMJ (effect size [ES] = 1.21, 0.97, 0.64), 20-m linear sprint (ES = -0.81, -0.55, -0.41), Illinois CoD (ES = -0.72, -0.79, -0.41), Yo-Yo IR1 (ES = 1.86, 1.19, 1.12), 2.4 km time trail (ES = -0.82, -0.62, -0.49), and MKD (ES = 0.60, 0.90, 0.72), respectively. Comparative analysis of SAND, GRASS, and LAND revealed that performing SSIT on SAND results in a significantly greater gain in CMJ than LAND (p = 0.041). Analyzing individual responses to training interventions indicated that the training surface had a favorable influence on CMJ (SAND vs. LAND, p = 0.009), but on other variables no statistically significant (p > 0.05) differences were observed. Considering these findings, it is advised that strength and conditioning coaches use the SAND surface as the initial choice for SSIT sessions regarding greater gains (i.e., ES) in performance. This recommendation aims to facilitate more favorable transfer in physical fitness adaptation on a soccer grass pitch. In case of unavailability of SAND surface, GRASS surface would be a suitable alternative to enhance the physical fitness of collegiate female soccer players.

Optimizing Short Sprint Interval Training for Young Soccer Players: Unveiling Optimal Rest Distributions to Maximize Physiological Adaptations.

Present study aimed to compare the effects of SSIT intervention with varying rest distributions on hormonal, physiological, and performance adaptations in soccer players. Thirty-six players were randomly divided into three SSIT groups, each performing 4 sets of 6-10 repetitions of 6-second all-out running with rest intervals at ratios of 1:3, 1:6, and 1:9. Prior to and following the 7-week training period, aerobic fitness indices and anaerobic power were evaluated using a graded exercise test with a gas collection system and a lower-body Wingate test, respectively. Also, sport-specific bio-motor abilities were determined by measuring vertical jump, 20-m sprint, and T-test change of direction speed, Yo-Yo IR1 and maximal kicking distance. Hormonal status was also monitored by evaluating testosterone and cortisol levels. Following the 7-week training period, all SSIT interventions resulted in significant enhancements (p < 0.05) in soccer-related performance, physiological parameters, and hormonal adaptations, exhibiting effect sizes that ranged from small to large. Comparative analysis indicated that the 1:9 SSIT results in greater adaptive responses (p < 0.05) in the vertical jump, peak power, testosterone, and cortisol compared to the 1:3 SSIT group. By contrast, the 1:3 SSIT group induced more adaptive responses (p < 0.05) in the mean power output, maximum oxygen consumption (V̇O2max), and Yo-Yo IR1 compared to the 1:9 SSIT group. Hence, for enhancing physical performance, especially vertical jump height, anaerobic peak power, and hormonal adaptations, the 1:9 SSIT ratio is preferable. Conversely, shorter rest intervals (specifically, the 1:3 SSIT ratio) are better suited for eliciting heightened adaptive responses in mean power output, V̇O2max, and Yo-Yo IR1 over the 7-week training period among young male soccer players.

Repeated-sprint sets test: a new method for evaluating and forecasting fitness in elite young male soccer players

The objective of the current study was to explore the correlation between repeated sprint sets (RSS) ability and several physical attributes, including maximum sprint speed, maximal aerobic speed, maximal anaerobic speed, aerobic capacity, and explosive strength. Moreover, the aim was to assess the suitability of RSS as a comprehensive evaluation tool for physical qualities and to determine which physical field tests most accurately predict RSS in elite young male soccer players. A total of thirty-two young elite male soccer players (mean age 14.6 ± 0.3 years; predicted years from peak height velocity (PHV): − 0.4 ± 0.3; years in training: 3.7 ± 0.5) voluntarily participated in the study. The players participated in eight consecutive specific physical tests, with a minimum 72-h recovery between each session to minimize the impact of fatigue during the second trial. The participants completed the tests in the following order: RSS test, Vam-Eval test, a constant velocity test performed until exhaustion at 100% of vVO2max (tlim100), 20-m Multi-Stage Shuttle Run test (VMSRT), Yo-Yo Intermittent Recovery Test level 1 (Yo-Yo IR1), Maximal Anaerobic Shuttle Running Test (VMASRT), Maximal Sprinting Speed Test (20-m flying sprint), Countermovement Jump (CMJ), and Standing Long Jump test (SLJ). The results of the study showed that there were very large negative correlations between tlim100 and SST (sum of sprint times), and large negative correlations between Yo-Yo IR1, Vam-Eval, and SST during RSS in young elite male soccer players (p < 0.05). Additionally, VMASRT and SLJ demonstrated a moderate negative correlation with SST (p < 0.05). In contrast, significant positive correlations were found between 20-m flying sprint and the SST (p < 0.05). According to the stepwise multiple linear regression analysis, the primary predictors of SST, ranked by importance, were tlim100 and Yo-Yo IR1. These two predictors collectively accounted for 72% of the variance in players’ SST (p < 0.0001). Due to the importance of aerobic capacity and short repeated accelerations/sprint sets for overall competitive performance in soccer, in conclusion, our results suggest that elite young male soccer players should perform both high intensity interval training and aeorobic capactity exercises as part of soccer training if the primary outcome is to improve repeated sprint ability performance.

Vertical Jump and Relative Strength are Strongly Associated with Change of Direction in Professional Male Basketball Players

Purpose: The aim of this study was to examine the predictors of change of direction (COD) in highly trained/national level male basketball players using field assessments.&#x0D; Methods: Eight professional male basketball players (age: 24.0 ± 5.5 years; body mass index (BMI): 24.1 ± 1.6 kg m-2) volunteered for participation in this study. All the evaluations were carried out during 2 sessions as follows: First day_1) body composition, 2) unilateral and bilateral squat jump (SJ) and countermovement (CMJ), and 3) Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1); Second day_1) COD performance, and 2) one repetition maximum (1RM) hang clean (HC) and bench press (BP). A linear regression was performed to evaluate the determinants of COD amongst all other measured variables. Furthermore, we applied Pearson correlation coefficient and in the case of non-normally distributed variables, Spearman’s correlation coefficient for the selected variables.&#x0D; Results: The linear regression indicated that only SJ height was a significant determinant of COD (R2 = 58.8%, p = 0.016). Significant correlations were identified between COD test and SJ (r = -0.75, p = 0.034; very large), and relative HC 1 RM (r = -0.74, p = 0.038; very large).&#x0D; Conclusions: The associations found between COD performance and physical parameters should be considered when developing athletic conditioning programs. Especially, the vertical jump heigh could explain the greatest variability in COD performance..

Follow-Up Weekly Training Distribution and Accumulated Internal Load Effects on Young Football Players' Well-Being, Physical Fitness, and Technical Performance.

This study aimed to quantify the relationships among internal training load, wellness, physiological, isokinetic profile, and technical performance and assessed changes before and after a six-week pre-season structured combining physical fitness, small-sided-game and skill-based training program in young soccer players. Forty-five national-level young male soccer players (16.8 ± 0.9 years) were evaluated. There were no significant correlations between the wellness index and the physiological, isokinetic, or specific soccer skill parameters. Moderate correlations were observed between fatigue and stress (r = 0.47, moderate, p < 0.01), fatigue and average muscle soreness (r = 0.38, moderate, p = 0.01), and a large correlation between average stress and muscle soreness (r = 0.53, large, p < 0.01) were presented. All physiological, isokinetic, and technical parameters improved after a six-week pre-season training program (0.1 to -61.0%). Significant alterations in the physiological domain were observed after a six-week period, particularly in the fatigue index of the Bangsbo sprint test, YO-YO IR1 performance, and YO-YO peak La- (p < 0.01; -61.0%, 25.3%, and -19.8%, respectively). As such, the implementation of structured training and the monitoring of stress responses can lead to appropriate adaptation and balancing in the psychological and physical well-being of young national-level soccer players, particularly in the pre-season period.

ACE gene polymorphisms (rs4340) II and DI are more responsive to the ergogenic effect of caffeine than DD on aerobic power, heart rate, and perceived exertion in a homogeneous Brazilian group of adolescent athletes.

The purpose of this study was to verify the association between angiotensin-converting enzyme (ACE) genotypes DD, DI, and II and caffeine (CAF) ingestion on endurance performance, heart rate, ratio of perceived exertion (RPE), and habitual caffeine intake (HCI) of adolescent athletes. Seventy-four male adolescent athletes (age: DD=16±1.7; DI=16±2.0; II=15±1.7 years) ingested CAF (6 mg/kg) or placebo (PLA) one hour before performing the Yo-Yo Intermittent Recovery level 1 (Yo-Yo IR1) test. No difference was found among groups for HCI. However, CAF increased the maximal distance covered and VO2max in DI and II genotype carriers compared to PLA (DD: Δ=31 m and 0.3 mL·kg-1·min-1; DI: Δ=286 m and 1.1 mL·kg-1·min-1; II: Δ=160 m and 1.4 mL·kg-1·min-1). Heart rate of DI and II genotype carriers increased with CAF compared to PLA, while RPE was higher in the II and lower in the DD genotypes. The correlations between HCI and maximal distance covered or VO2max were significant in the II genotype carriers with CAF. CAF increased endurance capacity, heart rate, and RPE in adolescent athletes with allele I, while endurance performance and aerobic power had a positive correlation to HCI in the II genotype group. These findings suggested that DD genotype were less responsive to CAF and that genetic variations should be taken into account when using CAF supplementation to enhance exercise performance.

High-Intensity Interval Training Combined with High-Load Strength Training Improves Aerobic Fitness, Match Goals and Match Result during the In-Season Period in Under-19 Soccer Players.

This study compared the effects of adding a weekly session of either strength training followed by high-intensity interval training (HIIT) or high load plyometric training followed by small-sided games (SSG) on aerobic fitness, goals scored and conceded, and match results. Twenty-nine players from two youth elite teams competing in an under 19 (U19) first division league took part in the study. Of those, 16 players from one team followed the HIIT program (age: 17.8 ± 0.6 years) and 13 players from the other team trained once a week, following the SSG program (age: 18.0 ± 0.6 years). The training intervention lasted for 11 weeks and was applied once per week. For the HIIT team it included high-load strength training (80-95% of 1 RM) followed by high-intensity intermittent running, whereas for the SSG team (n = 13) it included plyometric exercises followed by SSG. Aerobic fitness was assessed before and after the intervention, while goals scored and conceded, as well as match results during the intervention period, were compared with the 11-week period preceding it. Only the HIIT team improved Yo-Yo IR2 performance (running distance: from 902.5 ± 147.5 to 1092.5 ± 155.8 m, p < 0.001) while there was no change for the SSG group. Moreover, during the 11-week intervention, the HIIT team improved the number of goals scored in the last 30 min of the game compared with the pre-intervention period (0.36 ± 0.50 to 1.27 ± 0.90 per match, p < 0.05) and the scored vs. conceded goals were higher in the second half (1.36 ± 1.03 vs. 0.27 ± 0.47, p < 0.05). No significant differences were found for these parameters in the SSG team. Regarding match result, the HIIT team increased the proportion of wins from 5 wins in 11 matches (or 45%) in the pre-intervention period to 9 wins in 11 matches (or 82%) during the intervention period, while this profile remained unchanged for the SSG team. In conclusion, the present study demonstrated that the HIIT program performed once per week was superior to SSG as it improves aerobic fitness, scored and conceded goals, and match result during the in-season period.

Adequate Interval between Matches in Elite Female Soccer Players.

The present study compared four different intervals between three simulated soccer matches for changes in muscle damage and performance parameters. Thirteen well-trained female university soccer players performed three bouts of 90-min Loughborough Intermittent Shuttle Test (LIST) with four different intervals between bouts; one (1d), two (2d), three (3d) and four days (4d), with >12-weeks between conditions in a counterbalanced order. Heart rate, blood lactate, rating of perceived exertion and distance covered in each LIST were measured. Changes in several muscle damage markers (e.g., maximal voluntary isometric torque of the knee extensors: MVC-KE, muscle soreness), performance parameters (e.g., Yo-Yo intermittent recovery test level 1: Yo-Yo IR1), and blood measures (e.g., osmolality, high sensitivity cardiac troponin T) before the first LIST, 1 h after each LIST, and one to five days after the third LIST were compared among the conditions. The total distance covered during the first two LISTs was not different among the conditions, but that during the third LIST was shorter (P < 0.05) for the 1d (9,416 ± 885 m) and 2d conditions (9,737 ± 246 m) than the 3d (10,052 ± 490 m) and 4d conditions (10,432 ± 538 m). Changes in all measures were smaller (P < 0.05) in the 3d and 4d conditions (e.g., the decrease in MVC-KE at one day after the third LIST was -13 ± 4% and -10 ± 3%, respectively) when compared with the 1d and 2d conditions (-20 ± 7%, -18 ± 5%). Performance parameters showed smaller (P < 0.05) changes in the 4d (e.g., the decrease in Yo-Yo IR1 at one day after the third LIST was -9 ± 3%) and 3d (-13 ± 6%) conditions when compared with the 1d (-19 ± 4%) and 2d (-20 ± 8%) conditions. These results suggest that muscle damage and fatigue accumulate when soccer matches are performed three consecutive days or every other day, but if more than three days are inserted between matches, this could be minimized.

Effect of Periodized Interval Training in Combination with Explosive Strength and Speed in Game-Like Situation on Agility and High Intensity Aerobic Capacity of Youth Soccer Players

Study purpose. High-intensity aerobic capacity (HIAC) is essential for soccer players because they have to perform sprints of short duration in the shortest possible time. At the same time, they need to quickly change direction with and without the ball, which requires agility. The purpose of the study was to investigate the effect of a periodized (8-week) training plan that combines interval training (IT), explosive strength (ES), speed, and game-like situations on agility and HIAC in youth soccer players. Materials and methods. This research is an experimental study in which the population was male youth soccer players (N = 23) (aged 16.7±2.1). The Arrowhead Agility Test and the HIAC Yo-Yo Intermittent Recovery Test Level 1 (YYIR1) have taken the pre- and post-data of agility. By using the formula for YYIR1 test: VO₂max (mL kg-1 min-1) = IR1 distance (m) × 0.0084 + 36.4, we get an estimation of the volume of maximum oxygen consumption (VO₂max). The data analysis used a t-test at 0.05% as the significance level. Results. Based on the results, the mean of the pre-tests in agility, YO-YO IR1, and VO₂max showed 17.911, 14.8100, and 55.25510. After training for eight weeks, there was an improvement: the mean showed 16.667, 15.9750, and 60.06960. As per the results of the data on the hypothesis in the study, it was found that there was a significant effect of periodized IT in combination with ES and speed on agility performance and HIAC of the youth soccer players. Conclusions. There was a significant effect of periodized IT in combination with ES and speed on improving youth soccer players’ agility performance and HIAC.

Small-Sided Games 5v5: Improving Aerobic Endurance of Youth Football Players

The purpose of this study was to determine the effect of small-sided games 5v5 on increasing aerobic endurance in football players. Materials and methods. This type of study is a quasi-experiment with a one-group pretest-posttest design. The population of this study was Gama Muda Football School (SSB) players in Pasaman Regency (Indonesia), totaling 60 persons. Sampling was performed using a targeted sampling technique, so the sample was determined to be a maximum of 20 individuals. The players’ endurance capacity was determined by measuring their VO2max capacity. The study used the Yo-Yo Intermittent Recovery Test (Yo-Yo IR Test) as an instrument to obtain research data. Data analysis in this study used the mean difference test (t-test) statistical method. Before testing our hypothesis, we first performed a normality test using the Lilliefors test. Results. After hypothesis testing, the results obtained show the value of t-count (10.15) &gt; t-table (1.729), indicating that small-sided games 5v5 training effectively improves the aerobic endurance ability of young football players. Conclusions. The results of this study demonstrate that small-sided games 5v5 training can improve the aerobic endurance of young football players.