Professional Youth Soccer Players Research Articles

Applicability Of Existing Age-predicted Maximal Heart Rate Equations In Professional Youth Soccer Players.

Applicability Of Existing Age-predicted Maximal Heart Rate Equations In Professional Youth Soccer Players.

Locomotor activities and subjective load differences between professional youth soccer players and professional development loans: A comparative analysis

This study quantified and compared the weekly locomotor activity and subjective load between elite and development loan youth soccer players registered to a primary club. Development loan players were loaned to a lower-league club and trained part-time with their loan club whilst being available for development fixtures and training with the primary club. Data were collected in 16 squad players and 4 development loan players at loan clubs across a 41 week competitive phase of the 2018/2019 season. Analysis was completed on total distance (m), PlayerLoadTM (au), low intensity running (<14.4 km·h−1, m), running (19.8–24.98 km·h−1, m), sprinting (>24.98 km·h−1, m), accelerations (>2 m·s−2 count) and decelerations (<−2 m·s−2, count). Point estimates for the development loan players consistently showed lower weekly values than squad players for all variables ranging from 5.2% (weekly sRPE) to 16.8% (weekly sprint distance covered). Differences, however, were not found to be statistically significant ( p ≥ 0.07). Variance ranged from 23.6% (weekly distance) to 37.7% (weekly high-intensity accelerations). Although the goals of a development loan are likely to be multifactorial, this is the first study to quantify and compare locomotor activities and subjective loading of players within the development loan environment.

Congested Period in Professional Youth Soccer Players Showed a Different High Decelerations Profile in the Group Performance and a Specific Positional Behaviour.

Present soccer demands are increasing in terms of running requirements and the number of matches until youth soccer players experience several periods of fixture congestion during the season. Currently, congested periods have not been extensively studied in this population. For this reason, this study aimed to compare the running demands of professional youth soccer players in congested periods according to their specific playing positions. Twenty youth players were grouped according to their position: Central Defenders (CD), Fullbacks (FB), Midfielders (MF), Wide Midfielders (WM) and Strikers (ST). A GPS system was used to monitor the players during the first (M1), second (M2) and third (M3) matches played during a congested period, measuring their total distance covered (TDC), DC 18.0-20.9 km·h-1, DC 21.0-23.9 km·h-1, DC > 24.0 km·h-1, number of high accelerations (>2.5 m·s-2), number of high decelerations (<2.5 m·s-2) and peak speed (km·h-1). M1, M2 and M3 showed the same TDC, DC 18.0-20.9 km·h-1, DC 21.0-23.9 km·h-1, DC > 24.0 km·h-1, number of high accelerations, and peak speed (p > 0.05). The statistical analysis showed significant differences between M1, M2 and M3 in the decelerations recorded between M1 and M3 (p < 0.05). Likewise, each position showed specific behaviours during the congested period, with all showing at least one difference in DC 18.0-20.9 km·h-1, 21.0-23.9 km·h-1 or >24.0 km·h-1 between M1, M2 and M3 (p < 0.05). In conclusion, coaches should pay attention to the fatigue produced by the number of high decelerations. Secondly, an individualized training protocol should be considered according to the running requirements of each position when youth professional soccer players are involved in a congested period.

Effects of High-Intensity Position-Specific Drills on Physical and Technical Skill Performance in Elite Youth Soccer Players.

Cuong Le, C, Ma'ayah, F, Nosaka, K, Hiscock, D, and Latella, C. Effects of high-intensity position-specific drills on physical and technical skill performance in elite youth soccer players. J Strength Cond Res 37(5): e332-e340, 2023-Soccer physical preparation has been extensively researched with previous emphasis on high-intensity interval running and small-sided games. However, neither approach considers positional differences. The purpose of this study was to investigate the feasibility and short-term effects of a novel position-specific conditioning training (PSCT) paradigm on physical and technical abilities of young soccer players. Fifteen male Vietnamese professional youth soccer players (16.1 ± 0.4 years, 171.7 ± 4.8 cm, 63.9 ± 3.8 kg) undertook a 3-week control period followed by a 3-week intervention with PSCT drills performed twice per week. Position-specific conditioning training comprised purposely designed drills for attackers, defenders, and wingers, respectively. The intensity and duration were the same for all drills (4 × 4 minutes at ∼90% heart rate maximum [HRmax], separated by a 4-minute recovery at 70% HRmax) but differed in the technical and tactical actions performed. Outcome measures included Yo-Yo intermittent recovery test level 1, repeated sprint ability, 10-m and 30-m sprint time, and the Loughborough Soccer Passing Test for technical skills in a fatigued and nonfatigued state. Position-specific conditioning training drills induced a desirable intensity for effective conditioning purpose (89.0 ± 2.1% HRmax) with low interplayer variability (coefficient of variation = 2.4%). Yo-Yo intermittent recovery test level 1 performance improved ( p < 0.05) after the control (Δ178.7 ± 203.3 m) and intervention (Δ176.0 ± 225.7 m) periods without a difference between. These results confirmed the feasibility of PSCT as a novel high-intensity training approach for soccer players. Improvements in aerobic capacity were noted, despite no effect on other physical and technical measures. PSCT may be suitable for individual training, return-to-play stages of rehabilitation, during off-season, or in academy settings when time is not a constraint.

Effects of COVID-19 Lockdown on Physical Performance, Sleep Quality, and Health-Related Quality of Life in Professional Youth Soccer Players.

BackgroundIn March 2020, the COVID-19 outbreak led to the declaration of a pandemic. The accompanying restrictions on public life caused a change in the training routines of athletes worldwide. The present study aimed to investigate the effects of a 13-week supervised home training program on physical performance, sleep quality, and health-related quality of life in professional youth soccer players during the first COVID-19 lockdown in Germany.MethodsEight professional soccer players (age range 16–19; height: 1.81 ± 0.07 m; body weight: 72.05 ± 6.96 kg) from a Bundesliga team in Germany participated in this study. During the lockdown, they trained 5–6 days per week with home-based training plans and were monitored via tracking apps and video training. To determine the effects of home training, measurements were taken before (March 2020) and after (June 2020) the home training period. Bioelectrical impedance analysis was used to determine body composition, and an isokinetic strength test and a treadmill step test, including lactate measurements, were used to measure physical performance. Two questionnaires were responded to in order to assess health-related quality of life [Short-Form 36 Health Survey (SF-36)] and sleep quality (Pittsburgh Sleep Quality Index).ResultsWhen comparing measurements before and after the home training period, we observed significant increases in the following variables: body weight (72.05 ± 6.96 kg vs. 73.50 ± 6.68 kg, p = 0.034), fat mass (11.99 ± 3.13 % vs. 13.98 ± 3.92 %, p = 0.030), body mass index (22.04 ± 0.85 kg/m2 vs. 22.49 ± 0.92 kg/m2, p = 0.049), and mental health component summary score (MCS) of the questionnaire SF-36 (53.95 ± 3.47 vs. 58.33 ± 4.50, p = 0.044). Scores on the general health (77.88 ± 14.56 vs. 89.75 ± 13.76, p = 0.025) and mental health (81.50 ± 9.30 vs. 90.00 ± 11.71, p = 0.018) subscales of the SF-36 also increased significantly.ConclusionThe COVID-19 lockdown led to an increase in body composition parameters and showed an improvement in the MCS and scores on the general and mental health subscales of the SF-36. Physical performance and sleep quality could be maintained during the home training period. These observations may help trainers for future training planning during longer interruptions in soccer training.

Long-standing pubic-related groin pain in professional academy soccer players: a prospective cohort study on possible risk factors, rehabilitation and return to play

BackgroundDespite being a common overuse entity in youth soccer, scientific data on risk factors, rehabilitation and return to play for long-standing pubic-related groin pain is still rare. The current prospective cohort study aims to evaluate potential risk-factors, propose a criteria-based conservative rehabilitation protocol and assess return-to-play outcomes among professional youth soccer players suffering from long-standing pubic-related groin pain.MethodsMale soccer players with long-standing (> 6 weeks) pubic-related groin pain from a professional soccer club’s youth academy were analyzed for possible risk factors such as age, team (U12 - U23), younger/older age group within the team, position and preinjury Functional movement score. All injured players received a conservative, standardized, supervised, criteria-based, 6-level rehabilitation program. Outcome measures included time to return to play, recurrent groin pain in the follow-up period and clinical results at final follow-up two years after their return to play.ResultsA total of 14 out of 189 players developed long-standing pubic-related groin pain in the 2017/2018 season (incidence 7.4%). The average age of the players at the time of the injury was 16.1 ± 1.9 years. Risk factor analysis revealed a significant influence of the age group within the team (p = .007). Only players in the younger age group were affected by long-standing pubic-related groin pain, mainly in the first part of the season. Injured players successfully returned to play after an average period of 135.3 ± 83.9 days. Only one player experienced a recurrence of nonspecific symptoms (7.1%) within the follow-up period. The outcome at the 24-month follow-up was excellent for all 14 players.ConclusionsLong-standing pubic-related groin pain is an overuse entity with a markedly high prevalence in youth soccer players, resulting in a relevant loss of time in training and match play. In particular, the youngest players in each team are at an elevated risk. Applying a criteria-based rehabilitation protocol resulted in an excellent return-to-play rate, with a very low probability of recurrence.Trial registrationThe trial was retrospectively registered under DRKS00016510 in the German Clinical Trials Register on 19.04.2021.

A preliminary study of the reliability of soccer skill tests within a modified soccer match simulation protocol

ABSTRACT Aim This study examined test-retest reliability of soccer-specific skills within a modified version of the soccer match simulation (SMS) protocol. Methods Ten professional youth academy soccer players (18 ± 1 years) from the United Kingdom completed 30 minutes of the modified SMS on two occasions under standardised conditions. During each trial, participants performed 20-m dribbling, short passing (4.2-m), long passing (7.9-m), shooting skills, and 15-m sprints within four blocks of soccer specific activity. Results Collapsed normative data (mean (SD)) for trial 1 and trial 2 for dribbling speed was 2.7 (0.2) m/s, for sprint speed 5.9 (0.4) m/s, for short pass speed 11.1 (0.5) km/h, for long pass speed was 12.2 (0.5) km/h, and for shooting speed was 13.3 (0.4) km/h. Mean results from trial 1 and trial 2 were not different for all measures evaluated (P > 0.05). Good to excellent reliability (ICC 0.76-0.99) was observed for long and short passing speed, shooting speed, sprint speed, and long pass accuracy, with CVs typically < 5-10%. Moderate reliability (ICC 0.50-0.75) was observed for dribbling speed. Poor reliability (ICC <0.50) was observed for dribbling accuracy and shooting accuracy. Conclusions The reliability of the modified version of the SMS protocol is promising for most of the skills assessed, with the exception of dribbling and shooting accuracy in this group of professional youth soccer players. The modified protocol is easy to implement within professional clubs without specialist equipment, but due to the limited sample size the reliability requires further confirmation in a larger sample.

Relationship Between Subjective and External Training Load Variables in Youth Soccer Players.

To quantify and describe relationships between subjective and external measures of training load in professional youth soccer players. Data from differential ratings of perceived exertion (dRPE) and 7 measures of external training load were collected from 20 professional youth soccer players over a 46-week season. Relationships were described by repeated-measures correlation, principal component analysis, and factor analysis with oblimin rotation. Significant positive (.44 ≤ r ≤ .99; P < .001) within-individual correlations were obtained across dRPE and all external training load measures. Correlation magnitudes were found to decrease when training load variables were expressed per minute. Principal component analysis provided 2 components, which described 83.3% of variance. The first component, which described 72.9% of variance, was heavily loaded by all measures of training load, while the second component, which described 10.4% of the variance, appeared to have a split between objective and subjective measures of volume and intensity. Exploratory factor analysis identified 4 theoretical factors, with correlations between factors ranging from .5 to .8. These factors could be theoretically described as objective volume, subjective volume, objective running, and objective high-intensity measures. Removing dRPE measures from the analysis altered the structure of the model, providing a 3-factor solution. The dRPE measures are significantly correlated with a range of external training load measures and with each other. More in-depth analysis showed that dRPE measures were highly related to each other, suggesting that, in this population, they would provide practitioners with similar information. Further analysis provided characteristic groupings of variables.

The effects of 14-week betaine supplementation on endocrine markers, body composition and anthropometrics in professional youth soccer players: a double blind, randomized, placebo-controlled trial

ObjectiveBetaine supplementation may enhance body composition outcomes when supplemented chronically during an exercise program. The purpose of this study was to evaluate the effect of betaine supplementation on development-related hormones, body composition, and anthropometrics in professional youth soccer players during a competitive season.MethodsTwenty-nine players (age, 15.45 ± 0.25 years) were matched based upon position and then randomly assigned to a betaine group (2 g/day; n = 14, BG) or placebo group (PG, n = 15). All subjects participated in team practices, conditioning, and games. If a subject did not participate in a game, a conditioning protocol was used to ensure workload was standardized throughout the 14-week season. Growth hormone (GH), insulin-like growth factor-1 (IGF-1), testosterone, cortisol, height, weight, and body composition were assessed at pre-season (P1), mid-season (P2) and post-season (P3). Anthropometric variables were also measured following a one-year follow-up (F).ResultsSignificant (p < 0.05) group x time interactions were found for testosterone and testosterone to cortisol ratio (T/C). Both variables were greater in BG at P2 and P3 compared to P1, however, the testosterone was less in the PG at P3 compared to P2. There was no significant group by time interactions for GH, IGF-1, lean body mass, or body fat. There was a significant (p < 0.05) group x time interaction in height and weight at F, with the greater increases in BG compared to PG.ConclusionBetaine supplementation increased testosterone levels and T/C ratio in youth professional soccer players during a competitive season. Betaine supplementation had no negative effects on growth (height and weight) and may attenuate reductions in testosterone due to intense training during puberty.

Effects of 14-weeks betaine supplementation on pro-inflammatory cytokines and hematology status in professional youth soccer players during a competition season: a double blind, randomized, placebo-controlled trial

ObjectiveSystemic elevations in pro-inflammatory cytokines are a marker of non-functional over reaching, and betaine has been shown to reduce the secretion of pro-inflammatory cytokines in vitro. The aim of this study was to investigate the effects of betaine supplementation on tumor necrosis factor alpha (TNF-α), interleukins-1 beta (IL-1β), − 6 (IL-6) and the complete blood cell (CBC) count in professional youth soccer players during a competitive season.MethodsTwenty-nine soccer players (age, 15.5 ± 0.3 years) were randomly divided into two groups based on playing position: betaine group (BG, n = 14, 2 g/day) or placebo group (PG, n = 15). During the 14-week period, training load was matched and well-being indicators were monitored daily. The aforementioned cytokines and CBC were assessed at pre- (P1), mid- (P2), and post- (P3) season.ResultsSignificant (p < 0.05) group x time interactions were found for TNF-α, IL-1β, and IL-6. These variables were lower in the BG at P2 and P3 compared to P1, while IL-1β was greater in the PG at P3 compared to P1 (p = 0.033). The CBC count analysis showed there was significant group by time interactions for white blood cells (WBC), red blood cells (RBC), hemoglobin (Hb), and mean corpuscular hemoglobin concentration (MCHC). WBC demonstrated increases at P3 compared to P2 in PG (p = 0.034); RBC was less at P3 compared to P1 in BG (p = 0.020); Hb was greater at P2 compared to P1, whilst it was less at P3 compared to P3 for both groups. MCHC was greater at P3 and P2 compared to P1 in BG, whereas MCHC was significantly lower at P3 compared to P2 in the PG (p = 0.003).ConclusionThe results confirmed that 14 weeks of betaine supplementation prevented an increase in pro-inflammatory cytokines and WBC counts. It seems that betaine supplementation may be a useful nutritional strategy to regulate the immune response during a fatiguing soccer season.

The influence of a soccer season on non-contact injury and isokinetic peak torque of the quadriceps and hamstrings in professional youth soccer players

ABSTRACT Isokinetic strength screening is utilized in professional soccer. However, there has been little research on the interaction between seasonal changes in players’ peak torque (PT) and injury incidence. Twenty-five (age 16.50.68 years) professional youth soccer players participated in the study. Bilateral isokinetic concentric (CON) and eccentric (ECC) testing of Quadriceps (Q) and Hamstrings (H) were conducted at three time-points across the season. Absolute CON and ECC PT were measured at 60 degree/sec and in a supine 170-degree position. Testing data was normalized to body mass. A mixed design (2 by 3) repeated measures ANOVA with injury as a co-variate was conducted to evaluate the effect of season and/or limb dominance on PT and injury incidence. With regard to the seasonal variation and injury incidence, an interaction was identified with respect to non-dominant limb (NDL) QCON (p = 0.01) and to a lesser extent the dominant limb (DL) QCON (p = 0.05). The seasonal variation of the PT of the NDL QCON was different between the injured and non-injured individuals. Non-injured individuals, QCON strength increased over the course of the season. While for the Injured players, QCON declined from pre-season to mid-season then increased but never recovered to starting pre-season values.

Dose-Response Relationship Between Training Load and Changes in Aerobic Fitness in Professional Youth Soccer Players.

To compare the dose-response relationship between traditional arbitrary speed thresholds versus an individualized approach, with changes in aerobic fitness in professional youth soccer players. A total of 14 youth soccer players completed a 1500-m time trial to estimate maximal aerobic speed (MAS, km·h-1) at the start and at the end of a 6-week period. Training load was monitored on a daily basis during this study. External load measures were total distance covered and total acceleration and deceleration distance >2m·s-2. Arbitrary high-speed running measures were meters covered and time spent at >17km·h-1 (m > high-speed distance, t > high-speed distance) and 21km·h-1 (m > very-high-speed distance, t > very-high-speed distance). Individualized high-speed running measures were meters covered and time spent at >MAS km·h-1 (m > MAS, t > MAS) and 30% anaerobic speed reserve (m > 30ASR, t > 30ASR). In addition, internal load measures were also collected: heart rate exertion and rating of perceived exertion. Linear regression analysis was used to establish the dose-response relationship between mean weekly training load and changes in aerobic fitness. Very large associations were found between t > MAS and changes in aerobic fitness (R2 = .59). Large associations were found for t > 30ASR (R2 = .38) and m > MAS (R2 = .25). Unclear associations were found for all other variables. An individualized approach to monitoring training load, in particular t > MAS, may be a more appropriate method than using traditional arbitrary speed thresholds when monitoring the dose-response relationship between training load and changes in aerobic fitness.

Prediction of Overuse Injuries in Professional U18-U21 Footballers Using Metrics of Training Distance and Intensity.

Bacon, CS and Mauger, AR. Prediction of overuse injuries in professional U18-U21 footballers using metrics of training distance and intensity. J Strength Cond Res 31(11): 3067-3076, 2017-The most common injury in professional football is an overuse injury to the lower limb. A significant external risk factor of this injury is the mismanagement of training and match loads. The aim of the current study was to examine the predictability of overuse injuries in professional youth soccer players using volume and intensity variables derived from Global Positioning Systems. A total of 41 players (age: 17.8 ± 1.1 years) training and match loads were assessed. These external loads were measured over 2 competitive seasons for every training session and match for each individual. A linear regression was used to test the predictability of the injury based on load, which were grouped using loading groups calculated from squad weekly averages. The load groupings assigned were: low load = 1 SD below the squad mean score; normal load = ±1 SD from the squad mean; high load = 1 SD above squad mean. The analysis demonstrated that total distance significantly predicted overuse injury incidence rates (F 1,39 = 6.482, p = 0.015), whereas high-speed running meters could not (F 1,39 = 1.003, p = 0.323). This study demonstrated that distance covered in training and matches can impact on the incidence of overuse injury in youth soccer players. Coaches should seek to monitor player training loads and incorporate this metric into their decision making for protecting players from overuse injury.

The Effects of a Single Whole-Body Cryotherapy Exposure on Physiological, Performance, and Perceptual Responses of Professional Academy Soccer Players After Repeated Sprint Exercise.

Russell, M, Birch, J, Love, T, Cook, CJ, Bracken, RM, Taylor, T, Swift, E, Cockburn, E, Finn, C, Cunningham, D, Wilson, L, and Kilduff, LP. The effects of a single whole-body cryotherapy exposure on physiological, performance, and perceptual responses of professional academy soccer players after repeated sprint exercise. J Strength Cond Res 31(2): 415-421, 2017-In professional youth soccer players, the physiological, performance, and perceptual effects of a single whole-body cryotherapy (WBC) session performed shortly after repeated sprint exercise were investigated. In a randomized, counterbalanced, and crossover design, 14 habituated English Premier League academy soccer players performed 15 × 30 m sprints (each followed by a 10 m forced deceleration) on 2 occasions. Within 20 minutes of exercise cessation, players entered a WBC chamber (Cryo: 30 seconds at -60° C, 120 seconds at -135° C) or remained seated (Con) indoors in temperate conditions (∼25° C). Blood and saliva samples, peak power output (countermovement jump), and perceptual indices of recovery and soreness were assessed pre-exercise and immediately, 2-hour and 24-hour postexercise. When compared with Con, a greater testosterone response was observed at 2-hour (+32.5 ± 32.3 pg·ml, +21%) and 24-hour (+50.4 ± 48.9 pg·ml, +28%) postexercise (both P = 0.002) in Cryo (trial × treatment interaction: P = 0.001). No between-trial differences were observed for other salivary (cortisol and testosterone/cortisol ratio), blood (lactate and creatine kinase), performance (peak power output), or perceptual (recovery or soreness) markers (all trial × treatment interactions: P > 0.05); all of which were influenced by exercise (time effects: all P ≤ 0.05). A single session of WBC performed within 20 minutes of repeated sprint exercise elevated testosterone concentrations for 24 hours but did not affect any other performance, physiological, or perceptual measurements taken. Although unclear, WBC may be efficacious for professional soccer players during congested fixture periods.

The variance of daily training load in Arabic professional youth soccer players after a change of head coach during the in-season

The variance of daily training load in Arabic professional youth soccer players after a change of head coach during the in-season

Methods of monitoring the training and match load and their relationship to changes in fitness in professional youth soccer players

Previous studies examining methods of monitoring the training and match load in soccer players have simply compared those methods to each other, not to changes in fitness. Training and match load measures from nine professional youth soccer players were collected for a period of six weeks. A lactate threshold test was conducted before and after this period. Mean weekly training and match load as determined by session-RPE, Banister's TRIMP, Team TRIMP and individualised TRIMP (iTRIMP) were correlated with each other, percentage changes in the velocity at 2 mmol · L−1 (vLT) and 4 mmol · L−1 (vOBLA) blood lactate concentration, and heart rate at 2 mmol · L−1 (LTHR) and 4 mmol · L−1 (OBLAHR). There were no significant changes in fitness across the six weeks: vLT (p = 0.54), vOBLA (p = 0.16), LTHR (p = 0.51) and OBLAHR (p = 0.63). Banister's TRIMP was significantly correlated with session-RPE (r = 0.75; p = 0.02) and Team TRIMP (r = 0.92; p < 0.001). The percentage change in vLT was significantly correlated to mean weekly iTRIMP (r = 0.67; p = 0.04). The results suggest that an individualised measure of internal load (iTRIMP) related better than other methods to changes in vLT in professional youth soccer players.

Hydration Status, Fluid Intake, and Electrolyte Losses in Youth Soccer Players

The purpose of the study was to determine the hydration status, fluid intake, and electrolyte losses of 21 male professional youth soccer players (age 17.1 ± 0.7 y) training in a cool environment. Pretraining and posttraining measurements of body mass, urine (freezing-point osmolality method), and sweat concentration (flame-emission spectroscopy) were collected. Fourteen players were found to be hypohydrated before training. The amount of fluid lost due to exercise equated to a 1.7% loss in body mass, which equated to a gross dehydration loss of 0.5%. Overall, the soccer players replaced 46% ± 88% of sweat loss during training, and only 4 remained hypohydrated after training. No significant correlations between sweat loss and sweat concentrations of Na+ (r = -.11, P = .67) or K+ (r = .14, P = .58) were found, but there was a significant correlation with Mg2+ (r = -.58, P < .009). This study found large variability in pretraining hydration status that the players were able to rehydrate during the training sessions. However, given the numbers starting training in a hypohydrated state, adequate hydration status before training should be considered by youth players, coaches, and sports-science support staff.

Dietary Analysis of Young Professional Soccer Players for 1 Week During the Competitive Season

Limited data exist concerning the dietary practices of young professional soccer players that compete within the United Kingdom. Therefore, the purpose of this study was to investigate the nutritional and activity habits of professional male soccer players (n = 10; age: 17 ± 1 years, height: 1.72 ± 0.01 m, mass: 67.5 ± 1.8 kg, estimated maximal aerobic capacity: 57.8 ± 0.9 ml·kg·min) who played for the youth team of a UK-based Championship club. All players recorded their 7-day dietary intake and activity habits during a competitive week that included a match day, 4- training days, and 2 rest days in the first half of the 2009/2010 playing season. The intake of carbohydrates (5.9 ± 0.4 g·kg·d), proteins (1.7 ± 0.1 g·kg·d), and fats (1.5 ± 0.1 g·kg·d) represented 56 ± 1, 16 ± 1, and 31 ± 1% of the mean daily energy intake respectively. The intake of fiber was found to be significantly lower than Recommended Nutrient Intake (RNI) values (67% of RNI, p < 0.001), whereas all other analyzed micronutrients met or exceeded recommended values. A mean daily energy deficit of 788 ± 174 kcal existed because daily energy expenditures exceeded that of intake (3,618 ± 61 vs. 2831 ± 164 kcal, p = 0.001). The mean daily fluid intake was 3.2 ± 0.3 L. Consequently, the nutritional practices of the sampled group of professional youth soccer players were inadequate to sustain optimized performance throughout training and match play. Youth soccer players should therefore seek to ensure that their diets contain adequate energy through increased total caloric intake, while also optimizing the proportion of energy derived from carbohydrates and ensuring that enough fiber-rich foods are consumed.

Lactate threshold responses to a season of professional British youth soccer

Objective: To examine the changes in aerobic endurance performance of professional youth soccer players throughout the soccer season. Methods: Nine youth soccer players were tested at six different time points...

Physiological adaptations to soccer specific endurance training in professional youth soccer players

Background: Improved oxygen uptake improves soccer performance as regards distance covered, involvements with the ball, and number of sprints. Large improvements in oxygen uptake have been shown using interval running....