Reliability and validity of field-based fitness tests in youth soccer players

Purpose:The purpose of the study was to assess the reliability and validity of a newly developed laboratory protocol to measure prolonged repeated-sprint ability (RSA) during soccer-specific exercise.Methods:To assess reliability, 12 youth soccer players age 15.2 ± 0.3 y performed 2 trials of a soccer-specific intermittent-exercise test (SSIET) separated by 3 months. The test was performed on a nonmotorized treadmill. A separate sample of 12 youth soccer players (15.2 ± 0.3 y) completed the SSIET while simultaneously HR, VO2, and blood lactate (BLa) were monitored. The SSIET was designed to replicate the demands of competing in one half of a soccer match while sprint performance was monitored. The test included a 5-s sprint every 2 min.Results:The mean coefficient of variation was 2.5% for the total distance covered during the SSIET and 3.8% for the total distance sprinted; measures of power output were less reliable (>5.9%). Participants covered 4851 ± 251 m during the SSIET, working at an average intensity of 87.5% ± 3.2% HRpeak and 70.2% ± 3.1% VO2peak, with ~7mmol/L BLa accumulation. A significant reduction (P < .05) in sprint performance was ob served over the course of the SSIET.Conclusion:The SSIET provided a reliable method of assessing prolonged RSA in the laboratory. The distance covered and the physiological responses during the SSIET successfully recreated the demands of competing in a soccer match.

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Reliability and Validity of Maximal Mean and Critical Speed and Metabolic Power in Australian Youth Soccer Players

Journal of Human Kinetics ◽

10.2478/hukin-2019-0135 ◽

2020 ◽

Vol 73 (1) ◽

pp. 93-102

Author(s):

Cameron Lord ◽

Anthony J. Blazevich ◽

Chris R. Abbiss ◽

Fadi Ma’ayah

Keyword(s):

Critical Speed ◽

Moving Average ◽

Time Windows ◽

Reliability And Validity ◽

Field Tests ◽

Soccer Players ◽

Metabolic Power ◽

Youth Soccer ◽

Coefficients Of Variation ◽

Absolute Agreement

AbstractThe reliability and validity of maximal mean speed (MMS), maximal mean metabolic power (MMPmet), critical speed (CS) and critical metabolic power (CPmet) were examined throughout the 2016-2017 soccer National Youth League competitions. Global positioning system (GPS) data were collected from 20 sub-elite soccer players during a battery of maximal running tests and four home matches. A symmetric moving average algorithm was applied to the instantaneous velocity data using specific time windows (1, 5, 10, 60, 300 and 600 s) and peak values were identified. Additionally, CS and CP¬met values calculated from match data were compared to CS and CPmet values determined from previously validated field tests to assess the validity of match values. Intra-class correlation (one-way random absolute agreement) scores ranged from 0.577 to 0.902 for speed, and from 0.701 to 0.863 for metabolic power values. Coefficients of variation (CV) ranged from good to moderate for speed (4-6%) and metabolic power (4-8%). Only CS and CPmet values were significantly correlated (r = 0.842; 0.700) and not statistically different (p = 0.066; 0.271) to values obtained in a shuttle-running critical test. While the present findings identified match-derived MMS, MMPmet, CS and CPmet to be reliable, only CS and CPmet derived from match play were validated to a CS field test that required changes in speed and direction rather than continuous running. This suggests that both maximal mean and critical speed and metabolic power analyses could be alternatives to absolute distance and speed in the assessment of match running performance during competitive matches.

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Spanish Elite Soccer Reserve Team Configuration and the Impact of Physical Fitness Performance

Journal of Human Kinetics ◽

10.2478/hukin-2019-0085 ◽

2020 ◽

Vol 71 (1) ◽

pp. 211-218 ◽

Cited By ~ 1

Author(s):

Asier Los Arcos ◽

Raúl Martínez-Santos ◽

Daniel Castillo

Keyword(s):

Physical Fitness ◽

Soccer Players ◽

Countermovement Jump ◽

Training Process ◽

Youth Soccer ◽

Fitness Tests ◽

Soccer Team ◽

The Impact ◽

Selection Of

AbstractThe aim of this study was threefold: 1) to assess the configuration of an elite reserve soccer team, 2) to compare physical fitness performance of promoted and new players according to the playing position, and 3) to analyze the level of competitive participation attained by these players. We considered physical fitness tests (5 m and 15 m sprint, countermovement jump [CMJ] and aerobic endurance) performed by 192 players (age = 20.2 ± 2.3 years) enrolled in the reserve team of a Spanish La Liga club from 1994 to 2013. The players were classified according to the previous club criterion (promoted from the soccer academy and new players signed from other clubs), b) their playing position, and c) the competitive level attained until the 2016/2017 season (Spanish 1st and 2nd Divisions and the remaining competition levels). The proportion of promoted and new players was similar (p = 0.47). Overall, no substantial differences (unclear-small) were found in physical fitness performance between promoted and new players. Considering the playing position, promoted lateral defenders (LDs) showed better sprinting (ES = moderate) and CMJ (ES = moderate) performance than new LDs. In addition, promoted central midfielders (CMs) demonstrated better performance in the 5 m sprint and the CMJ (ES = moderate) than new CMs. The percentage of players who later competed in the Spanish 1st and 2nd Divisions was greater in promoted players compared to new players (p = 0.006). Physical fitness performance did not determine the selection of new players in a soccer elite reserve team. We may conclude that soccer academies should prioritize the selection and the training process of youth soccer players.

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Reliability and Validity of the Carminattiʼs Test for Aerobic Fitness in Youth Soccer Players

The Journal of Strength and Conditioning Research ◽

10.1519/jsc.0000000000000534 ◽

2014 ◽

Vol 28 (11) ◽

pp. 3264-3273 ◽

Cited By ~ 8

Author(s):

Anderson S. Teixeira ◽

Juliano F. da Silva ◽

Lorival J. Carminatti ◽

Naiandra Dittrich ◽

Carlo Castagna ◽

...

Keyword(s):

Aerobic Fitness ◽

Reliability And Validity ◽

Soccer Players ◽

Youth Soccer

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SHOE SIZING SYSTEM FOR MALAYSIAN YOUTH SOCCER PLAYERS: A PRELIMINARY STUDY ON THE FOOT ANTHROPOMETRY

10.15282/mohe.2014.ses.072 ◽

2014 ◽

Author(s):

Zahari Taha ◽

◽

Mohd Azri Aris ◽

Mohd Hasnun Arif Hassan ◽

Anwar PP Abdul Majeed ◽

...

Keyword(s):

Soccer Players ◽

Youth Soccer ◽

Sizing System ◽

Preliminary Study

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Maximal oxygen consumption and oxygen muscle saturation recovery following repeated anaerobic sprint test in youth soccer players

The Journal of Sports Medicine and Physical Fitness ◽

10.23736/s0022-4707.19.10162-4 ◽

2020 ◽

Vol 60 (3) ◽

Cited By ~ 1

Author(s):

Yiannis Michailidis ◽

Aristeidis Chatzimagioglou ◽

Dimitrios Mikikis ◽

Ioannis Ispirlidis ◽

Thomas Metaxas

Keyword(s):

Oxygen Consumption ◽

Maximal Oxygen Consumption ◽

Saturation Recovery ◽

Soccer Players ◽

Youth Soccer

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Factors Influencing Creatine Kinase Response in Youth National Team Soccer Players

Sports Health A Multidisciplinary Approach ◽

10.1177/1941738121999387 ◽

2021 ◽

pp. 194173812199938

Author(s):

Gabor Schuth ◽

Gyorgy Szigeti ◽

Gergely Dobreff ◽

Peter Revisnyei ◽

Alija Pasic ◽

...

Keyword(s):

Creatine Kinase ◽

Prediction Models ◽

Soccer Players ◽

Linear Regression Models ◽

Level Of Evidence ◽

Internal Load ◽

Youth Soccer ◽

National Team ◽

Weekly Training ◽

The Relationship

Background: Previous studies have examined the relationship between external training load and creatine kinase (CK) response after soccer matches in adults. This study aimed to build training- and match-specific CK prediction models for elite youth national team soccer players. Hypothesis: Training and match load will have different effects on the CK response of elite youth soccer players, and there will be position-specific differences in the most influential external and internal load parameters on the CK response. Study Design: Prospective cohort study. Level of Evidence: Level 4. Methods: Forty-one U16-U17 youth national team soccer players were measured over an 18-month period. Training and match load were monitored with global positioning system devices. Individual CK values were measured from whole blood every morning in training camps. The dataset consisted of 1563 data points. Clustered prediction models were used to examine the relationship between external/internal load and consecutive CK changes. Clusters were built based on the playing position and activity type. The performance of the linear regression models was described by the R2 and the root-mean-square error (RMSE, U/L for CK values). Results: The prediction models fitted similarly during games and training sessions ( R2 = 0.38-0.88 vs 0.6-0.77), but there were large differences based on playing positions. In contrast, the accuracy of the models was better during training sessions (RMSE = 81-135 vs 79-209 U/L). Position-specific differences were also found in the external and internal load parameters, which best explained the CK changes. Conclusion: The relationship between external/internal load parameters and CK changes are position specific and might depend on the type of session (training or match). Morning CK values also contributed to the next day’s CK values. Clinical Relevance: The relationship between position-specific external/internal load and CK changes can be used to individualize postmatch recovery strategies and weekly training periodization with a view to optimize match performance.

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Does Resisted Sled Towing Improve the Physical Qualities of Elite Youth Soccer Players of Differing Maturity Status?

Journal of Science in Sport and Exercise ◽

10.1007/s42978-020-00087-w ◽

2021 ◽

Author(s):

Rhys Morris ◽

Tony Myers ◽

Stacey Emmonds ◽

Dave Singleton ◽

Kevin Till

Keyword(s):

Body Mass ◽

Bayesian Regression ◽

Soccer Players ◽

Height Velocity ◽

Regression To The Mean ◽

Peak Height Velocity ◽

Maturity Group ◽

Youth Soccer ◽

Professional Soccer ◽

The Impact

Abstract Purpose Sled towing has been shown to be an effective method to enhance the physical qualities in youth athletes. The aim of this study was to evaluate the impact of a 6-week sled towing intervention on muscular strength, speed and power in elite youth soccer players of differing maturity status. Method Seventy-three male elite youth soccer players aged 12–18 years (Pre-Peak Height Velocity [PHV] n = 25; Circa-PHV n = 24; Post-PHV n = 24) from one professional soccer academy participated in this study. Sprint assessments (10 m and 30 m), countermovement jump and isometric mid-thigh pull were undertaken before (T1) and after (T2) a 6-week intervention. The training intervention consisted of 6 weeks (2 × per week, 10 sprints over 20 m distance) of resisted sled towing (linear progression 10%–30% of body mass) during the competitive season. Bayesian regression models analysed differences between T1 and T2 within each maturity group. Results There were minimal changes in strength, speed and power (P = 0.35–0.80) for each maturity group across the 6-week intervention. Where there were changes with greater certainty, they are unlikely to represent real effect due to higher regression to the mean (RTM). Conclusion It appears that a 6-week sled towing training programme with loadings of 10%–30% body mass only maintains physical qualities in elite youth soccer players pre-, circa-, and post-PHV. Further research is required to determine the effectiveness of this training method in long-term athletic development programmes.

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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

Journal of the International Society of Sports Nutrition ◽

10.1186/s12970-021-00441-5 ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Hadi Nobari ◽

Jason M. Cholewa ◽

Jorge Pérez-Gómez ◽

Alfonso Castillo-Rodríguez

Keyword(s):

Inflammatory Cytokines ◽

Blood Cells ◽

Well Being ◽

Soccer Players ◽

Mean Corpuscular Hemoglobin ◽

Significant Group ◽

Youth Soccer ◽

Tnf Α ◽

Betaine Supplementation ◽

Pro Inflammatory Cytokines

Abstract Objective Systemic 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. Methods Twenty-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. Results Significant (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). Conclusion The 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.

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