Soccer-drill specificity in top-class male players with reference to peak match locomotor demands.

To compare the locomotor demands of several ball/running drills with the official match peak, locomotor demands determined across different time-windows of the same duration in top-class male soccer players (n = 40). Total distance (TD), high-speed running (HSR, 15-20 km⋅h-1), very high-speed running (VHSR, 20-24 km⋅h-1), sprint and acceleration+deceleration (Acc+Dec >±3 m⋅s-2) distances were measured during training and official matches. A total of 9372 individual observations were classified as technical-tactical drills, small-sided games (SSGs), super-SSGs (pitch-area >340 m2·player), SSGs with rules modifications (SSGmodified), individual positional drills or running drills. The relative (m·min-1) TD, HSR, VHSR, sprint and Acc+Dec were compared with the peak locomotor demands determined during official matches across different time-windows (1, 2, 3, 4 and 5-min). Individual position-specific drill, super-SSGs, SSGmodified and running drills showed similar (P > 0.05) or higher (P < 0.05; ES:1.17/4.61) than match TD, HSR and VHSR, while sprint and Acc+Dec were lower (P < 0.05). Conversely, technical-tactical drills and SSGs showed lower (P < 0.05; ES:-1.00/-3.45) TD, HSR, VHSR, sprint and Acc+Dec than official match peak demands. Locomotor loads during technical-tactical drills and SSGs were lower than peak demands, particularly for VHSR and sprint. Since training intensity is a key factor for high-performance development, these results may help to prepare top-class players for the official match peak demands.

Recreational futsal provides broad-spectrum fitness and health benefits but no blood pressure effects in men with treated hypertension - a randomised controlled trial.

We determined the coadjuvant effect of a recreational futsal (RF) programme versus standard care alone (CON) in men with treated arterial hypertension (TAHT). Thirty-nine men with TAHT were randomised to RF (N = 20; 48 ± 8 years; systolic blood pressure [SBP]: 122 ± 14 mmHg) with 2-3 one-hour sessions/week for 3 months, or to CON (N = 19; 51 ± 6 years; SBP: 126 ± 13 mmHg). Participants were assessed at baseline, at 3 months, and after 1 month of training cessation (4 months). Mean training attendance was 60 ± 23%. At 3-months, there were no between-group differences in BP parameters (SBP: 0.44 mmHg; 95% CI: -5.79, 6.67). However, compared to CON, RF was effective for peak oxygen uptake (2.76 mL.min-1.kg-1; 95% CI: 0.26, 5.26), time to exhaustion (1.15 min; 95% CI: 0.59, 1.69), Yo-Yo IE1 performance (365 m; 95% CI: 175, 556), resting heart rate (RHR; -5 b.min-1; 95% CI: -10, -1), glycated haemoglobin (-0.52 mmol/L; 95% CI: -0.84, -0.19), blood glucose (-0.25 mmol/L; 95% CI: -0.44, -0.06), left femur bone mineral content (1.96 g; 95% CI: 0.29, 3.65), and postural balance (-2.3 falls; 95% CI: -3.9, -0.6). Similar findings were observed after 1-month of training cessation, except for RHR and blood glucose that returned to baseline levels in the RF group. In conclusion, RF provides broad-spectrum fitness and health benefits but no BP effects in men with TAHT.

Use of Exploratory Factor Analysis to Assess the Fitness Performance of Youth Football Players.

ABSTRACT: Perroni, F, Castagna, C, Amatori, S, Gobbi, E, Vetrano, M, Visco, V, Guidetti, L, Baldari, C, Luigi Rocchi, MB, and Sisti, D. Use of exploratory factor analysis to assess the fitness performance of youth football players. J Strength Cond Res 37(7): e430-e437, 2023-Football performance involves several physical abilities that range in aerobic, anaerobic, and neuromuscular domains; however, little is known about their interplay in profiling individual physical attributes. This study aimed to profile physical performance in youth football players according to their training status. One hundred seven young male soccer players (age 13.5 ± 1.4 years; height 168 ± 7 cm; body mass 57.4 ± 9.6 kg; and body mass index 20.2 ± 2.1 kg·m -2 ) volunteered for this study. Players' physical performance was assessed with football-relevant field tests for sprinting (10 m sprint), vertical jump (countermovement jump), intermittent high-intensity endurance (Yo-Yo Intermittent Recovery Test Level 1, YYIRT1), and repeated sprint ability (RSA). The training status was assumed as testosterone and cortisol saliva concentrations; biological maturation was estimated using the Pubertal Development Scale. Exploratory factor analysis (EFA) revealed 3 main variables depicting anthropometric (D1, 24.9%), physical performance (D2, 18.8%), and training status (D3, 13.3%), accounting for 57.0% of total variance altogether. The level of significance was set at p ≤ 0.05. The RSA and YYIRT1 performances were largely associated with D2, suggesting the relevance of endurance in youth football. This study revealed that for youth football players, a 3-component model should be considered to evaluate youth soccer players. The EFA approach may help to disclose interindividual differences useful to talent identification and selection.

Technical match actions and plasma stress markers in elite female football players during an official FIFA Tournament.

This study analyzed the impact of performing four consecutive football matches separated by 48-72 hours during a FIFA tournament on physical load, technical performance and plasma markers of redox state, muscle damage and inflammation in elite female players. Forty-eight players from three national teams were evaluated at seven time points: before (baseline) and throughout the tournament (after each match and before two training sessions). Only data from players who played all matches were included in the analyses (N = 13). The players were divided into high-rank (N = 6) and low-rank (N = 7) team players according to FIFA standards. Plasma creatine kinase (CK), C-reactive protein (CRP), total antioxidant status (TAS), and uric acid (UA) were analyzed at the selected time points. Technical performance and physical load were also quantified according to team rank. Players from low-rank teams played significantly more time than high-rank players (85 ± 10 vs 67 ± 15 minutes; P = .02; d = 1.51). Low-rank team players presented higher values in technical performance actions than the high-rank team players, but most of the differences were explained by the longer match time played. UA content differed across the matches, increasing from baseline (F(4,40)  = 3.90; P = .01) and more in the high-rank team players (F(1,10)  = 20.46; P = .001), while CRP only differed across the matches (F(4,36)  = 2.66; P = .05), also increasing from baseline. A large time effect was shown for UA only in the high-rank players (η2 p  = 0.50; P = .02). Four consecutive matches did not result in considerable alterations in plasma stress markers, physical load, and technical performance in elite female football players from distinct rank levels.

Estimation of maximal oxygen uptake using the heart rate ratio method in male recreational football players.

Maximal oxygen uptake (VO2max) is associated with cardiovascular and metabolic health in the general population. The heart rate (HR) ratio method (HRratio) is a valid, easy and accessible method for estimating VO2max in well-trained subjects. This study examined the validity of using the HRratio to estimate VO2max in recreational football players in the untrained and trained states. Sixty-six participants (age 39.3 ± 5.8 years) were tested pre-training and 28 after 12 weeks, for VO2max assessment, running on a treadmill alternating speed (1 km h-1) and inclination (1%) increments every 30 s until exhaustion. Maximal HR (HRmax) was assessed directly with a multiple approach and estimated with selected equations. Resting HR (HRrest) was measured in supine position, after 15 min of rest. The HRratio method considers the product of HRmax/HRrest ratio by a theoretical proportionality factor (15 ml kg-1 min-1, TPF) to estimate VO2max. This population-specific proportionality factor (SPF) was 14.6 ± 2.6 ml kg-1 min-1. In the untrained state (n = 66), participants' actual VO2max (41.3 ± 6.2 ml kg-1 min-1) was moderately lower (~ 2 ml kg-1 min-1) than the estimated VO2max using the TPF. A nonsignificant difference (0.7 ml kg-1 min-1) was found when the VO2max was estimated using the SPF. When using HRmax equations and the TPF, a small nonsignificant difference (~ 1.5 ml kg-1 min-1) was reported between actual and estimated VO2max. In the trained state (n = 28), the estimated VO2max values were not significantly different from the actual VO2max (44.2 ± 5.2 ml kg-1 min-1), with large effect sizes when considering TPF and estimated HRmax. The results of this study provide evidence of the applicability of HRratio in estimating VO2max in male adult/middle-aged recreational football players.

UEFA expert group statement on nutrition in elite football. Current evidence to inform practical recommendations and guide future research.

Football is a global game which is constantly evolving, showing substantial increases in physical and technical demands. Nutrition plays a valuable integrated role in optimising performance of elite players during training and match-play, and maintaining their overall health throughout the season. An evidence-based approach to nutrition emphasising, a 'food first' philosophy (ie, food over supplements), is fundamental to ensure effective player support. This requires relevant scientific evidence to be applied according to the constraints of what is practical and feasible in the football setting. The science underpinning sports nutrition is evolving fast, and practitioners must be alert to new developments. In response to these developments, the Union of European Football Associations (UEFA) has gathered experts in applied sports nutrition research as well as practitioners working with elite football clubs and national associations/federations to issue an expert statement on a range of topics relevant to elite football nutrition: (1) match day nutrition, (2) training day nutrition, (3) body composition, (4) stressful environments and travel, (5) cultural diversity and dietary considerations, (6) dietary supplements, (7) rehabilitation, (8) referees and (9) junior high-level players. The expert group provide a narrative synthesis of the scientific background relating to these topics based on their knowledge and experience of the scientific research literature, as well as practical experience of applying knowledge within an elite sports setting. Our intention is to provide readers with content to help drive their own practical recommendations. In addition, to provide guidance to applied researchers where to focus future efforts.

Ecological and Construct Validity of a Repeated Sprint Test in Male Youth Soccer Players.

ABSTRACT: Fernandes-Da-Silva, J, Castagna, C, Teixeira, AS, Carminatti, LJ, Francini, L, Póvoas, SCA, and Antonacci Guglielmo, LG. Ecological and construct validity of a repeated sprint test in male youth soccer players. J Strength Cond Res 35(7): 2000-2009, 2021-This study aimed to examine the relationship between a repeated sprint ability (RSA) test (5 bouts of 30-m sprints interspersed by 30 seconds of recovery) and match-related physical performance in male youth soccer players. Although 60 outfield players were evaluated, only data from players who participated in the full matches (n = 39) were retained (8 central defenders, 7 external defenders, 8 central midfielders, 8 external midfielders, and 8 forwards). To verify the ecological validity of this RSA protocol, the association between the best (RSAbest) and mean (RSAmean) sprint time in the 5 × 30-m and physical match performance during friendly youth soccer games was examined. Physical match demands were assessed using global positioning system technology (10 Hz) considering distance covered in selected arbitrary speed categories. The absolute speed thresholds were the same for all the players. Players were categorized into 2 groups based on the 5 × 30-m performance: RSAmean times below (i.e., faster) and above (i.e., slower) the median value. Players with faster RSAmean times covered significantly more distance sprinting during friendly matches (606 ± 204 m, +47.0%; t = 4.953; effect size = 1.88, 1.24; 2.52, p ≤ 0.001) compared to their slower counterparts (322 ± 145 m). A large negative correlation (r = -0.63, -0.77; -0.44, p ≤ 0.001) was found between RSAbest time (4.59 ± 0.27 seconds) and match sprint distance (457 ± 229 m). Likewise, RSAmean time (4.76 ± 0.25 seconds) was also largely associated (r = -0.60, -0.75; -0.39; p ≤ 0.001) with in-game sprinting performance. The results of this study provided evidence to support the construct and ecological validity of the 5 × 30-m protocol in male youth soccer players. Furthermore, differences in 5 × 30-m performance explained the amount of sprinting activity performed during the match.

Submaximal field testing validity for aerobic fitness assessment in recreational football.

Submaximal field tests are especially recommended when repeated testing is warranted. This study aimed at assessing the validity of the submaximal versions of the Yo-Yo intermittent tests in male recreational football players in untrained and trained status. The participants' (n = 66; age 39.3 ± 5.8 years, VO2max 41.2 ± 6.2 mL·kg-1 ·min-1 , body mass 81.9 ± 10.8 kg, height 173.2 ± 6.4 cm) heart rate after 2 minutes (HR2min ) during the level 1 (YYIE1HR2min ) and 2 (YYIE2HR2min ) versions of the Yo-Yo intermittent endurance test and the level 1 version of the Yo-Yo intermittent recovery test (YYIR1HR2min ) was plotted against individual VO2max values. Thirty-two participants performed all the tests after a 12-week recreational football intervention for test responsiveness. Associations between VO2max and YYIE1HR2min were large to small (P = .0001). Large to trivial associations were found between YYIE2HR2min , YYIR1HR2min , and VO2max (P < .01). Maximal Yo-Yo performances were large, significant, and inversely related to HR2min (-0.68 to -0.49, P < .0001). Pre- to post-intervention ICC values were good for YYIE1HR2min and YYIE2HR2min , and excellent for YYIR1HR2min . Post-intervention associations between HR2min and Yo-Yo maximal performances were large to very large (-0.55 to -0.72; P < .002, n = 32). Training-induced changes in VO2max moderately correlated with YYIR1HR2min (-0.48; P = .007; n = 32). HR2min lower than 89%, 98%, and 91% HRmax for YYIE1HR2min , YYIE2HR2min , and YYIR1HR2min , respectively, may be considered as signs of good to excellent VO2max levels. Since in the YYIE1HR2min , the participants attained 84% HRmax and test specificity increased for HR2min values <89%, this test may be the preferred choice when repeated assessment of aerobic fitness, using submaximal intermittent Yo-Yo tests, is considered in recreational football.

Yo-Yo intermittent tests are a valid tool for aerobic fitness assessment in recreational football.

PURPOSE: To examine the suitability of three versions and two levels of the Yo-Yo intermittent tests for assessing and tracking aerobic fitness status development in male recreational football players. Sixty-six untrained participants (age 39 ± 6 years, VO2max 41.2 ± 6.2 ml kg-1 min-1, body mass 81.9 ± 10.8 kg, height 173.2 ± 6.4 cm) partook in a 12-week recreational football training program. They were evaluated during the Yo-Yo intermittent endurance level 1 (YYIE1) and 2 (YYIE2) tests and the Yo-Yo intermittent recovery level 1 test (YYIR1), and during a treadmill test for VO2max assessment, at baseline. Thirty-two out of these 66 participants replicated all these tests at post-intervention. An additional group of 30 male age-matched recreational football players that afterwards started the 12-week recreational football program (age 39 ± 6 years, VO2max 45.3 ± 5.8 ml kg-1 min-1, body mass 82.5 ± 7.8 kg, height 172.8 ± 5.4 cm) was evaluated at baseline to test cross-validation. RESULTS: The Yo-Yo tests showed very large associations with VO2max at baseline (r = 0.75-0.77; P < 0.0001) and at post-intervention (r = 0.76-0.82; P < 0.0005). Post-training, very large associations were found between YYIE2 performance and VO2max (r = 0.65, P < 0.0001). Cross-validation revealed small to large differences between the observed and estimated VO2max values (1.5-2.96 ml kg-1 min-1) with moderate typical error of estimation (7.9-8.7%) across the tests. Performance in the YYIE1, YYIE2 and YYIR1 tests of ≥ 1760, 480 and 600 m, respectively, indicated good to excellent VO2max values. CONCLUSIONS: The Yo-Yo tests considered here showed robust and consistent criterion validity. The YYIE2 could be a more accurate option to track aerobic fitness development in recreational football players.

Estimation of maximal heart rate in recreational football: a field study.

PURPOSE: To examine the accuracy of practical indirect methods (i.e., recreational football match and estimation equations) in assessing individual maximal heart rate (HRmax) in recreational football players. Sixty-two untrained male participants engaged in a recreational football intervention (age 39.3 ± 5.8 years, VO2max 41.2 ± 6.2 ml·kg-1·min-1, body mass 81.9 ± 10.8 kg, height 173.2 ± 6.4 cm) were tested for HRmax using a multiple approach, at baseline and post-intervention (i.e., in the untrained and trained status, respectively). Observed HRmax was plotted against peak match HR (Match-HRpeak) and HRmax estimated from prediction equations (EstHRmax) at both time-points. RESULTS: In the untrained status, only the 211 - 0.64 × Age and 226 - Age equations showed non-significant (medium-to-small) differences with observed HRmax. The differences between observed HRmax and Match-HRpeak were large (P < 0.0001). At post-intervention, the observed HRmax (Post-HRmax) was significantly and largely lower than at baseline. The prediction equations under consideration provided EstHRmax values that were lower than Post-HRmax, with small-to-large differences (P > 0.05). The exception was for the 226 - Age and 211 - 0.64 × Age equations, with values largely higher than Post-HRmax. CONCLUSIONS: This study suggests caution when considering EstHRmax and Match-HRpeak in recreational football interventions to track HRmax. The accuracy of EstHRmax may vary according to training status, suggesting the need for different approaches and equations across training interventions.

Assessment of Biomechanical Response to Fatigue through Wearable Sensors in Semi-Professional Football Referees.

Quantifying muscle fatigue is a key aspect of everyday sport practice. A reliable and objective solution that can fulfil this task would be deeply important for two main reasons: (i) it would grant an objective indicator to adjust the daily training load for each player and (ii) it would provide an innovative tool to reduce the risk of fatigue-related injuries. Available solutions for objectively quantifying the fatigue level of fatigue can be invasive for the athlete; they could alter the performance or they are not compatible with daily practice on the playground. Building on previous findings that identified fatigue-related parameters in the kinematic of the counter-movement jump (CMJ), this study evaluates the physical response to a fatigue protocol (i.e., Yo-Yo Intermittent Recovery Test Level 1) in 16 football referees, by monitoring CMJ performance with wearable magneto-inertial measurement units (MIMU). Nineteen kinematic parameters were selected as suitable indicators for fatigue detection. The analysis of their variations allowed us to distinguish two opposites but coherent responses to the fatigue protocol. Indeed, eight out of sixteen athletes showed reduced performance (e.g., an effective fatigue condition), while the other eight athletes experienced an improvement of the execution likely due to the so-called Post-Activation Potentiation. In both cases, the above parameters were significantly influenced by the fatigue protocol (p < 0.05), confirming their validity for fatigue monitoring. Interesting correlations between several kinematic parameters and muscular mass were highlighted in the fatigued group. Finally, a "fatigue approximation index" was proposed and validated as fatigue quantifier.

Maximal heart rate assessment in recreational football players: A study involving a multiple testing approach.

This study aimed at examining the suitability of a standard treadmill test (TT), popular intermittent field tests, and small-sided football matches to induce maximal heart rate (HRmax ) in recreational football players. Sixty-six inactive untrained male subjects (age: 39.3 ± 5.8 years, VO2max : 41.2 ± 6.2 mL kg-1  min-1 , body mass: 81.9 ± 10.8 kg, height: 173.2 ± 6.4 cm) were evaluated. On separate occasions, the players were randomly submitted to a progressive VO2max TT, to the Yo-Yo intermittent endurance level 1 (YYIE1) and level 2 (YYIE2) tests, to the Yo-Yo intermittent recovery level 1 (YYIR1) test, and to 7v7 (43 × 27 m pitch, 83 m2 /player) football matches (45 minutes; 2-4 matches/player). To ensure data consistency, exercise HR was recorded using the same HR monitors in all the experimental conditions. A total of 73%, 24%, 18%, 17%, and 30% of the players achieved their HRmax during the YYIE1, YYIE2, YYIR1, TT, and the small-sided football matches, respectively. The probability of achieving HRmax increased proportionally to test duration, with 7.8 minutes as the cutoff time. Variations in HRpeak of ±2 b min-1 should be regarded as of practical relevance. YYIE1 HRpeak provided the most accurate estimation of a subject's individual HRmax and much higher probability of reaching HRmax . Nevertheless, the results of this study suggest caution in considering a reference test for HRmax assessment in this population. The use of confirmation tests is still highly advisable when the test duration is shorter than 7.8 minutes. In this regard, field tests seem to be suitable and accurate for individual HRmax assessment in recreational football players.

Association Between Match Activity, Endurance Levels and Maturity in Youth Football Players.

The aim of the study was to examine the associations between maximal and submaximal field tests with match physical activity and biological maturation in youth football players. Sixty-eight youth football players (U14, U15, U16, U17) performed maximal and submaximal field endurance tests. Biological maturity was estimated calculating the distance from peak height velocity (Y-PHV). Physical match activities were tracked using GPS units and players' post-match rate of perceived exertion (RPE) was recorded. Mainly moderate associations were found between field tests and match activities. Large correlations were found between Yo-Yo Intermittent Recovery test level 1, distance covered at high and very high-speed running, the quantity of very high and maximal metabolic power running. Small to moderate associations between match activities and Y-PHV were observed. The magnitude of correlation between match activities and field tests increased from moderate to large when matches with an RPE>5 were considered. The results provide further evidence of the association between young football players' aerobic performance and match work rate. Submaximal field tests demonstrate ecological validity and may constitute a practical alternative to performing maximal tests. Maturation was found to have a moderate effect on youth players' match work rate.

Aerobic Fitness in Top-Class Soccer Referees.

Castagna, C, Bizzini, M, Araújo Póvoas, SC, Schenk, K, Büsser, G, and D'Ottavio, S. Aerobic fitness in top-class soccer referees. J Strength Cond Res 33(11): 3098-3104, 2019-The aim of this study was to examine the aerobic fitness status of top-class male soccer officials using a cross-sectional design and known population group constructs. Fifty-two field referees (FRs, age 38.4 ± 3.3 years; height 181 ± 5.6 cm; body mass 76.8 ± 6.8 kg; body mass index [BMI] 23.4 ± 1.7 kg·m; body fat 20.4 ± 3.6%; and international refereeing experience 5 ± 3.5 years) and 104 assistant referees (ARs, age 37.8 ± 4.1 years; height 176.9 ± 7.5 cm; body mass 72.1 ± 7.4 kg; BMI 23 ± 1.6 kg·m; body fat 19.2 ± 3.6%; and international refereeing experience 7 ± 3.8 years) from 53 National Football Associations worldwide, and candidates of the preliminary open-list developed by the FIFA Refereeing Department for the 2014 World Cup Final Tournament, were tested for aerobic fitness in laboratory conditions with a progressive speed treadmill test to exhaustion. Large (+8.54%, d = 0.8) and small (+3.1%, d = 0.3) differences in absolute (L·min) and relative (ml·kg·min) VO2max were found between FR and AR, respectively. Trivial differences (d = 0.07) were shown in running economy (RE) (6 minutes at 8 km·h) between AR and FR. Using the scaling notation (b = 0.64), medium and significant differences were found between match officials for VO2max and RE (FR > AR; d = 0.6 and 0.67, respectively). Using receiver operating characteristic curve statistics, cutoff values of 3.93 L·min and 50.6 ml·kg·min were detected in absolute and relative VO2max for the FR and the AR (FR > AR), respectively. The FR showed superior aerobic fitness compared with AR. Training prescription should consider intensities at anaerobic threshold speed (14 km·h, 91% heart rate max) when aerobic fitness development is the aim in elite officials.

Ecological Validity and Reliability of an Age-Adapted Endurance Field Test in Young Male Soccer Players.

Castagna, C, Krustrup, P, D'Ottavio, S, Pollastro, C, Bernardini, A, and Araújo Póvoas, SC. Ecological validity and reliability of an age-adapted endurance field test in young male soccer players. J Strength Cond Res 33(12): 3400-3405, 2019-The purpose of this study was to examine the reliability and the association with relevant match activities (ecological validity) of an age-adapted field test for intermittent high-intensity endurance known as Yo-Yo intermittent recovery level 1 children's test (YYIR1C) in young male soccer players. Twenty-eight young male outfield soccer players (age 11.1 ± 0.9 years, height 142 ± 4.4 cm, body mass 37.0 ± 5.9 kg) with at least 2 years of experience in soccer competitions were tested twice using YYIR1C and an age-adapted competitive small-sided game (i.e., 9v9), 7 days apart in a random order. The YYIR1C performance showed an excellent relative (intraclass correlation coefficient = 0.94) and a good absolute reliability (typical error of measurement as percentage of the coefficient of variation = 5.1%). Very large and significant associations were found between YYIR1C performance and match high-intensity activity (r = 0.53). Large correlations were found between YYIR1C and match sprinting (r = 0.42) and high-intensity metabolic power (r = 0.46) distances. Match total distance was largely associated with YYIR1C (r = 0.30). The results of this study showed that YYIR1C may be considered a valid and reliable field test for assessing intermittent high-intensity endurance in young male soccer players. Because of the relevance of aerobic fitness in youth soccer, future studies testing the sensitiveness of YYIR1C are necessary.

The Construct Validity of the CODA and Repeated Sprint Ability Tests in Football Referees.

As of 2017, the international football federation introduced the change of direction ability test (CODA) and the 5×30 m sprint test for assistant referees (ARs) and continued the 6×40 m sprint test for field referees (FRs) as mandatory tests. The aim of this study was to evaluate the association between performance in these tests and running performance during matches at the top level in Norway. The study included 9 FRs refereeing 21 matches and 19 ARs observed 53 times by a local positioning system at three stadiums during the 2016 season. Running performance during matches was assessed by high-intensity running (HIR) distance, HIR counts, acceleration distance, and acceleration counts. For the ARs, there was no association between the CODA test with high-intensity running or acceleration (P>0.05). However, the 5×30 m sprint test was associated with HIR count during the entire match (E -12.9, 95% CI -25.4 to -0.4) and the 5-min period with the highest HIR count (E -2.02, 95% CI -3.55 to -0.49). For the FRs, the 6×40 m fitness test was not associated with running performance during matches (P>0.05). In conclusion, performance in these tests had weak or no associations with accelerations or HIR in top Norwegian referees during match play.

Reliability of Submaximal Yo-Yo Tests in 9- to 16-Year-Old Untrained Schoolchildren.

PURPOSE: To examine the reliability of age-adapted submaximal Yo-Yo (Yo-Yosubmax) intermittent tests in untrained schoolchildren aged 9-16 years (n = 139; 72 boys and 67 girls) and within children with high and low percentage of body fat (%BF). METHODS: Yo-Yo intermittent recovery level 1 children's (YYIR1C), Yo-Yo intermittent endurance level 1 (YYIE1), and Yo-Yo intermittent endurance level 2 (YYIE2) tests were performed 7 days apart by 9- to 11-, 12- to 13-, and 14- to 16-year-old children, respectively. Reliability was tested for Yo-Yosubmax heart rate (HRsubmax), peak HR, and maximal distance. RESULTS: HRsubmax typical errors of measurement (TEM) in YYIR1C, YYIE1, and YYIE2 were 2.2% (1.7%-2.9%), 2.4% (1.9%-3.3%), 1.9% (1.6%-2.5%) and 2.4% (1.9%-3.3%), 2.4% (1.9%-3.2%), 1.9% (1.5%-2.4%) for girls and boys, respectively. HRsubmax intraclass correlation coefficient values were good to excellent (.62-.87) in all age groups and in schoolchildren of different %BF. TEM for HRsubmax ranged from 2.1% to 2.3% in high and low %BF groups. Maximal distance intraclass correlation coefficients were excellent and TEM values ranged from 11% to 12% in both %BF groups. HRsubmax was moderately to largely associated (r = -.46 to -.64; P < .002) with Yo-Yo maximal distance across the age groups. CONCLUSION: Yo-Yosubmax tests are a reliable tool providing useful and sustainable aerobic performance testing in physical education, irrespective of individual %BF.

Influence of Team's Rank on Soccer Referees' External and Internal Match Loads During Official Matches.

Castillo, D, Castagna, C, Cámara, J, Iturricastillo, A, and Yanci, J. Influence of team's rank on soccer referees' external and internal match loads during official matches. J Strength Cond Res 32(6): 1715-1722, 2018-The aim was to examine the external and the internal match loads (ML) of field referees (FRs) attending teams of different ranking during championship matches. Twenty FR who officiated in 30 official soccer matches (30 observations) participated in our study. The criteria for allocating the soccer referees' ML results were based on the teams' final league positions as follows: matches performed by Top 10 teams (TOP10), matches performed by bottom 10 teams (BOT10), and matches played among TOP10 and BOT10 teams (MIXED). External (match activities, accelerations [Acc], and decelerations [Dec]) and internal MLs (Edwards' heart rate [HR]-derived training impulse [TRIMPEDW], HRmean expressed as a percentage of HRpeak [%HRpeak], and differentiated rating of perceived exertion [dRPE]) were recorded. The main results showed that FR, who officiated TOP10 matches, covered more distance at a low walking speed (<3.6 km·h) and performed a higher percentage of high-intensity accelerations and decelerations than those FR who officiated lower ranked teams' matches. Moreover, FR who officiated MIXED matches registered lower values of TRIMPEDW MLs and %HRpeak and declared higher respiratory (sRPEres ML) and muscular (sRPEmus ML) perceived MLs during the second half. Considering those FR who officiate matches between teams of a higher competitive level will need to produce higher match responses, especially regarding the percentage of distance covered at high intensity, accelerations, and decelerations; physical trainers of soccer referees at a high competitive level should implement these high-intensity short-term actions in specific training regimes.

Sex Differences in Aerobic Fitness in Top-Class Soccer Referees.

Castagna, C, Bizzini, M, D'Ottavio, S, and Araújo Póvoas, SC. Sex differences in aerobic fitness in top-class soccer referees. J Strength Cond Res 32(11): 3216-3221, 2018-The aim of this study was to assess the aerobic-fitness differences between male and female top-class soccer field referees (FRs). This with the purpose to provide cutoff values useful for training prescription in female FRs. Forty female top-class FRs (age 34.18 ± 3.50 years and 5 ± 3.9 years international refereeing experience) and 52 male FRs (age 38.4 ± 3.3 years and 5 ± 3.5 years international refereeing experience) candidates in the preliminary open list developed by the FIFA Refereeing Department for the 2014 and 2015 World Cup Tournaments, participated in the study. The FRs were tested for aerobic fitness under laboratory conditions with a progressive speed treadmill test until exhaustion. Female FRs showed to possess, on average, lower (large effect) levels of aerobic fitness and performance compared with their male counterparts. The female FRs' V[Combining Dot Above]O2max (48.1 ± 4.4 ml·kg·min) was 7% (large effect) lower than the male FRs (51.9 ml·kg·min). Peak treadmill speed was 11% lower (large effect) in female FRs (16.27 ± 0.94 vs. 14.64 ± 0.96 km·h). The receiver operating characteristic curve analysis enabled cutoff values (47.8 ml·kg·min for V[Combining Dot Above]O2max) that may be used as preliminary cues to guide physiological selection and training prescription in female FRs aiming to officiate male-soccer matches. Only 2.5% of the female FRs showed V[Combining Dot Above]O2max higher than the mean values of male FRs when using the scaled notation (0.68). Female FRs aiming to officiate male competitions should consider training intensities at anaerobic threshold speed (13 km·h, 95% heart rate max) when developing aerobic fitness. Given the very large sex differences in aerobic performance, strength/power training should be proposed to perspective female top-class FRs.

Reliability Characteristics and Applicability of a Repeated Sprint Ability Test in Young Male Soccer Players.

Castagna, C, Lorenzo, F, Krustrup, P, Fernandes-da-Silva, J, Póvoas, SCA, Bernardini, A, and D'Ottavio, S. Reliability characteristics and applicability of a repeated sprint ability test in young male soccer players. J Strength Cond Res 32(6): 1538-1544, 2018-The aim of this study was to examine the usefulness and reliability characteristics of a repeated sprint ability test considering 5 line sprints of 30 m interspersed with 30 seconds of active recovery in nonelite, outfield, young, male soccer players. Twenty-six (age, 14.9 ± 1.2 years; height, 1.72 ± 0.12 cm; body mass, 62.2 ± 5.1 kg) players were tested 48 hours and 7 days apart for 5 × 30-m performance over 5 trials (T1-T5). Short-term (T1-T2) and long-term (T1-T3-T4-T5) reliabilities were assessed with intraclass correlation coefficient (ICC) and with typical error for measurement (TEM). Short- and long-term reliability ICCs and TEMs for total sprint time and best sprint performance were nearly perfect and satisfactory, respectively. Usefulness (as smallest worthwhile change and TEM ratio) resulted acceptable (i.e., = 1) and good (i.e., >1) for total sprint time and best sprint performance, respectively. The present study revealed that the 5 × 30-m sprint test is a reliable field test in short and long terms when the sum of sprint times and the best sprint performance are considered as outcome variables. Sprint performance decrements variables showed large variability across trials.