There have been considerable advances in monitoring training load in running-based team sports in recent years. Novel technologies nowadays offer ample opportunities to continuously monitor the ...activities of a player. These activities lead to internal biochemical stresses on the various physiological subsystems; however, they also cause internal mechanical stresses on the various musculoskeletal tissues. Based on the amount and periodization of these stresses, the subsystems and tissues adapt. Therefore, by monitoring external loads, one hopes to estimate internal loads to predict adaptation, through understanding the load-adaptation pathways. We propose a new theoretical framework in which physiological and biomechanical load-adaptation pathways are considered separately, shedding new light on some of the previously published evidence. We hope that it can help the various practitioners in this field (trainers, coaches, medical staff, sport scientists) to align their thoughts when considering the value of monitoring load, and that it can help researchers design experiments that can better rationalize training-load monitoring for improving performance while preventing injury.
ABSTRACTBeato, M, Bianchi, M, Coratella, G, Merlini, M, and Drust, B. A single session of straight line and change-of-direction sprinting per week does not lead to different fitness improvements in ...elite young soccer players. J Strength Cond Res XX(X)000–000, 2019—Effective prescription is especially important in elite soccer players, who have a very limited time to dedicate to specific physical development as a consequence of factors such as congested match schedules and travel. The aim of this study was to compare the effectiveness of one repeated-sprint training (RST) session per week over an 8-week period on physical performance. A second aim was to compare the effect of RST involving straight sprints (RST-SS) or changes of direction (RST-COD). This study used a randomized pre-post parallel group trial design. The elite soccer players were randomly assigned to either an RST-SS (10 players) or RST-COD (10 players). RST-SS was 3 sets of 7 × 30-m sprints with 20-second and 4-minute recovery between sprints and sets, respectively. RST-COD was 3 sets of 7 × 20 + 20 m (one COD of 180°) shuttle sprints with 20-second and 4-minute recovery between sprints and sets, respectively. The physical tests selected were long jump, repeated-sprint ability (RSA) best, RSA mean, 505 agility test, Yo-Yo recovery level 1, 10, 30, and 40 m sprints. RST-SS reported unclear variations in long jump, sprint 30 m, sprint 40 m, RSA best, and RSA mean, whereas RST-COD showed unclear and trivial variations in sprint 10 m, sprint 30 m, sprint 40 m, RSA best, and RSA mean. The between-group analysis did not report any statistical difference. In conclusion, a single session of RST-SS and RST-COD do not improve soccer-specific fitness indicators in elite youth players during the season.
The aim of the present study was to examine the relationship between intensities of exercise during match-play of elite-standard soccer referees with those of the players from the same match. Match ...analysis data were collected (Prozone® Leeds, UK) for 18 elite-standard soccer referees (age 26-49 years) on FA Premier League matches during the 2008/09 English FA Premier League season (236 observations). Running categories for referees and players were as follows: total distance covered (m); high-speed running distance (speed >19.8 km · h
−1
); and sprinting distance (speed >25.2 km · h
−1
). Analysis of the distance-time regression coefficients revealed no differences between the referees' and players' within-match rates of change for total distance covered (−0.594 ± 0.394 vs. −0.713 ± 0.269 m · min
−1
; P = 0.104), high-speed running (−0.039 ± 0.077 vs. −0.059 ± 0.030 m · min
−1
; P = 0.199), and sprinting (−0.003 ± 0.039 vs. −0.021 ± 0.017 m · min
−1
; P = 0.114). In addition, there were no differences between across-season rates of change for total distance (-26.756 ± 40.434 vs. −20.031 ± 25.502 m per match day; P = 0.439) and sprinting (-9.662 ± 7.564 vs. −8.589 ± 4.351 m per match day; P = 0.542). These results show that elite-standard soccer referees' intensities of exercise during match-play are interrelated with those of the players and thus demonstrate that referees are able to keep pace with the players during FA Premier League matches.
The complexity of the physical demands of soccer requires the completion of a multi-component training programme. The development, planning, and implementation of such a programme are difficult due ...partly to the practical constraints related to the competitive schedule at the top level. The effective planning and organisation of training are therefore crucial to the effective delivery of the training stimulus for both individual players and the team. The aim of this article is to provide an overview of the principles of training that can be used to prepare players for the physical demands of soccer. Information relating to periodisation is supported by an outline of the strategies used to deliver the acute training stress in a soccer environment. The importance of monitoring to support the planning process is also reviewed.
Soccer (association football) is a team sport that incorporates frequent fluctuations between high and low exercise intensities. These unpredictable changes may be accompanied by unorthodox patterns ...of movements and the performance of specific skills. The individual activity profiles are highly variable and include elements of self-pacing, since decision making about opportunities to become engaged in play dictates individual activities. Approaches utilised to investigate the demands placed on players during competitive performances include behavioural observations during games, physiological evaluations in matches and assessments of the physical capacity of players. Observations made during games to determine the work-rate patterns of individual players are highly variable and make generalisations based on individual activity patterns conditional, unless the sample sizes are large and data are collected on a number of occasions. The data may also be affected by the diverse methodological approaches to their collection and analysis and a failure to determine the reliability and objectivity of the relevant measuring tools. Techniques that can be used to collect data in matches are limited as the sports rules and regulations restrict some approaches. The validity of applying data from non-competitive matches to the competitive situation must, therefore, be subject to formal scrutiny. There is also a concern as to the degree to which principles of steady-state are applicable to dynamically changing exercise intensities. In the evaluation of the physical capacities of players, the variability in overall soccer performance is reduced to fitness statistics, whereas in reality, soccer performance is a construct based on many different performance components and their interaction at the level of both player and team. Despite these caveats, valuable insights have been acquired into the physiological requirements of the game that have subsequently informed both research projects and impacted upon practice. The challenge for future researchers is to overcome remaining research design hurdles and devise ways to understand more fully the complexities of invasive field games such as soccer. The interactions between individuals within a team require investigation and there is a need to refine and develop methods that employ sophisticated measurement techniques and yet possess both internal and external validity, such as laboratory-based simulations.
To assess the real‐life magnitude of the heading incidence in children's and youth’ football in eight European countries with different “football cultures,” a cross‐sectional observational design, in ...which one match per team in 480 different teams from eight European countries (2017/18‐2018/19), was recorded by video. One training session was recorded in 312 teams. Clubs with Under‐10, Under‐12 (female/male/mixed), and Under‐16 female and male teams were eligible to participate. Heading frequencies and types were analyzed. Results are presented as headers per match/training and per team. Incidence rates (IR) per 1000 match/training hours were calculated. Under‐10 teams carried out the lowest average number of headers per match (8.8), followed by Under‐16 female (17.7), Under‐12 (18.4), and Under‐16 male (35.5). Total number of headers per match and team varied between countries. 80% of the total number of headers were single intentional headers, 12% heading duels, 3% unintentional headers by getting hit, and 5% others (trends apparent in all age groups). Three head injuries occurred during match play corresponding to an IR of 0.70 (95% CI, 0.23‐2.16). The lowest number of headers per training and team was found in Under‐10 (21.3), followed by Under‐16 females (34.1), Under‐12 (35.8), and Under‐16 males (45.0). In conclusion, this large‐scale study presents novel data about the number and type of headers in youth’ football throughout Europe. A more precise understanding of the heading incidence, specifically in young players, is mandatory for the debate of restrictions on heading in youth football.
The mechanisms that regulate the enhanced skeletal muscle oxidative capacity observed when training with reduced carbohydrate (CHO) availability are currently unknown. The aim of the present study ...was to test the hypothesis that reduced CHO availability enhances p53 signaling and expression of genes associated with regulation of mitochondrial biogenesis and substrate utilization in human skeletal muscle. In a repeated-measures design, muscle biopsies (vastus lateralis) were obtained from eight active males before and after performing an acute bout of high-intensity interval running with either high (HIGH) or low CHO availability (LOW). Resting muscle glycogen (HIGH, 467 ± 19; LOW, 103 ± 9 mmol/kg dry wt) was greater in HIGH compared with LOW (P < 0.05). Phosphorylation (P-) of ACC(Ser79) (HIGH, 1.4 ± 0.4; LOW, 2.9 ± 0.9) and p53(Ser15) (HIGH, 0.9 ± 0.4; LOW, 2.6 ± 0.8) was higher in LOW immediately postexercise and 3 h postexercise, respectively (P < 0.05). Before and 3 h postexercise, mRNA content of pyruvate dehydrogenase kinase 4, mitochondrial transcription factor A, cytochrome-c oxidase IV, and PGC-1α were greater in LOW compared with HIGH (P < 0.05), whereas carnitine palmitoyltransferase-1 showed a trend toward significance (P = 0.09). However, only PGC-1α expression was increased by exercise (P < 0.05), where three-fold increases occurred independently of CHO availability. We conclude that the exercise-induced increase in p53 phosphorylation is enhanced in conditions of reduced CHO availability, which may be related to upstream signaling through AMPK. Given the emergence of p53 as a molecular regulator of mitochondrial biogenesis, such nutritional modulation of contraction-induced p53 activation has implications for both athletic and clinical populations.
To investigate the relationship between whole-body accelerations and body-worn accelerometry during team-sport movements.
Twenty male team-sport players performed forward running and anticipated 45° ...and 90° side-cuts at approach speeds of 2, 3, 4, and 5 m/s. Whole-body center-of-mass (CoM) accelerations were determined from ground-reaction forces collected from 1 foot-ground contact, and segmental accelerations were measured from a commercial GPS accelerometer unit on the upper trunk. Three higher-specification accelerometers were also positioned on the GPS unit, the dorsal aspect of the pelvis, and the shaft of the tibia. Associations between mechanical load variables (peak acceleration, loading rate, and impulse) calculated from both CoM accelerations and segmental accelerations were explored using regression analysis. In addition, 1-dimensional statistical parametric mapping (SPM) was used to explore the relationships between peak segmental accelerations and CoM-acceleration profiles during the whole foot-ground contact.
A weak relationship was observed for the investigated mechanical load variables regardless of accelerometer location and task (R
values across accelerometer locations and tasks: peak acceleration .08-.55, loading rate .27-.59, and impulse .02-.59). Segmental accelerations generally overestimated whole-body mechanical load. SPM analysis showed that peak segmental accelerations were mostly related to CoM accelerations during the first 40-50% of contact phase.
While body-worn accelerometry correlates to whole-body loading in team-sport movements and can reveal useful estimates concerning loading, these correlations are not strong. Body-worn accelerometry should therefore be used with caution to monitor whole-body mechanical loading in the field.
We investigated the association of multiple single nucleotide polymorphisms (SNPs) with athlete status and power/speed performance in elite male youth soccer players (ESP) and control participants ...(CON) at different stages of maturity. ESP (n = 535; aged 8-23 years) and CON (n = 151; aged 9-26 years) were genotyped for 10 SNPs and grouped according to years from predicted peak-height-velocity (PHV), i.e. pre- or post-PHV, to determine maturity status. Participants performed bilateral vertical countermovement jumps, bilateral horizontal-forward countermovement jumps, 20m sprints and modified 505-agility tests. Compared to CON, pre-PHV ESP demonstrated a higher ACTN3 (rs1815739) XX ('endurance') genotype frequency distribution, while post-PHV ESP revealed a higher frequency distribution of the PPARA (rs4253778) C-allele, AGT (rs699) GG genotype and NOS3 (rs2070744) T-allele ('power' genotypes/alleles). BDNF (rs6265) CC, COL5A1 (rs12722) CC and NOS3 TT homozygotes sprinted quicker than A-allele carriers, CT heterozygotes and CC homozygotes, respectively. COL2A1 (rs2070739) CC and AMPD1 (rs17602729) GG homozygotes sprinted faster than their respective minor allele carrier counterparts in CON and pre-PHV ESP, respectively. BDNF CC homozygotes jumped further than T-allele carriers, while ESP COL5A1 CC homozygotes jumped higher than TT homozygotes. To conclude, we have shown for the first time that pre- and post-PHV ESP have distinct genetic profiles, with pre-PHV ESP more suited for endurance, and post-PHV ESP for power and speed (the latter phenotypes being crucial attributes for post-PHV ESP). We have also demonstrated that power, acceleration and sprint performance were associated with five SNPs, both individually and in combination, possibly by influencing muscle size and neuromuscular activation.
ABSTRACTWard, PA, Ramsden, S, Coutts, AJ, Hulton, AT, and Drust, B. Positional differences in running and nonrunning activities during elite American football training. J Strength Cond Res ...XX(X)000–000, 2017—The aim of this investigation was to describe differences in training loads between position groups within professional American football. Integrated micro technology data were collected on 63 NFL football players during an American football training camp. Five key metrics (total distance, high-speed distance, player load (PL), PL per minute, and total inertial movement analysis IMA) served to quantify both running and nonrunning activities. Players were classified into position groups (defensive back DB, defensive linemen DL, linebacker, offensive linemen OL, quarterback, running back, tight end, and wide receiver WR). Training sessions were identified by their relationship to the upcoming match (e.g., -4, -3, and -2). Running and nonrunning activities varied between position groups relative to the training day. Differences in total distance between DB and WR were observed to be unclear across the 3 training days (game day GD -474 ± 392 m; GD -3−122 ± 348 m; and GD -2−222 ± 371 m). However, moderate to large differences were observed between these 2 positions and the other positional groups. A similar relationship was observed in PL and PL per minute, with the DB and WR groups performing greater amounts of load compared with other positional groups. Differences in high-speed distance varied across positional groups, indicating different outputs based on ergonomic demands. The OL and DL groups ran less but engaged in a higher amount of nonrunning activities (total IMA) with differences ranging from moderate to large across the 3 training days. Total IMA differences between offensive and defensive linemen were unclear on GD -4 (−4 ± 9) and GD -2 (−2 ± 8) and likely moderate on GD -3 (−9 ± 9). Positional differences with regard to running and nonrunning activities highlight the existence of position-specific training within a training microcycle. In addition, total IMA provides a useful metric for quantifying sport-specific movements within the game of American football.
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