Physical and metabolic demands of training and match-play in the elite football player

Train Like You Compete? Physical and Physiological Responses on Semi-Professional Soccer Players

Background: Decision-making in soccer has repercussions and depends on the environment of training or competition. The demands on the players can reveal if the decision-making is similar or different from that required during competition. Objectives: The aim of this study was to assess the physical and physiological responses of players in training matches (TM) and official competition matches (CM) according to the playing position (external defenders, internal defenders, midfielders, and forwards/extremes). Methods: Twenty semi-professional male soccer players and 10 CM (n = 40) and 10 TM (n = 40) were studied using global positioning system technology, and paired and one-way ANOVA tests were carried out to compare physical (distances and number of sprints) and physiological (heart rates) responses with the factors a) match environments (TM and CM) and b) the playing position, respectively. Results: The results revealed that during CM, players covered higher total distance, partial distances, and sprints at different speeds (0–21 km/h) and produced higher physiological responses. Midfielders covered the greatest total distance in both TM (7227.6 m) and CM (11,225.9 m), in comparison to the other playing positions. However, forwards and extremes spent more time (56.8% of the CM [d = 0.78]) at 76% to 84% of their maximal heart rates. Conclusions: First, the physical and physiological responses in TM were significantly lower than in CM. Second, these responses were different according to the playing position, so this study was able to verify the exact amount of variation between the load produced in TM and CM. These results will help the coach and technical staff to design training tasks to complement the responses found in TM.

Physical and Physiological Demands of Elite International Female Field Hockey Players During Competitive Match Play

McGuinness, A, Malone, S, Petrakos, G, and Collins, K. The physical and physiological demands of elite international female field hockey players during competitive match play. J Strength Cond Res 33(11): 3105-3113, 2019-The aim of the current investigation was to quantify the physical and physiological demands of elite international female field hockey match play across halves of play. Thirty-eight participants (24 ± 5 years; 173 ± 5 cm; 72 ± 5 kg) took part in 19 competitive matches during the 2014-2015 season. Participants were monitored with global positioning system technology and heart rate monitors. Players were categorized based on 3 different playing positions. Activity was categorized into total (m), high-speed running distance (m; >16 km·h), and relative distance (RD) (m·min) due to the use of rolling substitutions. Heart rate was classified based on the percentage of players' individual peak heart rate (HRpeak) determined by a Yo-Yo intermittent recovery level 1 test. Players spent on average 44 ± 7 minutes in match play. The total distance (TD) covered was 5,558 ± 527 m (125 ± 23 m·min) with 589 ± 160 m (13 ± 4 m·min) completed at high speed. Defenders covered a greater TD compared with other positions of play (p ≤ 0.001). Midfield players covered a greater distance at high speed (p ≤ 0.001) with the forwards having a higher relative distance (p ≤ 0.001). The HRpeak of the players was 199 ± 1 b·min with a mean exercise intensity of 86 ± 7.8% of HRpeak. The time spent >85% HRpeak decreased significantly across the halves (p = 0.04, η = 0.09, small). Defenders were found to spend more time >85% HRpeak when compared with forwards (p ≤ 0.001). The current investigation provides normative data that coaches should consider when constructing training regimen.

Physiological and Tactical On-court Demands of Water Polo

Botonis, PG, Toubekis, AG, and Platanou, TI. Physiological and tactical on-court demands of water polo. J Strength Cond Res 33(11): 3188-3199, 2019-The purpose of the present review is to provide a quantification of the specific game's activities performed by elite water polo players and a comprehensive overview of the physiological requirements reflecting physical and tactical on-court demands in water polo. Game analysis demonstrates that various swimming movements occur throughout a match play, although approximately 50% of these are recorded in horizontal body position. The various offensive and defensive tactical actions transiently modify the playing intensity, which overall corresponds to the players' lactate threshold. Even play corresponds to 60% of total game actions, whereas the respective percentage of power-play and counterattacks may exceed 30%. The ability to perform high-intensity activities with short recovery periods is critical for water polo players. Elite water polo players present a high level of aerobic power and endurance as indicated by their maximal oxygen uptake and speed at the lactate threshold. Depending on the positional roles, outfield players are characterized as centers or peripherals. The overall physiological load seems to be similar between players at various positions, despite that centers execute more dynamic body contacts, whereas peripherals more swimming bouts. Despite limitations concerning the experimental setting, the current findings indicate that the incidence of fatigue deteriorates playing intensity and performance. Nonetheless, data from the reviewed studies should be cautiously interpreted because in some of the studies, players' substitutions were not allowed. A high conditioning level is essential for water polo, as it is associated with superior technical and tactical efficacy and lower decline of physical or technical performance within the game.

Fatigue in U12 Soccer-7 Players During Repeated 1-Day Tournament Games-A Pilot Study

Sanchez-Sanchez, J, Sanchez, M, Hernandez, D, Ramirez-Campillo, R, Martínez, C, and Nakamura, FY. Fatigue in U12 Soccer-7 players during repeated 1-day tournament games-a pilot study. J Strength Cond Res 33(11): 3092-3097, 2019-The aim of this study was to describe and compare the distances and displacement speeds of U12 Soccer-7 athletes during 4 tournament Soccer-7 games (TG) played in less than 24 hours (experimental condition) with those recorded during 2 league Soccer-7 games (LG) with 24 hours of rest before the match (control condition). Ten participants (age = 10.3 ± 0.5 years) were recruited for the study. Main data analyzed during games included distance completed relative to match duration (Drel), maximal velocity, and distance completed at different running speeds (including acceleration, deceleration, standing, walking, jogging, medium-intensity running, high-intensity running, and sprinting). For data collection during games, athletes wore a global positioning system unit. Different (p ≤ 0.05) mean playing time was recorded during TG and LG (15.1 and 31.8 minutes/match, respectively). Drel during the 4 TG was maintained between 85.7 ± 8.5 and 87.5 ± 8.5 m·min (p > 0.05) and during the 2 LG between 84.2 ± 10.9 and 87.5 ± 9.9 m·min (p > 0.05). Moreover, similar Drel was recorded during TG and LG (86.8 and 85.9 m·min, respectively). Compared with LG, during TG, maximal velocity was lower (23.0 and 21.3 km·h, respectively; p ≤ 0.05). In addition, compared with the last game of the tournament, in the preceding games, the distance covered at low speeds (3.1-8.0 km·h) was lower (37.7 and 32.4%, respectively; p ≤ 0.05) and at high speeds (≥18.1 km·h) tends to be higher (2.5 and 3.3%, respectively). Therefore, compared with the control condition, accumulated Soccer-7 games with less than 24 hours of interday rest negatively affect displacement speed distribution (but not overall relative distances) in U12 Soccer-7 athletes. These results may help to better plan training and competition schedules to youth players.

Predictive modelling of the physical demands during training and competition in professional soccer players

OBJECTIVES

The present study aimed to predict the cut-off point-values that best differentiate the physical demands of training and competition tasks including friendly matches (FM), small sided games (SSG), large sided games (LSG), mini-goal games (MG) and ball circuit-training (CT) in professional soccer players.

DESIGN

Experimental randomized controlled trial.

METHODS

Fourteen professional players participated in all tasks with the CT, SSG and MG consisting of 8 repetitions of 4-min game play, interspersed by 2-min of active recovery. The training data were compared to the first 32-min of the LSG and two competitive FM per player. All movement patterns from walking to sprint running were recorded using 10Hz GPS devices while player perception of exertion was recorded via a visual analogue scale, post-task. Decision tree induction was applied to the dataset to assess the cut-off point-values from four training drills (SSG, LSG, MG, and CT) and FM for every parameter combination.

RESULTS

Distance covered during jogging (2.3-3.3m/s; >436m), number of decelerations (≤730.5) and accelerations (≤663), and maximum velocity reached (>5.48m/s) characterized the physical demands during competition (FM) with great variability amongst training drills.

CONCLUSION

The use of these novel, cut-off points may aid coaches in the design and use of training drills to accurately prepare athletes for soccer competition.

Assessing the Perceived Exertion in Elite Soccer Players during Official Matches According to Situational Factors

This study aimed to assess the match perceived exertion (PE) declared by starter and non-starter junior elite soccer players, according to the level of the opponents, and by playing at home or away. Nineteen young soccer players who competed in the Spanish U19 League participated in this study. PE was registered during the entire regular season (30 official matches). Players were grouped by match playing time: starters (players who started the game and played at least 45 min) and non-starters (substitute players who participated for less than 45 min). Moreover, the matches were classified according to the opponent level (i.e., high, medium, or low) and the match location (i.e., home or away). Starters who competed against high-level opponents (8.7 ± 0.6) declared higher PE ratings than against medium (8.1 ± 0.7, p < 0.01) and low (8.4 ± 0.7, p < 0.01) level opponents. In addition, starters competing at home declared lower PE ratings than when playing away (8.2 ± 0.8 vs. 8.5 ± 0.6, p < 0.01). However, no significant differences (p > 0.05) were observed for non-starters. Coaches should consider not only tactical–strategic needs, but also these contextual factors when managing the match playing time of the starter players.

Comparison between Continuous and Fractionated Game Format on Internal and External Load in Small-Sided Games in Soccer

This study aimed to identify the effects of continuous and fractionated game formats on internal and external load in small-sided games in soccer. Twenty male professional soccer players participated in the study performing the same exercise (5 vs. 5 players) continuously (1 × 24 min) and in a repeated/fractioned manner (2 × 12 min, 4 × 6 min, and 6 × 4 min). A comparison between playing conditions was assessed by means of standardized mean differences calculated with combined variance and respective confidence intervals of 90%. The limits for the statistics were 0.2, trivial; 0.6, small; 1.2, moderate; 2.0, large; and >2.0, very large. The results indicate that the use of the continuous method seems to present the tendency of less physical impact on the internal and external loads compared to the fractionated method. In addition, the higher number of exercise repetitions in the fractionated method was found to increase the external load compared to the continuous method. This study showed that application of small-sided games by the fractionated method tends to result in higher training loads.

Relationship between body composition and physical capacities in junior soccer players

Abstract The number of studies related to soccer has been growing exponentially in the last years because the modality is considered the most popular in the world. It is known that the development of some specific physical capacities, even in young individuals, is essential to high-level performance and these capacities might be related to anthropometrics variables. The purpose of this study was to verify the relationship between body composition and physical capacities in young soccer players. Study participants were athletes from junior categories (under-12 and under-13) belonging to the Soccer Association of Chapecó, Brazil.. Athletes were submitted to agility, (Illinois), vertical jump (Sargent Jump), aerobic condition (TCAR), flexibility and sit-and-reach (Wells Bench) tests, as well as anthropometric assessment. All procedures were performed at UNOESC campus, Chapecó. Statistical analysis consisted of the Spearman’s Rô test, measuring the correlation among variables, additionally, significance level of p<0.05 was adopted. Results showed significantly correlation in agility (p=0.000; ρ=0.530) and vertical jump tests (p=0.003; ρ=-0.437) with body fat percentage. It was concluded that there is relationship between body fat percentage and agility and explosive power of lower limbs.

Eating Habits and Body Composition of International Elite Soccer Referees

Soccer referees are a specific group of the athletes' population whose careers peak from 30 to 45 years old. An athlete's performance is not only determined by physical training but also by a lifestyle, e.g. eating habits. The purpose of this study was to verify current eating habits and resulting body composition of a group of elite international soccer referees. At an international FIFA seminar 60 elite international soccer referees (aged 39.2 ± 4.2 years) were enrolled. A body composition assessment was performed with skinfold thickness and bio impedance analysis, while eating habits were evaluated with a multi-pass 24-hour dietary recall. The body composition showed a normal weight condition with a fat content of 11.4 ± 2.5%. Macronutrients showed a low level of carbohydrates (43.6 ± 5.4%) and a high level of fat (40.0 ± 4.5%). Micronutrients showed a low level of calcium, potassium, zinc, magnesium, iodine, vitamin B12 and vitamin B9. Even though their body composition was within the normal range, the current eating habits of elite international soccer referees did not appear to follow the nutrition guidelines. Therefore, it would be advisable to provide knowledge on nutrition for this particular category of sports subjects, an individualized nutritional plan would be advisable, in order to achieve and maintain better performance and appropriate body composition for their role.

Effect of Different Physical Training Forms on Change of Direction Ability: a Systematic Review and Meta-analysis

BACKGROUND

The ability to perform a rapid change of direction (COD) is a critical skill in numerous court- and field-based sports. The aim of this review is to investigate the effect of different physical training forms on COD performance.

METHODS

A systematic review of the literature was undertaken using the following databases: PubMed, SPORTDiscus and Google Scholar. Studies were eligible if they met the following criteria: (1) a COD test measuring performance before and after the training intervention, with specific description of the test in terms of length and number of changes in a direction with specified angles, (2) involve training intervention like plyometric, strength, sprint, specific COD training, or a combination of these training forms targeting the lower extremities, (3) the study had to state training background in terms of which sport they participated in and their competitive level and a detailed methodological description. Non-English articles were excluded. Percentage difference and effect sizes were calculated in order to compare the effects of different training interventions.

RESULTS

A range of studies performing plyometrics, strength, sprint, specific COD training, training with post-activation potentiation or a combination of these training forms were examined. The percentage of change and effect size (ES) were calculated. Seventy-four studies met the inclusion criteria, comprising 132 experimental groups and 1652 unique subjects. The review revealed no clear consensus on which training form is optimal to develop COD performance. All training forms resulted in an increase in performance from almost no ES to large ES.

CONCLUSIONS

The results of the study indicate that COD ability is a specific skill, whereas the COD task, the sports require determines which training form is the most effective to develop COD ability. Training targeting improvement in COD performance should address the duration of the training in line with which energy system is utilized. The complexity of the COD task with respect to the individual athlete must be considered. Consequently, the number of changes in direction and the angles of the task are relevant when organizing training.

The Physical Demands of NCAA Division I Women's College Soccer

Extensive research into women's collegiate soccer is scarce, leaving gaps in the literature with little information available detailing the physical demands at different standards of play. Our purpose was to elucidate the physical demands of the Division I collegiate level and identify differences between playing positions. Twenty-three field players were observed during four competitive seasons using 10-Hz GPS units (Catapult Sports, Melbourne, Australia). Descriptive statistics and 95% confidence intervals were used to determine group and position-specific physical demands. Linear mixed modelling (LMM) was used to compare attacker, midfielder, and defender position groups. Total distance, high-speed distance, and sprint distance were 9486 ± 300 m, 1014 ± 118 m, and 428 ± 70 m, respectively. Furthermore, attackers were observed to cover the greatest distance at all speeds compared to midfielders and defenders. Our findings suggest that the physical demands of Division I women's soccer differ by position and appear lower compared to higher standards of play. Therefore, coaches and sports scientists responsible for the physical training of Division I collegiate players should consider the specific physical demands of the collegiate level and playing position when prescribing training, as well as in the development of their annual training programs.

Effect of pre-season training phase on anthropometric, hormonal and fitness parameters in young soccer players

The aims of the study were to investigate 1) the effect of 8 weeks of PSP training on anthropometrics, salivary hormones and fitness parameters in youth soccer players, 2) the correlations between fitness and hormonal parameters, and 3) the impact of the experience of the coach and his methodology of training on these parameters. Weight, height, BMI, pubertal development (PDS), salivary Cortisol (sC), salivary Testosterone (sT), salivary sDHEAS, intermittent tests (VO_2max), and countermovement jump test (CMJ) modifications of 35 youth soccer players (age: 14±0 yrs; BMI: 20.8±1.8 k/m²) from two Italian clubs (“Lupa Frascati” -LF-; “Albalonga” -AL) were analysed. A significant (p<0.05) time by club effect was observed in sC (F_(1,31) = 9.7, ES = 1.13), sT (F_(1,31) = 4.2, ES = 0.74), CMJ (F_(1,28) = 26.5, ES = 1.94), and VO_2max (F_(1,28) = 8.5, ES = 1.10). Statistical differences (p<0.05) in weight (F_(1,32) = 25.5, ES = 0.11), sC (F_(1,31) = 32.1, ES = 1.43), sT/sC ratio (F_(1,31) = 10.1, ES = 0.97), sDHEAS/sC ratio (F_(1,31) = 6.3, ES = 0.70), and VO_2max (F_(1,28) = 64.3, ES = 1.74) were found within time factor. Between clubs, differences (p<0.05) in sC (F_(1,32) = 8.5, ES = 1.17), sT (F_(1,31) = 4.2, ES = 0.74), CMJ (F_(1,28) = 26.5, ES = 1.50), and VO_2max (F_(1,28) = 8.5, ES = 1.10) were found. CMJ was inversely correlated with sDHEAS (r = -0.38) before PSP, while Δ of CMJ showed significant correlations with Δ of sC (r = 0.43) and ΔVO_2max was inversely correlated with ΔBMI (r = -0.54) and ΔsC (r = -0.37) in all subjects. Considering each single club, ΔVO_2max showed correlations with ΔBMI (r = -0.45) in AL, while ΔCMJ showed correlations with ΔPDS (r = 0.72) in LF club. Since the PSP is often limited training time to simultaneously develop physical, technical and tactical qualities, an efficient method to distribute the training load is important in youth soccer players to increase the performance and to avoid injuries.

Intra- and Post-match Time-Course of Indicators Related to Perceived and Performance Fatigability and Recovery in Elite Youth Soccer Players

PURPOSE

Our aims were to examine (i) the internal load during simulated soccer match-play by elite youth players; and (ii) the time-course of subsequent recovery from perceived and performance fatigability.

METHODS

Eleven male youth players (16 ± 1 years, 178 ± 7 cm, 67 ± 7 kg) participated in a 2 × 40-min simulated soccer match, completing 30 rounds (160 s each) with every round including multidirectional and linear sprinting (LS20m), jumping (CMJ) and running at different intensities. During each round, LS20m, CMJ, agility, heart rate (HR), oxygen uptake (VO2), energy expenditure (EE), substrate utilization and perceived exertion RPE were assessed. In addition, the blood level of lactate (Lac) was obtained after each of the five rounds. Creatine kinase (CK) concentration, maximal voluntary isometric knee extension and flexion, CMJ, number of skippings in 30 s, and subjective ratings on the Acute Recovery and Stress Scale (ARSS) were examined before and immediately, 24 and 48 h after the simulation.

RESULTS

During the game %HRpeak (p < 0.05, d = 1.08), %VO2 peak (p < 0.05; d = 0.68), Lac (p < 0.05, d = 2.59), RPEtotal (p < 0.05, d = 4.59), and RPElegs (p < 0.05, d = 4.45) all increased with time during both halves (all p < 0.05). Agility improved (p < 0.05, d = 0.70) over the time-course of the game, with no changes in LS20m (p ≥ 0.05, d = 0.34) or CMJ (p ≥ 0.05, d = 0.27). EE was similar during both halves (528 ± 58 vs. 514 ± 61 kcal; p = 0.60; d = 0.23), with 62% (second half: 65%) carbohydrate, 9% (9%) protein and 26% (27%) fat utilization. With respect to recovery, maximal voluntary knee extension (p ≥ 0.05, d = 0.50) and flexion force (p ≥ 0.05, d = 0.19), CMJ (p ≥ 0.05, d = 0.13), number of ground contacts (p ≥ 0.05, d = 0.57) and average contact time (p ≥ 0.05, d = 0.39) during 30-s of skipping remained unaltered 24 and 48 h after the game. Most ARSS dimensions of load (p < 0.05, d = 3.79) and recovery (p < 0.05, d = 3.22) returned to baseline levels after 24 h of recovery. Relative to baseline values, CK was elevated immediately and 24 h after (p < 0.05, d = 2.03) and normalized 48 h later.

CONCLUSION

In youth soccer players the simulated match evoked considerable circulatory, metabolic and perceptual load, with an EE of 1042 ± 118 kcal. Among the indicators of perceived and performance fatigability examined, the level of CK and certain subjective ratings differed considerably immediately following or 24-48 h after a 2 × 40-min simulated soccer match in comparison to baseline. Accordingly, monitoring these variables may assist coaches in assessing a U17 player's perceived and performance fatigability in connection with scheduling training following a soccer match.

Increased Parasympathetic Activity by Foot Reflexology Massage after Repeated Sprint Test in Collegiate Football Players: A Randomised Controlled Trial

Foot reflexology massage (FRM) has positive effects on cardiovascular and haemodynamic functions. However, information regarding the physiological changes after FRM post exercise-stress is limited. This study investigated the acute effects of FRM on heart rate variability (HRV) after the repeated sprint ability (RSA) test and the Yo-Yo Intermittent Recovery Test Level 1 (YY). Twenty-six collegiate male football players were randomly assigned to the FRM group (n = 14) or to the control group (n = 12). Electrocardiographic (ECG) signals were recorded for 15 min in supine position before and after the intervention/control period in the RSA test and the YY test. In comparison to the control group, the FRM group demonstrated higher values of root mean squared successive difference in the RR interval (RMSSD; p = 0.046, ES = 0.76) and in the proportion of differences of adjacent RR intervals >50 ms (pNN50; p = 0.031, ES = 0.87); and higher percent changes in mean RR interval (%MeanRR; p = 0.040, ES = 0.99), standard deviation of RR intervals (%SDNN; p = 0.008, ES = 1.10), normalised high-frequency power (%nHFP; p = 0.008, ES = 0.77), total power (%TP; p = 0.009, ES = 0.84) and standard deviation 1 and 2 (%SD1; p = 0.008, ES = 1.08, %SD2; p = 0.020, ES = 1.04) after the RSA test. The magnitude effect of post-exercise HRV was small after the FRM RSA protocol (ES = 0.32–0.57). Conversely, the results demonstrated a moderate and large magnitude effect of HRV in the RSA and YY protocols of the control group (ES: RSA = 1.07–2.00; YY = 0.81–1.61) and in the YY protocol of the FRM group (ES = 0.99–1.59). The FRM intervention resulted in beneficial effects on the cardiac parasympathetic reactivity and the sympatho-vagal balance after RSA performance.

Contextual Factors Influencing External and Internal Training Loads in Collegiate Men's Soccer

Curtis, RM, Huggins, RA, Benjamin, CL, Sekiguchi, Y, Adams, WM, Arent, SM, Jain, R, Miller, SJ, Walker, AJ, and Casa, DJ. Contextual factors influencing external and internal training loads in collegiate men's soccer. J Strength Cond Res 34(2): 374-381, 2020-This study investigated factors influencing training loads (TL) in collegiate men's soccer. Total distance, high-speed running distance (>14.4 km·h), high-intensity heart-rate zone duration (HI HRZ, >70% heart rate relative to maximum), and session rating of perceived exertion were assessed daily from 107 male soccer players competing for 5 National Collegiate Athletics Association Division I teams. Differences between athlete role (starter and reserve), position (defender, midfielder, and forward), season phase (preseason, in-season, and postseason), days relative to match (MD-1 to MD-5+), days between matches (<4, 4-5, >5 days), previous match outcome (win, loss, and draw), and upcoming opponent relative ranking (weaker, trivial, and stronger) were examined. Mean differences (MD) and effect sizes (ESs) with 90% confidence intervals were reported. There were trivial and insignificant differences by player role, position, or upcoming opponent strength, and small-moderate increases in preseason TL compared with in-season (ES [range] = 0.4-0.9). TLs were lower for MD-1 and higher for MD-5+ (ES [range] = 0.4-1.3) when compared with MD-2-4. External loads (ES = -0.40 ± 0.20) were less after wins compared with losses. TLs are increased in the preseason, when training sessions occur greater than 5 days from a match and after losses. Contextualizing factors affecting TLs has implications for developing workload prescription and recovery strategies.

Seasonal Accumulated Workloads in Collegiate Men's Soccer: A Comparison of Starters and Reserves

Curtis, RM, Huggins, RA, Benjamin, CL, Sekiguchi, Y, Arent, S, Armwald, B, Pullara, JM, West, CA, and Casa, DJ. Seasonal accumulated workloads in collegiate men's soccer: a comparison of starters and reserves. J Strength Cond Res XX(X): 000-000, 2019-The purpose of this investigation was to quantify and compare player's season total-, match-, and training-accumulated workload by player status characteristics (i.e., starter vs. reserve) in American collegiate men's soccer. Global positioning system (GPS) and heart rate (HR)-derived workloads were analyzed from 82 collegiate male soccer athletes from 5 separate teams over the 2016 and 2017 seasons. Differences in total physical and physiological workloads (i.e., total distance, accelerations, and weighted HR-zone training impulse [TRIMP] score) as well as workloads over a range of intensity zones were examined using multilevel mixed models, with mean difference (MD) and effect size (ES) reported. Starters accumulated substantially more total distance (MD = 82 km, ES = 1.23), TRIMP (MD = 2,210 au, ES = 0.63), and total accelerations (MD = 6,324 n, ES = 0.66) over the season. Total accumulated distance in all velocity zones (ES [range] = 0.87-1.08), all accelerations zones (ES [range] = 0.54-0.74), and time spent at 70-90% HRmax (ES [range] = 0.60-1.12) was also greater for starters. Reserves accumulated substantially more total distance (MD = 20 km, ES = 0.43) and TRIMP (MD = 1,683 au, ES = 0.79) during training. Although reserves show elevated physical and physiological loads during training compared with starters, there is an imbalance in overall workloads between player roles, with starters incurring substantially more match and total seasonal workloads. These results indicate managing player workloads in soccer requires attention to potential imbalances between players receiving variable match times. Coaches and practitioners in collegiate men's soccer may consider implementing strategies to reduce discrepancies in loading between starters and reserves. Individualized monitoring of training and match workloads may assist in the implementation of more balanced load management programs.

Pitch Size and Game Surface in Different Small-Sided Games. Global Indicators, Activity Profile, and Acceleration of Female Soccer Players

López-Fernández, J, Gallardo, L, Fernández-Luna, Á, Villacañas, V, García-Unanue, J, and Sánchez-Sánchez, J. Pitch size and game surface in different small-sided games. Global indicators, activity profile, and acceleration of female soccer players. J Strength Cond Res 33(3): 831-838, 2019-The aim of this research was to evaluate the influence of game surface and pitch size on the movement profile in female soccer players during small-sided games (SSGs) of 4 v 4. Sixteen women played 3 different 4-a-side (400, 600, and 800 m) on 3 surfaces (ground [GR], artificial turf [AT], and natural grass [NG]). Time-motion variables were assessed through GPS devices (Spi Pro X, GPSports, Australia). Ground had the worst outputs on most variables. NG achieved higher results than AT in terms of total distance (SSG 400 [+37.000 m; p = 0.006]; SSG 600 [+59.989 m; p < 0.001]; and SSG 800 [+42.284 m; p = 0.001]). However, the smaller SSG (400) had the lowest values on most variables. However, although the middle SSG (600) presented higher output than the bigger one (800) for body load (NG [+7.745 a.u.; p < 0.001]; AT [+8.207 a.u.; p < 0.001]; and GR [+5.879 a.u.; p < 0.001]), it had lower results for high-intensity distance (NG [-13.15 m; p = 0.025] and AT [-13.59 m; p = 0.026]). Despite women's performance being higher on AT than GR, the NG surface still showed the highest outcomes in the most intense SSG. Moreover, although the performance increases in bigger pitches, if the size is too large the outputs could be reduced.

A new approach to study the relative age effect with the use of additive logistic regression models: A case of study of FIFA football tournaments (1908-2012)

The relative age effect plays an important role in the pursuit of excellence, providing advantage to athletes born at the beginning of the year or near the cut-off date. This phenomenon has been observed in areas such as sports, education or business. Traditionally, the chi-square test has been used to analyze whether there are statistically significant differences in the distribution of births in each of the four quarters of the year. However, this approach is limited, focusing only on the analysis of the response variable, without taking into account the effect of a set of predictive variables. In this paper a new approach is proposed to study the relative age effect with the use of a logistic regression additive model. The new method has been evaluated with a sample of 21,639 players involved in football tournaments organized by the Fédération Internationale de Football Association (FIFA) between 1908 and 2012. New conclusions have been established that the relative age effect exists regarding player age and the year of the competition in male FIFA competitions and its effect is dynamic and complex.

Effects of a 12-Month Complex Proprioceptive-Coordinative Training Program on Soccer Performance in Prepubertal Boys Aged 10-11 Years

Boraczyński, MT, Sozański, HA, and Boraczyński, TW. Effects of a 12-month complex proprioceptive-coordinative training program on soccer performance in prepubertal boys aged 10-11 years. J Strength Cond Res 33(5): 1380-1393, 2019-The aim was to examine the effects of a series of on-field proprioceptive-coordinative (P-C) exercises on motor performance (MP) in prepubertal soccer players. Fifty-three male soccer players aged 10.1-11.8 years were randomized among 2 experimental programs receiving P-C training (P-CT; n = 26) or regular training (RT; n = 27). A control group (C; n = 22) consisted of age-matched (10.3-11.9 years) cohorts not involved in any regular physical activity. Both experimental groups completed an identical 12-month comprehensive soccer program except training in P-CT was modified to substitute small-sided conditioning games with 24 multimode P-C exercises with modulated exercise intensity (every 8-9 weeks based on predicted maximal heart rate [HRmax]). Pre-, peri-, and posttraining measures included anthropometry and 5 tests assessing soccer-specific MP: movement rhythm (turning the ball backwards-T1), motor adaptation (running with the ball around poles-T2), spatial orientation (running to sequentially numbered balls-T3), balance (single-leg static balance-T4), and kinesthetic differentiation of movement (landing the ball on a 2 × 2 m sector-T5). Repeated-measures analysis of variance revealed no significance between-group differences for age, anthropometry, and body-fat percentage at baseline. Significant main effects for group (P-CT vs. RT) were found in all tests (T1-T5) and main effects for time (group P-CT) in T3-T5, whereas a significant group × time interaction was observed only in T4 (F = 2.98, p = 0.0204). Post hoc tests indicated that P-CT attained significantly better results than RT at peritraining (by 26.4%; p < 0.01) and posttraining (by 31.9%, p < 0.01). Modulated exercise intensity had little effect on soccer performance (T1-T3, T5). Based on the results, it is recommended that the training of young soccer players be supplemented with the bilateral balance exercises and games used in the study. Furthermore, the suitability of monitoring HR in P-C exercises targeting the analyzed MP skills is questionable.

External Load Variables Affect Recovery Markers up to 72 h After Semiprofessional Football Matches

Background: Player tracking devices are commonly used to monitor external load from training and matches in team sports. Yet, how the derived external load variables relate to fatigue and recovery post-training or post-match is scarcely researched. The objective was, therefore, to investigate how external load variables affect recovery markers up to 72 h post-match.

Methods: Semiprofessional players from six teams wore tracking devices during three experimental football matches. External load variables including individual playing duration, total distance, PlayerLoad™, high-intensity running, and high-intensity events were derived from the tracking devices, and blood samples and performance tests from 24–59 players were undertaken post-match. The effect of the external load variables on creatine kinase, myoglobin, and countermovement jump at 1, 24, 48, and 72 h, and 30-m sprint and Yo-Yo intermittent recovery tests level 1 at 72 h post-match, were modeled. Effects were gauged as two standard deviations of the external load and interpreted as the difference between a typical high-load and a typical low-load match. The effects were evaluated with 90% confidence intervals and magnitude-based inferences.

Results: High-intensity running had very likely substantial effects on creatine kinase and myoglobin (moderate factor increases of 1.5–2.0 and 1.3–1.6 respectively), while duration, total distance, and HIE showed small, likely substantial effects. PlayerLoad™ and total distance had likely substantial effects on 30-m sprint time (small increases of 2.1–2.6%). Effects on countermovement jump performance were generally non-substantial. Despite these relationships, the uncertainty was too large to predict the recovery of individual players from the external load variables.

Conclusions: This study provides evidence that external load variables have an effect on recovery markers up to 72 h post-match. Hence, tracking external load in matches may be helpful for practitioners when managing training load and recovery strategies post-match. However, it is recommended that several different external load variables are monitored. Future research should continue to address the problem of predicting recovery from external load variables.

Influence of warm-up duration on perceived exertion and subsequent physical performance of soccer players

The aim of this study was to analyse the effects of three warm-up protocols with different durations in semiprofessional soccer players. Fifteen semi-professional soccer players performed three warm-up protocols (Wup25min: 25 min, Wup15min: 15 min and Wup8min: 8 min duration) on three different days. Before (pre-test) and after (post-test) each warm-up protocol, the players' physical performance (sprint, vertical jump and change of direction) was evaluated and all the players were asked to respond to the subjective scale of readiness to play a match. Also, after completing each warm-up protocol, all players responded to the rating of perceived exertion (RPE) scale. Although all protocols significantly improved the feeling of players being prepared to play the game (p<0.05 or p<0.01), after performing the Wup25min protocol the players performed worse in the 10 m sprint (p<0.01) and in the 20 m sprint (p<0.05). However, the Wup8min protocol significantly improved performance in both the 10 m sprint (p<0.05) and the 20 m sprint (p<0.05). In addition, with the Wup25min protocol players stated a higher perceived exertion (RPE) (p < 0.05) than in the Wup15min and Wup8min protocols. The Wup8min protocol was the only one that improved the acceleration ability of the soccer players in this study.

Physical and Physiological Responses during the Stop-Ball Rule During Small-Sided Games in Soccer Players

Small-sided games (SSGs) are a recommended training method for significant performance enhancement, and training efficiency. The stop-ball (SSG-SB) effects on physical responses (e.g., acceleration, deceleration, sprints, total distance, and indicator of workload) have not been investigated yet. This study aimed to investigate the effects of the SSG-SB compared to the small-goals SSG (SSG-SG) on physical and heart rate (HR) responses at high intensity (total distance (>18 km/h)), sprints (>18 km/h), and acceleration and deceleration (>3 m/s²) during a 4 vs. 4 SSG format in youth professional soccer players. Sixteen male elite young soccer players (mean ± SD body height, 176.5 ± 6.3 cm; age, 18.3 ± 0.7 years; body weight, 73.4 ± 7.2 kg) performed two forms of SSGs, i.e., SSG-SB or SSG-SG, for 4 × 4 min with a recovery of 2 min between sets. Data were compared using the t-test. The SSG-SB induced a significantly higher mean HR (180.0 ± 2.0 vs. 173.0 ± 3.0 beats per minute; p < 0.05) compared to the SSG-SG. Likewise, the SSG-SB was significantly higher compared to the SSG-SG for total distance (2580 ± 220.3 vs. 2230 ± 210 m; p < 0.001), player load (98.07 ± 12.5 vs. 89.4 ± 10.5; p < 0.05), sprint distance (7.9 ± 2.3 vs. 5.2 ± 2.0 m; p < 0.05), acceleration (15.6 ± 2.75 vs. 12.5 ± 1.75; p < 0.05), and deceleration (17.3 ± 3.20 vs. 14.4 ± 2.55; p < 0.05). However, no significant difference was found between the SSG-SG and the SSG-SB for maximal velocity, power, and sprints duration. This study provides new information about the effectiveness of the SSG-SB as a training stimulus for soccer.

A comparison of the isometric force fatigue-recovery profile in two posterior chain lower limb tests following simulated soccer competition

Aim

To evaluate the reliability of isometric peak force (IPF) in a novel “long-length” 90°Hip:20°Knee (90:20) strength test and to compare the simulated soccer match induced fatigue-recovery profile of IPF in this test with that of an isometric 90°Hip:90°Knee (90:90) position test.

Methods

Twenty semi-professional soccer players volunteered for the study of which 14 participated in the first part of the study which assessed 90:20 reliability (age = 21.3 ± 2.5 years, height = 1.79 ± 0.07 m, body mass = 73.2 ± 8.8 kg), while 17 completed the second part of the study evaluating fatigue-recovery (age 21.2±2.4 yrs., height = 180 ± 0.09 m, body mass 73.8 ± 8.9 kg). We evaluated the inter-session reliability of IPF in two 90:20 test protocols (hands on the wall (HW); and hands on chest (HC)) both performed on two occasions, 7 days apart. We then assessed 90:20 (HC) and 90:90 IPF immediately before (PRE) and after (POST) after a simulated soccer match protocol (BEAST90mod) and 48 (+48 h) and 72 hours (+72 h) later.

Results

Part one: the 90:20 showed moderate to high overall reliability (CV’s of 7.3% to 11.0%) across test positions and limbs. CV’s were lower in the HW than HC in the dominant (7.3% vs 11.0%) but the opposite happened in the non-dominant limb where CV’s were higher in the HW than HC (9.7% vs 7.3%). Based on these results, the HC position was used in part two of the study. Part two: 90:20 and 90:90 IPF was significantly lower POST compared to PRE BEAST90mod across all testing positions (p<0.001). IPF was significantly lower at +48 h compared to PRE in the 90:20 in both limbs (Dominant: p<0.01,Non-dominant: p≤0.05), but not in the 90:90. At +72 h, IPF was not significantly different from PRE in either test.

Conclusions

Simple to implement posterior IPF tests can help to define recovery from competition and training load in football and, potentially, in other multiple sprint athletes. Testing posterior chain IPF in a more knee extended 90:20 position may provide greater sensitivity to fatigue at 48 h post simulated competition than testing in the 90:90 position, but also may require greater degree of familiarization due to more functional testing position.

Jump height as performance indicator for the selection of youth football players to national teams

BACKGROUND

Different jump tests such as the Countermovement Jump (CMJ), Abalakov Jump (AJ) and Standing Long Jump (SLJ) are often used in practice to evaluate muscular power and functional performance in football. These tests are also used in different selection processes and talent identification, but the significance of the tests for the selection of youth players to national teams are relatively unknown. The aim of this study was to compare jump ability between youth football players selected or not selected for the national team.

METHODS

In this cross-sectional study, 22 players (aged 17±2 years), 11 national players (NP) and 11 non-national players (NNP) were evaluated in three different jump tests; CMJ, AJ and SLJ. Mean scores for the tests were analyzed and compared.

RESULTS

Significant differences were found between the groups regarding jump height in favor of the NP group in both the CMJ (NP 39.9±5.0 cm vs. NNP 34.2±4.9 cm, P=0.013) and the AJ (NP 47.1±5.4 vs. NNP 40.9±4.7, P=0.010). No group difference was found regarding jump length in SLJ (NP 246.2±17.9 vs. NNP 232.9±16.5, P=0.084).

CONCLUSIONS

The results suggest that tests, measuring jump height, could be used as a performance indicator and part of the selection process of youth football players to national teams, whereas the use of jump length could be questioned.

Caffeine Supplementation: Ergogenic in Both High and Low Caffeine Responders

Purpose: Inconsistent results among studies examining the effects of caffeine on exercise performance are potentially due to interindividual variability in biological responses to caffeine ingestion. The aims, therefore, of the present study were to identify high and low caffeine responders and compare the influence of caffeine on exercise performance and biological responses between groups during a simulated soccer-game protocol on treadmill. Methods: Well-trained soccer players were distinguished as high (n = 11) and low (n = 9) caffeine responders based on resting blood pressure, plasma glycerol, nonesterified fatty acid, and epinephrine responses to caffeine. Participants underwent 2 simulated soccer-game protocols on a treadmill after caffeine (6 mg·kg−1) or placebo ingestion. Exercise performance and several biological responses were evaluated. Results: Exercise performance did not differ between the high and low responders to caffeine (P > .05). However, time to fatigue (high, caffeine: 797 [201] s vs placebo: 487 [258] s; low, caffeine: 625 [357] s vs placebo 447 [198] s) and countermovement jump (high, caffeine: 42.1 [5.5] cm vs placebo: 40.5 [5.7] cm; low, caffeine: 41.0 [3.8] cm vs placebo: 38.8 [4.6] cm) improved with caffeine relative to placebo (P < .001). Rating of perceived exertion was lower (P < .001) in high (13.4 [2.3]) than in low responders (14.3 [2.4]) with caffeine ingestion. Conclusions: Caffeine improved aerobic endurance and neuromuscular performance in well-trained soccer players regardless of their responsiveness to caffeine at rest. Since no changes in substrate utilization were found with caffeine supplementation, performance improvements could be attributed to positive effects on the central nervous system and/or neuromuscular function, although the precise mechanism remains unclear.

Soccer Footedness and Between-Limbs Muscle Strength: Systematic Review and Meta-Analysis

Purpose: Limb dominance and consequent between-limbs muscle strength in soccer players should be explored to determine a standard musculoskeletal profile to maintain and establish during screening protocols and postinjury rehabilitation. The primary aim of this review was to identify dominant- vs non-dominant-lower-extremity muscle-strength characteristics of healthy soccer players, with secondary aims to consider available between-limbs outcome measures and directions for future research. Methods: Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. Five electronic databases were used for study identification with guidance from a medical librarian. Inclusion criteria consisted of studies employing a cross-sectional design assessing soccer players of all ages, genders, and levels of play that identified limb dominance and associated lower-extremity muscle strength as a main purpose of the experiment. Results: The literature search identified 3471 articles. After screening titles, abstracts, and full texts, 17 articles were included in the review. Peak torques and hamstring-to-quadriceps ratios via isokinetic dynamometry were commonly used, and subsequent meta-analyses were conducted to yield remarkable between-limbs symmetry. Additional results of individual studies also demonstrate symmetry, except 1 article of velocity-dependent measures that reported greater strength in the dominant limb. Conclusions: In soccer, between-limbs muscle strength measured by maximal isokinetic dynamometry demonstrates symmetry across ages, genders, and levels of play. Future testing using alternative measures that more specifically replicate the movement demands of soccer players may further classify between-limbs characteristics.

Assessment of Selected Exercise-induced CD3+ Cell Subsets and Cell Death Parameters Among Soccer Players

Background

Molecular mechanisms of biological adaptation to training in professional soccer players are unclear. The aim of this study was to assess the impact of progressive physical effort on peripheral T-cells and their molecular response.

Methods

Thirteen soccer players form Pogo Szczecin S.A., a top league soccer club, (median age 21, range 18– 31, years old) performed progressive efficiency tests on a mechanical treadmill until exhaustion at the start (period 1) and the end (period 2) of a competition round. Venous blood T-lymphocyte subsets, selected hallmarks of cell death and plasma cytokine levels were determined by flow cytometry three times: pre-exercise, post-exercise, and in recovery.

Results

Although significant changes in T, Tc and Tc-naïve cell percentages were found in both periods, Th-naïve cell percentages were altered only in period 1. Post-exercise IL-10 plasma levels were higher than pre-exercise, while an increase in TNF-α levels was noticed in recovery from both periods. An increase in recovery IL-12p70 levels was observed in the second period. Increases in the percentage of T-cells with disrupted mitochondrial membrane potentials, elevated levels of phosphorylated H2AX histones and increases in early apoptotic T-cells were also observed.

Conclusions

The immune system in soccer players creates space for naïve CD3⁺CD8⁺ cells by inducing mechanisms of cell death. It seems that the cumulative effect of physical activity during a competition round induced an adaptive mechanism, since the cell death process was induced faster during period 2.

Match-Play and Performance Test Responses of Soccer Goalkeepers: A Review of Current Literature

Goalkeepers are typically the last defensive line for soccer teams aiming to minimise goals being conceded, with match rules permitting ball handling within a specific area. Goalkeepers are also involved in initiating some offensive plays, and typically remain in close proximity to the goal line while covering ~ 50% of the match distances of outfield players; hence, the competitive and training demands of goalkeepers are unique to their specialised position. Indeed, isolated performance tests differentiate goalkeepers from outfield players in multiple variables. With a view to informing future research, this review summarised currently available literature reporting goalkeeper responses to: (1) match play (movement and skilled/technical demands) and (2) isolated performance assessments (strength, power, speed, aerobic capacity, joint range of motion). Literature searching and screening processes yielded 26 eligible records and highlighted that goalkeepers covered ~ 4-6 km on match day whilst spending ~ 98% of time at low-movement intensities. The most decisive moments are the 2-10 saves·match^-1 performed, which often involve explosive actions (e.g. dives, jumps). Whilst no between-half performance decrements have been observed in professional goalkeepers, possible transient changes over shorter match epochs remain unclear. Isolated performance tests confirm divergent profiles between goalkeepers and outfield players (i.e. superior jump performance, reduced [Formula: see text]_2max values, slower sprint times), and the training of soccer goalkeepers is typically completed separately from outfield positions with a focus primarily on technical or explosive drills performed within confined spaces. Additional work is needed to examine the physiological responses to goalkeeper-specific training and match activities to determine the efficacy of current preparatory strategies.

Fat Oxidation Rates in Professional Soccer Players

PURPOSE

Large interindividual variation exists in maximal fat oxidation (MFO) rates and the exercise intensity at which it occurs (FATMAX). However, there are no data describing the shape of the fat oxidation curve or if individual differences exist when tested on separate occasions. Furthermore, there are limited data on fat metabolism in professional team sport athletes. Therefore, the aim of this study was to test-retest the concavity (shape) and intercept (height) of fat oxidation curves within a group of professional soccer players.

METHOD

On two occasions, 16 professional male soccer players completed a graded exercise test in a fasted state (≥5 h). Rates of fat oxidation were determined using indirect calorimetry. Maximal oxygen uptake (V˙O2max) was measured to calculate FATMAX (%V˙O2max). The shape of the fat oxidation curves were modeled on an individual basis using third-degree polynomial. Test-by-test differences, in the shape and vertical shift of the fat oxidation curves, were established to assess within-individual variability.

RESULTS

Average absolute MFO was 0.69 ± 0.15 g·min (range, 0.45-0.99 g·min). On a group level, no significant differences were found in MFO between the two tests. No differences were found (P > 0.05) in the shape of the fat oxidation curves in 13 of 16 players (test 1 vs test 2). There were also no differences (P > 0.05) in the vertical shift of the fat oxidation curves in 10 players.

CONCLUSIONS

In general, the shape of the fat oxidation curve does not change within an individual; however, the vertical shift is more susceptible to change, which may be due to training status and body composition. Understanding a player's metabolism may be of value to practitioners working within sport, with regard to personalizing nutrition strategies.

Profiling the Responses of Soccer Substitutes: A Review of Current Literature

Depending upon competition regulations, the laws of soccer allow between three and an unlimited number of substitutions that can be made on either a permanent or rolling basis. Substitutes are typically introduced to minimise/offset the effects of fatigue, alter tactics, replace players deemed as underperforming or injured, and/or give playing time to youth players or to squad members returning from injury. While the match-day practices of substitutes include participation in the pre-match warm-up, and sporadic periods of rewarm-up activity, it is currently unclear as to whether these pre-entry preparations facilitate optimal match performance thereafter. Acknowledging the contextual factors that possibly influence substitutes' performance, this review summarises the presently available literature on soccer substitutes, and makes recommendations for future research. Literature searching and screening yielded 13 studies, which have typically focused on characterising: (1) the patterns, including timing, of substitutes' introduction; (2) indices of match-performance; and (3) the emotional experiences of soccer substitutes. The majority of substitutions occur after the first-half has ended (i.e. at half-time or during the second-half), with introduced players exceeding the second-half physical performances of those who started the match. Observations of progressive improvements in running performance as playing time increases, and findings that substitutes mostly experience negative emotions, highlight the potential inadequacies of pre-match preparations, and present future research opportunities. Additional work is therefore needed to confirm these findings and to determine the efficacy of current preparation strategies, thereby providing opportunities to assess then address substitutes' pre-pitch entry preparations, on-field performance and emotional responses.

The Effect of In-Season Traditional and Explosive Resistance Training Programs on Strength, Jump Height, and Speed in Recreational Soccer Players

PURPOSE

Resistance training is often performed in a traditional training style using deliberate relatively longer repetition durations or in an explosive training style using maximal intended velocities and relatively shorter repetition durations. Both improve strength, "power" (impulsivity), and speed. This study compared explosive and traditional training over a 6-week intervention in 30 healthy young adult male recreational soccer players.

METHOD

Full body supervised resistance training was performed 2 times a week using 3 sets of each exercise at 80% of one repetition maximum to momentary failure. Outcomes were Smith machine squat 1 repetition maximum, 10 meter sprint time, and countermovement jump.

RESULTS

Both groups significantly improved all outcomes based on 95% confidence intervals not crossing zero. There were no between-group differences for squat 1 RM (TRAD = 6.3[5.1 to 7.6] kg, EXP = 5.2[3.9 to 6.4] kg) or 10 meter sprint (TRAD = -0.05[-0.07 to -0.04] s, EXP = -0.05[-0.06 to -0.03] s). Explosive group had a significantly greater increase in countermovement jump compared to the traditional group (TRAD = 0.7[0.3 to 1.1] cm, EXP = 1.3[0.9 to 1.7] cm).

CONCLUSION

Both the traditional training and explosive training performed to momentary failure produced significant improvements in strength, speed, and jump performance. Strength gains are similar independent of intended movement speed. However, speed and jump performance changes are marginal with resistance training.

Differences in the Offensive and Defensive Actions of the Goalkeepers at Women's FIFA World Cup 2011

The aim of this study was to analyze the technical and tactical offensive and defensive actions of the goalkeepers and to determine the relationship between these actions and the qualifying results of their respective teams. The sample studied is made up of the goalkeepers (n = 20) of the senior national teams that participated in the FIFA Women's World Cup in Germany 2011. A descriptive analysis was developed comparing the offensive and defensive actions in competition carried out by the goalkeepers on qualified teams (pass the group stage) with the goalkeepers on unclassified teams (not pass the group stage). For the inter-group comparison, the value of the coefficient of variation was incorporated and the effect size calculated. All data were treated with a statistical significance level of p < 0.05. The results show that the goalkeepers on qualified teams have higher offensive registers, as well as a higher number of passes successfully completed in different areas of the field. The goalkeepers on unclassified teams show higher defensive records such as saves inside the area, foot stops and wrong clearances among others.

Exercise intensity effects on total sweat electrolyte losses and regional vs. whole-body sweat [Na+], [Cl-], and [K+]

PURPOSE

To quantify total sweat electrolyte losses at two relative exercise intensities and determine the effect of workload on the relation between regional (REG) and whole body (WB) sweat electrolyte concentrations.

METHODS

Eleven recreational athletes (7 men, 4 women; 71.5 ± 8.4 kg) completed two randomized trials cycling (30 °C, 44% rh) for 90 min at 45% (LOW) and 65% (MOD) of VO2max in a plastic isolation chamber to determine WB sweat [Na+] and [Cl-] using the washdown technique. REG sweat [Na+] and [Cl-] were measured at 11 REG sites using absorbent patches. Total sweat electrolyte losses were the product of WB sweat loss (WBSL) and WB sweat electrolyte concentrations.

RESULTS

WBSL (0.86 ± 0.15 vs. 1.27 ± 0.24 L), WB sweat [Na+] (32.6 ± 14.3 vs. 52.7 ± 14.6 mmol/L), WB sweat [Cl-] (29.8 ± 13.6 vs. 52.5 ± 15.6 mmol/L), total sweat Na+ loss (659 ± 340 vs. 1565 ± 590 mg), and total sweat Cl- loss (931 ± 494 vs. 2378 ± 853 mg) increased significantly (p < 0.05) from LOW to MOD. REG sweat [Na+] and [Cl-] increased from LOW to MOD at all sites except thigh and calf. Intensity had a significant effect on the regression model predicting WB from REG at the ventral wrist, lower back, thigh, and calf for sweat [Na+] and [Cl-].

CONCLUSION

Total sweat Na+ and Cl- losses increased by ~ 150% with increased exercise intensity. Regression equations can be used to predict WB sweat [Na+] and [Cl-] from some REG sites (e.g., dorsal forearm) irrespective of intensity (between 45 and 65% VO2max), but other sites (especially ventral wrist, lower back, thigh, and calf) require separate prediction equations accounting for workload.

The value of tibial mounted inertial measurement units to quantify running kinetics in elite football (soccer) players. A reliability and agreement study using a research orientated and a clinically orientated system

In elite football, measurement of running kinetics with inertial measurement units (IMUs) may be useful as a component of periodic health examination (PHE). This study determined the reliability of, and agreement between a research orientated IMU and clinically orientated IMU system for initial peak acceleration (IPA) and IPA symmetry index (SI) measurement during running in elite footballers. On consecutive days, 16 participants performed treadmill running at 14kmph and 18kmph. Both IMUs measured IPA and IPA SI concurrently. All measurements had good or excellent within-session reliability (intraclass correlation coefficient (ICC_2,1) range = 0.79-0.96, IPA standard error of measurement (SEM) range = 0.19-0.62 g, IPA SI SEM range = 2.50-8.05%). Only the research orientated IMU demonstrated acceptable minimal detectable changes (MDCs) for IPA at 14kmph (range = 7.46-9.80%) and IPA SI at both speeds (range = 6.92-9.21%). Considering both systems, between-session IPA reliability ranged from fair to good (ICC_2,1 range = 0.63-0.87, SEM range = 0.51-1.10 g) and poor to fair for IPA SI (ICC_2,1 range = 0.32-0.65, SEM range = 8.07-11.18%). All MDCs were >10%. For IPA and SI, the 95% levels of agreement indicated poor between system agreement. Therefore, the use of IMUs to evaluate treadmill running kinetics cannot be recommended in this population as a PHE test to identify prognostic factors for injuries or for rehabilitation purposes.

Match Demands of National Collegiate Athletic Association Division I Men's Soccer

Curtis, RM, Huggins, RA, Looney, DP, West, CA, Fortunati, A, Fontaine, GJ, and Casa, DJ. Match demands of National Collegiate Athletic Association Division I men's soccer. J Strength Cond Res 32(10): 2907-2917, 2018-This study aimed to profile positional movement characteristics of National Collegiate Athletic Association (NCAA) Division I male soccer players. Eighteen Division I male soccer players were monitored using global positioning systems, inertial movement, and heart rate (HR) technology during 24 matches over a full competitive season (N = 235 observations). Positional groups were classified as either a forward (F), center midfielder (CM), wide midfielder (WM), or defender (D). Movement was profiled by locomotor (walking [0-7.19 km·h], jogging [7.20-14.39 km·h], running [14.40-21.59 km·h], and sprinting [>21.6 km·h]), and acceleration/deceleration characteristics (low intensity [0-1.99 m·s], moderate intensity [2-3.99 m·s], and high intensity [>4 m·s]). Players averaged distances of 9,367 ± 2,149 m per match at speeds of 91 ± 20 m·min and physiological intensities of 78 ± 8 %HRmax. Center midfielder demonstrated the highest average speeds (97 ± 20 m·min) and covered the most distance (9,941 ± 2,140 m). Wide midfielder accumulated the most sprint distance (391 ± 145 m) and high-intensity accelerations (129 ± 30 n)/decelerations (96 ± 24 n). Several practically meaningful differences exist between positions for internal and external load metrics. Match loads seen in NCAA Division I soccer vary from reports of professional soccer; however, the effects of match regulation, structure, and congestion, which are unique to NCAA soccer, require further investigation. Physical and physiological load monitoring of NCAA soccer may aid coaches and practitioners in the periodization of training programs leading up to and during a competitive soccer season. These data speak to the necessity for examining both internal and external loads by position.

Differences between training and game loads in young basketball players

Abstract The same training stimulus can provide different physiological adaptations for athletes of the same team.The aim of this study was to compare training and game loads in young male basketball players. Data were obtained from 4 training sessions and one game session usingPolar Team Pro equipment. Physiological data (HR) were used to monitor internal responses through Edwards’TRIMP,and data on distance traveled by the player on the court (External Training Load).To observe differences between eTRIMP,HR max and distance traveled,the T-Test was used for paired samples. The mean internal training load, according to Edwards’TRIMP, for the four training sessions was 132 ± 69. Mean HR max and distance traveled values were 143 ± 67 and 2.273 ± 1170, respectively. Regarding game load, Edwards’TRIMP,maximum HR and distance traveled were 108 ± 33, 199 ± 4 and 2.240 ± 617, respectively. No statistically significant differences were found between the mean values of training sessions compared to the game session in relation to the Edwards’ TRIMP measures and distance traveled, but HR max was significantly higher during the game compared to training. It was concluded that the loads applied during training are similar to those applied in the game.