Soccer-specific Exercise Research Articles

Age-Related Differences in Functional Hamstring/Quadriceps Ratio Following Soccer Exercise in Female Youth Players: An Injury Risk Factor.

Fatigue negatively alters dynamic knee control, and the functional hamstring/quadriceps ratio (H/QFUNC) plays an important role in stabilizing the joint. The aim of this study was to investigate the influence of soccer-specific exercise on H/QFUNC in under (U) 13-, U15-, and U17-year-old female soccer players. A total of 36 female players performed concentric and eccentric actions of the hamstrings at 60°, 120°, and 180°/s before and after an age group-specific field-based soccer protocol. H/QFUNC was determined in the first 30° of knee flexion. Significant angle × velocity (P = .001) and time × angle (P = .033) interaction effects were found indicating a lower H/QFUNC with increased movement velocity at 0°-10° as opposed to greater knee flexion angles. Fatigue-related effects were only evident near full knee extension. Probabilistic inferences indicated that changes in H/QFUNC were generally unclear in U13s, likely detrimental in U15s, and very likely beneficial in U17s. Altered muscular control following soccer-specific exercise is age dependent with players' 1-year post-peak height velocity at greatest risk of injury. Injury prevention and screening need to be age and maturation appropriate, should consider the effects of fatigue, and include movements near full extension.

Leg Stiffness in Female Soccer Players: Intersession Reliability and the Fatiguing Effects of Soccer-Specific Exercise.

De Ste Croix, MBA, Hughes, JD, Lloyd, RS, Oliver, JL, and Read, PJ. Leg stiffness in female soccer players: intersession reliability and the fatiguing effects of soccer-specific exercise. J Strength Cond Res 31(11): 3052-3058, 2016-Low levels of leg stiffness and reduced leg stiffness when fatigue is present compromise physical performance and increase injury risk. The purpose of this study was to (a) determine the reliability of leg stiffness measures obtained from contact mat data and (b) explore age-related differences in leg stiffness after exposure to a soccer-specific fatigue protocol in young female soccer players. Thirty-seven uninjured female youth soccer players divided into 3 subgroups based on chronological age (under 13 [U13], under 15 [U15], and under 17 [U17] year-olds) volunteered to participate in the study. After baseline data collection, during which relative leg stiffness, contact time, and flight time were collected, participants completed an age-appropriate soccer-specific fatigue protocol (SAFT). Upon completion of the fatigue protocol, subjects were immediately retested. Intersession reliability was acceptable and could be considered capable of detecting worthwhile changes in performance. Results showed that leg stiffness decreased in the U13 year-olds, was maintained in the U15 age group, and increased in the U17 players. Contact times and flight times did not change in the U13 and U15 year-olds, but significantly decreased and increased, respectively, in the U17 age group. The data suggest that age-related changes in the neuromuscular control of leg stiffness are present in youth female soccer players. Practitioners should be aware of these discrepancies in neuromuscular responses to soccer-specific fatigue, and should tailor training programs to meet the needs of individuals, which may subsequently enhance performance and reduce injury risk.

A comparison of isomaltulose versus maltodextrin ingestion during soccer-specific exercise

PurposeThe performance and physiological effects of isomaltulose and maltodextrin consumed intermittently during prolonged soccer-specific exercise were investigated.MethodsUniversity soccer players (n = 22) performed 120 min of intermittent exercise while consuming 8% carbohydrate–electrolyte drinks (equivalent to ~ 20 g h−1) containing maltodextrin (Glycaemic Index: 90–100), isomaltulose (Glycaemic Index: 32) or a carbohydrate-energy-free placebo in a manner replicating the practices of soccer players (i.e., during warm-up and half-time). Physical (sprinting, jumping) and technical (shooting, dribbling) performance was assessed.ResultsBlood glucose and plasma insulin (both P < 0.001) concentrations varied by trial with isomaltulose maintaining > 13% higher blood glucose concentrations between 75 and 90 min versus maltodextrin (P < 0.05). A decline in glycaemia at 60 min in maltodextrin was attenuated with isomaltulose (−19 versus −4%; P = 0.015). Carbohydrates attenuated elevations in plasma epinephrine concentrations (P < 0.05), but isomaltulose proved most effective at 90 and 120 min. Carbohydrates did not attenuate IL-6 increases or reductions in physical or technical performances (all P > 0.05). Ratings of abdominal discomfort were influenced by trial (P < 0.05) with lower values for both carbohydrates compared to PLA from 60 min onwards.ConclusionsAlthough carbohydrates (~ 20 g h−1) did not attenuate performance reductions throughout prolonged soccer-specific exercise, isomaltulose maintained higher blood glucose at 75–90 min, lessened the magnitude of the exercise-induced rebound glycaemic response and attenuated epinephrine increases whilst maintaining similar abdominal discomfort values relative to maltodextrin. When limited opportunities exist to consume carbohydrates on competition-day, low-glycaemic isomaltulose may offer an alternative nutritional strategy for exercising soccer players.

The influence of a 12% carbohydrate-electrolyte beverage on self-paced soccer-specific exercise performance.

To assess the physiological and performance effects of a 12% carbohydrate-electrolyte beverage consumed at practically applicable time-points (i.e., before each half) throughout simulated soccer match-play. Randomised, counterbalanced, crossover. Fed players (n=15) performed 90-min of soccer-specific exercise (including self-paced exercise at the end of each half). Players consumed carbohydrate-electrolyte (CHO; 60g×500ml-1, Na+ 205mg×500ml-1), placebo-electrolyte (PL) or water (Wat) beverages at the end of the warm-up (250ml) and half-time (250ml plus ad-libitum water). Blood was drawn before each half and every 15-min during exercise. Physical (15-m sprinting, countermovement jumps, self-paced distance, acceleration/deceleration count), technical (dribbling) and cognitive (memory, attention, decision-making) performance was assessed. Ratings of perceived exertion (RPE) and abdominal discomfort were measured. Against Wat and PL, CHO increased (all p<0.05) mean accelerations >1.5m·s-2 during self-paced exercise (>+25%) and dribbling speed from 60-min onwards (>+3%). Mean sprinting speed improved (+2.7%) in CHO versus Wat. Blood glucose increased before and during each half in CHO versus PL and Wat (all p<0.05). A 27% decline in glycaemia occurred at 60-min in CHO. RPE was comparable between trials. Cognition reduced post-exercise (p<0.05); this decline was not attenuated by CHO. Abdominal discomfort increased during exercise but was similar between trials. Using more realistic fluid ingestion timings than have been examined previously, consuming a 12% carbohydrate-electrolyte beverage increased blood glucose, self-paced exercise performance, and improved dribbling speed in the final 30-min of exercise compared to water and placebo. Carbohydrates did not attenuate post-exercise reductions in cognition.

The effects of an increased calorie breakfast consumed prior to simulated match-play in Academy soccer players

Dietary analysis of Academy soccer players highlights that total energy and carbohydrate intakes are less than optimal, especially, on match-days. As UK Academy matches predominantly kick-off at ∼11:00 h, breakfast is likely the last pre-exercise meal and thus may provide an intervention opportunity on match-day. Accordingly, the physiological and performance effects of an increased calorie breakfast consumed ∼135-min before soccer-specific exercise was investigated. English Premier League Academy soccer players (n = 7) repeated a 90-min soccer match simulation on two occasions after consumption of habitual (Bhab; ∼1100 kJ) or increased (Binc; ∼2100 kJ) energy breakfasts standardised for macronutrient contributions (∼60% carbohydrates, ∼15% proteins and ∼25% fats). Countermovement jump height, sprint velocities (15-m and 30-m), 30-m repeated sprint maintenance, gut fullness, abdominal discomfort and soccer dribbling performances were measured. Blood samples were taken at rest, pre-exercise, half-time and every 15-min during exercise. Although dribbling precision (P = .522; 29.9 ± 5.5 cm) and success (P = .505; 94 ± 8%) were unchanged throughout all time-points, mean dribbling speed was faster (4.3 ± 5.7%) in Binc relative to Bhab (P = .023; 2.84 vs 2.75 m s−1). Greater feelings of gut fullness (67 ± 17%, P = .001) were observed in Binc without changes in abdominal discomfort (P = .595). All other physical performance measures and blood lactate and glucose concentrations were comparable between trials (all P > .05). Findings demonstrate that Academy soccer players were able to increase pre-match energy intake without experiencing abdominal discomfort; thus, likely contributing to the amelioration of energy deficits on match-days. Furthermore, whilst Binc produced limited benefits to physical performance, increased dribbling speed was identified, which may be of benefit to match-play.

Biomechanical Analysis of the Dominant Foot and Non-Dominant Foot during Shooting with the Internal Instep as a Basis for Soccer Specific Exercises

Biomechanical Analysis of the Dominant Foot and Non-Dominant Foot during Shooting with the Internal Instep as a Basis for Soccer Specific Exercises

Test-Retest Reliability of Physiological and Performance Responses to 120 Minutes of Simulated Soccer Match Play.

Harper, LD, Hunter, R, Parker, P, Goodall, S, Thomas, K, Howatson, G, West, DJ, Stevenson, E, and Russell, M. Test-retest reliability of physiological and performance responses to 120 minutes of simulated soccer match play. J Strength Cond Res 30(11): 3178-3186, 2016-This study investigated the test-retest reliability of physiological and performance responses to 120 minutes (90 minutes plus 30 minutes extra-time [ET]) of the soccer match simulation (SMS). Ten university-standard soccer players completed the SMS on 2 occasions under standardized conditions. Capillary and venous blood was taken pre-exercise, at half-time, and at 90 and 120 minutes, with further capillary samples taken every 15 minutes throughout the exercise. Core temperature (Tcore), physical (20- and 15-m sprint speeds and countermovement jump height), and technical (soccer dribbling) performance was also assessed during each trial. All variables except blood lactate demonstrated no systematic bias between trials (p > 0.05). During the last 15 minutes of ET, test-rest reliability (coefficient of variation %, Pearson's r, respectively) was moderate to strong for 20-m sprint speed (3.5%, 0.71), countermovement jump height (4.9%, 0.90), dribble speed (2.8%, 0.90), and blood glucose (7.1%, 0.93), and very strong for Tcore (1.2%, 0.99). Moderate reliability was demonstrated for 15-m sprint speed (4.6%, 0.36), dribble precision (11.5%, 0.30), plasma insulin (10.3%, 0.96), creatine kinase ([CK] 28.1%, 0.38), interleukin-6 (24%, 0.99), nonesterified fatty acids ([NEFA] 13.2%, 0.73), glycerol (12.5%, 0.86), and blood lactate (18.6%, 0.79). In the last 15 minutes of ET, concentrations of blood glucose and lactate and sprint and jump performances were reduced, whereas Tcore, NEFA, glycerol, and CK concentrations were elevated (p ≤ 0.05). The SMS is a reliable protocol for measuring responses across the full 120 minutes of soccer-specific exercise. Deleterious effects on performance and physiological responses occur during ET.

Changes in Acceleration and Deceleration Capacity Throughout Professional Soccer Match-Play.

Russell, M, Sparkes, W, Northeast, J, Cook, CJ, Love, TD, Bracken, RM, and Kilduff, LP. Changes in acceleration and deceleration capacity throughout professional soccer match-play. J Strength Cond Res 30(10): 2839-2844, 2016-As the acceleration and deceleration demands of soccer are currently not well understood, this study aimed to profile markers of acceleration and deceleration capacity during professional soccer match-play. This within-player observational study required reserve team players from a Premier League club to wear 10-Hz Global Positioning System units throughout competitive matches played in the 2013-14 competitive season. Data are presented for players who completed 4 or more games during the season (n = 11), and variables are presented according to six 15-minute intervals (I1-6: 00:00-14:59 minutes, 15:00-29:59 minutes, 30:00-44:59 minutes, 45:00-59:59 minutes, 60:00-74:59 minutes, and 75:00-89:59 minutes, respectively). During I6, the distance covered (total, per minute, and at high intensity), number of sprints, accelerations (total and high intensity), decelerations (total and high intensity), and impacts were reduced compared with I1 (all p ≤ 0.05). The number of high-intensity impacts remained unchanged throughout match-play (p > 0.05). These findings indicate that high-intensity actions and markers of acceleration and deceleration capacity are reduced in the last 15 minutes of the normal duration of match-play. Such information can be used to increase the specificity of training programs designed for soccer players while also giving further insight in to the effects of 90 minutes of soccer-specific exercise. Interventions that seek to maintain the acceleration and deceleration capacity of players throughout the full duration of a soccer match warrant investigation.

The Creative Soccer Platform: New Strategies for Stimulating Creativity in Organized Youth Soccer Practice

Creativity is essential in soccer due to the unpredictable and complex situations occurring in the game, where stereotypical play gradually loses its efficiency. Further, creativity is an important psychological factor for the development of soccer expertise, and valuing creativity increases satisfaction and well-being. Although creative players are highly desired by coaches, the subject of cultivating creativity is mostly ignored and traditional training settings may even hamper the players' creativity. The purpose of this article is to introduce a novel approach for enhancing soccer players' creativity, The Creative Soccer Platform (TCSP), and to demonstrate the implications of applying it in youth soccer practice, by means of soccer-specific creativity exercises. TCSP encompasses four theoretically based didactic principles (task focus, parallel thinking, horizontal thinking, and no experienced judgment), shown to increase creativity in educational settings. Creativity is defined as unlimited application of bodily-kinesthetic knowledge, which refers to players not being limited by professional, social and cultural constraints in soccer. Analysis of qualitative data obtained during three training sessions where TSCP was implemented at a youth team indicate that the application of TCSP exercises establishes a playful, judgment-free and autonomy-supportive training environment, where soccer players are able to unfold their creative potential. The creative environment helped the youth players in the intervention engage in unfamiliar activities that they did not dare to do in normal training sessions (i.e., performed difficult, new and playful technical skills), which developed creative abilities important for game performance (i.e., idea generation abilities and not fearing mistakes).

The biomechanical and physiological response to repeated soccer-specific simulations interspersed by 48 or 72 hours recovery

PurposeTo assess the residual fatigue response associated with the completion of two successive soccer-specific exercise protocols (SSEP). MethodsTwenty male soccer players were pair-matched before completing SSEPs, interspersed by either 48 or 72 h. Outcome variables were measured every 15 min, and comprised uni-axial measures of PlayerLoad, mean (HR) and peak heart rate (HRpeak), blood lactate concentration, mean and peak (V˙O2peak) oxygen consumption, and rating of perceived exertion (RPE). ResultsNo significant (P > 0.05) group interactions were identified for any outcome variables. Uni-axial (and total) PlayerLoad exhibited a significant (P < 0.05) main effect for time, with the exception of the relative contribution of medial lateral PlayerLoad™. Total PlayerLoad during the final 15 min (222.23 ± 15.16 a.u) was significantly higher than all other time points. All other outcome variables also exhibited a significant main effect for time, with HR, HRpeak and V˙O2peak also exhibiting significantly higher values in the first trial. There was also a significant (P = 0.003) trial*time interaction for RPE. ConclusionsWith equivalence at baseline, there was no difference in the fatigue response associated with two SSEPs interspersed by either 48 or 72 h recovery. The current study has implications for the design and micro management of training and competition schedules.

Impact Of “Extra-time” On Performance And Physiological Responses To Simulated Soccer Match-play

The physiological and performance responses to 90 min of soccer-specific exercise are well known. However, the responses to 120 min of soccer-specific exercise (i.e., inclusion of an extra-time period; ET) are unclear. This is despite the importance of ET in determining match outcomes in tournament match-play.

Neuromuscular Fatigue In Response To 120 Minutes Of Soccer-specific Exercise

Soccer matches are normally played over 90 minutes, however it is common for players to encounter a period of extra-time (ET; 30 min) during knockout competitions such as the FIFA World Cup. Despite the importance of ET in terms of deciding the match outcome, there is a paucity of data investigating responses to ET. Notably, no investigation has attempted to profile the neuromuscular fatigue response. Thus, the precise mechanisms of neuromuscular fatigue during prolonged soccer-specific exercise are unknown.

Physiological and performance effects of carbohydrate gels consumed prior to the extra-time period of prolonged simulated soccer match-play.

The physiological and performance effects of carbohydrate-electrolyte gels consumed before the 30min extra-time period of prolonged soccer-specific exercise were investigated. Randomised, double-blind, crossover. Eight English Premier League academy soccer players performed 120min of soccer-specific exercise on two occasions while consuming fluid-electrolyte beverages before exercise, at half-time and 90min. Carbohydrate-electrolyte (0.7±0.1gkg(-1) BM) or energy-free placebo gels were consumed ∼5min before extra-time. Blood samples were taken before exercise, at half-time and every 15min during exercise. Physical (15-m and 30-m sprint speed, 30-m sprint maintenance and countermovement jump height) and technical (soccer dribbling) performance was assessed throughout each trial. Carbohydrate-electrolyte gels improved dribbling precision (+29±20%) and raised blood glucose concentrations by 0.7±0.8mmoll(-1) during extra-time (both p<0.01). Supplementation did not affect sprint velocities (15m and 30m), 30-m sprint maintenance or dribbling speed as reductions compared to 0-15min values occurred at 105-120min irrespective of trial (all p<0.05). Plasma osmolality and blood sodium concentrations increased post-exercise vs. the opening 15min (p<0.05) but no effect of supplementation existed. Selected markers of physical performance (jump height, 30-m sprint velocity and 30-m repeated sprint maintenance) also reduced by >3% during half-time (all p<0.05). Carbohydrate-electrolyte gel ingestion raised blood glucose concentrations and improved dribbling performance during the extra-time period of simulated soccer match-play. Supplementation did not attenuate reductions in physical performance and hydration status that occurred during extra-time.

Effect of tyrosine ingestion on cognitive and physical performance utilising an intermittent soccer performance test (iSPT) in a warm environment.

The aim of this study was to investigate the effect of tyrosine (TYR) ingestion on cognitive and physical performance during soccer-specific exercise in a warm environment. Eight male soccer players completed an individualised 90 min soccer-simulation intermittent soccer performance test (iSPT), on a non-motorised treadmill, on two occasions, within an environmental chamber (25 °C, 40 % RH). Participants ingested tyrosine (TYR; 250 mL sugar free drink plus 150 mg kg body mass(-1) TYR) at both 5 h and 1 h pre-exercise or a placebo control (PLA; 250 mL sugar free drink only) in a double-blind, randomised, crossover design. Cognitive performance (vigilance and dual-task) and perceived readiness to invest physical effort (RTIPE) and mental effort (RTIME) were assessed: pre-exercise, half-time, end of half-time and immediately post-exercise. Physical performance was assessed using the total distance covered in both halves of iSPT. Positive vigilance responses (HIT) were significantly higher (12.6 ± 1.7 vs 11.5 ± 2.4, p = 0.015) with negative responses (MISS) significantly lower (2.4 ± 1.8 vs 3.5 ± 2.4, p = 0.013) in TYR compared to PLA. RTIME scores were significantly higher in the TYR trial when compared to PLA (6.7 ± 1.2 vs 5.9 ± 1.2, p = 0.039). TYR had no significant (p > 0.05) influence on any other cognitive or physical performance measure. The results show that TYR ingestion is associated with improved vigilance and RTIME when exposed to individualised soccer-specific exercise (iSPT) in a warm environment. This suggests that increasing the availability of TYR may improve cognitive function during exposure to exercise-heat stress.

Sex differences in acute translational repressor 4E-BP1 activity and sprint performance in response to repeated-sprint exercise in team sport athletes.

The physiological requirements underlying soccer-specific exercise are incomplete and sex-based comparisons are sparse. The aim of this study was to determine the effects of a repeated-sprint protocol on the translational repressor 4E-BP1 and sprint performance in male and female soccer players. Cross-over design involving eight female and seven male university soccer players. Participants performed four bouts of 6 × 30-m maximal sprints spread equally over 40 min. Heart rate, sprint time and sprint decrement were measured for each sprint and during the course of each bout. Venous blood samples and muscle biopsies from the vastus lateralis were taken at rest, at 15 min and 2h post-exercise. While males maintained a faster mean sprint time for each bout (P < 0.05) females exhibited a greater decrement in sprint performance for each bout (P < 0.05), indicating a superior maintenance of sprint performance in males, with no sex differences for heart rate or lactate. Muscle analyses revealed sex differences in resting total (P < 0.05) and phosphorylated (P < 0.05) 4E-BP1 Thr37/46, and 15 min post-exercise the 4E-BP1 Thr37/46 ratio decreased below resting levels in males only (P < 0.05), indicative of a decreased translation initiation following repeated sprints. We show that females have a larger sprint decrement indicating that males have a superior ability to recover sprint performance. Sex differences in resting 4E-BP1 Thr37/46 suggest diversity in the training-induced phenotype of the muscle of males and females competing in equivalent levels of team-sport competition.

Altered neuromuscular control of leg stiffness following soccer-specific exercise

To examine changes to neuromuscular control of leg stiffness following 42 min of soccer-specific exercise. Ten youth soccer players, aged 15.8 ± 0.4 years, stature 1.73 ± 0.06 m and mass 59.8 ± 9.7 kg, hopped on a force plate at a self-selected frequency before and after simulated soccer exercise performed on a non-motorised treadmill. During hopping, muscle activity was measured using surface electromyography from four lower limb muscles and analysed to determine feedforward- and feedback-mediated activity, as well as co-contraction. There was a small, non-significant change in stiffness following exercise (26.6 ± 10.6 vs. 24.0 ± 7.0 kN m(-1), p > 0.05, ES = 0.25), with half the group increasing and half decreasing their stiffness. Changes in stiffness were significantly related to changes in centre of mass (CoM) displacement (r = 0.90, p < 0.01, extremely large correlation) but not changes in peak ground reaction force (r = 0.58, p > 0.05, large correlation). A number of significant relationships were observed between changes in stiffness and CoM displacement with changes in feedforward, feedback and eccentric muscle activity of the soleus and vastus lateralis muscles following exercise (r = 0.64-0.98, p < 0.05, large-extremely large correlations), but not with changes in co-contraction (r = 0.11-0.55, p > 0.05, small-large correlations). Following soccer-specific exercise individual changes in feedforward- and reflex-mediated activity of the soleus and vastus lateralis, and not co-contraction around the knee and ankle, modulate changes in CoM displacement and leg stiffness.

Carbohydrate ingestion before and during soccer match play and blood glucose and lactate concentrations.

The ingestion of carbohydrate (CHO) before and during exercise and at halftime is commonly recommended to soccer players for maintaining blood glucose concentrations throughout match play. However, an exercise-induced rebound glycemic response has been observed in the early stages of the second half of simulated soccer-specific exercise when CHO-electrolyte beverages were consumed regularly. Therefore, the metabolic effects of CHO beverage consumption throughout soccer match play remain unclear. To investigate the blood glucose and blood lactate responses to CHOs ingested before and during soccer match play. Crossover study. Applied research study. Ten male outfield academy soccer players (age = 15.6 ± 0.2 years, height = 1.74 ± 0.02 m, mass = 65.3 ± 1.9 kg, estimated maximal oxygen consumption = 58.4 ± 0.8 mL·kg(-1)·min(-1)). Players received a 6% CHO-electrolyte solution or an electrolyte (placebo) solution 2 hours before kickoff, before each half (within 10 minutes), and every 15 minutes throughout exercise. Blood samples were obtained at rest, every 15 minutes during the match (first half: 0-15, 15-30, and 30-45 minutes; second half: 45-60, 60-75, and 75-90 minutes) and 10 minutes into the halftime break. Metabolic responses (blood glucose and blood lactate concentrations) and markers of exercise intensity (heart rate) were recorded. Supplementation influenced the blood glucose response to exercise (time × treatment interaction effect: P ≤ .05), such that glucose concentrations were higher at 30 to 45 minutes in the CHO than in the placebo condition. However, in the second half, blood glucose concentrations were similar between conditions because of transient reductions from peak values occurring in both trials at halftime. Blood lactate concentrations were elevated above those at rest in the first 15 minutes of exercise (time-of-sample effect: P < .001) and remained elevated throughout exercise. Supplementation did not influence the pattern of response (time × treatment interaction effect: P = .49). Ingestion of a 6% CHO-electrolyte beverage before and during soccer match play did not benefit blood glucose concentrations throughout the second half of exercise.

Exposure to hot and cold environmental conditions does not affect the decision making ability of soccer referees following an intermittent sprint protocol.

Soccer referees enforce the laws of the game and the decisions they make can directly affect match results. Fixtures within European competitions take place in climatic conditions that are often challenging (e.g., Moscow ~ −5°C, Madrid ~30°C). Effects of these temperatures on player performance are well-documented; however, little is known how this environmental stress may impair cognitive performance of soccer referees and if so, whether exercise exasperates this. The present study aims to investigate the effect of cold [COLD; −5°C, 40% relative humidity (RH)], hot (HOT; 30°C, 40% RH) and temperate (CONT; 18°C, 40% RH) conditions on decision making during soccer specific exercise. On separate occasions within each condition, 13 physically active males; either semi-professional referees or semi-professional soccer players completed three 90 min intermittent treadmill protocols that simulated match play, interspersed with 4 computer delivered cognitive tests to measure vigilance and dual task capacity. Core and skin temperature, heart rate, rating of perceived exertion (RPE) and thermal sensation (TS) were recorded throughout the protocol. There was no significant difference between conditions for decision making in either the dual task (interaction effects: FALSE p = 0.46; MISSED p = 0.72; TRACKING p = 0.22) or vigilance assessments (interaction effects: FALSE p = 0.31; HIT p = 0.15; MISSED p = 0.17) despite significant differences in measured physiological variables (skin temperature: HOT vs. CONT 95% CI = 2.6 to 3.9, p < 0.001; HOT vs. COLD 95% CI = 6.6 to 9.0, p < 0.001; CONT vs. COLD 95% CI = 3.4 to 5.7, p < 0.01). It is hypothesized that the lack of difference observed in decision making ability between conditions was due to the exercise protocol used, as it may not have elicited an appropriate and valid soccer specific internal load to alter cognitive functioning.

The efficacy of acute nutritional interventions on soccer skill performance.

The use of nutritional ergogenic aids in team sports such as soccer is now commonplace. Aligned with the primary aim of soccer, which is to score more goals than the opposition within the allotted time, the quality of performance of technical actions (i.e., skills) executed during soccer-specific exercise is likely to determine success. However, when seeking to maintain soccer skill performance, information about the efficacy of nutritional interventions is lacking and factors which might modulate the efficacy of such strategies are unclear. This review aimed (i) to systematically evaluate the current research that examines the efficacy of nutritional interventions on soccer skills, and (ii) to provide a qualitative commentary on factors that have the potential to modulate the efficacy of such strategies. Relevant databases (PubMed and SPORTDiscus) were searched up to and including 1 July, 2013 for studies that investigated the efficacy of acute nutritional interventions on soccer skill performances. Overall, 279 records were retrieved. Articles were sequentially excluded from the review based on specific criteria, being: (A) articles that did not report outcomes directly relating to skilled performances in soccer, (B) articles that examined the influence of interventions that were not nutritional in origin and/or were nutritional in origin but provided >3 hours before skill testing commenced, (C) articles that were review papers, and (D) post-acceptance withdrawal of articles methods from database. Articles were independently assessed for the quality of the methods employed based upon the Physiotherapy Evidence Database (PEDro) scale. Records achieving a minimum PEDro score of 5 out of 10 were included in this review. Qualitative appraisal of 13 articles was performed after the application of exclusion criteria and quality assurance processes. The majority (n = 8) of articles examined the influence of carbohydrates on technical performance whereas fewer studies investigated the influence of caffeine ingestion (n = 2) and fluid provision (n = 3). Findings were reported for a total of 171 participants and all but one of the included articles used cross-over study designs. Most participants (94 %) were male, highly trained (reported maximal aerobic capacity range 50-59 ml·kg(-1)·min(-1)) and exercised in temperate environments (reported temperature range 13-25 °C). Six of the eight studies reported that carbohydrates, consumed in the form of a 6-8 % solution of glucose, sucrose or maltodextrin at rates of 30-60 g·h(-1), enhanced at least one aspect of skilled performance over the duration of exercise (75-90 min). Although some evidence exists to support the consumption of caffeine (6 mg·kg(-1) body mass [BM]) and prescribed fluid to preserve skills performed during soccer-specific exercise, findings from the small number of included studies were inconsistent. The outcome measures and methods used to quantify skilled performance were not consistent across studies; consequently, it was not possible to perform meta-analyses to produce pooled effect sizes in this review. The findings from this systematic review suggest that nutritional interventions, which provide carbohydrate, caffeine and fluid, have potential to preserve skills performed under conditions that induce soccer-specific fatigue. The weight of current evidence supports the consumption of carbohydrate, but is less conclusive with respect to caffeine and fluid provision. It is likely that the efficacy of a nutritional intervention will be modulated by factors including the dose consumed, the mode of administration, individual responsiveness to the intervention and interactions with other physiological changes occurring during soccer-specific exercise. Consequently, these factors should be considered when using carbohydrates, caffeine and fluid provision to maintain skilled performances in soccer. Future research should seek to optimise the nutritional strategies employed to maintain technical performance throughout match-play.

Effect of a carbohydrate drink on soccer skill performance following a sport-specific training program

Monitoring personal hydration status as well as examining the contents of sports beverages is crucial to improve physical performance in soccer players. This study examined the effects of 60 minutes of soccer-specific training on skill performance, hydration status, and core temperature (Tc) of soccer players after ingesting either a carbohydrate-containing (CHO) or a carbohydrate-free (CHO-F) drink. This study recruited seven healthy male soccer players (age: 23 ± 2.9 years, height: 1.7 ± 0.04 m, mass: 62.7 ± 6.7 kg), each of whom completed a CHO and a CHO-F trial in a randomized crossover design. The participants underwent skill tests [Loughborough Soccer Passing Test (LSPT)] prior to and after 60 minutes of training in a hot and humid environment (30 °C, 85% relative humidity). They consumed 2 mL of fluid per/kg body mass every 15 minutes during exercise. Blood glucose, blood lactate, and Tc were monitored throughout the exercise session. Improvement was observed in movement time (p = 0.034) and overall LSPT performance (p = 0.031) postexercise in those consuming CHO drinks compared with those consuming CHO-F drinks. No differences were observed in Tc or absolute and relative body mass loss between the trial groups (p > 0.05). Urine output was greater in the CHO trial group (CHO: 0.086 ± 0.051 L; CHO-F: 0.030 ± 0.028 L; p = 0.043). Compared with the consumption of a CHO-F drink, that of a CHO drink during a 60-minute soccer-specific exercise session in a hot and humid climate can improve postexercise skill performance. Additionally, Tc can be regulated efficiently by commencing training in a state of euhydration and by regular ingestion of fluids throughout the exercise period.