The demands of the extra-time period of soccer: A systematic review

Influence of Carbohydrate Intake on Different Parameters of Soccer Players' Performance: Systematic Review

BACKGROUND

The objective of this systematic review is to analyze the influence of carbohydrate (CHO) intake on physical and technical aspects, glucose and muscle glycogen levels, fatigue, cognition, and gastrointestinal comfort involved in the performance of soccer players, as well as to examine whether there are any differences between men and women.

METHODS

A bibliographic search was conducted in PubMed, Web of Science, Scopus, and SportDiscus, resulting in 61 selected articles. The PRISMA recommendations and the Cochrane Handbook for Systematic Reviews guidelines were followed.

RESULTS

The results indicate that CHO intake before and during the match improves speed and the number of sprints, attenuates the decrease in shooting accuracy and speed, increases time to fatigue, and enhances cognitive function. There is no consensus on passing, dribbling, jumping, or agility improvements. Glucose levels drop during the first 15 min of the second half without affecting performance.

CONCLUSIONS

It is recommended that players ingest 6-8 g/kg/d of CHO the day before, a meal with 1-3 g/kg 3-4 h before, and 30-60 g/h during the match. Muscle glycogen drops drastically at the end of the match, remaining low at 48 h. Hence, 1-1.5 g/kg/h is recommended during the first 4 h, starting from the first 20 min. Female soccer players have a similar physical demand to men, and energy availability is low, especially in the post-match periods, as they underestimate their energy expenditure and do not consume enough CHO. Therefore, the recommended guidelines should be followed, individualized, and periodized according to each athlete's energy needs.

Effects of Caffeinated Chewing Gum on Exercise Performance and Physiological Responses: A Systematic Review

BACKGROUND

Caffeine intake in the form of chewing gum is characterized by rapid absorption and utilization.

OBJECTIVES

The purpose of this study was to investigate the effects of caffeinated chewing gum on exercise performance and physiological responses in a systematic review.

METHODS

All articles were searched using the PubMed and Scopus databases to include articles published up to June 2024, following the Preferred Reporting Items for Systematic Evaluation and Meta-Analysis (PRISMA) protocol.

RESULTS

Thirty-two studies were finally included. Most studies have found that pre-exercise caffeinated chewing gum supplementation is effective in improving endurance, repetitive sprinting, lower limb strength, and sport-specific performance, as well as lowering rating of perceived exertion (RPE) or fatigue index even with lower dosages of caffeine. Sympathetic activation may be one of the mechanisms by which caffeinated chewing gum affects athletic performance. No significant effect on energy metabolism indicators (blood glucose, blood lactate, free fatty acids) was found. In addition, two studies found that caffeinated chewing gum reduced or maintained cortisol levels and increased testosterone levels. However, caffeinated chewing gum intake does not have an impact on catecholamines and β-endorphins. There have been inconsistent results for explosive performance, agility performance, and pain perception. Only a few studies have examined balance performance. In conclusion, a low dose of caffeine (100-300 mg or 2-4 mg/kg) in the form of chewing gum is rapidly absorbed and utilized, positively impacting most exercise and physiological performance.

CONCLUSIONS

Future studies should also consider the performance variables of agility, pain perception, and explosive performance to gain a more comprehensive understanding of the effects of caffeinated chewing gum on sympathetic activation and exercise performance.

Caffeine Gum Improves Reaction Time but Reduces Composure Versus Placebo During the Extra-Time Period of Simulated Soccer Match-Play in Male Semiprofessional Players

This study aimed to determine whether caffeine gum influenced perceptual-cognitive and physical performance during the extra-time period of simulated soccer match-play. Semiprofessional male soccer players (n = 12, age: 22 ± 3 years, stature: 1.78 ± 0.06 m, mass: 75 ± 9 kg) performed 120-min soccer-specific exercise on two occasions. In a triple-blind, randomized, crossover design, players chewed caffeinated (200 mg; caffeine) or control (0 mg; placebo) gum for 5 min following 90 min of soccer-specific exercise. Perceptual-cognitive skills (i.e., passing accuracy, reaction time, composure, and adaptability) were assessed using a soccer-specific virtual reality simulator, collected pre- and posttrial. Neuromuscular performance (reactive-strength index, vertical jump height, absolute and relative peak power output, and negative vertical displacement) and sprint performance (15 and 30 m) were measured at pretrial, half-time, 90 min, and posttrial. Caffeine gum attenuated declines in reaction time (pre: 90.8 ± 0.8 AU to post: 90.7 ± 0.8 AU) by a further 4.2% than placebo (pre: 92.1 ± 0.8 AU to post: 88.2 ± 0.8 AU; p < .01). Caffeine gum reduced composure by 4.7% (pre: 69.1 ± 0.8 AU to post: 65.9 ± 0.8 AU) versus placebo (pre: 68.8 ± 0.8 AU to post: 68.3 ± 0.8 AU; p < .01). Caffeine gum did not influence any other variables (p > .05). Where caffeine gum is consumed by players prior to extra-time, reaction time increases but composure may be compromised, and neuromuscular and sprint performance remain unchanged. Future work should assess caffeine gum mixes with substances like L-theanine that promote a relaxed state under stressful conditions.

Summarizing physical performance in professional soccer: development of a new composite index

The aims of this study were to create a composite index to measure the overall players' physical performance in professional soccer matches and analyze the effect of individual playing time and positional differences on this composite index. A total of 830 official matches from LaLiga men's first division and Spanish Copa del Rey were analyzed, which resulted in 24,980 match observations collected from 1138 male players (forwards, n = 286; midfielders, n = 441; defenders, n = 411). The physical performance variables, which represent the locomotor demands, were collected using electronic performance tracking systems. A Partial Least-Squares Structural Equation Model (PLS-SEM) was used to measure performance. The PLS-SEM output had three significant latent components, which explained 95% of the initial variability, that were related to the acceleration-specific performance (component 1), high-intensity running-related variables (component 2), and medium intensity actions variables (component 3). Also, a linear regression analysis was used to explore relationships between playing activity time (hours-X axis) and the composite index (10-point scale-Y axis), in which a strong and positive correlation was observed between individual playing time and the composite index (r = 0.76; p < 0.001; R2 = 0.58). Also, significant positive correlations were observed in forwards (r = 0.85; p < 0.001; R2 = 0.74), midfielders (r = 0.80; p < 0.001; R2 = 0.64), and defenders (r = 0.67; p < 0.001; R2 = 0.45). However, significant differences between playing positions with a small effect size (p < 0.05; eta-squared = 0.01) were found. From a practical perspective, this study may serve as a reference for sports performance practitioners to create a composite index that measures the overall players' physical performance. The instructions to create this index are available in the manuscript.

Carbohydrate Nutrition and Skill Performance in Soccer

In soccer, players must perform a variety of sport-specific skills usually during or immediately after running, often at sprint speed. The quality of the skill performed is likely influenced by the volume of work done in attacking and defending over the duration of the match. Even the most highly skilful players succumb to the impact of fatigue both physical and mental, which may result in underperforming skills at key moments in a match. Fitness is the platform on which skill is performed during team sport. With the onset of fatigue, tired players find it ever more difficult to successfully perform basic skills. Therefore, it is not surprising that teams spend a large proportion of their training time on fitness. While acknowledging the central role of fitness in team sport, the importance of team tactics, underpinned by spatial awareness, must not be neglected. It is well established that a high-carbohydrate diet before a match and, as a supplement during match play, helps delay the onset of fatigue. There is some evidence that players ingesting carbohydrate can maintain sport-relevant skills for the duration of exercise more successfully compared with when ingesting placebo or water. However, most of the assessments of sport-specific skills have been performed in a controlled, non-contested environment. Although these methods may be judged as not ecologically valid, they do rule out the confounding influences of competition on skill performance. The aim of this brief review is to explore whether carbohydrate ingestion, while delaying fatigue during match play, may also help retain sport soccer-specific skill performance.

Effects of combined plyometric, strength and running technique training program on change-of-direction and countermovement jump: A two-armed parallel study design on young soccer players

CONTEXT AND OBJECTIVE

Players must be capable to have a good change-of-direction (COD) skill aiming to be the fastest as possible to react immediately to the opponent or even to help players to be more agile since COD is a physical determinant of agility. Thus, the aim of this study was to test the effects of a six-week combined training intervention in the COD and countermovement jump (CMJ) of young soccer players, while comparing with a control group only performing the regular field-based training sessions.

METHODS

A sample of 80 non-professional players (40 experimental group and 40 control group) between the ages of ten and twelve was taken [(Age: 10.70 ± 1.02)]. The tests that were carried out from the beginning to the end of the intervention were: CMJ test, 505COD Test and Illinois Test. Paired sample t-test was used for determining differences as a repeated measures analysis (pre- post). An ANCOVA test was performed using the pretest as a covariate and the times pre and post as factors.

RESULTS AND CONCLUSIONS

Repeated measures ANCOVA revealed significant influence of baseline level on the 5-0-5 COD (p = 0.001; ηp2=0.170), the Illinois (p = 0.018; ηp2=0.070) and the CMJ (p = 0.047; ηp2=0.050). Significant interactions group*time (p < 0.001; ηp2=0.137), 5-0-5 COD (p < 0.001; ηp2=0.274), and CMJ (p < 0.001; ηp2=0.392) were found, while no significant interactions were found in Illinois (p = 0.293; ηp2=0.014). The current research revealed that a combined training intervention consisting of strength training, plyometrics, and running techniques can be significantly beneficial for improving COD performance and CMJ.

The effect of physical activity on sleep disturbance in various populations: a scoping review of randomized clinical trials

BACKGROUND

Promoting physical activity (PA) in different populations experiencing sleep disturbance may increase population PA levels and improve sleep. This scoping review aimed to examine the effect of various PA intervention strategies on sleep across different populations, identify key sleep outcomes, and analyze knowledge gaps by mapping the relevant literature.

METHODS

For this study, we systematically searched articles published till March 2022 from PubMed, Web of Science, Cochrane Library, and Embase databases for randomized clinical trials (RCTs) regarding the effect of physical activity on sleep. Two authors extracted key data and descriptively analyzed the data. Thematic analysis was used to categorize the results into themes by all authors. Arksey and O'Malley's scoping review framework was used to present the findings.

RESULTS

Twenty-one randomized controlled trials out of 3052 studies were finally included with 3677 participants (2852 females (78%)). Five trials were conducted in healthy working-age adults with sleep disturbance but without the diagnosis of insomnia, five in healthy older adults, two in perinatal women, four in patients with cancer, three in mental illness related subjects, and another two in other disease-related areas. PA interventions were diverse, including walking, resistance training, aerobic exercise, housework, water exercise, basketball, smartphone/tablet "apps", web, online videos or wearable actigraphy, and self-determined exercise. Three major themes were identified: (1) Sleep environment may be important to address prior to instituting PA interventions, (2) All types of PA were effective for improving sleep in all populations studied, (3) Self-tolerated PA is safe for improving sleep in the elderly and in co-morbid or perinatal populations.

CONCLUSIONS

PA is effective and safe for improving sleep in both healthy and co-morbid populations with sleep disturbance by increasing daily activity levels using a variety of strategies, even low intensity, such as housekeeping, sit-to-stand repetitions, along with encouraging PA through web pages, videos, and self-goal setting apps. In addition, this scoping review identifies the need for further therapeutic research and future exploration in populations with sleep initiation or sleep maintenance disturbance.

Extended Match Time Exacerbates Fatigue and Impacts Physiological Responses in Male Soccer Players

PURPOSE

This study evaluated how extended match time (90 + 30 min) affected physiological responses and fatigue in male soccer players.

METHODS

Twenty competitive players (mean ± SD: age, 20 ± 1 yr; maximal oxygen uptake, 59 ± 4 mL·min -1 ·kg -1 ) completed an experimental match with their activity pattern and heart rate assessed throughout the game, whereas countermovement jump performance and repeated sprint ability were tested and quadriceps muscle biopsies and venous blood samples were taken at baseline and after 90 and 120 min of match play.

RESULTS

Less high-intensity running (12%) was performed in extra time in association with fewer intense accelerations and decelerations per minute compared with normal time. Peak sprint speed was 11% lower in extra time compared with normal time, and fatigue also manifested in impaired postmatch repeated sprint ability and countermovement jump performance (all P < 0.05). Muscle glycogen declined from 373 ± 59 mmol·kg -1 dry weight (dw) at baseline to 266 ± 64 mmol·kg -1 dw after 90 min, with a further decline to 186 ± 56 mmol·kg -1 dw after extra time ( P < 0.05) and with single-fiber analyses revealing depleted or very low glycogen levels in ~75% of both slow and fast twitch fibers. Blood glucose did not change during the first 90-min but declined ( P < 0.05) to 81 ± 8 mg·dL -1 after extra time. Plasma glycerol and ammonia peaked at 236 ± 33 mg·dL -1 and 75 ± 21 μmol·L -1 after the extra period.

CONCLUSIONS

These findings demonstrate exacerbated fatigue after extra time compared with normal time, which seems to be associated with muscle glycogen depletion, reductions in blood glucose levels, and hyperammonemia. Together, this points to metabolic disturbances being a major part of the integrated and multifaceted fatigue response during extended soccer match play.

Nutritional Intake and Training Load of Professional Female Football Players during a Mid-Season Microcycle

Football (soccer) is a high-intensity intermittent sport with large energy demands. In a repeated-measures design, we analysed the nutritional intake and training load of fourteen female football players (22.50 ± 4.38 y; 57.23 ± 8.61 kg; 164 ± 6.00 cm; 18.33 ± 2.48% of fat mass and 23.71 ± 2.51 kg of muscle mass) competing in the highest female Football Portuguese League across a typical mid-season microcycle. The microcycle had one match day (MD), one recovery session (two days after the MD, MD+2), three training sessions (MD-3, MD-2, MD-1) and two rest days (MD+1). Energy intake and CHO (g.kg.BW−1) intake were lower on the days before the competition (MD+2, MD-3, MD-2 and MD-1 vs. MD; p < 0.05; ES: 0.60−1.30). Total distance, distance covered at high-speed running (HSRD) and the high metabolic distance load (HMLD) were lower on MD+2, MD-3 and MD-1 compared with MD (p < 0.05; ES: <0.2−5.70). The internal training load was lower in all training sessions before the competition (MD+2, MD-3, MD-2 and MD-1 vs. MD; p ≤ 0.01; ES: 1.28−5.47). Despite the small sample size and a single assessment in time, the results suggest that caloric and CHO intake were below the recommendations and were not structured based on the physical requirements for training sessions or match days.

Creatine Supplementation for Muscle Growth: A Scoping Review of Randomized Clinical Trials from 2012 to 2021

Creatine supplementation is the most popular ergonomic aid for athletes in recent years and is used for improving sport performance and muscle growth. However, creatine supplementation is not always effective in all populations. To address these discrepancies, numerous studies have examined the use of creatine supplementation for muscle growth. This scoping review aimed to investigate the effects of creatine supplementation for muscle growth in various populations, in which Arksey and O'Malley's scoping review framework is used to present the findings. For this study, we performed a systematic search of the PubMed, Embase, and Web of Science databases for theses and articles published between 2012 and 2021. A manual search of the reference lists of the uncovered studies was conducted and an expert panel was consulted. Two reviewers screened the articles for eligibility according to the inclusion criteria. Methodological quality was assessed using the National Heart, Lung and Blood Institute's (NHLBI's) quality assessment tool. A total of 16 randomized controlled trials (RCTs) were finally included. All the authors extracted key data and descriptively analyzed the data. Thematic analysis was used to categorize the results into themes. Three major themes related to muscle growth were generated: (i) subjects of creatine supplementation-muscle growth is more effective in healthy young subjects than others; (ii) training of subjects-sufficient training is important in all populations; (iii) future direction and recommendation of creatine supplementation for muscle growth-injury prevention and utilization in medical practice. Overall, creatine is an efficient form of supplementation for muscle growth in the healthy young population with adequate training in a variety of dosage strategies and athletic activities. However, more well-designed, long-term RCTs with larger sample sizes are needed in older and muscular disease-related populations to definitively determine the effects of creatine supplementation on muscle growth in these other populations.

The effects of collagen peptide supplementation on body composition, collagen synthesis, and recovery from joint injury and exercise: a systematic review

Collagen peptide supplementation (COL), in conjunction with exercise, may be beneficial for the management of degenerative bone and joint disorders. This is likely due to stimulatory effects of COL and exercise on the extracellular matrix of connective tissues, improving structure and load-bearing capabilities. This systematic review aims to evaluate the current literature available on the combined impact of COL and exercise. Following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, a literature search of three electronic databases—PubMed, Web of Science and CINAHL—was conducted in June 2020. Fifteen randomised controlled trials were selected after screening 856 articles. The study populations included 12 studies in recreational athletes, 2 studies in elderly participants and 1 in untrained pre-menopausal women. Study outcomes were categorised into four topics: (i) joint pain and recovery from joint injuries, (ii) body composition, (iii) muscle soreness and recovery from exercise, and (iv) muscle protein synthesis (MPS) and collagen synthesis. The results indicated that COL is most beneficial in improving joint functionality and reducing joint pain. Certain improvements in body composition, strength and muscle recovery were present. Collagen synthesis rates were elevated with 15 g/day COL but did not have a significant impact on MPS when compared to isonitrogenous higher quality protein sources. Exact mechanisms for these adaptations are unclear, with future research using larger sample sizes, elite athletes, female participants and more precise outcome measures such as muscle biopsies and magnetic imagery.

The Effect of Contextual Variables on Match Performance across Different Playing Positions in Professional Portuguese Soccer Players

This study investigated the position-specific physical demands of professional Portuguese players. The effects of situational variables on the physical performance demands were also analysed (match location, match half and match result). Match performance observations were collected using Global Navigation Satellite System devices across 11 matches during a competitive season (2019-2020). Data were analysed according to five playing positions: goalkeepers (n = 11), central defenders (n = 42), wide defenders (n = 31), central midfielders (n = 34), open attackers (n = 28), and centre forwards (n = 14). Central midfield players completed the greatest total distance (10,787 ± 1536 m), while central defenders covered the least distance (9272 ± 455; p < 0.001). Open attackers covered the greatest high and very-high-speed distance (1504 ± 363 m), number of high-speed decelerations per match (11 ± 4) and were the fastest players (30.6 ± 1.5 km/h), along with center forwards (30.6 ± 2.0 km/h), versus all other positions (p < 0.05). Greater distances were performed in teams that were winning (9978 ± 1963 m) or drawing (10,395 ± 875 m) versus losing (9415 ± 2050) p = 0.036 and p = 0.006, respectively. Increases in distance covered at walking speeds were observed during the 2nd half (1574 ± 179 m) compared with the 1st half (1483 ± 176; (p < 0.003). A higher number of decelerations across all speeds were performed in the 1st half (144 ± 39) versus the 2nd half (135 ± 37). The distance covered in home matches (10,206 ± 1926 m) far exceeded away matches (9471 ± 1932 m; p < 0.001). The number of faster accelerations were higher in away (7 ± 5) versus home matches (6 ± 4; p < 0.049). The data demonstrate the different physical demands of each playing position and suggest that situational variables influence physical performance. These findings suggest position-specific physical training is required to condition players for the bespoke demands of each playing position.