The biomechanics of soccer: A review

Abstract

The purpose of this investigation was to determine whether combining two mental preparation strategies would be more effective in enhancing performances than a single strategy. Subjects (n = 40) practiced on a basketball free throw task (20 shots) using one of the following mental preparation strategies: (a) imagery, (b) relaxation, (c) relaxation plus imagery, (d) placebo control. To simulate game conditions, subjects were allowed only 10 s in which to use their mental preparation strategy. After the practice session, subjects shot 20 test free throws using their designated technique. Results indicated a significant main effect with the imagery group performing significantly better than the placebo control group although there were no specific differences between the three experimental groups. The results are discussed in terms of potential variables mediating the effectiveness of imagery in enhancing sport performance, and future directions for research are offered.     

Measurement properties and feasibility of the Loughborough soccer passing test: A systematic review

The purpose of this paper was to systematically review the literature and examine the research methodological quality, measurement properties and feasibility of the Loughborough Soccer Passing Test (LSPT). Databases were searched up to June 2017. Twenty five studies fulfilled the eligibility criteria. The main methodological limitations of the studies were the small sample size and the lack of information on participants and eligibility criteria. Results showed that test-retest reliability of the LSPT was moderate to excellent. Good discriminative validity was found between playing levels and ages. The LSPT was positively correlated with sprint, dribbling, and agility test; however, a weak correlation was established with in-game performance. Test responsiveness (an ability to detect change over time) to some external interventions was observed in studies. Adjusted Cronbach’s alpha (α = 0.67), smallest worthwhile change (SWC = 0.8–3.8) and minimal detectable change (MDC₅₀ = 1.9–11.3) were calculated based on available data. The findings indicate that the LSPT has acceptable test-retest reliability and discriminative validity. However, it may not be a feasible and effective way to interpret the intra-individual change of skill performance in practice. Future work should be undertaken to establish additional measurement properties of the LSPT, and to improve its practical feasibility.     

A systematic review of drop-out from organized soccer among children and adolescents

Bronfenbrenner’s bioecological model of human development was used as a framework to systematically review factors associated with drop-out from soccer among children and adolescents. Keyword searches for the population (child or youth or adolescent), sport (soccer or football) and construct of interest (drop-out or attrition or discontinued or quit) identified scholarly peer-reviewed publications from the entire contents of seven databases to 31 December 2013. Publications with participants at any level of organized soccer were eligible for inclusion. The initial search identified 137 studies with 14 ultimately meeting the inclusion criteria, 11 from Europe and 3 from the United States, and 97% (n = 1125,001) of study participants were male. The proportion of children and adolescents who dropped out from one season to the next ranged from 18 to 36%, except for one study of high-level players where the rate of drop-out was 60%. These players felt the time demands of soccer, especially ‘travelling to compete’, were onerous. Prominent person-level factors associated with drop-out were lower perceptions of competence and the lack of fulfilment of basic psychological needs. Contextual factors associated with drop-out were poor relationships with teammates or coaches, lack of enjoyment, lack of opportunity to play, competing time demands, and later birthdate in relation to competitive year. Interactions between the individual and their environment were rarely examined. Future research on drop-out from soccer would benefit from expanding the demographics of those being studied and by concurrently examining interactions between the individual and the environment.     

The yips in sport: A systematic review

ABSTRACT

The yips are a psycho-neuromuscular movement disorder, which affects sports in which fine motor precision skills are required for success. This review aims to examine key components of the yips within sport literature using a systematic approach. Twenty-five published studies were used in the systematic review, the majority of which focused on the yips in golf (n = 18); case studies were the most popular methodological approach (n = 12). Four components of the yips were identified: psychological, physiological, neurological and performance. This review describes evidence associated with each component according to research design, sample characteristics and main findings. Key findings associated with each component are evaluated and gaps within the existent literature are highlighted. It is concluded that future research incorporates a multi-discipline theory-driven approach on a wider range of sports using a more precise definition of yips types in order to enhance our understanding of the predictors and mechanisms of the yips which, in turn, will allow practitioners to develop effective interventions for athletes.     

Effects of plyometric jump training in female soccer player’s vertical jump height: A systematic review with meta-analysis

ABSTRACT

To assess the effects of plyometric jump training (PJT) in female soccer player’s vertical jump height, a review was conducted using the data sources PubMed, MEDLINE, Web Of Science and SCOPUS. Only peer-review articles were included. To qualify for inclusion in the meta-analysis, studies must have included (i) a PJT programme of at least 2 weeks, (ii) cohorts of healthy female soccer players with no restriction for age, (iii) a control group, (iv) a measure of countermovement jump (CMJ). The inverse variance random-effects model for meta-analyses was used. From 7,136 records initially identified through database searching, 8 were eligible for meta-analysis, comprising 9 training groups (n = 99) and 9 control groups (n = 94). The magnitude of the main effect was moderate (ES = 1.01 [95%CI = 0.36–1.66], Z = 3.04, p = 0.002). Sub-group analyses were performed (i.e., PJT frequency, duration and total number of sessions), revealing no significant subgroup differences (p = 0.34–0.96). Among the studies included in this review, none reported injury or other adverse effects. In conclusion, PJT is effective in female soccer players for the improvement of vertical jump height. In future, research must identify specific dose–response relationships following PJT, particularly in the long term.     

The measurement of proprioceptive accuracy: A systematic literature review

Background:Proprioceptive accuracy refers to the individual’ s ability to perceive proprioceptive information,that is,the information referring to the actual state of the locomotor system,which originates from mechanoreceptors located in various parts of the locomotor system and from tactile receptors located in the skin.Proprioceptive accuracy appears to be an important aspect in the evaluation of sensorimotor functioning;however,no widely accepted standard assessment exists.In this systematic ...     

Golf-related injuries: A systematic review

Abstract

A review was undertaken to assess the prevalence of musculoskeletal injuries in golf and to stimulate the discussion on possible injury mechanisms. The main conclusion of most published studies is that although professional and amateur golfers show a similar anatomical distribution of injuries by body segment, differences tend to be seen in the ranking of injury occurrence by anatomical site. This could be due to many things, including the player's handicap, age, golf swing biomechanics, and training or playing habits. The impact of golf injuries deserves special attention due to the interaction of the nature of the injury, practice routines, amount of practice, handicap, and frequency of activity. Individual differences and clinical and coaching procedures deserve investigation. Other epidemiological information should be regarded as insufficient with respect to a full understanding of injury mechanisms, which can give us a better insight into the evolutionary nature of the injury. Also, a better understanding of golf swing mechanisms and individual neuromuscular aspects can help explain why some individuals are more injury-prone than others.     

Fatigue in soccer: a brief review

This review describes when fatigue may develop during soccer games and the potential physiological mechanisms that cause fatigue in soccer. According to time-motion analyses and performance measures during match-play, fatigue or reduced performance seems to occur at three different stages in the game: (1) after short-term intense periods in both halves; (2) in the initial phase of the second half; and (3) towards the end of the game. Temporary fatigue after periods of intense exercise in the game does not appear to be linked directly to muscle glycogen concentration, lactate accumulation, acidity or the breakdown of creatine phosphate. Instead, it may be related to disturbances in muscle ion homeostasis and an impaired excitation of the sarcolemma. Soccer players' ability to perform maximally is inhibited in the initial phase of the second half, which may be due to lower muscle temperatures compared with the end of the first half. Thus, when players perform low-intensity activities in the interval between the two halves, both muscle temperature and performance are preserved. Several studies have shown that fatigue sets in towards the end of a game, which may be caused by low glycogen concentrations in a considerable number of individual muscle fibres. In a hot and humid environment, dehydration and a reduced cerebral function may also contribute to the deterioration in performance. In conclusion, fatigue or impaired performance in soccer occurs during various phases in a game, and different physiological mechanisms appear to operate in different periods of a game.     

Coping in sport: A systematic review

The aim of this paper was to systematically review the literature on coping in sport, examining evidence for both the trait and process perspectives, the types of coping strategies used by athletes, gender differences, age-related differences, and coping effectiveness. A comprehensive literature search of SPORTdiscus, PsychLIT, and PsychINFO in November 2004 yielded 64 studies spanning 16 years (1988 - 2004). The results indicated that athletes use a variety of coping strategies. Forty-six papers supported or adopted the process perspective (Lazarus, 1999; Lazarus & Folkman, 1984). There were also gender and age-related differences. Evidence was found to support three of the different models of coping effectiveness (goodness-of-fit approach, choice of coping strategy, and automacity). Based on this evidence, future research should address some of the methodological and measurement limitations of the sport psychology coping literature. In particular, prospective research designs that minimize the time delay between recall and the stressful experience are required to assess how coping changes over time. More attention to developmental issues to guide the formulation of sport-specific models to enhance our theoretical understanding is also required. Finally, coping effectiveness should be examined both in the short and long term, as a greater understanding of coping effectiveness has the potential to make a significant impact on applied practice.     

Influence of technical instructions on the physiological and physical demands of small-sided soccer games

Abstract

The aim of the present study was to examine the effects of changes in the number of ball contacts allowed per individual possession on the physiological, technical, and physical demands within small-sided games in elite soccer. Twenty international players (age 27.4±1.5 years, body mass 79.2±4.2 kg, height 1.81±0.02 m, velocity at [Vdot]O_2max 17.4±0.8 km ·h^?1, percent body fat 12.7±1.2%) performed three different small-sided game formats (i.e. 2 vs. 2; 3 vs. 3; 4 vs. 4) on three different occasions in which the number of ball contacts authorized per possession was fixed (one touch, two touches, and free play). The relative pitch per player ratio was similar for all small-sided games. The small-sided games were performed with four support players (placed around the perimeter of pitch) with instructions to keep possession of the ball. The total duration of the small-sided games was the effective time of play. The physical demands, technical requirements, heart rates, post-exercise blood lactate concentrations, and ratings of perceived exertion (RPE) were assessed. The percentages of successful passes and numbers of duels were significantly lower when the small-sided game was played with one touch (P<0.001), whereas the number of balls lost increased (P<0.001 for 2 vs. 2 and 3 vs. 3; P<0.01 for 4 vs. 4). The small-sided game played with one touch also induced increases in blood lactate concentration and RPE, as well as greater physical demands in the total distance covered in sprinting and high-intensity runs. In conclusion, the main findings of this study are that by altering the number of ball contacts authorized per possession in small-sided games, the coach can manipulate both the physical and technical demands within such games.     

Loneliness and physical activity: A systematic review

This article aims to provide an overview of the current state of research on the relationship between loneliness and physical activity (PA). A systematic literature search was conducted to identify all empirical studies assessing this relationship. A total of 37 studies stemming from 36 publications met the inclusion criteria. Study analyses comprised an individual consideration of each study and a systematic summarization of the studies. The majority of eligible studies focused on adolescent or elderly populations. Direct negative associations between PA and loneliness were found in half of the 24 cross-sectional studies. Of the seven identified longitudinal studies, one found a direct negative influence of PA on loneliness. Four longitudinal studies found evidence for a reverse influence, namely of loneliness on PA. Five intervention studies found PA to reduce loneliness. Two of the cross-sectional studies and one of the intervention studies found social support and social competence to moderate or to mediate the relationship between PA and loneliness. The findings indicate that PA can contribute to a decrease in loneliness. However, studies also indicate that any beneficial effect is dependent upon the quality of relationships present during physical activity. Additionally, loneliness itself might reduce the probability of being physically active.     

Choking interventions in sports: A systematic review

ABSTRACT

Choking under pressure describes suboptimal sport performance in stressful situations, which has led to two fundamental ‘choking’ models: distraction and self-focus. The purpose of this review was to provide an overview of empirical studies that have tested interventions used to alleviate choking. The systematic review includes 47 empirical studies published up to April 2017, including experimental, quasi-experimental, and single-case studies with athletes. These studies encompassed a variety of interventions (n?=?13) that were either distraction based or self-focus based. In addition, a third group – acclimatisation interventions – was identified. The results indicate that, in general, choking interventions based on both choking models and on acclimatisation provide a benefit to performance under pressure. The most reported effective interventions were pre-performance routines, quiet eye training, left-hand contractions, and acclimatisation training. The use of dual task was beneficial for performance under pressure but harmful when used in training. Mixed evidence was found for analogy learning, and null effects were reported for goal setting, neurofeedback training, and reappraisal cues. These results may help athletes and coaches select and implement effective strategies and methods to improve performance under pressure.     

The physical demands of professional soccer goalkeepers throughout a week-long competitive microcycle and transiently throughout match-play

ABSTRACT

The physical demands of English Premier League soccer goalkeepers were quantified during training and match-play in a two-part study. Goalkeeper-specific micromechanical electrical systems (MEMS) devices, profiled training and match-day activities throughout one competitive week (n=8; part A). Changes in MEMS-derived outputs were also profiled throughout match-play (100 matches; n=8, 18±14 observations per goalkeeper; part B). In part A, goalkeeping-training elicited the most dives (51±11) versus all activities (all p≤0.030) except shooting-training (p=0.069). Small-sided games elicited the fewest (5±3) dives (all p≤0.012). High-speed distance covered in match (103±72 m) was similar to goalkeeping-training (p=0.484), while exceeding shooting-training, small-sided games, pre-match shooting, and pre-match warm-up (all p=0.012). Most changes of direction (34±12) and explosive efforts (70±18) occurred during goalkeeping-training, with values exceeding match (both p=0.012). In part B, between-half reductions in total distance, but increased high-speed changes of direction and explosive efforts, occurred (both p≤0.05). Excluding the number of high jumps, all variables differed from 0-15-min during at least one match epoch, with more dives (1.3±1.4 vs 1.0±1.1) and explosive efforts (2.5±2.4 vs 2.0±1.8) performed between 75-90-min versus 0-15-min (all p<0.05). These data highlight the differing physical demands of various activities performed by professional soccer goalkeepers throughout a competitive week.     

Health benefits of Kung Fu: A systematic review

Abstract

The Chinese martial arts (Kung Fu) have existed for centuries and are generally accepted as being beneficial for health without much empirical data. The aim of this systematic review was to assess the health effects of “hard” Kung Fu styles by performing electronic and manual searches of the literature. The aspects of health and the Kung Fu style examined varied between most studies; in some cases, the martial art group consisted of practitioners of other martial art styles also. Of 2103 references identified, only nine papers were eligible and reviewed. All were observational studies, observing a range of health aspects possibly related to Kung Fu training or performance. Our findings suggest that there is no evidence that Kung Fu practice is associated with the prevention or treatment of any health condition. However, as a moderate- to high-intensity form of aerobic exercise, it may confer benefits similar to those attributed to other aerobic training modalities. However, this hypothesis remains to be tested in clinical trials. Physiological benefits (e.g., aerobic capacity and bone density) may be associated with long-term Kung Fu practice. Future research in this area should adopt experimental designs, clearly identifying eligibility criteria, testing and training protocols, and include health-related outcomes and documentation of adverse events, to advance knowledge in this field.     

Fundamental motor skills: A systematic review of terminology

The three aims of this systematic review are to describe: (1) use of the term fundamental motor/movement skills (FMS) in published articles; (2) the quality of definitions; and (3) relative use of process- and product- oriented assessments to measure FMS. The inclusion criteria included: (a) peer-reviewed article, (b) printed in English, (c) published between January 2000 and 31 December 2015, (d) presence of either the term “fundamental motor or movement skill” in the title and/or abstract, and (e) FMS were a measured outcome. There has been an increase in the number of publications on FMS in recent years, with the majority of studies conducted in Australia (n = 41, 33%). Approximately 24% of studies (n = 30) did not provide any explicit definition of FMS. A majority of studies reported the use of process-oriented measures (n = 98, 79%) compared to product-oriented measures (n = 23, 19%), and few studies used both (n = 6, 5%). We recommend that researchers provide: (1) an operational definition of FMS that states FMS are the “building blocks” (or similar terminology) of more advanced, complex movements; (2) specific categories of skills that compose FMS; and (3) at least one specific example of a FMS.     

The prevalence of urinary incontinence in nulliparous female sportswomen: A systematic review

Urinary incontinence is the complaint of involuntary loss of urine and is a social and hygienic problem. While pregnancy and delivery have been described as etiological factors, observational studies show that urinary incontinence is also prevalent in nulliparous female athletes. Therefore, the general belief that physically fit women have stronger pelvic floor muscles preventing them from developing urinary incontinence may be questioned. The aim of this study was to systematically review studies investigating the prevalence of urinary incontinence in nulliparous female athletes. The electronic databases Medline, Embase, Cinahl, and Cochrane Library were systematically searched for eligible studies. Two independent researchers assessed the quality of the included studies and extracted the data in a standardised data extraction spreadsheet. Twenty-three studies were included in this systematic review. The urinary incontinence prevalence measured during sport activity varied from 5.7% to 80%. Urinary incontinence prevalence differs based on the type of sport. Trampolinists were found to have the highest prevalence of urinary incontinence. The findings suggest that urinary incontinence occurs often in female athletes, especially those involved in high impact sports. Future studies should investigate the mechanisms by which high impact sport activities may affect pelvic floor muscles leading to the development of urinary incontinence.     

The psychology of elite cycling: a systematic review

This systematic review sought to synthesise what is currently known about the psychology of elite cycling. Nine electronic databases were searched in March 2017 for studies reporting an empirical test of any psychological construct in an elite cycling sample. Fourteen studies (total n = 427) met inclusion criteria. Eight studies were coded as having high risk of bias. Themes extracted included mood, anxiety, self-confidence, pain, and cognitive function. Few studies had similar objectives meaning that in many instances findings could not be synthesised in a meaningful way. Nevertheless, there was some cross-study evidence that elite cyclists have more positive mood states (relative to normative scores), pre-race anxiety impairs performance (among male cyclists), and associative strategies are perceived as helpful for pain management. Among single studies coded as having low risk of bias, evidence suggests that implicit beliefs affect decision making performance, elite cyclists are less susceptible to mental fatigue (than non-elite cyclists), and better leadership skills relates to greater social labouring. Limitations include non-standardisation of measures, lack of follow-up data, small sample sizes, and overall poor research quality. The findings of this systematic review might be used to inform research and theory development on the psychology of elite endurance cycling.     

Biomechanical determinants of cross-country skiing performance: A systematic review

ABSTRACT

Cross-country skiing is a complex endurance sport requiring technical skills, in addition to considerable physiological and tactical abilities. This review aims to identify biomechanical factors that influence the performance of cross-country skiers. Four electronic databases were searched systematically for original articles in peer-reviewed journals addressing the relationship between biomechanical factors (including kinematics, kinetics, and muscle activation) and performance while skiing on snow or roller skiing. Of the 46 articles included, 22 focused exclusively on the classical technique, 18 on the skating technique, and six on both. The indicators of performance were: results from actual or simulated races (9 articles); speed on specific tracts (6 articles); maximal or peak speed (11 articles); skiing economy or efficiency (11 articles); and grouping on the basis of performance or level of skill (12 articles). The main findings were that i) cycle length, most often considered as a major determinant of skiing speed, is also related to skiing economy and level of performance; ii) higher cycle rate related with maximal speed capacity, while self-selected cycle rate improves skiing economy at sub-maximal speeds; iii) cross-country skiing performance appears to be improved by joint, whole-body, ski, and pole kinematics that promote forward propulsion while minimizing unnecessary movement.     

Sport event legacy: A systematic quantitative review of literature

The study of sport event legacies has grown rapidly since 2000 across a number of disciplines related to planning and hosting large-scale sport events. However, to date, there have been limited attempts to systematically review and synthesise extant sport event legacy research, reflect on existing knowledge, and identify key gaps for future research. In this article, the authors reviewed the state of sport event legacy research through a systematic quantitative review of 305 original, peer-reviewed research articles published in English language journals between 2000 and 2016. Results demonstrate that a small group of academics concentrated in particular countries are driving the publication of studies on sport event legacy in predominately specialised sport and event journals. There is a clear research interest in legacy outcomes realised through hosting sport events in areas of public life, politics, and culture, as well as mass participation sport. The authors identify key areas for future research and make recommendations for empirical research designs to progress scholarship and better inform policy and practice pertaining to sport event legacy.     

Physiological demands of top-class soccer refereeing in relation to physical capacity: effect of intense intermittent exercise training

To examine the activity profile and physiological demands of top-class soccer refereeing, we performed computerized time-motion analyses and measured the heart rate and blood lactate concentration of 27 referees during 43 competitive matches in the two top Danish leagues. To relate match performance to physical capacity and training, several physiological tests were performed before and after intermittent exercise training. Total distance covered was 10.07 - 0.13 km (mean - s x ), of which 1.67 - 0.08 km was high-intensity running. High-intensity running and backwards running decreased (P ? 0.05) in the second half. Mean heart rate was 162 - 2 beats· min -1 (85 - 1% of maximal heart rate) and the mean blood lactate concentration was 4.9 - 0.3 (range 1.7-14.0) mmol·l -1 . The amount of high-intensity running during a match was related to the Yo-Yo intermittent recovery test ( r 2 = 0.57; P ? 0.05) and the 12 min run ( r 2 = 0.21; P ? 0.05). After intermittent training ( n = 8), distance covered during high-intensity running was greater (2.06 - 0.13 vs 1.69 - 0.08 km; P ? 0.05) and mean heart rate was lower (159 - 1 vs 164 - 2 beats· min -1 ; P ? 0.05) than before training. The results of the present study demonstrate that: (1) top-class soccer referees have significant aerobic energy expenditure throughout a game and episodes of considerable anaerobic energy turnover; (2) the ability to perform high-intensity running is reduced towards the end of matches; (3) the Yo-Yo intermittent recovery test can be used to evaluate referees' match performance; and (4) intense intermittent exercise training improves referees' performance capacity during a game.