Sports Medicine - Open最新文献

Background: There has been an increasing interest in the development and prevention of sports injuries from a complex dynamic systems perspective. From this perspective, injuries may occur following critical fluctuations in the psychophysiological state of an athlete. Our objective was to quantify these so-called Early Warning Signals (EWS) as a proof of concept to determine their explanatory performance for injuries. The sample consisted of 23 professional youth football (soccer) players. Self-reports of psychological and physiological factors as well as data from heart rate and GPS sensors were gathered on every training and match day over two competitive seasons, which resulted in an average of 339 observations per player (range = 155-430). We calculated the Dynamic Complexity (DC) index of these data, representing a metric of critical fluctuations. Next, we used this EWS to predict injuries (traumatic and overuse).

Results: Results showed a significant peak of DC in 30% of the incurred injuries, in the six data points (roughly one and a half weeks) before the injury. The warning signal exhibited a specificity of 95%, that is, correctly classifying non-injury instances. We followed up on this promising result with additional calculations to account for the naturally imbalanced data (fewer injuries than non-injuries). The relatively low F₁ we obtained (0.08) suggests that the model's overall ability to discriminate between injuries and non-injuries is rather poor, due to the high false positive rate.

Conclusion: By detecting critical fluctuations preceding one-third of the injuries, this study provided support for the complex systems theory of injuries. Furthermore, it suggests that increasing critical fluctuations may be seen as an EWS on which practitioners can intervene. Yet, the relatively high false positive rate on the entire data set, including periods without injuries, suggests critical fluctuations may also precede transitions to other (e.g., stronger) states. Future research should therefore dig deeper into the meaning of critical fluctuations in the psychophysiological states of athletes.

Key points: Complex Systems Theory suggests that sports injuries may be preceded by a warning signal characterized by a short window of increased critical fluctuations. Results of the current study showed such increased critical fluctuations before 30% of the injuries. Across the entire data set, we also found a considerable number of critical fluctuations that were not followed by an injury, suggesting that the warning signal may also precede transitions to other (e.g., healthier) states. Increased critical fluctuations may be interpreted as a window of opportunity for the practitioner to launch timely and targeted interventions, and researchers should dig deeper into the meaning of such fluctuations.

Background: Extended Reality (XR) technologies, such as Virtual Reality (VR) and 360°VR are growing rapidly in the scientific literature and sporting practice. These have been used for a range of skills, particularly perceptual-cognitive skills. However, to our knowledge, there is no systematic scoping review on this topic identifying the current state of play of the research area by characteristics such as study type, technology type, or sport investigated, and such a review would help guide the future direction of this area. Therefore, this study aimed to systematically review the extent of XR technology in sport for assessing and training athletes' and officials' perceptual-cognitive skills.

Methods: Electronic databases (SCOPUS, Web of Science, SPORTDiscus, PsycINFO) were searched for relevant articles up until January 2024. Studies were included if they used XR technologies to assess or develop sport-specific, higher order perceptual-cognitive skills.

Results: 57 studies met the inclusion criteria for this review, of which 67% were published from 2020. Most studies conducted quantitative research designs, with 66% of studies adopting a cross-sectional assessment approach and 28% conducting an intervention to assess performance improvements. Decision-making was the most prevalent skill investigated, across 60% of studies. The most common technology was head mounted display (51%) presenting animated environments and the most common sports investigated were football and handball (32% and 19% of studies, respectively).

Conclusions: This review highlights a significant growth in the research exploring XR technologies in sport for perceptual-cognitive skill development and understanding, with most studies published in the last 4 years. Prominent technology types (e.g. animated HMD), perceptual-cognitive skills (e.g. decision making), study designs (e.g. quantitative assessment), and sports (e.g. football) are identified and discussed along with practical implications and future research.

Key points: Extended reality technologies for sports perceptual-cognitive skills is an emerging field, marked by key trends in the types of technology used and the perceptual-cognitive skills being studied. Decision-making is the most commonly studied perceptual-cognitive skill, and these technologies report to have high representativeness and engagement when being used. More research is required to explore the effectiveness of this technology through intervention study designs, and further understand how it can be used and the perceptual-cognitive processes through qualitative research designs.

Background: The presence of inter-limb asymmetry in the human body has traditionally been perceived to be detrimental for athletic performance. However, a systematic review addressing and comprehensively assessing the association of asymmetry between the lower limbs and middle- and long-distance running performance-related metrics is currently lacking.

Objective: The main purpose of this systematic review was to examine the relationship between lower inter-limb asymmetry and determinants of running performance in healthy middle- and long-distance runners. The secondary objective was to identify possible avenues for further research in this area.

Methods: PubMed, Web of Science and SPORTDiscus were systematically searched for studies investigating the relationship between lower inter-limb asymmetry and (determinants of) running performance in healthy and injury-free middle- and long-distance runners. The quality of studies eligible for inclusion was assessed using the Downs and Black Quality Index Tool.

Results: Out of 4817 articles screened, 8 studies were included in this review which assessed the association between functional, morphological, kinematic and kinetic asymmetry and running performance-related metrics. The quality score of the included research varied between 5/10 and 9/10. Our results revealed mixed findings, showing both significant negative (n = 16) and positive (n = 1) associations as well as no significant associations (n = 30) between inter-limb asymmetry and running performance-related metrics.

Conclusions: A high heterogeneity across study methods and outcomes was apparent, making it difficult to draw a straightforward conclusion. Our results indicate that the majority of metrics of functional, morphological, kinematic and kinetic inter-limb asymmetry are negatively or not associated with running performance (and/or its determinants). Thus, a more extensive high-quality body of research using standardised asymmetry magnitude metrics is essential to determine whether, and to what extent asymmetry between the lower limbs could affect middle- and long-distance running performance. Future studies should establish potential trade-off values to help practitioners develop evidence-based training programs.

Key points: In the majority of the metrics, the magnitude of lower inter-limb asymmetry was negatively or not associated with middle- and long-distance running performance. Coaches, athletes and researchers should be attentive of the task, time- and metric-specificity as well as the inter- and intra- individual variability of magnitude outcomes, when assessing inter-limb asymmetries.

Background: Climbing places high loads through the hands and fingers, and climbers may benefit from specific finger strength training (hangboarding) protocols. The purpose of this study was to evaluate the effect of a 10-minute low intensity hangboard finger strengthening protocol ("Abrahangs"), compared with the generally accepted Max Hangs protocol for training maximal grip strength.

Methods: We retrospectively evaluated the change in grip strength and Strength: Weight following Max Hangs, Abrahangs, or the two protocols performed concurrently in rock climbers who used the Crimpd app to log their training. Users who had completed two finger strength tests within a 4-16-week period were included. Climbers were grouped by the number of training sessions into: "Climbing Only", "Abrahangs Only", "Max Hangs Only" and "Both" Max Hangs and Abrahangs.

Results: Frequent low intensity finger loading was as effective at improving grip strength in climbers as training with maximal loads. Additionally, combining low intensity and maximal load training resulted in additive strength gains.

Conclusions: These results suggest that low-intensity long duration holds provide a promising training paradigm for training finger strength that is gentle enough to incorporate into existing training programs.

Background: Despite the high prevalence of disordered eating and eating disorders amongst elite athletes, it remains unclear whether risk factors and psychological processes align with those in the general population or if there are unique sport-factors associated with heightened risk. This cross-sectional study investigated if sport-specific factors (including pressures and psychological processes) explained additional variance in elite athletes' disordered eating symptoms, controlling for established population-general risk factors. Current elite athletes (N = 178, 72.4% female, mean age = 23.9, standard deviation age = 7.0) completed online surveys assessing disordered eating, body dissatisfaction, perfectionistic traits, population-general and sport-specific pressures, as well as general (thin-ideal, muscular-ideal) and athlete-specific (drive for leanness for performance, athletic identity) psychological processes.

Results: Disordered eating was highly prevalent, with 78.2% of athletes reporting at least moderate risk, 46.4% at least high risk, and 20.6% very high risk. Controlling for demographic covariates and population-general pressures, sport-specific pressures explained significant additional variance (13.5%) in disordered eating. Even when controlling for perfectionistic traits, greater weight pressures in sport (β = .35) was uniquely associated with greater disordered eating. In a separate multivariate analysis controlling for covariates and general psychological processes, athlete-specific psychological processes explained significant additional variance (15.5%) in disordered eating. Even when controlling for body dissatisfaction, greater drive for leanness for performance (β = .17) and athletic identity (β = .13) were uniquely associated with greater disordered eating.

Conclusions: These findings support evidence that elite athletes may experience dual pressures and psychological processes associated with disordered eating: those congruent with appearance-oriented models and others independent of appearance. This duality should be considered in the modification of interventions for disordered eating in elite athletes.

Key points: 1. Disordered eating was highly prevalent in a sample of 178 elite adult athletes, with 78.2% reporting at least moderate risk for having related symptoms or behaviours. 2. Greater weight pressures in sport was significantly associated with greater disordered eating, even when controlling for demographic covariates and population-general appearance-related pressures from family and the media. 3. Both appearance-based (drive for thinness, body dissatisfaction) and non-appearance (drive for leanness for performance, athletic identity) psychological processes were uniquely associated with greater disordered eating.

Background: Most studies on injuries of professional dancers used a medical-attention and/or time-loss definition and did not analyse all health problems. Further, almost all studies included just one company. The aim was to analyse all self-reported health problems of professional ballet and contemporary dancers during one season and compare sexes and five companies in Germany.

Methods: Dancers of five professional companies completed weekly health questionnaires during the season (September 2022 to June 2023). Numerical rating scales were used for severity of all health problems, musculoskeletal pain, impairment of the ability to dance at full potential, physical and mental workload in the previous seven days. If the severity of all health problems were rated greater than "0", the dancers were asked to report the type and consequences of their most severe health problem.

Results: During 43 weeks, 98 dancers (39.8% male) completed 3123 weekly reports (response rate 74.1%). The season prevalence of any health problem was 100% and of time-loss health problems 74.5%. The average weekly prevalence of any health problem was 62.7%, of musculoskeletal pain 83.4% and of impaired ability to dance at full potential, due to health problem 48.6%. While the season prevalence and type of health problems was similar between sexes, the average weekly prevalence of severe health problems was higher in female than in male dancers (Chi² = 23.2; p < .001), and female dancers saw a qualified health professional more often than male dancers (Chi² = 19.5; p < .001). Companies differed in almost all investigated variables, with more health problems in companies where more dancers rated their workload higher than "ideal".

Conclusion: Health problems are frequent in professional dancers and affect their ability to dance. Future studies should analyse the impact of physical and mental workload on health problems.

Background: Throwing velocity is an important research topic in sports science, and it is an essential performance variable for athletes in overarm-throwing sports like baseball, team handball, water polo, softball, and cricket. The aim of the present review was to investigate the effect of specific strength training on throwing velocity for overarm throws.

Methods: The literature was analysed using the Preferred Reporting Items for Systematic reviews and Meta-analyses, searching in SPORTDiscus and MEDLINE. Seventeen studies were included in this review, and the training studies were divided into four categories: (a) overweight and underweight balls, (b) forearm loading, (c) pulley device training, and (d) strength training with a resistance band.

Results: All strength training studies with resistance band and the forearm loading categories increased the throwing velocity, varying from 3.7 to 26%. However, only half of these studies found that training was associated with a significantly higher increase versus the control group. Findings were inconsistent in other categories.

Conclusion: Based on the findings of the present review, no clear conclusion can be made on which of the specific strength training methods is best for increasing throwing velocity. However, some recommendations can be offered. Firstly, the throwing training period should be long enough (≥ 6 weeks) with a high enough workload. Throwing training with a resistance band increases throwing velocity significantly for junior and less experienced overarm-throwing athletes. Furthermore, throwing with underweighted balls of similar size will ensure a positive effect on throwing velocity. Also, throwing training with combined over- and underweighted balls can be used if the overweighted balls are carefully selected to ensure there is no negative impact on throwing kinematics and injuries. For the other categories, the results were conflicting. Furthermore, due to the low number of studies in the pulley device and forearm loading categories, more studies should be conducted to investigate their effects on throwing velocity.