Sports Medicine - Open最新文献

Background: Previous research has demonstrated a relationship between modifiable (e.g. hamstring strength, muscle fascicle length and high-speed running load), non-modifiable factors (e.g. age, previous injury) and hamstring strain injury (HSI) risk. However, these factors have mostly been assessed in isolation and no study to date has investigated the associations between running load, strength and muscle architecture with HSI risk. The study aim was to explore the interactions between modifiable HSI risk factors that are commonly assessed within elite Australian footballers.

Methods: A prospective cohort study design. Eccentric knee flexor strength and biceps femoris long head (BFlh) fascicle lengths were measured in 299 unique elite-level Australian Football players (age 24 ± 4 years, height 188 ± 8 cm, and weight 87 ± 9 kg) during two pre-seasons. Data from wearable micro-sensor units (high-speed running at ≥ 24k/hr and total distance) were collected over two seasons of elite Australian Football.

Results: Across 408 player-seasons there were 67 HSIs (16.4%), which took an average of 17 ± 10 days and 23 ± 12 days to return to full training and competitive matches, respectively. Univariate analysis showed that BFlh pennation angle (OR 1.6, 95% CI 1.2-2.2), fascicle length (OR 0.6, 95% CI 0.5-0.9), weekly high-speed running distance (OR 1.7, 95% CI 1.2-2.4), weekly change in total distance (OR 1.5, 95% CI 1.1-2.2) and weekly change in high-speed running distance (OR 1.6, 1.2-2.2) were significantly different between the injured and uninjured group (P < 0.05). Combining strength and architectural variables of BFlh pennation angle, fascicle length and peak force was able to explain 12% of variance in the risk of sustaining a HSI. The addition of running load exposure variables of weekly distance and change in weekly distance to the multivariate model increased the explained variance to 20%.

Conclusion: Combining measures of running load exposure with hamstring strength and architecture, increases the variance explained by multivariate models for determining HSI risk. Despite this, there was still approximately 80% of unexplained variance in sustaining a HSI in this study.

Background: Intermittent hypoxia (IH) has emerged as a promising strategy to enhance physical performance by eliciting adaptive responses across cardiovascular, respiratory, and muscular systems. Various IH protocols have been applied in both trained and untrained individuals to improve aerobic capacity, strength, and repeated sprint ability. However, the growing number of systematic reviews and meta-analyses (SRs/MAs) has led to heterogeneous conclusions due to variability in populations, protocols, and outcome measures. This umbrella review aimed to synthesize and critically appraise the available SRs/MAs on the effects of IH protocols on physical performance across different fitness levels.

Methods: A systematic search, aligned with the PRIOR (Preferred Reporting Items for Overviews of Reviews) guidelines, was conducted across seven electronic databases (PubMed/MEDLINE, Web of Science, Cochrane Database of Systematic Reviews, Scopus, Embase, PsycINFO, and SciELO) from inception to June 2025. Eligible studies included systematic reviews (SRs) with or without meta-analyses (MAs) or network meta-analyses (NMAs) evaluating the effects of intermittent hypoxia protocols on physical performance. Methodological quality was assessed using the AMSTAR-2 tool.

Results: A total of 22 systematic reviews (14 with meta-analyses, 3 with network meta-analyses) analyzing 487 primary studies and 5,333 participants were included. Intermittent hypoxia (IH) protocols improved both aerobic and anaerobic performance, as well as muscular strength. Live high-train low (LHTL) and live low-train high (LLTH) protocols consistently enhanced V̇O₂max, especially when combined with sea-level training. Anaerobic-focused strategies like repeated sprint training in hypoxia (RSH) and RSH induced by voluntary hypoventilation at low lung volume (RSH-VHL) led to improvements in sprint-fatigue resistance and glycolytic capacity. Intermittent hypoxic interval training (IHIT) and high-intensity interval training (HIIT) under hypoxia showed robust aerobic benefits. However, the magnitude of these effects varied depending on the type of protocol, training status, and hypoxic dose.

Conclusion: IH is an effective and adaptable strategy to improve aerobic and anaerobic performance, as well as to enhance muscle strength and hypertrophy. These benefits often occur without consistent hematological changes. Future studies should focus on individualized approaches, standardization of terminology, and precise quantification of both hypoxic exposure and training load to optimize outcomes and ensure reproducibility.

Review registration: This overview was registered on the International Database of Systematic Review Protocols (PROSPERO ID: CRD42024465481).

Background: Generic neuromuscular assessments are widely used to monitor training responses in team sports. Emerging running-based measures have been proposed to offer greater sensitivity to residual neuromuscular training effects by aligning more closely with the exercise dose, yet their practical utility remains ambiguous. Concurrent evaluation is thus necessary to identify athlete monitoring assessments that best capture meaningful responses.

Objectives: We examined within-athlete relationships among common training response measures and their associations with prior weekly external training load in professional Australian Football athletes.

Design: Repeated-measures, observational.

Methods: Forty-three male athletes were regularly assessed over two pre-seasons following 48-hours of no training. Outcome measures were derived from maximal performances in adductor strength and countermovement jump (CMJ) assessments, the final minute of a continuous-fixed submaximal fitness test (CF-SMFT: 3-minutes, 12 km⋅h^-1), and the plateau-phase of a high-intensity intermittent-fixed run (HI-IR_plateau: 50 m, ~ 25 km⋅h^-1). External loads were derived from Global Navigation Satellite Systems. Repeated-measures correlations assessed relationships between the response measures, while linear mixed-effects models evaluated measurement variability. Generalised Additive Models examined associations between prior weekly external training loads and the response measures.

Results: Adductor strength and CMJ measures showed low within-athlete variability (coefficient of variation, CV = 4.3-6.6%) and limited associations with weekly external loads. Conversely, 2 standard deviation (SD) increases in weekly total distance were associated with reductions in CF-SMFT HR_ex of - 1.3%-points (95% Confidence Intervals, CI: - 0.9, - 1.8), and as large as - 3.2%-points. Similarly, 2 SD increases in very-high speed running (> 25 km.h^-1) were associated with declines in HI-IR_plateau velocity of - 0.4 km·h^-1 (95% CI: - 0.1, - 0.8), and as much as - 1.2 km·h^-1. Both effects exceeded thresholds of practical significance, as indicated by the typical error of measurement. Accelerometer-vector measures presented inconsistent associations.

Conclusions: Weekly external load changes were reflected in CF-SMFT HR_ex and HI-IR_plateau velocity, supporting their practical utility for athlete monitoring; whereas measures derived from generic neuromuscular tests (adductor strength, and CMJ) showed limited responsiveness. Associations between external loads and accelerometer-derived measures presented significant uncertainty, which currently limits confident recommendations on the utility of these emerging techniques.

Background and aims: The impact of physical activity during early-life is significant on long-term health outcomes. The aim of this study was to determine what factors contribute to the continuity or change in activity behaviors over time.

Methods: Out of 21,700 children born on Oct 1st, 1997 to Oct 1st, 1999, 17,055 (78.6%) were included in ABIS (All Babies in southeast Sweden) of whom 16,415 participants were included in this longitudinal prospective population-based birth cohort. Logistic regression was conducted to assess associations between the activity score and independent variables, with results presented as odds ratios, 95% confidence intervals, p values, and correlation coefficients (r values).

Results: At age 3, high physical activity (Q2) was correlated to: living in a house (r = 0.881, p = 0.003) with both parents (r = 0.833, p < 0.001), ≥1 siblings (r = 0.876, p < 0.001), having a dog (r = 0.773, p < 0.001), high parental education (r = 0.817, p < 0.001) and parents working part time (0-50%) (r = 0.496, p < 0.001). These factors were persistent at age 5, 8, 10-12 years. Participation in sports had strong correlation with Q2 from age 8- to 17-23-years (r = 0.763, p < 0.001). Less physical activity (Q1) was correlated to: at age 3 parental less education (r = 0.816, p < 0.001) with full time work (r = 0.816, p < 0.001), no siblings (r = 0.835, p = 0.004), child lives in split custody (r = 0.736, p < 0.001), and mother smoking (r = 0.789, p = 0.032). These patterns seemed persistent at age 5, 8, 10-12 years with Q1. Lower parental smoking was associated to higher physical activity in children.

Conclusion: The study identifies key factors affecting children and adolescents' physical activity, providing insights for targeted interventions.

The notion that problems with prediction can be resolved with more, and better, data has a long history. In this paper, we examine the role of chance and randomness (i.e., events where there is a low probability of occurrence) in athlete development, focusing on the influence of 'luck' on this process. More specifically, we briefly summarize the way luck has been considered in previous research on human achievement and how different types of luck (i.e., luck related to elements of the task, the athlete development environment, and biological processes) can affect athlete development. In addition, the implications and challenges of embracing the influence of luck on models of athlete development are discussed. Acknowledging the role of luck may lead to developmental environments that are more equitable (e.g., by creating greater opportunities for more individuals to get lucky) and realistic (i.e., by acknowledging that predictions of sport- and athlete-related outcomes will never be perfect).

Background: Sport-related concussions (SRCs) have emerged as a global health concern in sports medicine. Effective injury prevention programs have the potential to reduce the risk of SRCs, but, their efficacy remains inconclusive. Therefore, the aim of this systematic review and meta-analysis was to evaluate the efficacy of injury prevention programs in preventing SRCs and to examine whether different intervention types (physical- vs. educational-based) and athletic exposure context (practice vs. match) influenced the efficacy of interventions.

Methods: Six databases (PubMed, CINAHL, MEDLINE, SPORTDiscus, Scopus, and Embase databases) were searched in March 2024. Studies were included if (1) the physical training or educational intervention aimed to prevent SRC, (2) the incidence rate (IR) or other outcome data sufficient to calculate the IR for both the intervention and control groups were reported, and (3) the study employed a prospective design.

Results: A total of eight studies were included in the analysis, involving 2571 participants (intervention group: n = 1281; control group: n = 1290). Current injury prevention programs primarily targeted male athletes in rugby, American Football, and soccer. The analysis revealed a significant reduction in SRC rate among athletes who received injury prevention programs (incidence rate ratio = 0.66, 95% CI [0.50-0.85], p = .002). The moderator analysis indicated that neither the type of intervention nor the exposure context significantly influenced the efficacy of the injury prevention programs.

Conclusions: SRC prevention programs provided a significant protection effect, reducing injury rates by 34%. Importantly, their efficacy remains consistent across both physical training and educational-based programs, as well as in various exposure contexts. However, further prospective studies are needed to develop injury prevention protocols specifically for females and to investigate factors that may influence the efficacy of these interventions to enhance the prevention of SRC across various sports.

Background: Although handgrip strength (HS) is a useful indicator of various diseases, no study has yet investigated the effects of various influencing factors on HS over time. This study aims to analyze the spatiotemporal variation of relative HS, and its influencing factors, across diverse population groups in China.

Methods: Five national physical fitness surveys encompassing 831,878 adults aged 20-69 years were conducted in China from 2000 to 2020. Trained personnel recorded relative HS. A Bayesian spatiotemporal hierarchical model was employed to illustrate the spatiotemporal characteristics of HS, while a geodetector model assessed the impact and interaction of socioeconomic levels, living environments, and geographical factors on relative HS over time.

Results: From 2000 to 2020, the average relative HS in China declined, with a more pronounced decrease in men than women and among younger individuals relative to middle-aged and older counterparts. Spatial analysis revealed significant heterogeneity, with HS hot spots primarily in southern regions (excluding Tibet) and cold spots in the north. The 20-year decline in relative HS was primarily characterized by a more substantial decrease in individuals with initially higher HS. Before 2010, HS differences were primarily attributed to geographic factors, whereas post-2010, the influence of socioeconomic factors increased.

Conclusions: There is a need to address the greater decline of HS in men and especially in young individuals. China should implement targeted interventions in specific regions to mitigate the rapid decline in HS, taking into consideration diverse regional socioeconomic factors.

Background: Underpowered study designs undermine the reliability of experimental research, with growing concerns regarding randomised controlled trials (RCTs) informing musculoskeletal injury management. We assessed the statistical power and sample size calculations of such RCTs.

Methods: Electronic searches (MEDLINE and PEDro searched up to March 2024) identified meta-analyses of RCTs comparing conservative interventions for musculoskeletal injury, without restrictions on demographics, injury type, or outcome. Statistical power was estimated using two approaches: (1) meta-analytic-the RCT's power to detect the summary effect of the meta-analysis it contributed to, and (2) conventional-the RCT's power to detect Cohen's small (d = 0.2), medium (d = 0.5), and large (d = 0.8) effect sizes. The RCTs' manuscripts and registry entries were screened for sample size planning details.

Results: The search identified 4737 articles, with 41 eligible meta-analyses of 266 RCTs. The median power was 42% (54% among RCTs within statistically significant meta-analyses). Less than 1 in 3 RCTs from statistically significant meta-analyses had ≥ 80% power to detect the corresponding summary effect. The number of RCTs with ≥ 80% power to detect small, medium, and large effects was 0%, 7.9%, and 37.6%, respectively. One in four RCTs reported sample size calculations; 80% expected larger effects than they observed. RCTs not reporting sample size calculations were smaller and reported larger effects.

Conclusion: Low statistical power permeates musculoskeletal injury research, limiting the clinical utility of many RCTs. The underlying causes of low power in this field are multifactorial and extend beyond sample size calculation alone. Enhancing study power requires methodological improvements, including robust planning, stronger theoretical frameworks, multi-center collaboration, data sharing, and the use of valid, reliable outcome measures.

Background: Cross-education (CE) of strength refers to strength gains in the untrained limb after unilateral resistance training. Despite the long-standing recognition of this phenomenon, its potential implications in clinical and rehabilitation settings have only been studied extensively in recent decades.

Main body: The implementation of unilateral resistance training in early-stage sports rehabilitation remains underrated, likely due to the lack of consensus on evidence-based guidelines. Thus, this narrative review provides a current overview of the CE of strength, analyzes its practical implications for sports rehabilitation, and examines the training modalities and parameters that should be modulated to optimize CE adaptations, thereby supporting early intervention against post-injury neuromuscular decline.

Conclusions: Unilateral resistance training in the healthy limb appears to represent a cost-effective and accessible rehabilitation strategy for athletes who are unable to work on their injured limb from the early stages of rehabilitation. This strategy may ensure the maintenance of muscle strength levels in the trained limb while minimizing neuromuscular decline in the injured and immobilized limb. CE of strength may be implemented as an addition to traditional early-stage rehabilitation strategies, such as pain, swelling, and inflammation reduction, the progressive restoration of joint range of motion, and the progressive strength training in sports injury rehabilitation. Further research is required to make definitive recommendations.