Sports Medicine最新文献

Sports-related concussions (SRCs) are a major health issue in athletes of varying ages, ability levels, and sports. Concerns over the short- and long-term consequences of SRCs have incentivized a wealth of products and policies aimed at reducing SRC risk. Research suggesting the effectiveness of such interventions at reducing SRCs has facilitated their adoption by sports organizations and, in some cases, product commercialization. However, the body of SRC mitigation research is almost entirely devoid of placebo or sham groups, which raises important questions about the true clinical effectiveness of these interventions. This Current Opinion explores the plausibility of placebo effects within the scope of SRC prevention, describes why the lack of placebo/sham groups in the current body of literature is problematic, and provides recommendations for including placebo/sham groups in future SRC research.

Background

Although many studies have demonstrated a lower incidence of sudden cardiac arrest or death (SCA/D) in female athletes than in male, there is limited understanding of the specific underlying causes.

Objective

This systematic review aimed to assess the disparities in SCA/D incidence between male and female competitive athletes and explore the associated etiologies.

Methods

A comprehensive search was conducted for retrospective and prospective studies examining SCA/D incidence in male and female athletes. Incidence and incidence rate ratios (IRRs) according to sex were evaluated.

Results

Among the 16 studies analyzed, 1797 cases of SCA/D were observed; 1578 occurred in males (87.81%). Ages ranged from adolescent to adult. The incidence was 1.42/100,000 athlete-years (AY) in males (95% CI 0.97–2.09), and 0.32/100,000 AY in females (95% CI 0.17–0.59), resulting in an IRR of 5.55. When considering athletes aged ≤ 35 years, the incidence was 1.46/100,000 AY in males (95% CI 0.91–2.34) and 0.30/100,000 AY in females (95% CI 0.14–0.66), with an IRR of 5.47. The IRR was 5.13 (95% CI 3.94–6.67) for the most recent studies with athletes enrolled only after the year 2000, versus 6.02 (95% CI 4.59–7.90) for the remaining studies covering all observed years. Hypertrophic cardiomyopathy (HCM) was the predominant cause among males (45.12%), while congenital coronary anomalies were more prevalent in females (33.04%).

Conclusion

The incidence of SCA/D in females was approximately 6 times lower than in males, with sex differences also in the leading causes of SCA/D. Understanding these discrepancies could lead to targeted strategies for the prevention of SCD in athletes.

Registration number

(PROSPERO 2023 CRD42023432022)/05.07.2023.

The force-length relationship is usually obtained for isometric contractions with maximal activation, but less is known about how sarcomere length affects force during submaximal activation. During submaximal activation, length-dependent alterations in calcium sensitivity, owing to changes in cross-bridge kinetics (rate of attachment and/or detachment), result in an activation-dependent shift in optimal length to longer sarcomere lengths. It is known that sarcomere length, as well as temperature and phosphorylation of the regulatory light chains of myosin, can modify Ca²⁺ sensitivity by altering the probability of cross-bridge interaction. This altered calcium sensitivity is particularly important for submaximal force levels, as it can change the shape of the length dependence of force, with peak force occurring at sarcomere lengths longer than those associated with maximal filament overlap. In athletic contexts, contractions typically do not reach maximal intensity. Therefore, understanding that the ability to produce force under both maximal and submaximal conditions can differ, and that peak force can be generated at different lengths, could influence the development of targeted training regimens optimal for each sport.

Background: The actions required to achieve higher-quality and harmonised global surveillance of child and adolescent movement behaviours (physical activity, sedentary behaviour including screen time, sleep) are unclear.

Objective: To identify how to improve surveillance of movement behaviours, from the perspective of experts.

Methods: This Delphi Study involved 62 experts from the SUNRISE International Study of Movement Behaviours in the Early Years and Active Healthy Kids Global Alliance (AHKGA). Two survey rounds were used, with items categorised under: (1) funding, (2) capacity building, (3) methods, and (4) other issues (e.g., policymaker awareness of relevant WHO Guidelines and Strategies). Expert participants ranked 40 items on a five-point Likert scale from 'extremely' to 'not at all' important. Consensus was defined as > 70% rating of 'extremely' or 'very' important.

Results: We received 62 responses to round 1 of the survey and 59 to round 2. There was consensus for most items. The two highest rated round 2 items in each category were the following; for funding (1) it was greater funding for surveillance and public funding of surveillance; for capacity building (2) it was increased human capacity for surveillance (e.g. knowledge, skills) and regional or global partnerships to support national surveillance; for methods (3) it was standard protocols for surveillance measures and improved measurement method for screen time; and for other issues (4) it was greater awareness of physical activity guidelines and strategies from WHO and greater awareness of the importance of surveillance for NCD prevention. We generally found no significant differences in priorities between low-middle-income (n = 29) and high-income countries (n = 30) or between SUNRISE (n = 20), AHKGA (n = 26) or both (n = 13) initiatives. There was a lack of agreement on using private funding for surveillance or surveillance research.

Conclusions: This study provides a prioritised and international consensus list of actions required to improve surveillance of movement behaviours in children and adolescents globally.

Background: The growing interest in how exercise and carbohydrate (CHO) restriction may modify molecular responses that promote endurance adaptations has led to many interesting controversies.

Objective: We conducted a systematic review and a meta-analysis regarding the effect of low-carbohydrate availability (LOW) pre-, during, or post-exercise, on the mRNA content of commonly measured genes involved in mitochondrial biogenesis (PGC-1α, TFAM mRNA) and metabolism (PDK4, UCP3 and GLUT4 mRNA), and on muscle glycogen levels, compared with a high-CHO (CON) condition.

Methods: MEDLINE, Scopus, and Web of Science databases were searched following the PRISMA 2020 guidelines (with an end date of November 2023). In total, 19 randomized-controlled studies were considered for inclusion. We evaluated the methodological quality of all studies using the Cochrane Risk of Bias tool for randomized clinical studies. A meta-analysis was performed using a random effects model to calculate the standardized mean difference (SMD), estimated by Hedges' g, and 95% confidence intervals (CIs).

Results: The LOW condition was associated with an increased mRNA content of several genes during the early recovery period post-exercise, such as PDK4 (SMD 1.61; 95% CI 0.80-2.42), GLUT4 (SMD 1.38; 95% CI 0.46-2.30), and UCP3 (SMD 2.05; 95% CI 0.40-3.69). However, overall, there was no significant effect on the mRNA content of PGC-1α or TFAM. Finally, CHO restriction and exercise significantly reduced muscle glycogen levels (SMD 3.69; 95% CI 2.82-5.09). A meta-analysis of subgroups from studies with a difference in muscle glycogen concentration of > 200 mmol kg dw^-1 between the LOW and CON conditions showed an increase in exercise-induced PGC-1α mRNA (SMD 2.08; 95% CI 0.64-3.52; p = 0.005; I² = 75%) and a greater effect in PDK4 and GLUT4 mRNA.

Conclusion: The meta-analysis results show that CHO restriction was associated with an increase in the exercise-induced mRNA content of PDK4, UCP3, and GLUT4, but not the exercise-induced mRNA content of PGC-1ɑ and TFAM. However, when there were substantial differences in glycogen depletion between CON and LOW CHO conditions (> 200 mmol kg dw^-1), there was a greater effect of CHO restriction on the exercise-induced mRNA content of metabolic genes, and an increase in exercise-induced PGC-1α mRNA.

Background

Antarctic expeditions, although supported by scientific knowledge, face various challenges, with little research conducted to explore the physical demands that explorers experience.

Objective

To summarise physiological, psychological, body composition and nutritional changes faced during trek expeditions in the Antarctic’s continental portion.

Design

Systematic review.

Information sources

We used PubMed, SPORTDiscus, PsycINFO, Scopus, Cochrane databases, CINAHL and Medline Ovid to search for studies published up to January 2023.

Eligibility criteria

We included original articles or case reports published in English and in peer-reviewed journals, involving both sexes, using both quantitative and qualitative approaches, that considered Antarctic continent expedition, as well as solo exploration/group exploration. Animal studies, in vitro studies, explorers < 18 years of age, overwintering at research stations, tourist/organized visits to Antarctica or the South Pole, not sleeping on the ice, and ultraendurance events were excluded. The JBI critical appraisal checklist for case studies was used for quality assessment.

Results

A total of 12 studies met the eligibility criteria. The main findings are reversible changes in bone density and mineral content. Despite high-calorie intake (5000 kcal/day or more), participants experienced body weight loss and a decrease in appetite-regulating hormones. Motivation and goal orientation, positive interpersonal communication and support are important skills during polar expeditions. Multidisciplinary research revealed various physiological and cognitive responses, disrupted sleep patterns and mood changes.

Conclusion

Prolonged hypobaric hypoxia reduces aerobic capacity and increases anaerobic metabolism, while bone density changes are reversible and weight loss occurs despite high-calorie intake. Effective decision-making, teamwork and personal growth are crucial for Antarctic explorers. Future studies need to investigate strategies on how to improve physiological functions while maintaining homeostasis.

Registration

PROSPERO—CRD42022382609.