Sports Medicine最新文献

The causes of mental ill health in elite athletes are complex, influenced by socioeconomic and cultural factors. These factors are important in shaping discussions surrounding the mental health of athletes and the design of subsequent interventions to support them. However, such consideration is rare, particularly when considering the mental health of athletes in low- and middle-income countries. Therefore, this Current Opinion draws on behavioural change science and multi-disciplinary expertise in elite sport, medicine, health, psychology, coaching and anthropology in the context of elite runners in Kenya. The material conditions in this country are reflected in the prevalence of poor mental health and treatment availability. We explore the mental health of elite Kenyan runners within this context and provide recommendations surrounding the treatment of mental health conditions in elite sport globally. We conclude that a consensus on the mental health of elite athletes must be informed by contextual factors, including affordability, appropriateness, availability, and accessibility of mental health services relating to local conditions. This context-specific approach could be expanded to mental health in settings other than sport such as youth organisations.

Introduction: Global pregnancy physical activity guidelines recommend most individuals engage in at least 150 min/week of moderate-to-vigorous physical activity. However, exercise beyond these limits has received little investigation and assessment of safety. There is no consensus on safe durations of exercise bouts within the literature, with recommendations ranging from 10 to 60 min.

Objective: The aim was to examine the impact of long-duration endurance exercise (≥ 60 min/session) on maternal-fetal health outcomes.

Methods: A total of 331 participants who engaged in long-duration endurance exercise during pregnancy participated in an online survey.

Results: Participants were aged 33.2 ± 6.1 years and had 2.1 ± 1.2 pregnancies. Subgroup analyses were performed comparing: (1) those who exercised within guidelines, ≤ 300 min/week during the third trimester (T3), and (2) those who exercised above guidelines, > 300 min/week during T3. Participants who exceeded guidelines experienced reduced odds of delivery complications (odds ratio [OR] 0.12, 95% confidence interval [CI] 0.015-0.988, p < 0.05) but increased the odds of diastasis recti abdominis postpartum (OR 4.13, 95% CI 1.059-16.135, p < 0.05).

Conclusion: Exercising > 300 min/week in T3 reduces odds of delivery complications, but increases odds of diastasis recti abdominis postpartum. Endurance exercise > 300 min/week in T3 is generally well tolerated in a highly active population.

Background: The ability to change direction rapidly is crucial for enhancing performance in multidirectional sports. Evidence suggests that several biomechanical variables are associated with faster change of direction (COD) completion times. However, while it is understood that biomechanical factors influence COD performance, the evidence remains unclear because of the diverse range of biomechanical factors, inconsistent findings and potential influences from various moderating factors (e.g. sex, training experience).

Objective: The primary aim of this systematic review was to identify the biomechanical determinants of COD performance while the secondary aim was to examine the impact of moderating factors on the determinants. The findings of this review could assist practitioners in designing effective training and coaching strategies to improve COD performance.

Methods: A systematic literature search was conducted across the electronic databases of Scopus, PubMed, Web of Science, CINAHL, and SPORTDiscus. Studies were considered eligible if they involved healthy participants, considered biomechanical determinants of COD performance via correlational analyses and reported COD performance (i.e. time to completion). The quality of the study was assessed via the Kmet scale while study findings were collated.

Results: A total of 13 studies met the inclusion criteria and analysed 45-180° COD tasks involving 374 participants. Kmet scores ranged from 73 to 96%, indicating good-to-excellent methodological quality of studies. Several biomechanical variables were identified as contributors to quicker COD completion times, including shorter ground contact time, higher approach and exit velocities, increased braking and propulsive forces, greater trunk inclination angle, lower centre-of-mass height, and increased moments and power at the hip, knee and ankle. With respect to moderating factors, included studies utilised various COD tasks (45-180°), examined mostly male participants (79.4%) with inconsistent reporting of playing/training experience and all consisted of a pre-planned COD task only.

Conclusions: Our findings identified several key biomechanical variables that were important determinants of faster COD performance. However, the impact of moderating factors on COD performance was minimally examined in prior studies and requires further investigation. Recommendations are provided in this paper focussing on biomechanical contributors (e.g. ground contact time, approach velocity, braking forces), which may assist coaches with relevant training modalities to enhance COD performance.

Guidelines for aerobic exercise training (AET) often recommend training intensities on the basis of a percentage of peak effort (e.g. %peak heart rate [%HR_peak], %peak oxygen uptake [%VO_2peak]). However, such an approach could be associated with a higher inter-individual variability in acutely induced physiological responses (e.g. blood lactate, HR, VO₂) when compared with threshold-based prescription (i.e. ventilatory threshold [VT] or lactate threshold [LT]). Therefore, we performed a literature review to compare the acute physiological impact of AET prescription based on fraction of the peak effort versus threshold-based exercise prescription (VTs and LTs), and how these prescription options may influence the efficacy of exercise intervention in healthy subjects and patients with cardiovascular risk or disease. Data from cross-sectional studies (15 studies; 5312 participants) indeed reveal a greater inter-individual variance in acute physiological responses to a single exercise (e.g. HR, VO₂, blood lactate) when exercising at the same %HR_peak or % VO_2peak compared with exercising at (a fraction of) VT or LT. Data from randomised exercise intervention studies (3 studies; 135 participants) and a meta-analysis (1544 individuals from 42 studies) show that aerobic exercise prescription based on the percentage of peak effort leads to smaller improvements in VO_2peak and metabolic health when compared with aerobic exercise prescription based on the VTs or LT. These collective findings suggest that threshold-based AET intensity prescription elicit more homogeneous acute physiological responses, and greater VO_2peak improvements. Hence, it is time to move past standard recommendations and implement a threshold-based approach when prescribing the AET intensity.

Background: Handgrip strength (HGS) is an important marker of health. Using allometric scaling, we previously identified that adult HGS should be normalized by a cross-sectional or surface area measure of body size, although it is unclear whether scaling youth HGS by the same body size dimension is appropriate. We therefore aimed to (1) identify the optimal body size dimension(s) to normalize youth HGS for differences in body size and (2) generate norm-referenced values for HGS using the identified body size dimension(s).

Methods: Data were from the National Health and Nutrition Examination Survey (NHANES), a representative sample of the US non-institutionalized civilian population. Exclusions resulted in a final sample of 4816 youth (51.2% male) aged 6-19 years. Handgrip strength was measured using electronic hand dynamometry. Body size dimensions included body mass, height, and waist circumference. Allometry was used to identify the most appropriate dimension(s) associated with HGS. Population-weighted, sex-stratified generalized additive models for location, scale, and shape were used to develop norms by sex and age. Norms were tabulated as percentile values (3rd to 97th) and visualized as smoothed percentile curves.

Results: Predicting HGS using all three body size dimensions (three-dimensional) resulted in collinearity predominantly owing to the presence of waist circumference, prohibiting the use of all three body size dimensions as normalizers. However, collinearity was not an issue when two of the three dimensions (body mass and height) were adopted. Allometry identified a "generalizable" normalizing ratio as HGS_n =  $HGS/({\mathrm{HT}}^2\ast M^{0.333})$ . If only a single body size dimension were available, then HGS should be normalized using height² (i.e., $HGS/{\mathrm{HT}}^2$ ) because height was identified as the strongest single body size dimension associated with HGS. Sex- and age-specific norms for $HGS/({\mathrm{HT}}^2\ast M^{0.333})$ declined from age 6-8 years and progressively increased thereafter.

Conclusions: Allometrically scaling HGS by $({\mathrm{HT}}^2\ast M^{0.333})$ helps normalize strength for body size in population-based youth research.

Hamstring injuries are a major concern in sports owing to their high incidence and recurrence rates, highlighting the need for a deeper understanding of their mechanisms and prevention. This narrative review aims to inform hamstring injury prevention strategies by examining: (1) the causes of hamstring injuries, (2) the effectiveness of eccentric training in reducing injury risk, and (3) muscle adaptations from eccentric training that may offer protective effects. Hamstring injuries often occur during the late swing phase of running, potentially due to insufficient or delayed neural activation or an inability to generate the necessary force to decelerate the leg and resist active overstretching. In this phase, the hamstrings must produce large eccentric forces while operating at long lengths, placing them in a vulnerable position. Despite the potential of eccentric training to induce muscle adaptations that may reduce injury risk, current research has overly focused on architectural changes, particularly resting fascicle lengthening, without adequately exploring how these adaptations influence the functional behavior of hamstrings during exercise. In addition, the lack of research into adaptations of non-contractile and neural elements in the hamstrings following eccentric training represents a significant gap in the literature. This review argues for a broader focus on these underexplored areas to enhance hamstring injury prevention strategies. Further research is essential to fully understand the mechanisms behind muscle fascicle lengthening after eccentric training. Exploring functional and regional differences in hamstring adaptations and delving deeper into non-contractile and neural elements could enhance injury prevention strategies, potentially reducing the incidence of hamstring injuries.

Background

Symptom-limited exercise intolerance is a physiological sign of sport-related concussion. Possible etiologies include rest-induced aerobic deconditioning and/or impaired cardiopulmonary function.

Objective

This study examined cardiovascular and respiratory function at rest and during progressive cycle ergometer exercise in adolescents within 10 days of sport-related concussion compared with non-concussed athletes.

Methods

Concussed participants (n = 26, 15.4 ± 1.1 years, 54% male, 7.3 ± 1.8 days from injury) and control participants (n = 24, 15.8 ± 1.6 years, 58% male) performed the Buffalo Concussion Bike Test. Blood pressure, heart rate, stroke volume, cardiac output, respiratory rate, minute ventilation, oxygen consumption, and end-tidal CO₂ were collected at rest and continuously during exercise.

Results

Concussed participants exercised for 16.24 ± 5.6 min, experienced a greater than 2-point (on a 0–10 scale) exacerbation of their concussion symptoms at their final minute, and reported higher perceived exertion throughout exercise versus controls. Controls exercised for 25.08 ± 7.0 min up to voluntary exhaustion without reporting any concussion-like symptoms. Concussed participants’ cardiovascular and respiratory parameters did not differ at rest versus controls, but concussed participants had higher minute ventilation and their blood pressure plateaued at lower values during the first 10 min of exercise.

Conclusions

No evidence of aerobic deconditioning was found within 10 days of injury. Our study found attenuated cardiopulmonary responses to progressive aerobic exercise, which may be a cause for exercise intolerance in concussed adolescent athletes. Additional research is warranted to determine if this may be related to altered autonomic nervous system regulation.