Journal of Sport and Health Science最新文献

Background: Iron facilitates key biological functions underpinning sports performance, and up to 60% of female athletes experience iron deficiency. However, the effects of iron deficiency on sports performance in female athletes is unclear, as are the degree of benefits of iron supplementation (FeSup). This study characterizes the effects of iron deficiency and FeSup on sports performance in high-level female athletes.

Methods: Searches of the electronic databases MEDLINE, SPORTDiscus, Web of Science, Scopus, and CINAHL were performed in July 2023. Studies were included that evaluated the effects of iron deficiency or FeSup on sports performance in high-level (maximal oxygen uptake (VO_2max) > 45 mL/kg/min, or trained > 5 h/week) iron deficient (ID) (serum ferritin (sFer) < 40 µg/L) female athletes. Studies were assessed using a modified Downs and Black Quality Assessment Checklist.

Results: A total of 23 studies comprising 669 athletes (age range: 13-47 years) across 16 sports were included in the review. Iron deficiency negatively affects endurance performance by 3%-4%. However, endurance performance improved by 2%-20% when ID athletes were treated with 100 mg/day of elemental iron for up to 56 days via oral supplementation, or bi-daily via parenteral administration over 8-10 days. ID non-anemic athletes with low sFer stores may be predisposed to reduced maximal aerobic capacity. However, maximal aerobic capacity improved by 6%-15% following 16 mg/day-100 mg/day of elemental iron for 36-126 days. Isokinetic strength and anaerobic power performance may be impeded (-23% to +4%) among ID athletes, but the effect of FeSup on anaerobic power varied markedly (-5% to +9%) following 100 mg/day of elemental iron over 42-56 days, or 100 mg of elemental iron bi-daily over 8-10 days. The quality of studies was moderate (77%), ranging from low (57%) to high (100%). Moststudies (n = 18) contained group sizes ≤ 20 athletes, thus limiting the likelihood of detecting significant effects (statistical power > 0.80).

Conclusion: High-level ID female athletes experience a negative impact on endurance performance, which can be improved by supplementing with ∼100 mg of elemental iron per day or bi-daily. The decrements in other performance parameters characterizing a range of sports coincide with the severity of iron deficiency.

Background: While muscle contractility increases with muscle temperature, there is no consensus on the best warm-up protocol to use before resistance training or sports exercise due to the range of possible warm-up and testing combinations available. Therefore, the objective of the current study was to determine the effects of different warm-up types (active, exercise-based vs. passive) on muscle function tested using different activation methods (voluntary vs. evoked) and performance test criteria (maximum force vs. rate-dependent contractile properties), with consideration of warm-up task specificity (specific vs. non-specific), temperature measurement method (muscle vs. skin), baseline temperatures, and subject-specific variables (training status and sex).

Methods: A systematic search was conducted in PubMed/MEDLINE, Scopus, Web of Science, Cochrane, Embase, and ProQuest. Random-effects meta-analyses and meta-regressions were used to compute the effect sizes (ES) and 95 % confidence intervals (95 %CIs) to examine the effects of warm-up type, activation method, performance criterion, subject characteristics, and study design on temperature-related performance enhancement.

Results: The search yielded 1272 articles, of which 33 met the inclusion criteria (n = 921). Increasing temperature positively affected both voluntary (3.7 %/°C ± 1.8 %/°C (mean ± SD), ES = 0.28 (95 %CI: 0.14 to 0.41)) and evoked (3.2 %/°C ± 1.5 %/°C (mean ± SD), ES = 0.65 (95 %CI: 0.29 to 1.00)) rate-dependent contractile properties (dynamic, fast-velocity force production, and rate of force development (RFD)) but not maximum force production (voluntary: -0.2 %/°C ± 0.9 %/°C (mean ± SD), ES = 0.08 (95 %CI: -0.05 to 0.22); evoked: -0.1 %/°C ± 0.8 %/°C (mean ± SD), ES = -0.20 (95 %CI: -0.50 to 0.10)). Active warm-up did not induce greater enhancements in rate-dependent contractile properties (p = 0.284), maximum force production (p = 0.723), or overall function (pooled, p = 0.093) than passive warm-up. Meta-regressions did not reveal a significant effect of study design, temperature measurement method, warm-up task specificity, training status, or sex on the effect of increasing temperature (p > 0.05).

Conclusion: Increasing muscle temperature significantly enhances rate-dependent contractile function (RFD and muscle power) but not maximum force in both evoked and voluntary contractions. In contrast to expectation, no effects of warm-up modality (active vs. passive) or temperature measurement method (muscle vs. skin) were detected, although insufficient data prevented robust sub-group analyses.

Background: Physical activity (PA) is considered beneficial for lowering cardiovascular risks following type 2 diabetes mellitus (T2DM) and prediabetes, but existing evidence relies mainly on self-reported measurements. We aimed to describe the intensity-specific dose-response associations of PA and sedentary behavior (SB) with macrovascular and microvascular events among individuals with T2DM and prediabetes.

Methods: This study included 11,474 individuals with T2DM and prediabetes from the UK Biobank. PA, including total PA, moderate-to-vigorous intensity PA (MVPA), light-intensity PA (LPA), and SB, were measured by accelerometers over 7 days. MVPA was categorized according to the American Diabetes Association guideline-recommended level (at least 150 min/week), and total PA, LPA, and SB were grouped by tertiles. The outcomes were incidences of macrovascular events, microvascular events, heart failure (HF), and their combination (composite events). The events were ascertained using the International Classification of Diseases-10 (ICD-10) codes on the hospital or death records.

Results: During a median follow-up of 6.8 years, 1680 cases were documented, including 969 macrovascular events, 839 microvascular events, and 284 incidents of HF. Accelerometer-measured PA, irrespective of intensity, was inversely associated with the risk of composite events and each outcome in the dose-response patterns. Regarding categorized PA, engagement in total PA (high vs. low) was associated with decreased risk of macrovascular events (hazard ratio (HR) = 0.80; 95% confidence interval (95%CI): 0.67-0.95), microvascular events (HR = 0.76; 95%CI: 0.63-0.93), and HF (HR = 0.46; 95%CI: 0.32-0.66). Adherence to MVPA, but not LPA, above the guideline-recommended level (at least 150 min/week) was associated with reduced risk of macrovascular events (HR = 0.80; 95%CI: 0.68-0.95), microvascular events (HR = 0.76; 95%CI: 0.63-0.92), and HF (HR = 0.65; 95%CI: 0.46-0.92). The minimum dose of MVPA for lowering the risk of composite events was approximately 59.0 min/week. More time spent in SB was associated with an increased risk of composite events (high vs. low, HR = 1.17; 95%CI: 1.02-1.35) and HF (high vs. low, HR = 1.54; 95%CI: 1.09-2.20). Replacement of 30 min of SB (HR = 0.73; 95%CI: 0.65-0.81) and LPA (HR = 0.74; 95%CI: 0.66-0.83) with MVPA dramatically reduced the risk of composite events.

Conclusion: Adherence to a higher amount of accelerometer-measured PA, especially MVPA at least 59 min/week, is associated with reduced risks of macrovascular and microvascular events among individuals with T2DM and prediabetes. Replacement of SB and LPA with MVPA helped lower the risk of diabetic vascular events.

Background: It remains unclear whether the cardiovascular benefits of physical activity (PA) vary across populations with different predicted atherosclerotic cardiovascular disease (ASCVD) risks. This study aimed to determine the modification of predicted cardiovascular risk on the association between PA and ASCVD incidence.

Methods: A total of 94,734 participants without ASCVD in the Prediction for Atherosclerotic Cardiovascular Disease Risk in China (China-PAR) project were included, with a median follow-up of 6.0 years. PA volume (metabolic equivalent of task (MET)-h/day) and intensity (%, percentage of moderate-to-vigorous PA (MVPA)) were assessed by questionnaires. Based on the ASCVD 10-year and lifetime risk prediction scores, participants were classified into low-to-medium-risk and high-risk groups. Hazard ratios (HRs) and 95% confidence intervals (95%CIs) for ASCVD were calculated using Cox proportional hazards models.

Results: During 679,438 person-years of follow-up, 3470 ASCVD events occurred. Higher PA volume was associated with lower ASCVD incidence, which was more pronounced among high-predicted-risk individuals than their low-to-medium-risk counterparts, with HRs (95%CIs) of 0.58 (0.50-0.67) and 0.62 (0.53-0.71) for the highest vs. lowest quartiles of PA volume, respectively. Additionally, analyses for PA intensity showed similar results. Compared with inactive individuals, there was a 32% (95%CI: 25%-38%) and 23% (95%CI: 13%-32%) risk reduction in high- and low-to-medium-risk groups, respectively, when over half of the PA volume was from MVPA. Furthermore, the additive interactions between PA and predicted risk indicated a further risk reduction by increasing PA, especially MVPA, in high-risk individuals.

Conclusion: Engaging in more PA, especially MVPA, reduced the risk of ASCVD incidence, with greater benefits among high-risk individuals. These findings emphasize the imperative for personalized PA recommendations tailored to distinct risk populations-in particular, reinforcing PA guidance for high-risk individuals.