Sex differences in pacing during half-marathon and marathon race

ABSTRACT

The main aim of the present study was to examine differences in pacing between half-marathon and marathon in men and women. A total of 17,525 finishers in the marathon (n = 4807 men; n = 1278 women) and half-marathon race (n = 7624 men; n = 3816 women) in Vienna 2017 were considered. Their pacing was assessed through five race segments (0–23.7%, 23.7–47.4%, 47.4–71.1%, 71.1–94.8% and 94.8–100%) of the race. Compared to marathon (where absolute average change of speed [ACS] was 5.46% and 4.12% in men and women, respectively), a more even pacing was observed in half-marathon in both sexes (ACS = 3.60% and 3.36% in men and women, respectively). The more even pacing in women previously observed in marathon races was verified in half-marathon, too. However, the sex difference in pacing was smaller in half-marathon than in marathon. Since men and women endurance runners participate in both races, sport practitioners would have great benefit from these results since they could establish sex-based personalized race strategies and training programmes.     

Physical fitness in children with Developmental Coordination Disorder: Measurement matters

Children with Developmental Coordination Disorder (DCD) experience considerable difficulties coordinating and controlling their body movements during functional motor tasks. Thus, it is not surprising that children with DCD do not perform well on tests of physical fitness. The aim of this study was to determine whether deficits in motor coordination influence the ability of children with DCD to perform adequately on physical fitness tests. A case–control study design was used to compare the performance of children with DCD (n = 70, 36 boys, mean age = 8y 1mo) and Typically Developing (TD) children (n = 70, 35 boys, mean age = 7y 9mo) on measures of isometric strength (hand-held dynamometry), functional strength, i.e. explosive power and muscular endurance (Functional Strength Measurement), aerobic capacity (20 m Shuttle Run Test) and anaerobic muscle capacity, i.e. muscle power (Muscle Power Sprint Test). Results show that children with DCD were able to generate similar isometric forces compared to TD children in isometric break tests, but were significantly weaker in three-point grip strength. Performance on functional strength items requiring more isolated explosive movement of the upper extremities, showed no significant difference between groups while items requiring muscle endurance (repetitions in 30 s) and items requiring whole body explosive movement were all significantly different. Aerobic capacity was lower for children with DCD whereas anaerobic performance during the sprint test was not. Our findings suggest that poor physical fitness performance in children with DCD may be partly due to poor timing and coordination of repetitive movements.     

High-intensity interval training for health benefits and care of cardiac diseases——The key to an efficient exercise protocol

Aerobic capacity, which is expressed as peak oxygen consumption(VO_(2peak)), is well-known to be an independent predictor of all-cause mortality and cardiovascular prognosis. This is true even for people with various coronary risk factors and cardiovascular diseases. Although exercise training is the best method to improve VO_(2peak), the guidelines of most academic societies recommend 150 or75 min of moderate-or vigorous-intensity physical activities, respectively, every week to gain health benefits. For general health and primary and secondary cardiovascular prevention, high-intensity interval training(HIIT) has been recognized as an efficient exercise protocol with short exercise sessions. Given the availability of the numerous HIIT protocols, which can be classified into aerobic HIIT and anaerobic HIIT [usually called sprint interval training(SIT)],professionals in health-related fields, including primary physicians and cardiologists, may find it confusing when trying to select an appropriate protocol for their patients. This review describes the classifications of aerobic HIIT and SIT, and their differences in terms of effects, target subjects, adaptability, working mechanisms, and safety. Understanding the HIIT protocols and adopting the correct type for each subject would lead to better improvements in VO_(2peak) with higher adherence and less risk.     

Production and consumption of methane in freshwater lake ecosystems

The atmospheric concentration of methane (CH₄), a major greenhouse gas, is mainly controlled by the activities of methane-producing (methanogens) and methane-consuming (methanotrophs) microorganisms. Freshwater lakes are identified as one of the main CH₄ sources, as it was estimated that they contribute to 6-16% of natural CH₄ emissions. It is therefore critical to better understanding the biogeochemical cycling of CH₄ in these ecosystems. In this paper, the effects of environmental factors on methanogenic and methanotrophic rates are reviewed and an inventory of the methanogens and methanotrophs at the genus/species level in freshwater lakes is given. We focus on the anaerobic oxidation of methane, which is a still poorly known process but increasingly reported in freshwater lakes.     

运动心肺功能在冠心病PTCA术后康复评定中的应用

对１５例心肌梗塞和心绞痛病人经皮冠状动脉成形术（ＰＴＣＡ）术后测定运动心肺功能。采用麦加菲心肺运动仪测定气体代谢指标，如摄氧量（ＶＯ２）、二氧化碳排出量（ＶＣＯ２）、肺通气量（ＶＥ）、呼吸交换率（ＲＥＲ）、无氧阈值（ＡＴ）、氧脉搏（ＶＯ２／ＨＲ）等。根据病变程度和体能分为平板组（ＴＥＴ）和功率自行车组（ＥＥＴ）。１５例病人当运动强度增加时摄氧量（ＶＯ２）缓慢上升，达到较低的峰值ＶＯ２，尤其ＥＥＴ且     

HIF-1α在子宫内膜异位症中的研究进展

子宫内膜异位症(Endometriosis,EMs)是育龄妇女的常见病,但其发病机制至今仍不清楚。越来越多的证据表明,低氧与EMs发生发展有密切的联系。在EMs异位组织中低氧诱导因子-1α(HIF-1α)的表达明显增高;HIF-1α通过调节雌激素产生、血管生成、细胞增殖和炎症等相关基因,促进EMs发展;HIF-1α是EMs有氧糖酵解过程中关键的调节因子;抑制HIF-1α的表达有助于抑制EMs的发生发展,表明HIF-1α在EMs的病理形成中的作用。本文介绍HIF-1α的研究进展,着重论述其在EMs中的作用。     

The association of dietary patterns and cardiorespiratory fitness: A systematic review

AimsIn comparison to the traditional risk factors of cardiovascular diseases, little is known about the interaction between diet and cardiorespiratory fitness (CRF). The present systematic review aimed to provide comprehensive evidence regarding the relationship between the dietary patterns (DPs) with CRF in both children and adults.Data synthesisDatabases of PubMed, Scopus, and Web of Science were searched from inception up to December 2019. All observational studies that had extracted DPs using a posteriori and/or a priori methods, as well as had assessed CRF as the outcome, were eligible for inclusion in the review. Eleven studies (1 longitudinal and 10 cross-sectional studies) comprising a total of 198,271 subjects were included. There was considerable heterogeneity between studies in terms of the extracted DPs, their food items as well as the statistical reporting outcomes; which all made comparisons between the studies difficult. Despite some inconsistent results, overall there was a positive association between the DPs that were highly loaded with fruits and vegetables, as well as closer adherence to the high-quality diets particularly the Mediterranean diet, with higher values of CRF. While, an inverse association was found for unhealthy DPs that were generally characterized by a high intake of refined grains, sweets, meats, processed foods, and high-fat dairy products.ConclusionOverall, the evidence indicates the high-quality diets that are highlighted in the national dietary guidelines are associated with an optimal CRF. However, these findings should be confirmed by rigorous prospective and interventional studies.     

Oxygen levels during negative pressure wound therapy

Aim of the studyNegative pressure wound therapy (NPWT) has become an established treatment modality when dealing with chronic and infected wounds. The underlying mechanism of action is still under discussion and remains controversial. Evidence exists showing rather hypoxic conditions as the main reason for the positive results and bacterial clearance. In an attempt to further explain the mechanism of action, we investigated oxygen levels within the foam interface of a NPWT device.Materials and methodsWe used an optical sensor based on the principle of dynamic fluorescence quenching and tested five different commonly available NPWT systems used during our daily clinical routine. All measurements were done in an in vitro experimental design for at least 24 h and multiple vacuum intensities were investigated.ResultsOxygen levels decreased as much as 22.8% and the amount of vacuum applied inversely correlated with the oxygen reduction. A stepwise increase in vacuum of 25 mmHg showed a linear mean drop of 2.75% per setting. All devices were able to maintain a constant level of negative pressure, and no significant difference between the various dressings was found (p > 0.05).ConclusionTherefore, oxygen levels are decreased within the foam of NPWT dressings, likely leading to oxygen deprivation effects in the underlying wound tissue.