Impact loading in female runners with single and multiple bone stress injuries during fresh and exerted conditions

Background:Bone stress injuries(BSIs)are common in female runners,and recurrent BSI rates are high.Previous work suggests an association between higher impact loading during running and tibial BSI.However,it is unknown whether impact loading and fatigue-related loading changes discriminate women with a history of multiple BSIs.This study compared impact variables at the beginning of a treadmill run to exertion andthe changes in those variables with exertion among female runners with no history of BSI as well as among those with a history of single or multiple BSIs.Methods:We enrolled 45 female runners(aged 18-40 years)for this cross-sectional study:having no history of diagnosed lower extremity BSI(N-BSI,n=14);a history of 1 lower extremity BSI(1-BSI,n=16);and diagnosed by imaging,or a history of multiple(>3)lower extremity BSIs(M-BSI,n=15).Participants completed a 5-km race speed run on an instrumented treadmill while wearing an Inertial Measurement Unit.The vertical average loading rate(VALR),vertical instantaneous loading rate(VILR),vertical stiffness during impact via instrumented treadmill,and tibial shock determined as the peak po sitive tibial acceleration via Inertial Measurement Unit were measured at the beginning and the end of the run.Results:There were no differences between groups in VALR,VILR,vertical stiffness,or tibial shock in a fresh or exerted condition.However,compared to N-BSI,women with M-BSI had greater increase with exertion in VALR(-1.8%vs.6.1%,p=0.01)and VILR(1.5%vs.4.8%,p=0.03).Similarly,compared to N-BSI,vertical stiffness increased more with exertion among women with M-BSI(-0.9%vs.7.3%,p=0.006)and 1-BSI(-0.9%vs.1.8%,p=0.05).Finally,compared to N-BSI,the increase in tibial shock from fresh to exerted condition was greater among women with M-BSI(0.9%vs.5.5%,p=0.03)and 1-BSI(0.9%vs.11.2%,p=0.02).Conclusion:Women with 1-BSI or M-BSIs experience greater exertion-related increases in impact loading than women with N-BSI.These observations imply that exertion-related changes in gait biomechanics may contribute to risk of BSI.

How does high-intensity intermittent training affect recreational endurance runners? Acute and chronic adaptations: A systematic review

Objective: This systematic review aimed to critically analyze the literature to determine how high-intensity intermittent training(HIIT) affects recreational endurance runners in the short-and long-term.Methods: Electronic databases were searched for literature dating from January 2000 to October 2015. The search was conducted using the key words "high-intensity intermittent training" or "high-intensity interval exercise" or "interval running" or "sprint interval training" and "endurance runners" or "long distance runners". A systematic approach was used to evaluate the 783 articles identified for initial review. Studies were included if they investigated HIIT in recreational endurance runners. The methodological quality of the studies was evaluated using the Physiotherapy Evidence Database(PEDro) scale(for intervention studies) and the modified Downs and Black Quality Index(for cross-sectional studies).Results: Twenty-three studies met the inclusionary criteria for review. The results are presented in 2 parts: cross-sectional(n = 15) and intervention studies(n = 8). In the 15 cross-sectional studies selected, endurance runners performed at least 1 HIIT protocol, and the acute impact on physiological, neuromuscular, metabolic and/or biomechanical variables was assessed. Intervention studies lasted a minimum of 4 weeks, with 10 weeks being the longest intervention period, and included 2 to 4 HIIT sessions per week. Most of these studies combined HIIT sessions with continuous run(CR) sessions; 2 studies' subjects performed HIIT exclusively.Conclusion: HIIT-based running plans(2 to 3 HIIT sessions per week, combining HIIT and CR runs) show athletic performance improvements in endurance runners by improving maximal oxygen uptake and running economy along with muscular and metabolic adaptations. To maximize the adaptations to training, both HIIT and CR must be part of training programs for endurance runners.

Heart Rate Variability, Standard of Measurement, Physiological Interpretation and Clinical Use in Mountain Marathon Runners during Sleep and after Acclimatization at 3480 m

Fluctuations in autonomic cardiovascular regulation during exposure to high altitude may increase the risk of heart attack during waking and sleep. This study compared heart rate variability (HVR) and its components during sleep at low altitude and after 30 - 41 hours of acclimatization at high altitude (3480 m) in five mountain marathon runners controlled for diet, drugs, light-dark cycle and jet lag. In comparison to sea level, RR-intervals during sleep at high altitude decreased significantly (P 0.001). The significant increase in sympathetic autonomic cardiovascular modulation at high altitude protects against excessive oxygen deprivation during sleep. Increases in R-R intervals can require longer periods of acclimatization at3480 m to mitigate the effects of altitude/hypoxia on sympathetic tone, thus reducing cardiovascular distress at rest during waking and sleep and probably before during and after athletic performance at altitude.

Kinematic alterations after two high-intensity intermittent training protocols in endurance runners

Purpose:This study aimed to evaluate running kinematic characteristics during the early and late stages of 2 high-intensity intermittent training(HIIT)protocols with similar external load but different average running pace,as well as to compare the fatigue-induced changes during both HIIT protocols at a kinematic level.Methods:Eighteen endurance runners were tested on a track on 2 occasions:10 runs of 400 m with 90-120 s recovery between running bouts(10 × 400 m),and 40 runs of 100 m with 25-30 s recovery between running bouts(40 × 100 m).Heart rate was monitored during both protocols;blood lactate accumulation and rate of perceived exertion were recorded after both exercises.A high-speed camera was used to measure sagittalplane kinematics at the first and last runs during both HIIT protocols.The dependent variables were spatial-temporal parameters(step length and contact and flight time),joint angles during support(relative angles of the hip,knee,and ankle),and foot strike pattern.Results:High levels of exhaustion were reached by the athletes during both workouts(blood lactate accumulation>12 mmol/L,rate of perceived exertion>15;peak heart rate(HRpeak)>176 bpm).A within-protocol paired t test(first vs.last run)revealed no significant changes(p≥0.05)in kinematic variables during any of the HIIT sessions.A between-protocol comparison with the first run of each protocol revealed the effect of running speed on kinematics:+2.44 km/h during the 40 × 100 m:shorter contact and flight time(p<0.01)and longer step length(p= 0.001);greater hip flexion(p = 0.031)and ankle extension(p = 0.001)at initial contact;smaller knee and ankle flexion(p<0.001)at midstance;and greater hip extension at toe-off(p<0.001).Conclusion:HIIT sessions including runs for 15-90 s and performed at intensity above the velocity associated with maximal oxygen uptake did not consistently perturb the running kinematics of trained endurance runners.

Blood Chemistry, Acid-Base, Electrolyte, Blood Lactate Metabolism and Sleep at 3480 m in Mountain Marathon Runners

Altered blood chemistry, acid-base and electrolyte are suggested determinants of sleep disturbance, with frequent arousal at high altitude even in well and long-trained altitude marathon runners. In this sample of experienced altitude marathon runners with maximal aerobic power at sea level of 61.4 ± 2.7 ml/kg-1·min-1 we found that pO2 and percent of oxygen saturation (%SO2) were lower at2050 mand3480 mthan at sea level;pO2 was higher after 38 - 41 hours than after 30 - 31 hours of acclimatization at3480 m(P 2 decreased (P 2 and (P 2 at a sleeping altitude of3480 mwas lower (P Simple regression analysis disclosed a significant correlation between the changes in TST and the percent of REM sleep and the changes in %SpaO2 recorded during sleep (P 2 at higher altitude and the percent of W and of TST (P 2, tCO2 and [HCO3-] correlated negatively and significantly with the percent of REM sleep changes at high altitude (P 2 and pH and correlated negatively with the changes in %SO2, pCO2, tCO2, and [HCO3-] (P ++] and [BE] and negatively with the changes in buffered bases [BB] and [BEeffective] (P 2 and significantly and negatively with the changes in [K+] (P 2, tCO2, [HCO3-] and [K+]

Medication Use by Runners in Self-Care Situations

The benefits of running for cardiovascular health have long been established, but no relationship between runners/non-runners and their usage of prescription and over-the-counter (OTC) medications has been established. A comprehensive survey was sent out via Facebook, Inc., to self-identified runners to assess runners’ first response to 5 common self-care situations. The results were compared to the national average of the U.S. population who take prescription and OTC medications. What was also assessed was the relationship between average weekly miles run and the likelihood to choose OTC medications. 714 runners, residing predominately in the St. Louis, Missouri metropolitan area, completed the survey and their results were drastically different than the national average use for prescription and OTC medication in the general (non-runners) population. Approximately 30% of the runners in this study are on daily prescription medications versus a national average of 70% of the U.S. population. In each of the 5 common self-care situations, less than 50% of runners chose an OTC medication as their first option for self-care vs. the national average of 80%. Results of the study also showed that runners with a weekly mile average of 30 miles or more were less likely to choose an OTC option for self-care than runners with a weekly average of 15 miles or less. Overall, results of this survey suggest that runners are less likely to take medications and may be healthier than the average U.S. citizen overall.

The Effect of a Chocolate Bar Supplementation on Moderate Exercise Recovery of Recreational Runners

To study the effects of a chocolate bar supplementation before exercise on improving recovery of physiological and metabolic changes induced by exercise, 16 male students aged 18-20 years voluntarily served as subjects. A crossover design was employed. Each subject took part in two trials and ran an hour on a treadmill with the intensity of keeping heart rate at 148-150 min for each trial. Results showed that plasma glucose levels of subjects increased significantly (5.42±0.83 mmol/L) at 15 min after ingestion of a chocolate bar and maintained in moderate high levels (4.92 ±0.57 mmol/L) until 30 min after an hour's running while the glucose levels were low and dropped to under normal ranges (3.84 ± 0.31 mmol/L) at 30 min after exercise as they were with a supplement of placebo. Results of plasma FFA, blood lactate and plasma urea nitrogen levels and RPE all indicated that chocolate bar supplementation before exercise benefits to create the necessary prerequisite for exercise and recovery

Early Prevention of Exercise-induced Tibia Periostitis for Long-Distance Runners in China＇ s Regular Universities

Exercise-induced tibia periostitis is one of the most common sports injuries in the sports training of athletics in regular institutions of higher learning. It often occurs. When it is serious, periosteal proliferation would occur, It will result in fatigue fi^cture sometimes. This is relevant to tibialis anterior muscle restrained contraction in the events in the sports process. If measures are not adopted, early prevention should be strengthened. This would not only affect seriously the sports achievement of long-distance runners, but also affects their future ordinary lives. Through analysis and summaries, the main reasons for the occurrence of tibia periostitis for long-distance runners are shown. From the perspectives of reasonably arranging the exercise load, strengthening the field management and strengthening the self-protection and so on, the prevention of tibia periostitis for long-distance runners has been explored. It also helps the long-distance runners to train scientifically, which can effectively avoid and lessen the occurrence of tibia periostitis and the adverse effect it brings.

Nutrition For Marathon Runners In Competition Season

The week or ten days before competition is the time to cut down the amount of training,but the quality of the food must be improved, i.e.comprehensive nutrient must be supplied so as to increase the energy reserve and speed up the recovery form the pre-competition training.Calories in the food supply should be reduced lest it causes the increase of body fat and weight.In pre-competition food, glycogen reserve Should be fully guaranteed, acid food of protein of fat must be replenished exceessively. Runners should eat fruit and vegetables as much as possible to fill up various vitamins and inorganic salts.

Effects of age on marathon finishing time among male amateur runners in Stockholm Marathon 1979–2014

Purpose: The purpose of the present study was to investigate the age-related changes in the endurance performance among male amateur marathon runners.Methods: Subjects were taken from the 36 Stockholm Marathons held from 1979 through 2014, and age and finishing time were analyzed for a total of 312,342 male runners.Results: The relation was found to be a second-order polynomial, t = a + bx + cx^2, which models 99.7% of the variation in the average running time t as a function of age x. The model shows that the marathon performance of the average runner improves up to age 34.3 ± 2.6 years, thereafter,the performance starts to decline. A quantification of the age's influence on running time shows that it accounts for 4.5% of the total variance seen in the performance data.Conclusion: These outcomes indicate that the effect of age on performance in endurance running events is clearly measurable, quantifiable, and possible to describe. At the same time the findings indicate that other factors, such as training, affect the performance more. A comparison with the elite showed peak performance at the same age, but the rates of change in performance with age, improvement as well as degradation, was found to be higher among the elite.

Changes in balance ability,power output,and stretch-shortening cycle utilisation after two high-intensity intermittent training protocols in endurance runners

Purpose：This study aimed to describe the acute effects of 2 different high-intensity intermittent trainings（HIITs） on postural control,countermovement jump（CMJ）,squat jump（SJ）,and stretch-shortening cycle（SSC） utilisation,and to compare the changes induced by both protocols in those variables in endurance runners.Methods：Eighteen recreationally trained endurance runners participated in this study and were tested on 2 occasions：10 runs of 400 m with 90 s recovery between running bouts（10×400 m）,and 40 runs of 100 m with 30 s recovery between runs（40 × 100 m）.Heart rate was monitored during both HIITs;blood lactate accumulation and rate of perceived exertion were recorded after both protocols.Vertical jump ability（CMJ and SJ） and SSC together with postural control were also controlled during both HIITs.Results：Repeated measures analysis revealed a significan improvement in CMJ and SJ during 10 × 400 m（p〈0.05）,whilst no significan changes were observed during 40×100 m.Indexes related to SSC did not experience significan changes during any of the protocols.As for postural control,no significan changes were observed in the 40×100 m protocol,whilst significan impairments were observed during the 10×400 m protocol（p〈0.05）.Conclusion：A protocol with a higher number of shorter runs（40×100 m） induced different changes in those neuromuscular parameters than those with fewer and longer runs（10×400 m）.Whereas the 40×100 m protocol did not cause any significan changes in vertical jump ability,postural control or SSC utilisation,the 10×400 m protocol impaired postural control and caused improvements in vertical jumping tests.

Study of Radio-Sensitivity of Strawberry Runners <i>cv. Fortuna</i>under Moroccan Conditions

In recent years, strawberry is being successfully cultivated in Loukkos perimeter of Morocco and a wide range of varieties are being grown. The strawberry crop also generates 3 million working days per year. In fact, all plants are imported and prices are exorbitant. Varietal improvement is essential if a new impetus is to be given to the morocco strawberry. We have accordingly started a mutation breeding program by bud irradiation. Strawberry runners of cv. Fortuna were exposed to increasing doses of acute gamma rays. The physiological effects induced by irradiation were evaluated from cutting survival and growth. It has been determined that the doses of gamma and the varieties used are significant on the number of surviving plants and plant growth parameters. It was determined that low doses gamma irradiation respectively affected plant height, leaf length, leaf width and the number of leaves. These results allowed us, in the first instance, to fix the optimal dose range for cutting irradiated at 62 Grays.

Protein expression changes in Tibetan middle-to-long distance runners after the transition from high altitude to low altitude:Implications for enhancing endurance training

The study aims to investigate the differences in protein expressions in Xizang's(Tibetan)middle-to-long distance runners after the transition from high altitude to low altitude and reveal the molecular mechanisms underlying their enhanced middle-to-long distance running performance.In the study,eleven subjects were selected from native Tibetan middle-to-long distance runners to participate in an 8-week pre-competition exercise training program consisting of a 6-week training stage in Kangding City at an altitude of 2560 meters(m)and a subsequent 2-week training stage in Leshan City at an altitude of 360 m.Blood samples were collected twice from the runners before beginning altitude exercise training in Kangding and after going to sea level-Leshan City.Using a label-free quantitative method,peptides in the samples were analyzed by mass spectrometry.Proteomic analysis was performed to identify differentially expressed proteins and predict their biological functions.A total of 846 proteins were identified in the 21 samples,including 719 quantified proteins.In total,49 significantly differentially expressed proteins(p<0.05)were identified,including twenty-eight 0.2-fold up-regulated proteins or twenty-one 0.17-fold down-regulated proteins.The up-regulated proteins,including cystic fibrosis transmembrane conductance regulator(CFTR)and carbonic anhydrase I(CAI),were of particular interest due to their role in regulating the oxygen saturation in deep tissues.Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway analysis indicated that these proteins were mainly involved in regulating actin cytoskeleton,local adhesion,biotin absorption and metabolism,immune system,cancer,and membrane transport processes.In conclusion,Tibetan middle-to-long distance runners who resided in high-altitude areas benefited from repeated plateau-plain alternate training mode during the pre-competition period.The training mode induced positive changes in peripheral blood plasma proteins(CFTR and CAI),the biomarkers associated with aerobic capacity.Among the 11 runners,one female athlete won the gold medal in the 3000-m running event in this competition,demonstrating that the plateau-plain alternate training mode could enhance the aerobic capacity of athletes.

Risk factors for running-related injuries:An umbrella systematic review

Purpose:This umbrella systematic review(SR) of SRs and meta-analysis seeks to comprehensively synthesize existing literature to identify and consolidate the diverse range of risk factors contributing to running-related injuries(RRIs).Methods:Systematic searches were conducted on June 28,2023,across Web of Science,SPORTDiscus,Scopus,PubMed,and Cochrane Library.We included SRs,whether accompanied by meta-analyses or not,that focused on investigating risk factors for RRIs within observational studies.The methodological quality of the SRs was evaluated using the Assessing the Methodological Quality of Systematic Reviews Ⅱ.To assess the extent of overlap across reviews,the corrected covered area metric was calculated.Results:From 1509 records retrieved,13 SRs were included.The degree of overlap between SRs was low(4%),and quality varied from critically low(n=8) to low(n=5).Two hundred seven outcomes assessed in 148 primary studies were identified as being associated with the occurrence of RRIs.The effect sizes of the associations for which risk measures were reported(n=131) were classified as large(n=30,23%),medium(n=38,29%),small(n=48,37%) or no effect(n=15,11%).Running/training characteristics,health and lifestyle factors,along with morphological and biomechanical aspects,exhibit large effect sizes in increasing the risk for RRIs.Conclusion:Drawing from the outcomes of the low-quality SRs and associations with large effect sizes,our findings indicate that running/training characteristics and health and lifestyle factors,as well as morphological and biomechanical aspects,are all implicated in elevating the risk of RRIs,emphasizing the multifactorial basis of injury incidence in running.Given the low quality and heterogeneity of SR,individual findings warrant cautious interpretation.

A master-slave generalized predictive synchronization control for preheating process of multi-cavity hot runner system

As a key component of injection molding,multi-cavity hot runner(MCHR)system faces the crucial problem of polymer melt filling imbalance among the cavities.The thermal imbalance in the system has been considered as the leading cause.Hence,the solution may rest with the synchronization of those heating processes in MCHR system.This paper proposes a’Master-Slave’generalized predictive synchronization control(MS-GPSC)method with’Mr.Slowest’strategy for preheating stage of MCHR system.The core of the proposed method is choosing the heating process with slowest dynamics as the’Master’to track the setpoint,while the other heating processes are treated as‘Slaves’tracking the output of’Master’.This proposed method is shown to have the good ability of temperature synchronization.The corresponding analysis is conducted on parameters tuning and stability,simulations and experiments show the strategy is effective.

Optimization of Blade Geometry of Savonius Hydrokinetic Turbine Based onGenetic Algorithm

Savonius hydrokinetic turbine is a kind of turbine set which is suitable for low-velocity conditions.Unlike conventional turbines,Savonius turbines employ S-shaped blades and have simple internal structures.Therefore,there is a large space for optimizing the blade geometry.In this study,computational fluid dynamics(CFD)numerical simulation and genetic algorithm(GA)were used for the optimal design.The optimization strategies and methods were determined by comparing the results calculated by CFD with the experimental results.The weighted objective function was constructed with the maximum power coefficient Cp and the high-power coefficient range R under multiple working conditions.GA helps to find the optimal individual of the objective function.Compared the optimal scheme with the initial scheme,the overlap ratioβincreased from 0.2 to 0.202,and the clearance ratioεincreased from 0 to 0.179,the blade circumferential angleγincreased from 0°to 27°,the blade shape extended more towards the spindle.The overall power of Savonius turbines was maintained at a high level over 22%,R also increased from 0.73 to 1.02.In comparison with the initial scheme,the energy loss of the optimal scheme at high blade tip speed is greatly reduced,and this reduction is closely related to the optimization of blade geometry.As R becomes larger,Savonius turbines can adapt to the overall working conditions and meet the needs of its work in low flow rate conditions.The results of this paper can be used as a reference for the hydrodynamic optimization of Savonius turbine runners.

Mini Zoom IPG Runner系统双向电泳分析血浆蛋白实验条件优化

背景与目的优化MiniZoomIPGRunner系统双向电泳条件。材料与方法使用Invitrogen公司与MiniZoomIPGRunner系统配套的商品化预制胶(一向和二向)和溶液体系对血浆蛋白进行双向电泳,采用不同的聚焦条件和样品预处理,观察其对实验结果的影响。结果提高聚焦电压增强聚焦及脱盐处理可获得比推荐条件更好的双向电泳图谱。结论提高聚焦电压增强聚焦及脱盐处理可改善MiniZoomIPGRunner系统分析血浆样品的双向电泳结果。

基于WAP协议的负载测试研究

通过LoadRunner企业级测试工具,对基于WAP协议的移动增值服务进行负载测试研究。结合WAP协议,为负载测试生成一个实用的、高效的脚本,继而设计一个负载测试方案,最后对测试结果的分析得到系统的性能。

Counter-Rotating Type Tidal Range Power Unit

The counter-rotating type tidal range power unit composed of the axial flow type tandem runners and the peculiar generator with double rotational armatures is proposed to utilize effectively the tidal range. In the unit, the front and the rear runners counter-drive the inner and the outer armatures of the generator, respectively. Besides, the flow runs in the axial direction at the rear runner outlet while the flow has not the swirling component at the front runner inlet, because the angular momentum change through the rear runner must coincides with that through the front runner. Such operations are suitable for bidirectional flows, namely working at the seashore with the rising and the falling tidal ranges, and the unit may be able to take place of the traditional bulb type turbines. To promote more the tidal power generation by this type unit, the runners were modified so as to be suitable for both rising and falling flows. The hydraulic performances are acceptable and take the optimum efficiency at the on-cam operation, while the trailing profiles of the runner blades determine mainly the theoretical output.

On-Cam Operation of Counter-Rotating Type Hydroelectric Unit

The counter-rotating type hydroelectric unit, which is composed of the axial flow type tandem runners and the peculiar generator with double rotational armatures, has been proposed. In the unit, the front and the rear runners counter-drive the inner and the outer armatures of the generator, respectively. Besides, the flow direction at the rear runner outlet must coincide with the direction at the front runner inlet, because the angular momentum change through the rear runner must coincides with that through the front runner. In this paper, the tandem runners work at on-cam conditions in keeping the induced frequency constant, to provide the hydroelectric unit for the power grid system. The output and the hydraulic efficiency are affected by the adjusting angles of the front and the rear blades. Both optimum angles giving the maximum output or efficiency were presented at the various discharge/head circumstances, accompanying with the turbine performances.