Distance Runners Research Articles

Risk of Low Energy Availability, Disordered Eating, and Menstrual Dysfunction in Female Collegiate Runners.

Collegiate female distance runners may be at risk for low energy availability (LEA) due to increased exercise energy expenditure with or without decreased energy intake. Furthermore, this population has increased risk of disordered eating (DE), which can lead to LEA and negative health consequences, such as menstrual dysfunction (MD). 1) investigate risk of LEA and DE, 2) compare DE, training volume, and weight dissatisfaction among female collegiate runners at risk vs not at risk for LEA, and 3) compare risk for LEA between NCAA (National Collegiate Athletics Association) Division I, II, and III female collegiate runners. Cross-sectional study. Free-living. Female runners (n = 287) who competed on an NCAA (National Collegiate Athletics Association) Division I, II, or III cross-country and/or track team. A 45 question questionnaire was completed which included the Low Energy Availability in Females Questionnaire (LEAF-Q) and the Disordered Eating Screening Assessment (DESA-6). 54.5% (n = 156) of runners were at risk for LEA (score ≥ 8 on LEAF-Q), and 40.8% (n = 117) were at risk for DE (DESA-6 score ≥ 3), and 56.5% (n = 162) reported MD (LEAF-Q subsection MD score ≥ 4). Athletes "at risk" for LEA had significantly higher DESA-6 scores than athletes "not at risk" for LEA (p < 0.001). Athletes "at risk" for LEA had significantly greater weight dissatisfaction than those not at risk for LEA (X23, 156 = 15.92, p = 0.001). Higher weekly training volumes was not associated with risk for LEA (X22, 156 = 4.20, p = 0.112). A substantial percentage of collegiate female runners were found to be at risk for LEA, DE, and report MD. These findings demonstrate that risk for DE, MD, and weight dissatisfaction are associated with risk for LEA.

Development and feasibility of a virtual reality-based exergaming program to enhance cardiopulmonary fitness in children with developmental coordination disorder.

Developmental coordination disorder (DCD) is a neurodevelopmental disorder characterized by motor skill deficits. Such deficits often limit children's participation in physical activities, further affecting their overall health, including through reduced cardiopulmonary fitness. Because virtual reality (VR) devices offer interactive games and activities that require various movements and coordination, they can serve as motivating and enjoyable means for children to perform physical exercise. In this study, we developed a VR-based exergaming system and tested its ability to enhance the cardiopulmonary fitness of children with DCD. A total of 13 children with DCD and 10 young adults were recruited in phase I to examine the test-retest reliability and concurrent validity of our system (including a custom-made heart rate monitor) with a commercial heart rate device. In phase II, we included an additional 13 children with DCD to test the feasibility of the system. We tested the outcomes using the enjoyment rating scale, intrinsic motivation inventory (IMI), and 20-m shuttle run test (20mSRT). In phase I, test-retest reliability was good to excellent in the static task and moderate to good in the dynamic task. Concurrent validity was excellent in both tasks. In phase II, more than half of the children (18 out of 26) assigned the maximum rating for their enjoyment of the game; they also had high average scores on the IMI. Furthermore, after the 8-week training using the VR program, the average running distance of the 26 children in the 20mSRT had increased significantly from 129.23 m to 176.92 m (p < 0.001). Our VR-based exergaming program can serve as an alternative intervention for enhancing cardiopulmonary fitness in children with DCD.

Worst Case Scenarios in Soccer Training and Competition: Analysis of Playing Position, Congested Periods, and Substitutes

ABSTRACT Aim: To understand mean (WCSmean) and peak (WCSpeak) worst case scenarios within training and game play in male professional soccer. Methods: Thirty-one (n = 31) first team players were monitored across 37 matches and 14 MD-3 sessions. Playing status was distinguished, football drills analyzed, and performance explored in long-period: >6 days, moderate-period: 5–6 days, and congested-period: ≤4 days. Relative total distance (TD), high-speed running distance (HSRD, >19.8 km·h−1), sprint distance (SD, >25.2 km·h−1), accelerations/decelerations (A+D, >3 m·s−2), accelerations (Acc, >3 m·s−2), and decelerations (Dec, >−3 m·s−2) were measured as well as Maximum acceleration (Max Acc; m·s−2) and deceleration (Max Dec; m·s−2). Results: Analysis of variance found differences between matches and training in WCSmean for TD, HSRD, SD, and Max Dec in all positions (p < .001; partial η2 > .275). Fullbacks displayed differences between match and training in Max Acc (moderate ESs; p < .001), while center backs and central midfielders in Max Dec (large ESs; p > .05). Main effects of playing status were discovered for all metrics except Max Dec (p < .001; partial η2 > .124). Analysis showed differences between long- and congested-period for A+D and Dec (large ESs; p ≤ .05). Conclusions: Findings provide more insights into short peak intensity demands of soccer showing that the maximum high velocity action of acceleration and deceleration is not being replicated in training. Nonstarters lack maximum intensity exposure in matches (WCSpeak) increasing the gap between training and competition even higher during congested fixture periods.

Estimation of factors contributing to level differences in Japanese university decathlon athletes

This study aimed to estimate the factors that cause differences in competition level based on the competition performance structure among university student decathletes in Japan. The results of factor analysis using the maximum likelihood method (Oblimin rotation), assuming a five-factor structure estimated from parallel analysis and the information criterion, revealed the following competitive performance structures: "running speed and body projection,” "running endurance,” "rotational throwing power,” "translational throwing power,” and "vertical leaping power.” Some of these were similar to the competitive performance structures of the world’s top athletes, but they were found to have a unique structure: two throwing powers. The analysis results using latent rank theory allowed us to evaluate them on a seven-point scale. The calculated item reference profile, difficulty index, and discrimination index for each rank indicated that shot put and 100 and 400 m performance formed the basis of decathlon performance. In addition, high jump and pole vault, which fall under the category of "vertical leaping power," retained high difficulty and discrimination and were revealed to affect the stage of achievement of overall performance in the decathlon.

Norwegian double-threshold method in distance running

This study aimed to give a systematic literature review about the training of elite Norwegian long-distance runners (1500-10.000 meters). After a search in databases, we found 7 articles, that have systematically registered the training volume and intensity distribution of 13 elite runners over longer periods (n = 13). The results were the following: the best long-distance runners run 120 to 180 kilometers per week on average. The waist majority of this training (75-80 %) is done at low intensity (62-82% HRmax). Two to four sessions are done at the anaerobic threshold pace (82-20% HRmax), either in continuous or interval format during the base period, often done twice on the same day. One to two times weekly higher intensity sessions (&gt;97% HRmax) are done, in form of short intervals (&gt;800m) or short sprints. Longer intervals, above the anaerobic threshold (92-97 % HRmax) are rarely used during the base period. The training is closely monitored by a lactate meter or heart rate monitor. Before the racing season, in the pre-competition period, the athletes do fewer workouts at an anaerobic threshold pace and increase the number of sessions at a specific race pace.

Match-play, training workloads and sensorimotor and neuromuscular performance of elite young soccer players

Purpose: The purpose of this study was to assess sensorimotor and neuromuscular performance capabilities over an in-season microcycle in early-career professional soccer players and to examine the relationship with training and match-play workload. Methods: Sensorimotor and neuromuscular performance capabilities (isometric knee extensor: force replication error, peak force, electromechanical delay, rate of force development) of 12 professional soccer players were assessed over a 7-day period. Training and match-play workload was also recorded over the same period for each player (high-intensity running distance). Fluctuations in sensorimotor and neuromuscular performance and workload variables were analysed. Results: There was evidence of fluctuations in sensorimotor and neuromuscular performance capability over the microcycle that reached statistical (p &lt; .005) and practical (18.1% [baseline-to-peak]) significance alongside heterogeneity in training and match workload (264% [coefficient of variation], p &lt; .0005). Some temporal congruence among fluctuating patterns of intra-microcycle training and match-play load and concomitant electromechanical delay performance was noted (p &lt; .005). Asynchronous responses were observed for peak force, but rate of force development and force replication error capabilities were unchanged during the microcycle. Conclusion: While some neuromuscular performance capabilities fluctuate over an in-season microcycle and are influenced partially by high-intensity running workload, sensorimotor performance capabilities were unchanged during the microcycle.

BIO101 stimulates myoblast differentiation and improves muscle function in adult and old mice.

Muscle aging is associated with a consistent decrease in the ability of muscle tissue to regenerate following intrinsic muscle degradation, injury or overuse. Age-related imbalance of protein synthesis and degradation, mainly regulated by AKT/mTOR pathway, leads to progressive loss of muscle mass. Maintenance of anabolic and regenerative capacities of skeletal muscles may be regarded as a therapeutic option for sarcopenia and other muscle wasting diseases. Our previous studies have demonstrated that BIO101, a pharmaceutical grade 20-hydroxyecdysone, increases protein synthesis through the activation of MAS receptor involved in the protective arm of renin-angiotensin-aldosterone system. The purpose of the present study was to assess the anabolic and pro-differentiating properties of BIO101 on C2C12 muscle cells in vitro and to investigate its effects on adult and old mice models in vivo. The effects of BIO101 on C2C12 differentiation were assessed using myogenic transcription factors and protein expression of major kinases of AKT/mTOR pathway by Western blot. The in vivo effects of BIO101 have been investigated in BIO101 orally-treated (50mg/kg/day) adult mice (3months) for 28days. To demonstrate potential beneficial effect of BIO101 treatment in a sarcopenic mouse model, we use orally treated 22-month-old C57Bl6/J mice, for 14weeks with vehicle or BIO101. Mice body and muscle weight were recorded. Physical performances were assessed using running capacity and muscle contractility tests. Anabolic properties of BIO101 were confirmed by the rapid activation of AKT/mTOR, leading to an increase of C2C12 myotubes diameters (+26%, P<0.001). Pro-differentiating effects of BIO101 on C2C12 myoblasts were revealed by increased expression of muscle-specific differentiation transcription factors (MyoD, myogenin), resulting in increased fusion index and number of nuclei per myotube (+39% and +53%, respectively, at day 6). These effects of BIO101 were like those of angiotensin (1-7) and were abolished with the use of A779, a MAS receptor specific antagonist. Chronic BIO101 oral treatment induced AKT/mTOR activation and anabolic effects accompanied with improved physical performances in adult and old animals (maximal running distance and maximal running velocity). Our data suggest beneficial anabolic and pro-differentiating effects of BIO101 rendering BIO101 a potent drug candidate for treating sarcopenia and possibly other muscle wasting disorders.

Development of Test Results and Physical Condition Measurement Methods Using Fitness Applications in Performance Sports

The research entitled Development of Application-Based Physical Condition Test Results and Measurements in Short Distance Running Athletics, 1) Wants to Make an Application for Processing Test Results and Physical Condition Measurements of Athletes in Athletics Distance Running Numbers. 2) Can find out the results of physical test data processing, which is valid, practical and effective manually or using digital applications on athletic athletes short distance running numbers. The method used in this study is RD, which is a study that describes products in the form of fitness test applications and physical test component instruments applied to athletic athletes in short-distance running numbers. The results of the research conducted were material validation resulting in validity of 85%, language validation of 83% and media validation of 90%. In small-scale trials it produced practicality of 78% and in large-scale trials the level of practicality produced 84.9% and the effectiveness of test results from media applications in the "effective" category with a percentage of 84.9%. From the results of the study, it can be concluded that the development of application-based physical condition test results and measurements in athletic athletes short distance running numbers is valid, practical, and effective. And can be used by coaches, to process data on the results of the physical condition of athletic athletes short distance running numbers, in order to speed up processing test result data.

Discriminative validity of summarized hip and knee angular accelerations for lower extremity training load quantification in male soccer players during a standardised training drill

ABSTRACTThis study assessed the discriminative validity of summarized hip and knee angular accelerations during a standardized training drill. Twenty-eight soccer players performed a standardized training drill that mimics game demands. Discriminative validity was examined by assessment of between-group differences of summarized preferred kicking leg hip and knee angular accelerations, and Playerload between national and regional soccer players for the full training drill, and parts based on locomotor intensity, or additional pass and jumping header activities. Furthermore, relationships were assessed between the summarized hip and knee angular accelerations and conventional load indicators derived from a local positioning measurement system, such as high-intensity running distance and Playerload. National players had higher summarized hip (Mean difference: 62.7 A.U. ES = 0.77, p = 0.049) and knee (Mean difference: 137.1 A.U. ES = 1.06, p = 0.008) angular accelerations. Significant interaction effects were observed during high-intensity running (Hip: 0.2 A.U./m, ES = 0.98, p = 0.005; Knee: 0.61 A.U./m, ES = 1.52, p < 0.001), and sprinting (Hip: 0.3 A.U./m, ES = 1.01, p < 0.02; Knee: 0.56 A.U./m, ES = 1.57, p < 0.001). Between-group differences were not present for additional passing or jumping header activities. Compared to summarized hip and knee angular accelerations, Playerload had less ability to discriminate between players and activities. Moreover, the lower extremity training load indicators were unrelated to conventional load indicators. Together these results confirm discriminative validity of summarized hip and knee angular acceleration training load indicators during a standardised training drill.

Inhibiting the MAPK pathway improves heart failure with preserved ejection fraction induced by salt-sensitive hypertension

Heart failure (HF) preserved ejection fraction (HFpEF) accounts for almost 50% of HF, and hypertension is one of the pathogenies. The MAPK signaling pathway is closely linked to heart failure and hypertension; however, its function in HEpEF resulting from salt-sensitive hypertension is not well understood. In this work, a salt-sensitive hypertension-induced HEpEF model was established based on deoxycorticosterone acetate-salt (DOCA-salt) hypertension mice. The impact of the MAPK inhibitor (Doramapimod) on HEpEF induced by salt-sensitive hypertension was assessed through various measures, such as blood pressure, transthoracic echocardiography, running distance, and histological analysis, to determine its therapeutic effectiveness on cardiac function. In addition, the effects of high salt on myogenic cells were also evaluated in vitro using qRTPCR. The LV ejection fractions (LVEF) in DOCA-salt hypertension mice were over 50%, indicating that the salt-sensitive hypertension-induced HFpEF model was successful. RNA-seq revealed that the MAPK signaling pathway was upregulated in the HFpEF model compared with the normal mice, accompanied by hypertension, impaired running distance, restricted cardiac function, increased cross-sectional and fibrosis area, and upregulation of heart failure biomarkers, including GAL-3, LDHA and BNP. The application of Doramapimod could improve blood pressure, cardiomyocyte hypertrophy, and myocardial fibrosis, as well as decrease the aforementioned heart failure biomarkers. The qRTPCR results showed similar findings to these observations. Our findings suggest that the use of a MAPK inhibitor (Doramapimod) could be a potential treatment for salt-sensitive hypertension-induced HFpEF.

Retracted: Application of CT Multimodal Images in Rehabilitation Monitoring of Long-Distance Running

Retracted: Application of CT Multimodal Images in Rehabilitation Monitoring of Long-Distance Running

Can lifelong endurance exercise improve ageing through beneficial effects on circadian timing function, muscular performance and health status in men? Protocol for a comparative cross-sectional study.

A well-synchronized circadian system is a manifestation of an individual's health. A gradual weakening of the circadian timing function characterizes aging. Regular exercise has been suggested as a modality to improve many detrimental changes associated with aging. Therefore, we aim to examine the benefits and risks of lifelong endurance exercise on age-dependent changes in the circadian time-keeping function, the performance of the muscular system and health status. The study protocol has a comparative cross-sectional design, including groups of senior (65 to 75 years old, n=16) and young (20-30 years old, n=16) endurance runners and triathletes. Age-matched groups of young and elderly sedentary men are included as controls. The circadian function is evaluated mainly by measurement of urinary 6-sulphatoxymelatonin, a metabolite of the hormone melatonin shown to participate in the modulation of sleep cycles. The 6-sulphatoxymelatonin will be assessed in urine samples collected upon awakening in the morning and in the late evening, as a marker of melatonin production. In addition, sleep/activity rhythms and sleep quality will be measured by wrist actigraphy. Performance of the muscular system will be assessed by examination of muscular strength and quantifying of gene expression in the skeletal muscle tissue samples. Health status and age-induced reduction in immune function are to be analysed via the balance of pro- and anti-inflammatory immune markers in the plasma and skeletal muscle, body composition, bone density and physical fitness.

Forecasting individual exercise sweat losses from forecast air temperature and energy expenditure.

Recent success in predicting individual sweat losses from air temperature and energy expenditure measurements suggests a potential for forecasting individual sweat losses for future combinations of environment and exercise. The purpose of this study is to determine the plausibility of accurately forecasting exercise sweat losses from meteorological air temperature forecasts and individual running energy expenditure forecasts. The potential impact on plasma sodium is also estimated when setting drinking rates equal to forecast sweat losses. Individual exercise sweat losses (equated to water needs) and energy expended while running were measured in 33 participants along with air temperature and compared with forecasts of the same. Forecast inputs were used in a web app to forecast exercise sweat losses for comparison with observed values. The bias between forecast and observed exercise sweat losses was used to calculate the potential drinking impact on plasma sodium. The concordance correlation coefficient between forecast and observed values was 0.95, 0.96, and 0.91 for air temperature, energy expenditure, and exercise sweat losses, respectively, indicating excellent agreement and no significant differences observed via t-test. Perfect matching of water intake to sweat losses would lower plasma sodium concentrations from 140 to 138 mmol/L; calculations using the 95% limits of agreement for bias showed that drinking according to forecast exercise sweat losses would alter plasma sodium concentrations from 140 to between 136 and 141 mmol/L. The outcomes support the strong potential for accurately forecasting exercise sweat losses from commonly available meteorological air temperature forecasts and energy expenditure from forecast running distance.

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 2 560 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 3 000-m running event in this competition, demonstrating that the plateau-plain alternate training mode could enhance the aerobic capacity of athletes.

THE PHENOMENON OF AFRICAN RUNNERS

The advantage of athletes representing the "black" continent is obvious in track and field running competitions, especially in middle-distance, long-distance and marathon running. A quarter of a century has passed since African runners created an "atmosphere of invincibility" at international sports competitions. In many scientific studies, attempts to identify the phenomenon of the results of African runners in running competitions at various distances have been made. The purpose of the study is to identify the dominance of the strongest middle-distance and long-distance runners and marathon runners from African countries over runners from other regions of the world. The research results have reveal that the participation of runners of both sexes in all endurance competitions in all regions over the world has the following picture in percentages: a) men: Africa - 55.16, Europe - 19.66, North America - 13.38, Asia - 6.8, Central and South America - 1.44, Australia and Oceania - 3.56; b) Women: Africa - 35.2, Europe - 25.3, North America - 21.48, Asia - 12.92, Central and South America - 1.58, Australia and Oceania - 3.52.

ToSleep Dreaming Medals: Sleep Characteristics, Napping Behavior, and Sleep-Hygiene Strategies in Elite Track-and-Field Athletes Facing the Olympic Games of Tokyo 2021.

Few data are available on sleep characteristics of elite track-and-field athletes. Our study aimed to assess (1)differences in sleep between sexes and among different track-and-field disciplines, (2)the effect of individualized sleep-hygiene strategies on athletes' sleep parameters, and (3)daytime nap characteristics in track-and-field athletes. Sleep characteristics of 16 elite Olympic-level track-and-field athletes (male: n = 8; female: n = 8) were assessed during the preseason period, at baseline (T0), and during the in-season period, after the adoption of individualized sleep-hygiene strategies (T1). Sleep parameters were objectively monitored by actigraphy for a minimum of 10 days, for each athlete, at both T0 and T1. A total of 702 nights were analyzed (T0 = 425; T1 = 277). Female athletes displayed better sleep efficiency (88.69 [87.69-89.68] vs 91.72 [90.99-92.45]; P = .003, effect size [ES]: 0.44), lower sleep latency (18.99 [15.97-22.00] vs 6.99 [5.65-8.32]; P < .001, ES: 0.65), higher total sleep time (07:03 [06:56-07:11] vs 07:18 [07:10-07:26]; P = .030, ES: 0.26), earlier bedtime (00:24 [00:16-00:32] vs 00:13 [00:04-00:22]; P = .027, ES: 0.18), and lower nap frequency (P < .001) than maleathletes. Long-distance runners had earlier bedtime (00:10 [00:03-00:38] vs 00:36 [00:26-00:46]; P < .001, ES: 0.41) and wake-up time (07:41 [07:36-07:46] vs 08:18 [08:07-08:30]; P < .001, ES: 0.61), higher nap frequency, but lower sleep efficiency (88.79 [87.80-89.77] vs 91.67 [90.95-92.38]; P = .013, ES: 0.44), and longer sleep latency (18.89 [15.94-21.84] vs 6.69 [5.33-8.06]; P < .001, ES: 0.67) than athletes of short-term disciplines. Furthermore, sleep-hygiene strategies had a positive impact on athletes' total sleep time (429.2 [423.5-434.8] vs 451.4 [444.2-458.6]; P < .001, ES: 0.37) and sleep latency (14.33 [12.34-16.32] vs 10.67 [8.66-12.68]; P = .017, ES: 0.19). Sleep quality and quantity were suboptimal at baseline in Olympic-level track-and-field athletes. Large differences were observed in sleep characteristics between sexes and among different track-and-field disciplines. Given the positive effect of individualized sleep-hygiene strategies on athlete's sleep, coaches should implement sleep education sessions in the daily routine of top-level athletes.

Recreational Runners Gain Physiological and Biomechanical Benefits From Super Shoes at Marathon Paces.

Advanced footwear technology is prevalent in distance running, with research focusing on these "super shoes" in competitive athletes, with less understanding of their value for slower runners. The aim of this study was to compare physiological and biomechanical variables between a model of super shoes (Saucony Endorphin Speed 2) and regular running shoes (Saucony Cohesion 13) in recreational athletes. We measured peak oxygen uptake (VO2peak) in 10 runners before testing each subject 4 times in a randomly ordered crossover design (ie,Endorphin shoe or Cohesion shoe, running at 65% or 80% of velocity at VO2peak [vVO2peak]). We recorded video data using a high-speed camera (300Hz) to calculate vertical and leg stiffnesses. 65% vVO2peak was equivalent to a speed of 9.4km·h-1 (0.4), whereas 80% vVO2peak was equivalent to 11.5km·h-1 (0.5). Two-way mixed-design analysis of variance showed that oxygen consumption in the Endorphin shoe was 3.9% lower than in the Cohesion shoe at 65% vVO2peak, with an interaction between shoes and speed (P = .020) meaning an increased difference of 5.0% at 80% vVO2peak. There were small increases in vertical and leg stiffnesses in the Endorphin shoes (P < .001); the Endorphin shoe condition also showed trivial to moderate differences in step length, step rate, contact time, and flight time (P < .001). There was a physiological benefit to running in the super shoes even at the slower speed. There were also spatiotemporal and global stiffness improvements indicating that recreational runners benefit from wearing super shoes.

Within-Subject Principal Component Analysis of External Training Load and Intensity Measures in Youth Soccer Training.

Marynowicz, J, Lango, M, Horna, D, Kikut, K, Konefał, M, Chmura, P, and Andrzejewski, M. Within-participant principal component analysis of external training load and intensity measures in youth soccer training. J Strength Cond Res 37(12): 2411-2416, 2023-The aim of this study was to identify which combination of external training load (EL) and external intensity (EI) metrics during youth soccer training sessions captured similar or unique information. Data were collected from 18 youth soccer players during an 18-week in-season competition period using a 10-Hz global positioning system, rating of perceived exertion (RPE), and session-RPE (sRPE). External training load measures included total distance (TD, in meters), PlayerLoad (PL, in arbitrary units), high-speed running distance (HSR, in meters), and number of accelerations (ACC, n). All EL metrics were also divided by session duration (minutes) to obtain EI values. A total of 804 training observations were undertaken (43 ± 17 sessions per player). The analysis was performed by use of the principal component analysis technique. The first principal component (PC) captured 49-70% and 68-89% of the total variance in EI and EL, respectively. The findings show that from the 5 EI metrics, most of the information can be explained by either TD per minute or PL per minute, with a loading from 0.87 to 0.98 and from 0.76 to 0.95, respectively. The majority of EL information can be explained by PL (loading: 0.93-0.98), TD (loading: 0.95-0.99), ACC (loading: 0.71-0.91), or sRPE (loading: 0.70-0.93). The second PC for EL metrics is most strongly correlated with HSR, with loadings from 0.53 to 0.84. The results suggest that the majority of the information contained in the EL variables can be captured in 1 PC without losing much information. The findings suggest that stakeholders who intend to provide a fast and holistic view of EL information in a daily training environment should report TD, PL, ACC, or sRPE plus HSR to coaching staff as a metrics that provides additional unique information.

Assessment of and Intervention for The Running Endurance of Junior High School Students in Changchun City

In the current form, China's curriculum reform has developed with the development of the times, and the reform of physical education curriculum urgently needs the reform of teaching methods. Running endurance is a key aspect of physical fitness for middle school students, who are still in the development stage. This study aims to evaluate the running endurance level of junior high school students in Changchun City and provide an effective intervention method to improve the physical performance of students. The significance of this study is to provide information on the current situation of running endurance of junior high school students in Changchun City, as well as some suggested intervention strategies, which is expected to provide useful reference for physical education policymakers and teachers in the region.

A Quantitative Analysis of Gender Differences in the Improvement of High School Distance Runners

This paper presents a quantitative analysis of the gender differences in the improvement of high schooldistance runners to better understand the impact of gender on athletic performance. There is a lack of gender-specific studies regarding athletic performance in existing research, especially at the high school level. There is alsoa clear gap in available research comparing the improvement of males and females. To close this gap, this researchanalyzes 1600-meter race times of high school runners from MileSplit, a running time database. These times wereimported and analyzed by a Python code and Excel graphs. Results reveal that male runners experience greaterimprovement than females during high school and that elite runners improve at a faster rate than non-elite runners.These results can be connected back to the difference in growth patterns and hormonal processes of each gender.This research addresses gender-based performance differences among high school runners and serves as a basis forfuture investigations on athletic performance gaps between genders.