Race Time Research Articles

An analysis of the São Silvestre race between 2007–2021: An increase in participation but a decrease in performance

This study aimed to investigate the trends of finishers in the São Silvestre race in Brazil, taking into account sex, age, and performance levels. A total of 31 ​775 runners (women, n ​= ​13 ​847; men, n ​= ​17 ​928), aged (45.2 ​± ​16.8) years, finishers in the São Silvestre race between 2007 and 2021, were considered in the present analysis. Data (event year, date of birth, sex, and race times) were downloaded from the official race website. The man-Whitney U test, Spearman correlation, and robust regression model were computed. Participation increased over time for both sexes. Regarding age groups, “31–40 years” (women) and “> 60 years” (men) were those with the highest number of finishers. We found a decrease in performance across the years (β ​= ​2.45; p ​< ​0.005), as well as significant differences in race times for both sexes (U ​= ​42.844; p ​< ​0.001), with men presenting better performances than women. Over time, it was observed an increase in the performance gap between the sexes, but in general, the performance decreased (β ​= ​1.76; p ​< ​0.001). Stakeholders should consider improving the strategies to improve women and young people's participation in running events.

Changes in pacing variation with increasing race duration in ultra-triathlon races

Despite the increasing scientific interest in the relationship between pacing and performance in endurance sports, little information is available about pacing and pacing variation in ultra-endurance events such as ultra-triathlons. Therefore, we aimed to investigate the trends of pacing, pacing variation, the influence of age, sex, and performance level in ultra-triathlons of different distances. We analysed 969 finishers (849 men, 120 women) in 46 ultra-triathlons longer than the original Ironman® distance (e.g., Double-, Triple-, Quintuple- and Deca Iron ultra-triathlons) held from 2004 to 2015. Pacing speed was calculated for every cycling and running lap. Pacing variation was calculated as the coefficient of variation (%) between the average speed of each lap. Performance level (i.e., fast, moderate, slow) was defined according to the 33.3 and 66.6 percentile of the overall race time. A multivariate analysis (two-way ANOVA) was applied for the overall race time as the dependent variable with ‘sex’ and ‘age group’ as independent factors. Another multivariate model with ‘age’ and ‘sex’ as covariates (two-way ANCOVA) was applied with pacing variation (cycling and running) as the dependent variable with ‘race’ and ‘performance level’ as independent factors. Different pacing patterns were observed by event and performance level. The general pacing strategy applied was a positive pacing. In Double and Triple Iron ultra-triathlon, faster athletes paced more evenly with less variation than moderate or slower athletes. The variation in pacing speed increased with the length of the race. There was no significant difference in pacing variation between faster, moderate, and slower athletes in Quintuple and Deca Iron ultra-triathlon. Women had a slower overall performance than men. The best overall times were achieved at the age of 30–39 years. Successful ultra-triathlon athletes adapted a positive pacing strategy in all race distances. The variation in pacing speed increased with the length of the race. In shorter ultra-triathlon distances (i.e., Double and Triple Iron ultra-triathlon), faster athletes paced more evenly with less variation than moderate or slower athletes. In longer ultra-triathlon distances (i.e., Quintuple and Deca Iron ultra-triathlon), there was no significant difference in pacing variation between faster, moderate, and slower athletes.

Preoperative central corneal thickness in eyes with pediatric cataract versus normal fellow eyes

To compare the preoperative central corneal thickness (CCT) in eyes with unilateral cataract with their normal fellow eyes in the pediatric population. A retrospective chart review was conducted using the STORM Kids cataract database. Eyes with traumatic cataract, previous surgery or therapeutic manipulation, or age >18 years were excluded. Only eyes with a normal fellow eye were included. The intraocular pressure, age at time of surgery, race, sex, and type of cataract were also extracted from the record. A total of 70 eyes with unilateral cataract and 70 fellow normal eyes met inclusion criteria. The mean age at the time of surgery was 3.35 years (range, 0.08-15.05). The mean preoperative CCT in the operated eyes was 577 ± 58 μm (range, 464-898 μm). The mean preoperative CCT in fellow eyes was 570 ± 35 μm (range, 485-643 μm). There was no statistically significant difference between the preoperative CCT in cataract eyes versus unaffected fellow eyes (P = 0.183). When stratified by age, the difference in the CCT between cataract and fellow eyes was greatest in the <1 year age group, but was not statistically significant (P = 0.236). The mean preoperative corneal diameter of operative eyes was 11.0 mm (range, 5.5-12.5 mm [n = 68]). The mean preoperative IOP was 15.1 mm Hg (n = 66). In our study cohort, there was no significant difference in mean preoperative CCT between unilateral pediatric cataract eyes and unaffected fellow eyes.

Impact of race, insurance, and procedural timing on sterilization method

Impact of race, insurance, and procedural timing on sterilization method

Abstract P228: Accelerometer-Derived Daily Steps, Cognition, and Cognitive Impairment in U.S. Community-Dwelling Older Adults: The Atherosclerosis Risk in Communities Study

Introduction: Higher physical activity levels have been shown to preserve cognitive function and prevent cognitive impairment (CI). Whether daily steps, an easily interpretable physical activity metric, is associated with measures of brain health has not been widely studied. Hypothesis: Higher daily step count is associated with better cognitive function and lower odds of CI. Methods: Cross-sectional analysis of ARIC participants (mean age: 78 years, 41% male, 19% Black) who wore an accelerometer (ActiGraph GT3X) on the waist for ≥10 hours on ≥3 days between 2016-17. Daily steps were derived and examined continuously and by quartiles. Global and domain-specific (memory, language, executive function) factor scores were estimated from a battery of cognitive tests. Participants were classified as having CI if they had an adjudicated diagnosis of mild CI or dementia. Hypotheses were tested using linear and logistic regression models, adjusted for age, sex, race, education, and accelerometer wear time. Results: Among 454 participants, 88 (19.4%) had CI. The mean number of daily steps was 3,501 (SD=1,974). In adjusted models, a higher daily step count was associated with better global cognition and executive function factor scores (e.g., those in the 4 th daily-step quartile [≥4,499 steps] vs. 1 st [&lt;2074 steps] had a 0.43 [95% confidence interval: 0.24 to 0.61] higher executive function score). Associations of step count with memory or language scores were not supported. The odds of CI were lower for participants who had a higher daily steps count (e.g., those in the 4 th daily-step quartile vs. 1 st had 62% [odds ratio (OR)=0.38, 95% confidence interval: 0.16 to 0.90] lower odds of CI. The OR of CI for continuous daily steps shown in the Figure. Conclusions: Higher daily steps were associated with better cognitive function and may be a helpful marker in identifying participants with CI. Prospective studies of accelerometer-measured physical activity and cognitive outcomes are needed to understand the direction of these associations.

Impact of Running With and Without a Guide on Short Distance Running Performance for Athletes With a Vision Impairment.

This study aimed to investigate the difference of running with or without a guide on running performance (100, 200, and 400 m) for athletes with a vision impairment. Data including athletes' and guides' sex, age, and race times were extracted from 11 elite competitions. Male athletes predominantly ran without a guide (100 m = 91.4%, 200 m = 88.1%, 400 m = 84.8%), whereas female athletes mainly ran with a guide (100 m = 60.5%, 200 m = 80.0%, 400 m = 72.0%). No significant difference in 100-m race times was found between male athletes with or without a guide ( P = 0.647). For the 200 m ( P = 0.001) and 400 m ( P = 0.030), race times were significantly slower for male athletes running with a guide (mean rank 200 m = 36.80, 400 m = 33.57) compared to without a guide (mean rank 200 m = 19.43, 400 m = 21.69). Conversely, 100- ( P = 0.015), 200- ( P = 0.025), and 400-m ( P = 0.029) race times were significantly faster for female athletes with (mean rank 100 m = 18.25, 200 m = 13.71, 400 m = 11.00) compared with without a guide (mean rank 100 m = 27.74, 200 m = 22.67, 400 m = 21.69). Running with a guide affects vision impairment athletes' race times. The influence of running with a guide, and the gender mix of vision impairment athlete and guide, should be considered in any research with the aim of establishing a new classification system for vision impairment athletes.

Real-world use of darolutamide, enzalutamide, and apalutamide for non-metastatic castration-resistant prostate cancer (DEAR).

332 Background: Second-generation androgen receptor inhibitors (ARIs) are the preferred treatment for patients (pts) with non-metastatic castration-resistant prostate cancer (nmCRPC). In this setting, an important therapeutic goal is to minimize adverse events (AEs) and prolong time on ARI treatment. This is the first study to assess real-world (RW) utilization and outcomes of all currently available ARIs, darolutamide (daro), enzalutamide (enza), and apalutamide (apa) in pts with nmCRPC. Methods: DEAR (NCT05362149) is a retrospective observational chart review using electronic medical records from the Precision Point Specialty network of US urology practices. Eligibility criteria included nmCRPC diagnosis, no previous treatment with a novel hormonal agent, and ARI treatment initiation for the first time from August 2019 to March 2022. Pts were classified into 3 cohorts based on the first prescribed ARI in the nmCRPC stage. We present an interim report including the primary composite endpoint (DIS/MET): proportion of pts who discontinued initial ARI treatment (DIS) or progressed to metastasis (MET); and secondary endpoints: time to DIS/MET and underlying reasons. Results: In total, 666 pts were included (daro/enza/apa, n=276/280/110). The proportion of pts starting treatment with daro increased during the study period relative to enza or apa, which declined or remained stable, respectively. Median age (80/79/80 years), White race (68%/69%/74%) and median PSA doubling time (6.7/6.0/7.8 months) at baseline were similar in the daro/enza/apa cohorts, respectively. Median length of follow-up was similar. Fewer pts had a DIS/MET event during the study in the daro cohort (35.9%), compared with enza or apa (52.1%/50.9%); this trend was seen within 6 to 18 months after ARI start. Median time to DIS/MET was 33.4/20.8/18.5 months for daro/enza/apa, respectively. Most common reasons for DIS/MET in the daro/enza/apa cohorts were AEs (8.3%/15.0%/12.7%), death (3.3%/5.4%/2.7%), and MET (14.9%/22.9%/18.2%). Conclusions: This RW study in the US shows that, despite similar baseline characteristics, fewer nmCRPC pts treated with daro had DIS/MET (especially due to AEs/MET) versus enza and apa, and the time to this event was longer in the daro cohort. These findings may be attributed to daro being a structurally distinct ARI with low potential for blood–brain barrier penetration. [Table: see text]

Physiological Features of Olympic-Distance Amateur Triathletes, as Well as Their Associations with Performance in Women and Men: A Cross–Sectional Study

The purpose of this study was to verify the physiological and anthropometric determinants of triathlon performance in female and male athletes. This study included 40 triathletes (20 male and 20 female). Dual-energy X-ray absorptiometry (DEXA) was used to assess body composition, and an incremental cardiopulmonary test was used to assess physiological variables. A questionnaire about physical training habits was also completed by the athletes. Athletes competed in the Olympic-distance triathlon race. For the female group, the total race time can be predicted by V̇O2max (β = -131, t = -6.61, p < 0.001), lean mass (β = -61.4, t = -2.66, p = 0.018), and triathlon experience (β = -886.1, t = -3.01, p = 0.009) (r2 = 0.825, p < 0.05). For the male group, the total race time can be predicted by maximal aerobic speed (β = -294.1, t = -2.89, p = 0.010) and percentage of body fat (β = 53.6, t = 2.20, p = 0.042) (r2 = 0.578, p < 0.05). The variables that can predict the performance of men are not the same as those that can predict the triathlon performance of women. These data can help athletes and coaches develop performance-enhancing strategies.

A Machine Learning Approach to Finding the Fastest Race Course for Professional Athletes Competing in Ironman® 70.3 Races between 2004 and 2020.

Our purpose was to find the fastest race courses for elite Ironman® 70.3 athletes, using machine learning (ML) algorithms. We collected the data of all professional triathletes competing between 2004 and 2020 in Ironman 70.3 races held worldwide. A sample of 16,611 professional athletes originating from 97 different countries and competing in 163 different races was thus obtained. Four different ML regression models were built, with gender, country of origin, and event location considered as independent variables to predict the final race time. For all the models, gender was the most important variable in predicting finish times. Attending to the single decision tree model, the fastest race times in the Ironman® 70.3 World Championship of around ~4 h 03 min would be achieved by men from Austria, Australia, Belgium, Brazil, Switzerland, Germany, France, the United Kingdom, South Africa, Canada, and New Zealand. Considering the World Championship is the target event for most professional athletes, it is expected that training is planned so that they attain their best performance in this event.

Prediction of Marathon Performance using Artificial Intelligence.

Although studies used machine learning algorithms to predict performances in sports activities, none, to the best of our knowledge, have used and validated two artificial intelligence techniques: artificial neural network (ANN) and k-nearest neighbor (KNN) in the running discipline of marathon and compared the accuracy or precision of the predicted performances. Official French rankings for the 10-km road and marathon events in 2019 were scrutinized over a dataset of 820 athletes (aged 21, having run 10 km and a marathon in the same year that was run slower, etc.). For the KNN and ANN the same inputs (10-km race time, body mass index, age and sex) were used to solve a linear regression problem to estimate the marathon race time. No difference was found between the actual and predicted marathon performances for either method (p>0,05). All predicted performances were significantly correlated with the actual ones, with very high correlation coefficients (r>0,90; p<0,001). KNN outperformed ANN with a mean absolute error of 2,4 vs 5,6%. The study confirms the validity of both algorithms, with better accuracy for KNN in predicting marathon performance. Consequently, the predictions from these artificial intelligence methods may be used in training programs and competitions.

Dairy Cows’ Temperament and Milking Performance during the Adaptation to an Automatic Milking System

Adaptative responses of cows to an automatic milking system (AMS) could depend on their temperament, i.e., cows with certain temperament profiles could be able to cope more successfully with the AMS. The relationships between dairy cows' temperament, behaviour, and productive parameters during the changeover from a conventional milking system (CMS) to an AMS were investigated. Thirty-three multiparous cows were classified as 'calm' or 'reactive' based on each of the temperament tests conducted: race time, flight speed (FS), and flight distance, at 5, 25, and 45 days in milk at CMS, then the cows were moved from the CMS to the AMS. During the first five milkings in AMS, the number of steps and kicks during each milking were recorded. The daily milk yield was automatically recorded. The number of steps did not vary by temperament classification, but the number of kicks per milking was greater for calm (0.45 ± 0.14) than for reactive cows (0.05 ± 0.03) when they were classified by FS (p < 0.01). During the first seven days in the AMS, reactive cows for the FS test produced more milk than calm cows (36.5 ± 1.8 vs. 33.2 ± 1.6 L/day; p = 0.05). In conclusion, behavioural and productive parameters were influenced by cows´ temperament during the milking system changeover since the calm cows kicked more and produced less than the reactive ones.

Impact of air pollution on running performance

Air pollution exposures during training may impact race performances. We aggregated data on 334 collegiate male track & field athletes from 46 universities across the United States over 2010–2014. Using distributed lag non-linear models, we analyzed the relationship between race time and PM2.5, ozone, and two versions of the Air Quality Index (AQI) exposures up to 21 days prior to the race. We observed a 12.8 (95% CI: 1.3, 24.2) second and 11.5 (95% CI: 0.8, 22.1) second increase in race times from 21 days of PM2.5 exposure (10.0 versus 5.0 μg/m3) and ozone exposure (54.9 versus 36.9 ppm), respectively. Exposure measured by the two-pollutant threshold (PM2.5 and ozone) AQI was not significantly associated with race time; however, the association for summed two-pollutant AQI (PM2.5 plus ozone) was similar to associations observed for the individual pollutants (12.4, 95% CI: 1.8, 23.0 s). Training and competing at elevated air pollution levels, even at exposures within AQI’s good-to-moderate classifications, was associated with slower race times. This work provides an initial characterization of the effect of air pollution on running performance and a justification for why coaches should consider approaches to reduce air pollution exposures while training.

Abstract 72: Association Between Patient And Hospital-level Factors With Door-in-door-out Times In Stroke Transfers: Findings From Get With The Guidelines®

Introduction: Advanced acute stroke treatments (endovascular therapy (EVT), neurosurgery) are time sensitive and often require emergent interfacility transfer. Thus, Door-in-door-out (DIDO) times at transferring hospitals are an important quality improvement metric. We sought to characterize DIDO times for acute stroke transfers in the Get With The Guidelines® (GWTG)-Stroke registry and identify patient and hospital factors associated with DIDO time. Methods: Patients with stroke presenting between January 2019 and December 2021 transferred from the emergency department (ED) at the presenting hospital to another acute care hospital were included. Primary outcome was DIDO time (time of transfer out minus time of arrival to presenting ED). Generalized estimating equation (GEE) regression models were used to identify patient and hospital characteristics associated with DIDO time. Subgroup analyses were performed for hemorrhagic and ischemic stroke patients transferred for EVT. Results: Among 153,434 patients (age 67.3+15.0 years, 72.9% White, 51.2% male), 107,897 were ischemic and 41,736 hemorrhagic strokes. Overall, median DIDO time was 216 (25th-75th percentile 131 - 457) minutes. The following were associated with increased DIDO time: age &gt;80 years (+36.18 minute increase in median DIDO time), Black race (+11.23 min), Hispanic ethnicity (+9.65 min), ischemic stroke type (+156.51 min), and urban location (+44.54 min) while the following were associated with decreased DIDO time: EMS prenotification (-49.19 min) and NIHSS &gt;12 (-139.81 min). In the EVT ischemic stroke subgroup, age, sex, race, EMS prenotification, stroke severity, and after-hours timing were strongly associated with median DIDO time. Conclusions: Opportunities to reduce DIDO times for acute stroke interhospital transfers require focus on modifiable health system factors such as EMS pre-notification but also persistent race-ethnic and urban-rural disparities.

Relationship between Maximum Force-Velocity Exertion and Swimming Performances among Four Strokes over Medium and Short Distances: The Stronger on Dry Land, the Faster in Water?

Evaluating force-velocity characteristics on dry-land is of the utmost importance in swimming, because higher levels of these bio-motor abilities positively affect in-water performance. However, the wide range of possible technical specializations presents an opportunity for a more categorized approach that has yet to be seized. Therefore, the aim of this study was to identify feasible differences in maximum force-velocity exertion based on swimmers' stroke and distance specialization. To this scope, 96 young male swimmers competing at the regional level were divided into 12 groups, one for each stroke (butterfly, backstroke, breaststroke, and front crawl) and distance (50 m, 100 m, and 200 m). They performed two single pull-up tests, 5-min before and after competing in a federal swimming race. We assessed force (N) and velocity (m/s) exertion via linear encoder. There were no significant differences between pre-post maximum force-velocity exertions, despite the decreasing trend. Force-parameters highly correlated with each other and with the swimming performance time. Moreover, both force (t = -3.60, p < 0.001) and velocity (t = -3.90, p < 0.001) were significant predictors of swimming race time. Sprinters (both 50 m and 100 m) of all strokes could exert significantly higher force-velocity compared to 200 m swimmers (e.g., 0.96 ± 0.06 m/s performed by sprinters vs. 0.66 ± 0.03 m/s performed by 200 m swimmers). Moreover, breaststroke sprinters presented significantly lower force-velocity compared to sprinters specialized in the other strokes (e.g., 1047.83 ± 61.33 N performed by breaststroke sprinters vs. 1263.62 ± 161.23 N performed by butterfly sprinters). This study could provide the foundation for future research regarding the role of stroke and distance specializations in modeling swimmers' force-velocity abilities, thus influencing paramount elements for specific training and improvement towards competitions.

Is Real-Time Poolside Assessment of Upper Limb Errors in Front Crawl Swimming Technique Reliable and Equivalent to Video Analysis?

Swimming technique is widely believed to influence performance, but this relationship has rarely been tested objectively using a real-time poolside assessment. To determine the (1)test-retest reliability, interrater reliability, and criterion validity (live vs video) of real-time poolside assessment of upper limb (UL) errors in front crawl (FC) swimming technique and (2)the relationship between UL errors and FC swimming performance. Cross-sectional reliability, validity, and correlational study. Swim team practice at a college natatorium. Thirty-nine Division III college swimmers (21 women and 18 men, age = 19 [1]y, swimming experience = 11 [3]y). Seven UL errors in FC swimming technique, many of which involved unnecessary vertical and mediolateral motions, were assessed in real time from outside the pool during swim practice. Test-retest reliability, interrater reliability, and criterion validity were calculated using Cohen kappa (κ) and weighted kappa (κw). Swimming performance was determined by the participants' best FC events relative to the conference records. The correlation between total UL errors and FC swimming performance was assessed with Pearson r. Cohen κ and κw were moderate for the majority of errors, with the following ranges: 0.46 to 0.90 (test-retest), -0.01 to 1.00 (interrater), and 0.36 to 0.66 (criterion validity). There was a significant correlation between total UL errors and FC swimming performance: r(24) = -.59 (P = .001, R2 = .35). Reliability and validity were moderate for the majority of errors. The fewer UL errors swimmers made while practicing FC, the faster their best FC race times tended to be relative to the conference record. UL errors in FC swimming technique explained 35% of the variance in performance.

Bacteroides uniformis and its preferred substrate, α-cyclodextrin, enhance endurance exercise performance in mice and human males.

Although gut microbiota has been linked to exercise, whether alterations in the abundance of specific bacteria improve exercise performance remains ambiguous. In a cross-sectional study involving 25 male long-distance runners, we found a correlation between Bacteroides uniformis abundance in feces and the 3000-m race time. In addition, we administered flaxseed lignan or α-cyclodextrin as a test tablet to healthy, active males who regularly exercised in a randomized, double-blind, placebo-controlled study to increase B. uniformis in the gut (UMIN000033748). The results indicated that α-cyclodextrin supplementation improved human endurance exercise performance. Moreover, B. uniformis administration in mice increased swimming time to exhaustion, cecal short-chain fatty acid concentrations, and the gene expression of enzymes associated with gluconeogenesis in the liver while decreasing hepatic glycogen content. These findings indicate that B. uniformis enhances endurance exercise performance, which may be mediated by facilitating hepatic endogenous glucose production.

Usefulness of V˙O2 Kinetics and Biomechanical Parameters as Predictors of Athlete's Performance in 800 m Running Race.

Incremental tests to exhaustion have been usually employed as the "gold standard" to establish the fitness level of athletes. However, during real competition in many sport disciplines, exertion is not characterized by an increasing effort until failure. The purpose of this preliminary study was to add new evidence regarding the usability of parameters obtained from an on-field testing in 800 m running athletes. V˙O2 kinetics (mean, amplitude, phase time, and phase start time) and biomechanical parameters (velocity, stride frequency, and stride length) were analyzed in eight athletes during a maximal 800 m running race test. Our results showed that only the peak of blood lactate concentration after the 800 m test was correlated with the race time (p = 0.047). The race time was positively associated with both the phase duration and phase start time (all p-values &lt; 0.05). Conversely, race time was negatively correlated with velocity, stride frequency, and amplitude (p-values &lt; 0.05). Our results reveal that jointly studying the V˙O2 kinetics and biomechanical parameters during a maximal 800 m running race test is a useful tool to predict the athlete's upcoming performance and improve the planning and control of the training process of 800 m running athletes.

Predictors of half-marathon performance in male recreational athletes.

Few research has been conducted on predictors of recreational runners' performance, especially in half-marathon running. The purpose of our study was (a) to investigate the relationship of half-marathon race time with training, anthropometry and physiological characteristics, and (b) to develop a formula to predict half-marathon race time in male recreational runners. Recreational runners (n=134, age 44.2±8.7 years; half-marathon race time 104.6±16.2 min) underwent a physical fitness battery consisting of anthropometric and physiological tests. The participants were classified into five performance groups (fast, 73-92 min; above average, 93-99 min; average 100-107 min; below average, 108-117 min; slow group, 118-160 min). A prediction equation was developed in an experimental group (EXP, n=67), validated in a control group (CON, n=67) and prediction bias was estimated with 95 % confidence intervals (CI). Performance groups differed in half-marathon race time, training days, training distance, age, weight, (body mass index) BMI, body fat (BF) and maximum oxygen uptake (VO2max) (p≤0.001, η2≥0.132), where faster groups had better scores than the slower groups. Half-marathon race time correlated with physiological, anthropometric and training characteristics, with the faster the runner, the better the score in these characteristics (e.g., VO2max, r=0.59; BMI, r=-0.55; weekly running distance, r=-0.53, p<0.001). Race time in EXP might be calculated (R2=0.63, standard error of the estimate=9.9) using the equation 'Race time (min)=80.056+2.498×BMI-0.594×VO2max-0.191×weekly training distance in km'. Validating this formula in CON, no bias was shown (difference between observed and predicted value 2.3±12.8 min, 95 % CI -0.9, 5.4, p=0.153). Half-marathon race time was related to and could be predicted by BMI, VO2max and weekly running distance. Based on these relationships, a prediction formula for race time was developed providing a practical tool for recreational runners and professionals working with them.

Motion Kinematic Analysis of the Palestinian Athletics Team Players Under 20 Years in 1500 m Race

This study identifies the kinematic analysis of the Palestinian athletics team players under 20 years in a 1500 m race by calculating the kinematic variables, identifying the relationship between them and the performance stages, and identifying the differences between the kinematic variables of the performance stages and the time of the 1500 m race. The researchers followed the analytical descriptive approach and selected a purposive sample; the Palestinian athletics team players under 20 years who participated in 1500 m races from the southern governorates (i.e. three players). The research main results were identifying the kinematic variables and their values (step length, step frequency, contact time, flight time, step time, step speed, average speed and center of pressure position). There are no statistically significant relationships between the values of the kinematic variables and the 1500 m race time. Statically significant differences at 0.05 are observed for the values of the kinematic variables: step length, contact time, and flight speed. However, there are no statistically significant differences for the values of the other variables. The researchers recommend the Palestine Athletic Federation to benefit from the results of the study for each of the race’ stages to identify the strengths and weaknesses of players and hence improve their skills. Keywords: motion analysis, kinematic analysis, 1500 m race. https://doi.org/10.55463/issn.1674-2974.50.2.14

Normative data of the start in the 50 m events at the 2021 LEN European Championships and understanding its relationship with the final race

This study aimed to: (i) present normative data of the variables related to the start in the four swim strokes by tier and sex, and; (ii) understand the relationship between the 15th meter mark time and the final race time of the male and female swimmers competing in the four 50 m events at the 2021 European Championships. Participants were all male and female swimmers who competed in the 50 m events at the 2021 LEN European Championships held in Budapest. The official race times and block times were retrieved from the official competition website. All starting variables were analyzed in a dedicated software for race analysis. The 15th meter mark time was used as the start main outcome. For all events by sex, the 15th meter mark time was the variable presenting the highest and largest tier effect (p &lt; 0.001) besides the final race time. Overall, despite the swim stroke, the variables related to the underwater phase were also responsible for the significant tier effect (p &lt; 0.001). The 15th meter mark time presented a high to very-high relationship with the final race time in all four swim strokes. This relationship was stronger in freestyle (both sexes). That is, swimmers who achieve the 15th meter mark sooner are more likely to deliver better performances. Coaches must be aware that the underwater phase plays a key-role on the swimmers’ (both sexes) start performance. Nonetheless, different strategies can be used based on the swimmers’ strength and weaknesses. Moreover, the start performance in all four swim strokes and in both sexes can strongly predict the final race time.