Reliability and validity of three portable devices for quantifying spatiotemporal parameters in runners of different athletic abilities during treadmill running.

This study aimed to evaluate the validity and reliability of a wearable device and a phone application for measuring spatiotemporal parameters and their relationship with running economy (RE) by comparing them with photocell data in runners of different abilities. Twenty-three male runners were divided into well-trained and recreational groups and performed a 4-min running bout at 17 and 13 km·h-1 respectively. During the bout, were measured the spatiotemporal parameters with three devices (Stryd, Runmatic, and Optojump) and RE with a gas analyser. Pearson correlation showed perfect relationships for stride frequency (SF) and stride length (SL) between the devices, and moderate for flight time (FT) and contact time (CT). There were no correlations between the spatiotemporal parameters and RE measurements. Coefficient of variation was ~ 5% in all devices for CT, SF, and SL, and higher for FT (15-24%). CT was underestimated (15-16% with Runmatic and Stryd, respectively) and FT was overestimated (36-40%) compared to Optojump. Bland-Altman plots revealed that Runmatic could be a more accurate system than Stryd. In conclusion, both devices were valid tools for measuring spatiotemporal parameters during running at RE speed. Runmatic was more valid and reliable in comparison with Stryd. In addition, at lower running speeds the devices showed less reliability.

Modelling performance by continents in swimming.

Introduction: There is a growing interest in the scientific community about the progression and congruity in the performance of talented participants who complete representing different nations in the most important international events. The prediction of incoming performances is nowadays in demand with the objective of returning in talent investment. Talent identification programs have tried to select and develop sports talent over years. However, to our knowledge, there is a lack of research about success in swimming World Championships (WCs) performance considering continents-country and how successful outcomes are influenced by these variables. Therefore, the primary goal is to analyze the effect of early specialization comparing the performance progression model of the countries gathered by continents. Methods: Participant's data from all Junior and Senior WCs between 2006 and 2017 from International Swimming Federation (FINA). One-way ANOVA, ANCOVA and regression model were used to explain whether the variable category, age, best z-score, experience, and continent influences the performance obtained in Absolute WC. Results: Significant differences (p < 0.01) were found between the average performance obtained by the two different categories (junior: swimmers participating in junior WCs before senior WCs; senior: swimmers participating in senior WCs without previous participation in junior WCs), where swimmers from category junior showed significant better performance's times than seniors, except in America. ANCOVA results showed that generally, the greatest differences where in the earliest ages, with best performance registered in category junior in all the continents. Also, the experience was a significant variable in the general model. Conclusion: Swimmers who had participated in junior category prior absolute obtained better performance's times than those swimmers who participated directly in absolute, in the first participation in senior WC. Thus, early specialization is a key factor to obtain better results in senior WCs for all the continents, except in America.

Periodization of altitude training: A collective case study of high-level swimmers.

The objective was to quantify parallel changes in performance and physiological measures in relation to periodization of sequential altitude training over a season in elite swimmers. The altitude training of four female and two male international swimmers in selected seasons was examined using a collective case study approach. All swimmers were a medalist in World (WC) and/or European Championships (EC) 2013, 2014, 2016 and 2018 in short or long course competition. A traditional periodization model was employed using three macrocycles with 3-4 altitude camps (duration 21-24 days each) scheduled over the season, following a polarized training intensity distribution (TID) with a volume ranged between 729 km and 862 km. The timing of return from altitude prior to competition was between 20-32 days, with 28 days the most common period. Competition performance was assessed with major (international) and minor (regional or national) competitions. Hemoglobin concentration, hematocrit, anthropometric characteristics, were measured before and after each camp. Competition performance following the altitude training camps improved by 0.6% ± 0.8% (personal best time; mean ± SD) (95% confidence limits (CL) 0.1%-1.1%), 1.6% ± 0.7% (95% CL 1.2% to 2.0%) (season best time) and 1.6% ± 0.5% (95% CL 1.3%-1.9%) (previous season time). Hemoglobin concentration increased 4.9% from pre-to post-altitude training camps, while hematocrit increased by 4.5%. The sum of six skinfolds reduced by 14.4% (95% CL 18.8%-9.9%) and 4.2% (95% CL 2.4%-9.2%) for the two males (EC), and by 15.8% (95% CL 19.5%-12.0%) for two females (WC). Three to four altitude training camps in a competitive season, around 21-24 days of duration, scheduling the last return between 20-32 days before the main competition, integrated in a traditional periodized sequence, can induce worthwhile improvements in international swimming performance, hematological parameters, and anthropometric characteristics.

Efectos de la intensidad de nado en el rendimiento del triatlón / Effects of Swimming Intensity on Triathlon Performance

OBJETIVO: Analizar la influencia de diferentes intensidades de nado en los sectores de ciclismo y carrera a pie y en el rendimiento final del triatlón sprint. MÉTODOS: Siete triatletas sub23 y Absolutos (altura de 1,74 ± 0,04 m, peso de 70,82 ± 6,76 kg, edad de 23,42 ± 3,25 años, VO2 max de 63,54 ± 5,23 ml·kg-1·min-1) participaron en este estudio. Realizaron tres triatlones completos a intensidades de nado diferentes (70%, 80% y 90% de un test de 750m previo). Se midió la frecuencia cardíaca y el lactato al finalizar cada sector y el triatlón completo. RESULTADOS: La intensidad de nado del 90% obtuvo el mejor rendimiento final. El lactato y frecuencia cardíaca en el sector de nado para esta condición incrementó significativamente, sin diferencias en los sectores siguientes. CONCLUSIONES: Basándonos en la muestra estudiada, el rendimiento final en un triatlón sprint parece estar condicionado por la intensidad de nado, siendo el 90% la mejor intensidad observada en triatletas moderadamente entrenados

OBJECTIVE: To analyze the influence of different swimming intensities on the subsequent cycling and running sectors and overall sprint triathlon performance. METHODS: Seven sub23 and senior triathletes (height 1.74 ± 0.04 m, weight 70.82 ± 6.76 kg, age 23.42 ± 3.25 years, VO2 max 63.54 ± 5.23 ml • kg-1 • min-1) participated in this study. They carried out three complete triathlons at different swimming intensities (70%, 80% and 90% of a previous 750m test). Heart rate and lactate were measured at the end of each sector and after completing the whole triathlon. RESULTS: The 90% swimming intensity obtained the best final performance. Lactate and heart rate in the swimming sector for this condition increased significantly, without differences in the following sectors. CONCLUSIONS: Based on the sample studied, the final performance in a sprint triathlon seems to be conditioned by the swim intensity, being 90% the best intensity observed in moderately trained triathletes