Tensiomyography: from muscle assessment to talent identification tool.

Introduction: Tensiomyography (TMG) is a non-invasive and cost-effective tool that is gaining popularity in fields such as sports science, physical therapy, and medicine. In this narrative review, we examine the different applications of TMG and its strengths and limitations, including its use as a tool for sport talent identification and development. Methods: In the course of crafting this narrative review, an exhaustive literature search was carried out. Our exploration spanned several renowned scientific databases, such as PubMed, Scopus, Web of Science, and ResearchGate. The materials we sourced for our review included a broad spectrum of both experimental and non-experimental articles, all focusing on TMG. The experimental articles featured varied research designs including randomized controlled trials, quasi-experiments, as well as pre-post studies. As for the non-experimental articles, they encompassed a mix of case-control, cross-sectional, and cohort studies. Importantly, all articles included in our review were written in English and had been published in peer-reviewed journals. The assortment of studies considered provided a holistic view of the existing body of knowledge on TMG, and formed the basis of our comprehensive narrative review. Results: A total of 34 studies were included in the review, organized into three sections: 1) assessing muscle contractile properties of young athletes, 2) using TMG in the talent identification and development process and 3) Future research and perspectives. According to data presented here, the most consistent TMG parameters for determining muscle contractile properties are radial muscle belly displacement, contraction time, and delay time. Biopsy findings from the vastus lateralis (VL) confirmed TMG as a valid tool for estimating the ratio of myosin heavy chain (%MHC-I). Conclusion: TMGs ability to estimate the ratio of %MHC-I has the potential to aid in the selection of athletes with the muscle characteristics best suited for a particular sport, eliminating the need for more invasive procedures. However, more research is warranted to fully understand TMG's potential and its reliability when used with young athletes. Importantly, the use of TMG technology in this process can positively impact health status, reducing the frequency and severity of injuries and the duration of recovery, and subsequently can reduce drop out rates among youth athletes. Future studies should look at twin youth athletes, as a model capable of discriminating between the influence of hereditary factors vs. environmental factors, in therms of muscle contractility and TMG's potential for instance.

Energy cost differences between marathon runners and soccer players: Constant versus shuttle running.

Purpose: In the last decades, the energy cost assessment provided new insight on shuttle or constant running as training modalities. No study, though, quantified the benefit of constant/shuttle running in soccer-players and runners. Therefore, the aim of this study was to clarify if marathon runners and soccer players present specific energy cost values related to their training experience performing constant and shuttle running. Methods: To this aim, eight runners (age 34 ± 7.30y; training experience 5.70 ± 0.84y) and eight soccer-players (age 18.38 ± 0.52y; training experience 5.75 ± 1.84y) were assessed randomly for 6' on shuttle-running or constant-running with 3 days of recovery in-between. For each condition, the blood lactate (BL) and the energy cost of constant (Cr) and shuttle running (CSh) was determined. To assess differences for metabolic demand in terms of Cr, CSh and BL over the two running conditions on the two groups a MANOVA was used. Results: V·O2max were 67.9 ± 4.5 and 56.8 ± 4.3 ml·min-1 kg-1 (p = 0.0002) for marathon runners and soccer players, respectively. On constant running, the runners had a lower Cr compared to soccer players (3.86 ± 0.16 J kg-1m-1 vs. 4.19 ± 0.26 J kg-1 m-1; F = 9.759, respectively; p = 0.007). On shuttle running, runners had a higher CSh compared to soccer players (8.66 ± 0.60 J kg-1 m-1 vs. 7.86 ± 0.51 J kg-1 m-1; F = 8.282, respectively; with p = 0.012). BL on constant running was lower in runners compared to soccer players (1.06 ± 0.07 mmol L-1 vs. 1.56 ± 0.42 mmol L-1, respectively; with p = 0.005). Conversely, BL on shuttle running was higher in runners compared to soccer players 7.99 ± 1.49 mmol L-1 vs. 6.04 ± 1.69 mmol L-1, respectively; with p = 0.028). Conclusion: The energy cost optimization on constant or shuttle running is strictly related to the sport practiced.

Anthropometric variability of European taekwondo champions / Variabilidad antropométrica de los campeones europeos de taekwondo

SUMMARY: World Taekwondo (WT) as an Olympic sport gained much more attention than before, and there is a growing need for precise and specific profiles of successful taekwondo competitors. Aim of this investigation was to determine body composition, somatotype, and selected anthropometric parameters/indexes of elite taekwondo champions and medal winners on the most demanding taekwondo tournaments in the World. The sample for this research consisted of n=16 (n=4 male; n=12 female) elite taekwondo champions, n=8 juniors and n=8 seniors, who were European (n=13), and World (n=3) champions of European descent. Data was collected longitudinally for seven years since 2015. Obtained results revealed specific (absolute) phenotype of taekwondo champions, following: PI (11.50 female; 11.85 male), HWR (43.96 female; 44.47 male) and BMI (19.96 female; 22.04 male). Further analysis shows that champions have greater values of body height, and have slightly greater ectomorphy and mesomorphy values in regard to other elite competitors. Presented research is the first publication of referent values for the general anthropometric dataset, and such results represent the anthropometric variability of European WT champions.

World Taekwondo (TW) como deporte olímpico ha logrado una mayor importancia, y existe una creciente necesidad de contar con perfiles precisos y específicos de competidores exitosos de TW. El objetivo de esta investigación fue determinar la composición corporal, el somatotipo y parámetros/índices antropométricos seleccionados de campeones de TW de élite y los ganadores de medallas en los torneos de TW más exigentes del mundo. La muestra para esta investigación consistió en n=16 (n=4 hombres; n=12 mujeres) campeones de TW de élite, n=8 juniors y n=8 seniors, que eran europeos (n=13) y mundiales (n=3), campeones de ascendencia europea. Los datos se recopilaron longitudinalmente durante siete años desde 2015. Los resultados obtenidos revelaron un fenotipo específico (absoluto) de los campeones de TW, a continuación: PI (11,50 mujeres; 11,85 hombres), HWR (43,96 mujeres; 44,47 hombres) e IMC (19,96 mujeres; 22,04 hombres). Un análisis más detallado muestra que los campeones tienen mayores valores de altura corporal y tienen valores de ectomorfia y mesomorfia ligeramente mayores con respecto a otros competidores de élite. La investigación presentada es la primera publicación de valores de referencia para el conjunto de datos antropométricos generales, y dichos resultados representan la variabilidad antropométrica de los campeones europeos de TW.

Elite Croatian junior taekwondo competitors: morphological characteristics and body composition reference values / Competidores croatas de taekwondo junior de élite: características morfológicas y valores de referencia de composición corporal

SUMMARY: The main purpose of this study was to determine the body composition and anthropometric reference values of male and female junior Croatian taekwondo competitors according to official weight category. Additional aim of the study was to identify possible differences in variables between the weight categories. The sample comprised 247 junior participants of the national taekwondo championships divided into male (N=121) and female (N=126). The variable sample was defined by a set of 8 measurements: Body height (cm), Body mass (kg), Body mass index, Body fat (%), Body fat (kg), Muscle mass (kg), Lean body mass (kg) and Total body water (%). Results confirm previous studies proving that younger taekwondo practitioners have higher levels of body fat than their more experienced peers (seniors). Significant differences were only found between lean and heavy categories. Male junior taekwondo athletes show total body water percentages from 57.4 to 74.8 %, with significantly lower percentages in higher weight categories, while female athletes in heigher categories demonstrate a worrying level of hydration status, therefore endangering their performance and overall health. As the first paper that investigates the reference values of junior taekwondo athletes but based on official weight categories it is especially important as each weight category warrant different body composition requirements, as seen from significant differences across different variables. Future studies should include motor abilities inspection throughout the weight categories and possible use of calculation of metabolic age.

RESUMEN: El objetivo principal de este estudio fue determinar la composición corporal y los valores de referencia antropométricos de los competidores croatas masculinos y femeninos de taekwondo junior según la categoría oficial de peso. Además, se analizó identificar las posibles diferencias en las variables entre las categorías de peso. La muestra estuvo compuesta por 247 participantes junior de los campeonatos nacionales de taekwondo divididos en hombres (N = 121) y mujeres (N = 126). La muestra variable se definió mediante un conjunto de 8 medidas: altura corporal (cm), masa corporal (kg), índice de masa corporal, grasa corporal (%), grasa corporal (kg), masa muscular (kg), masa corporal magra (kg) y agua corporal total (%). Los resultados confirmaron estudios previos que demuestran que los practicantes de taekwondo más jóvenes tienen niveles más altos de grasa corporal que sus pares más experimentados (personas mayores). Solo se encontraron diferencias significativas entre las categorías magra y pesada. Los atletas masculinos de taekwondo junior muestran porcentajes de agua corporal total del 57,4 al 74,8 %, con porcentajes significativamente más bajos en las categorías de peso más alto, mientras que las atletas femeninas en las categorías más altas, demuestran un nivel preocupante de estado de hidratación, poniendo en peligro su rendimiento y salud en general. Como el primer artículo que investiga los valores de referencia de los atletas de taekwondo junior, pero basado en categorías de peso oficiales, es especialmente importante ya que cada categoría de peso garantiza diferentes requisitos de composición corporal, como se puede observar en las diferencias significativas entre las diversas variables. Los estudios futuros deberían incluir un análisis de las habilidades motoras en todas las categorías de peso y el posible uso del cálculo de la edad metabólica.

Reliability of Urinary Dehydration Markers in Elite Youth Boxers.

PURPOSE: To determine the reliability and diagnostic accuracy of noninvasive urinary dehydration markers in field-based settings on a day-to-day basis in elite adolescent amateur boxers. METHODS: Sixty-nine urine samples were collected daily from 23 athletes (17.3 ± 1.9 y) during their weight-stable phase and analyzed by field and laboratory measures of hydration status. Urine osmolality (UOSM), urine specific gravity (USG), total protein content (TPC), and body-mass stability were evaluated to determine fluid balance and hydration status. Overall macronutrient and water intake were determined using dietary records. According to their anthropometric characteristics, athletes were assigned into 2 groups: lightweight (LWB) and heavyweight (HWB) boxers. RESULTS: Data presented on UOSM demonstrated a uniform increment by 11.2% ± 12.8% (LWB) and 19.9% ± 22.7% (HWB) (P < .001) over the course of the study, even during the weight-stable phase (body mass, ICC = .99) and ad libitum fluid intake (42 ± 4 mL · kg-1 · d-1). The intraclass correlation coefficients (ICCs) ranged from .52 to .55 for USG and .38 to .52 for UOSM, further indicating inconsistency of the urinary dehydration markers. Poor correlations were found between USG and TPC metabolites (r = .27, P = .211). CONCLUSIONS: Urinary dehydration markers (both USG and UOSM) exhibit high variability and seem to be unreliable diagnostic tools to track actual body-weight loss in real-life settings. The ad libitum fluid intake was apparently inadequate to match acute fluid loss during and after intense preparation. The applicability of a single-time-point hydration-status assessment concept may preclude accurate assessment of actual body-weight deficits in youth boxers.