ECSS Paris 2023: OP-AP03
INTRODUCTION: Competitive interactions are an important phenomenon in most team and individual sports. However, research on competitive interactions is mainly conducted in controlled laboratory-based experiments, which raises the question of generalizability towards more dynamic environments in team sports. While studies in rugby and futsal investigated 1-vs-1 actions in training settings, they did not relate their findings to the successfulness of the actions. We seek to close this gap by studying 1-vs-1 actions in competition. Therefore, using a large-scale observation design, this study aims to identify determinants of successful 1-vs-1 actions in male elite soccer. METHODS: 1-vs-1 actions from 43 Dutch Eredivisie matches were manually selected and labelled on successfulness by three raters. Using tracking data, 24 variables of the 1-vs-1 actions were obtained, divided into three categories: individual (e.g. velocity of the defender), interaction (e.g. relative velocity between the attacker and the defender), and environmental (e.g. the location on the pitch of the action). Multivariate analysis was used to show which (category of) variables discriminated between successful and unsuccessful 1-vs-1 actions. RESULTS: In total 734 1-vs-1 actions were selected (Fleiss kappa = 0.76) of which 356 were successful and 378 unsuccessful (Fleiss kappa = 0.89). A MANOVA showed a main effect for successfulness (Wilks Λ = 0.881, F(23, 710) = 4.178, p < 0.001). Post-hoc analysis with a Bonferroni correction identified five individual variables that differed between successful and unsuccessful 1-vs-1 actions (p<0.03): the minimal distance between the attacker and the defender, the minimal distance between the ball and the defender, the variation in the distance between the attacker and the ball, the pressure on the attacker, and the median directional change of the attacker during the action. All five were variables that related to the interaction between the attacker and his environment, while variables for the individual and environment show no significant results. CONCLUSION: In conclusion, only the variables that were related to the interaction between the attacker and the defenders discriminated between successful and unsuccessful 1-vs-1 actions. These findings can be directly applied to talent identification and scouting in team sports. Although it is often thought that individual speed and acceleration are important for successful 1-vs-1 actions, the results show that the interaction between the attacker and the environment is more decisive for successfulness in 1-vs-1 actions than individual variables. Specifically, the successful 1-vs-1 actions differentiated from unsuccessful ones by showing less pressure exerted on the attacker during the action, a higher degree of ball control by the attacker, and a more direct approach during the action.
Read CV Gerard Alexander OonkECSS Paris 2023: OP-AP03
INTRODUCTION: Current talent identification programs struggle to successfully identify track-and-field talents at a younger age, mainly because of poor relation between youth and senior performances [1]. Instead, stable biological and performance-related factors, such as muscle fiber type composition (MFTC), may hold promise for more robust predictions. Fast and slow muscle fibers possess distinct characteristics and their ratio is discipline-dependent in elite track-and-field athletes [2]. With the advent of non-invasive techniques, the assessment of MFTC is no longer restricted to muscle biopsies, enabling its use in talented youth [3]. Therefore, the aim of this longitudinal prospective study is to investigate whether MFTC measured at a younger age, is a good predictor for later track-and-field performance. METHODS: Between 2010 and 2019, we included 64 talented youth athletes that were allowed into selective track-and field elite sport schools (age = 15.7 ± 1.3 years, range 12 to 18 years). Their MFTC was non-invasively estimated in the gastrocnemius muscle using 3T proton magnetic resonance spectroscopy of the fast-twitch metabolite carnosine. Youth athletes’ MFTC was compared to a discipline-specific elite athlete benchmark population (n = 87, ≥ 1050 IAAF points). A categorical approach was used to assign youth athletes as ‘match’ if their MFTC was within the range (mean ± 1 SD) of the elite athletes for their discipline, otherwise appointed as ‘mismatch’. The personal best IAAF-score was analyzed as performance parameter, with a follow-up period of 3 to 12 years after the muscle scan. Independent sample t-tests were used with significance set at p ≤ 0.05. RESULTS: The highest IAAF-score was obtained 3.4 ± 2.4 years after the scan. Two-thirds of the athletes were already training for a discipline matching their MFTC, indicating the importance of the coaches’ eye. Nevertheless, one-third was still misclassified. The ‘match’ athletes achieved a significantly higher IAAF-score (987 ± 110 vs 915 ± 93 points, p = 0.011) compared to ‘mismatch’ athletes, indicating a better later performance if MFTC at youth level matches with the MFTC of the elite benchmark for their discipline. Of all the matching athletes, 36% achieved an all-time best score above 1050 points, i.e. reaching international standards, compared to only 9% with a mismatching MFTC (p = 0.022). CONCLUSION: This study shows for the first time that youth track-and-field athletes who train for a discipline that is deemed optimal based on their MFTC, perform better at adult age. Therefore, the non-invasive measurement of MFTC can be seen as a new and valuable element in talent identification, identifying the ideal discipline for youth athletes around the age of 15 to 16 years. This is likely expandable to other sports, like cycling, where discipline specialization depends on MFTC. References: [1] Barth et al. (2023). Sports Medicine. [2] Costill et al. (1976). Journal of Applied Physiology. [3] Baguet et al. (2011). PLOS ONE.
Read CV Jonas VandecauterECSS Paris 2023: OP-AP03
INTRODUCTION: Parameters of the speed- or power-time relationship, such as critical speed (CS) and D-prime (D’) or critical power (CP) and W-prime (W’) enable non-invasive evaluation of physiological capacities, which can be used to model the ‘balance’ of W (W’BAL) during intermittent exercise [1]. However, their deterioration during prolonged exercise, described as ‘durability’ [2], may lead to inaccuracies in W’BAL modelling. This study evaluated i) changes in speed- or power-time parameters during team sport simulations and ii) the relationships between work done in the severe-intensity domain (SID) and the magnitude of change in parameters. METHODS: Twenty participants consented to take part in four testing visits. Familiarisation and baseline assessments of overground running 3-min tests (3MT) were conducted, with a global positioning system used to measure the speed-time relationship and mechanical work determined via energetic modelling, from which CP (W) and W’ (kJ) were calculated. Subsequent visits comprised a 40-min (one-half) or 80-min (full-match) rugby league movement simulation protocol, each followed by the 3MT (40-3MT and 80-3MT). The SID distance (m) >CS and work (kJ) >CP were calculated from each simulation. A repeated measures ANOVA analysed changes in parameters across baseline, 40-3MT and 80-3MT, with post-hoc comparisons where appropriate. Linear regression was used to explain the variance in power-time parameter changes based on SID work. The relationships between baseline parameters and durability were analysed with Pearson’s coefficients. Means±SD are presented. RESULTS: There were no differences (P>0.05) in CS or CP across simulation stages; however, D’ and W’ deteriorated at each simulation stage and were lowest after the 80-3MT (94±37 m, 19±8 kJ, respectively) compared to baseline (142±50 m, 28±12 kJ, respectively; P<0.001). The SID work explained 41.0% (P=0.01) variance in the W’ reductions between baseline 3MT and 80-3MT. There was no relationship between baseline CP or CS and the reduction in W’ after 80 min (P=>0.05), but there was an inverse relationship between baseline W’ and the reduction in W’ after 40 min (r=-0.69; P=0.001) and 80 min (r=-0.76; P=<0.001). CONCLUSION: These results demonstrate the magnitude and time-course of D’ and W’ reductions after half- and full-match simulations, whilst highlighting the maintenance of CS and CP. The W-prime reductions tended to be highest among those with higher baseline W’ values but were unrelated to CP or CS. The maintenance of CS and CP parameters across protocols was unanticipated, which adds complexity to the understanding of the interdependency between CP and W’ or CS and D’ parameters. These findings have implications for the accurate modelling of W’BAL during prolonged intermittent running and offer preliminary data to support the future adjustment of models to account for progressive exercise-induced reductions in baseline speed- or power-time parameters. 1. Skiba & Clarke (2021) 2. Maunder et al. (2021)
Read CV Christian VassalloECSS Paris 2023: OP-AP03