ECSS Paris 2023: OP-AP06
INTRODUCTION: Accurate alignment between coach and athlete perceptions of training intensity and recovery is important for training planning and injury prevention. Most studies reported no difference between coach and athlete self-reported training intensity (1). However, less is known about coach-athlete agreement based on coaches’ training observations in youth sports, especially for recovery. Therefore, the aim of this study was to examine whether coach observations during training can accurately estimate athlete-perceived intensity and recovery in elite youth volleyball. METHODS: Two coaches and thirty-four elite youth volleyball players (13.4±0.5y) participated in this prospective observational study for 4 weeks, consisting of 6 sessions per week. Athletes reported Total Quality of Recovery (TQR, 6-20 scale) before and Rating of Perceived Exertion (RPE, 6-20 Borg scale) after sessions. Coaches reported observed recovery (TQ-OR) after warm-up and observed exertion (ROE) after sessions for each athlete. This resulted in 750 paired RPE-ROE and 639 paired TQR-TQ-OR observations. Coach-athlete agreement was assessed per coach on pooled athlete data using ICC (2,1) with 95% confidence intervals, coach-athlete correlation with Pearson's r, and Bland-Altman analysis using athlete-self report as the criterion reporting systematic bias (±SD) with Cohen’s d effect size, and proportional bias via linear regression. Statistical significance was set at p<0.05. RESULTS: RPE agreement was poor (Coach 1: ICC=0.28 [0.19-0.36]; Coach 2: ICC=0.24 [0.13-0.34]). Linear association was weak but significant (Coach 1: r=0.28; Coach 2: r=0.25, both p<0.001). Bland-Altman analysis revealed opposite systematic biases (Coach 1: 0.33±1.95, d=0.17 p<0.001; Coach 2: -0.61±2.22, d=-0.28, p<0.001) and significant proportional bias (Coach 1: slope=-0.70, zero-bias point=14.5; Coach 2: slope=-0.72, zero-bias point=13.2; both p<0.001). TQR agreement was poor to negligible (Coach 1: ICC=0.22 [0.12-0.31]; Coach 2: ICC=0.05 [-0.07-0.16]). Linear association was weak for Coach 1 (r=0.23, p<0.001) and negligible for Coach 2 (r=0.05, p=0.445). Systematic bias was small and non-significant for Coach 2 (Coach 1: 0.35±2.07, d=0.17, p=0.001; Coach 2: 0.02±2.16, d=0.01, p=0.866), yet proportional bias was significant (Coach 1: slope=-0.84, zero-bias point=14.4; Coach 2: slope=-0.95, zero-bias point=14.1, both p<0.001). CONCLUSION: Coach observations cannot substitute for athlete self-reported intensity and recovery as results showed poor agreement. Coaches overestimated low and underestimated high athlete self-reported intensity and recovery. Therefore, we recommend directly collecting athlete self-report for training intensity and recovery monitoring as inaccurate coach estimates may lead to inappropriate training decisions, especially during intensive training. 1. Inoue, A., et al. (2022). Internal Training Load Perceived by Athletes and Planned by Coaches: A Systematic Review and Meta-Analysis. Sports Medicine - Open, 8(1), 35.
Read CV Wouter TimmermanECSS Paris 2023: OP-AP06
INTRODUCTION: Rapid weight loss (RWL) is widely used in judo under the assumption that competing against lighter opponents enhances performance [1]. Under current competition rules, athletes may weigh up to 5% above the upper limit of his/her weight category, potentially influencing hydration status and psychophysiological demands [2]. Thus, this study examined the effects of RWL magnitude on hydration, cardiac autonomic regulation, cognitive performance and competitive outcomes in elite judo athletes. METHODS: Thirty-seven nationally and internationally competitive judo athletes (27 males and 10 females; 20.3±2.1 years) were monitored during official competitions. Body mass was assessed at 10, 7 and 3 days before weigh-in, at official weigh-in, and on competition day. Athletes were classified according to RWL magnitude (<5%, n= 21; >5%, n= 16). Urinary osmolality, body water compartments, heart rate variability, cognitive performance and perceived self-control demands were assessed longitudinally. Competitive success was defined by match outcomes and medal attainment, while technical-tactical variables included scoring indices, technical variability and time motion analysis. Data were analyzed using analysis of variance and non-parametric tests when appropriate. Relationships were examined using Spearman correlation. Statistical significance was set at 5%. RESULTS: Body mass decreased progressively from -10 days to weigh-in and rebounded on competition day (p<0.001). Urinary osmolality increased significantly across the pre-competition period, with a median increase exceeding 250 mOsm/kg from -10 days to weigh-in (p<0.001). Athletes reducing >5% body mass showed greater osmolality deltas than those reducing <5% from -10 days to weigh-in (433 vs 166 mOsm/kg; p=0.001) and from -10 days to competition (207 vs 87 mOsm/kg; p=0.043). Heart rate variability indices, body water compartments and cognitive performance changed over time but did not differ between groups (p range = 0.06–0.90). No differences were observed between groups for winning probability (65±20% vs 70±26%), medal attainment, scoring efficiency (33±18% vs 28±23%) or time-motion, including total combat time (152±67s vs 148±71s) and effort-to-pause ratio (1.6± 0.5 vs 1.5±0.5). However, athletes reducing <5% body mass demonstrated greater technical variability than those reducing >5% (37±17% vs 26±15%, p=0.032). Finally, urinary osmolality at weigh-in was positively associated with perceived self-control demands measured at -10 days (r=0.52, p<0.001), -7 days (r=0.49, p=0.002) and -3 days (r=0.39, p=0.015). CONCLUSION: Under current judo competition rules, increasing the magnitude of RWL does not seem to increase competitive success, but increases cognitive and psychophysiological demands. Funding: FAPESP – 2024/18847-4 and 2024/08930-1; CNPq – 403032/2023-7, and 305507/2023-0. [1] Dos Santos et al. (2024) Phys Act Nutr. 28(3). [2] Ceylan et al. (2022) Biology 11(6).
Read CV Danilo Conceição-SantosECSS Paris 2023: OP-AP06
INTRODUCTION: Accurate and practical assessment of body composition is essential for monitoring health and performance in professional football. Dual-energy X-ray Absorptiometry (DXA) provides whole-body and regional body composition, while deuterium dilution (DD) provides whole-body estimates of fat-free mass and fat mass. However, routine use of laboratory methods is often limited by cost and logistics, leading practitioners to rely on anthropometric assessments. This study compared laboratory-based and anthropometric methods for assessing whole-body and regional body composition in elite male and female footballers, to inform interpretation and use for routine monitoring in professional football. METHODS: Body composition was assessed in 58 male and 23 female Dutch Eredivisie players using DXA (Classic and NHANES algorithms), DD, and anthropometry following International Society for the Advancement of Kinanthropometry (ISAK) standardisation, including raw skinfolds, skinfold-based prediction equations, and girth measurements. Bland–Altman analysis assessed agreement between BF% estimates (DXA Classic, DXA NHANES, DD, and skinfold-based prediction equations), while Pearson or Spearman correlations examined associations between measures with different units (raw skinfolds and girths vs DXA-derived body composition). RESULTS: DXA Classic showed good agreement with DD for BF%, with a small mean difference (−0.64%; limits of agreement: −3.42 to 2.15%), whereas DXA NHANES systematically overestimated BF% (mean difference: 3.77%; limits of agreement: 0.91 to 6.64%). Skinfold-based prediction equations consistently underestimated BF% relative to DXA, with mean differences up to ~5% in males and up to ~10% in females, with wide limits of agreement, indicating large individual error. Raw anthropometric measures, however, showed strong associations with laboratory-derived body composition. Specifically, the sum of eight skinfolds showed strong associations with DXA-derived BF% (r = 0.81 in males, r = 0.88 in females) and moderate to strong associations with DD BF% (r = 0.63 in males, r = 0.81 in females), outperforming the sum of four skinfolds. Analyses of the trunk, arms, and legs demonstrated moderate to strong associations between regional skinfolds and DXA-derived regional fat mass (r = 0.55–0.89), while girths were moderately to strongly associated with regional lean mass (r = 0.58–0.85). CONCLUSION: DXA Classic shows good agreement with deuterium dilution for BF% assessment and is therefore preferred over DXA NHANES, which systematically overestimates BF%. Skinfold-based prediction equations show limited agreement with laboratory-derived BF% due to large individual bias. In contrast, raw anthropometric measures, including skinfold thicknesses and girths, adequately reflect whole-body and regional body fat and lean mass relative to laboratory measures, supporting their use for individual-level monitoring in elite male and female footballers.
Read CV Jan-Willem van DijkECSS Paris 2023: OP-AP06