Biophysical Evaluation of Age-Group Swimmers During a Training Season

Understanding more about competitive swimmers and their athletic potential requires organized, systematic and consistent evaluation. The evaluation and training control of swimmers give the coach valuable information about an athlete's improvement, stagnation, or deterioration in training and competitive performance. Assessments addressing both biological and physical aspects are usually called biophysical studies. This type of integrated approach allows a deeper understanding of the determinant variables in swimming and how they combine to enhance performance. However, few biophysical studies have been conducted on age-group swimmers, and almost all of them have been crosssectional rather than longitudinal in design. Although cross-sectional analysis is relevant, it is not sufficient to fully describe time-course and factors influencing progression over a training period. The aim of this Thesis was to quantify change in and relationships between energetics, technique and anthropometrics characteristics in age-group swimmers during a training traditional periodization design. For that aim, we developed and validated methodological tools and protocols. Useful tools have been developed for the sports/research community, highlighting the importance of a biophysical approach to evaluate swimming performance through longitudinal studies. We validated the 400-m test (T400) against the gold standard 7 x 200-m incremental intermittent protocol, comparing physiological and biomechanical characteristics in national level age-group swimmers. We also paved the way towards a straightforward analysis of oxygen uptake (V̇ O2) kinetics in exercise by developing a freely available and open-source software, which eases the V̇ O2 kinetics analysis in exercise, and can be applied for research and performance diagnostics in elite, sub-elite or recreational athletes. We then performed three longitudinal experiments. In the first longitudinal study, physiological and biomechanical effects of a typical off-season period were quantified in age-group swimmers, controlling growth and non-swimming specific physical activities performed during this training cessation period. In the second study, we quantified changes and contributions of energetic, technique and anthropometric profiles across the first training macrocycle (16-week) in a traditional three-peak swimming season. Finaly, we identified changes in energetics, technique and anthropometric profile while following age-group swimmers over a training season trough a traditional three-peak preparation program. We are confident that these methodological and longitudinal studies provide relevant tools and cientific contribution to the sports and scientific community, helping to better understand the relationships between performance-related domains

The impact of a swimming training season on anthropometrics, maturation, and kinematics in 12-year-old and under age-group swimmers: a network analysis

Understanding fluctuations and associations between swimming performance-related variables provide strategic insights into a swimmer’s preparation program. Through network analysis, we verified the relationships between anthropometrics, maturation, and kinematics changes (1) in 25-m breaststroke (BREAST) and butterfly (FLY) swimming performance, before and after a 47-week swimming training season. Twenty age-group swimmers (n =11 girls: 10.0 ± 1.3 years and n = 9 boys: 10.5 ± 0.9 years) performed a 25-m all-out swim test (T25) in BREAST and FLY techniques, before and after 47 weeks. Three measures of centrality, transformed into a z-score, were generated: betweenness, closeness, and strength. Data were compared (t-test) and effect sizes were identified with Hedges’ g. Large effect sizes were observed for swimming performance improvements in BREAST (32.0 ± 7.5 to 24.5 ± 3.8 s; g = 1.26; 1 = −21.9 %) and FLY (30.3 ± 7.0 to 21.8 ± 3.6 s; g = 1.52; 1 = −26.5 %). Small to moderate effect sizes were observed for anthropometric changes. Moderate effect size was observed for maturity offset changes (−2.0 ± 0.9 to −1.3 ± 1.0; g = 0.73; 1 = 50.9 ± 281 %). Changes in maturity offset, stroke rate (SR), and stroke length for both BREAST and FLY swimming speeds were highlighted by the weight matrix. For betweenness, closeness, and strength, changes in arm span (AS) (BREAST) and stroke length (FLY) were remarkable. The dynamic process of athletic development and the perception of complexity of fluctuations and associations between performance-related variables were underpinned, particularly for simultaneous swimming techniques in age-group swimmers

NEUROMUSCULAR ACTIVATION DURING ROTATION AND PUSH-OFF PHASES OF BACKSTROKE TO BREASTSTROKE TURNING TECHNIQUES IN AGE-GROUP SWIMMERS

The aim of this study was to assess and compare, through electromyography, the neuromuscular activation during the rotation and push-off phases of four backstroke to breaststroke swimming turns. Eight male swimmers volunteered in this study, comparing the open turn, the back flip turn and the crossover turn. The crossover turn was the one that most activated the studied muscle. Erector spinae (ES) and rectus abdominis (RA), as well as latissimus dorsi (LD) were the main activated muscles during rotation phase. Gastrocnemius medialis (GM) and Tibialis anterior (TA) were mainly activated muscles during the explosive action of the push-off phase. These results provided better understanding about neuromuscular contributions during rotation and push-off of turning performance

Swimming with Swimsuit and Wetsuit at Typical vs. cold-water Temperatures (26 vs. 18 ℃)

The study aimed to compare three swimming conditions in a swimming flume with water at 26ºC (using swimsuit) and 18ºC (randomly with swimsuit and wetsuit). Seventeen swimmers (32.4±14.7 years old, 175.6±0.06cm height, and 70.4±9.8kg body mass) performed the three bouts until exhaustion at 400m front crawl pace (24h intervals). ANOVA repeated measures compared the experimental conditions. Swimming at 26ºC with swimsuit evidenced a higher metabolic demand (total energy expenditure; (E)), comparing to 18ºC swimsuit (p=0.05) and with 18ºC wetsuit (p=0.04). The 26ºC swimsuit condition presented higher peak oxygen uptake (VO2peak), blood lactate concentrations ([La-]peak), rate of perceived exertion (RPE), maximal heart rate (HRmax), anaerobic lactic energy (AnL), E, energy cost (C), VO2 amplitude (Ap), and stroke rate (SR), but lower stroke length (SL) and stroke index (SI) than 18ºC wetsuit. The 18ºC swimsuit condition (comparing to wetsuit) lead to higher V̇O2peak, [La-]peak, HRmax, E, C, Ap, and SR but lower SL and SI. Swimming at aerobic power intensity with swim and wetsuit at 18ºC does not induce physiologic and biomechanical disadvantages comparing to 26ºC, The results suggested that the use of wetsuit might increase performance at 18ºC water temperature for competitive master swimmers. Thus, its use is recommended in open water swimming competitions when the water temperature is 18-20ºC

Biomechanical Features of Backstroke to Breaststroke Transition Techniques in Age-Group Swimmers

This study aimed to identify the biomechanical features of backstroke to breaststroke transition techniques (open, somersault, bucket, and crossover) in age-group swimmers. Eighteen preadolescent swimmers (12.2 ± 0.4 years old and 3–4 Tanner stages) underwent 4 weeks of systematic contextual interference training, comprising 16 sessions (40 min·session−1). Soon after, experimental testing was conducted where swimmers randomly performed 12 × 15m maximal turns (composed of 7.5m turn-in and 7.5m turn-out of the wall segments), three in each transition technique. Kinematical, kinetic, and hydrodynamic variables were assessed with a dual-media motion capture system (12 land and 11 underwater cameras), triaxial underwater force plates, and inverse dynamics. Variables were grouped in turn-in (approach and rotation) and turn-out (wall contact, gliding, and pull-out) phases, with factor analysis used to select the variables entering on multiple regressions. For the turn-in phase, 86, 77, 89, and 87% of the variance for open, somersault, bucket, and crossover turning techniques, respectively, was accounted by the 7.5 and 2.5m times, mean stroke length, and rotation time. For the turn-out phase, first gliding distance and time, second gliding depth, turn-out time, and dominating peak_Z push-off force accounted for 93% in open turn, while wall contact time, first gliding distance, breakout distance and time, turn-out time, dominating peak_Y push-off force, and second gliding drag coefficient accounted for 92% in a somersault turn. The foot plant index, push-off velocity, second gliding distance, and turn-out time accounted for 92% in bucket turn while breakout and turn-out time, non-dominating peak_Y and peak_Z push-off force, first and second gliding drag force and second gliding drag coefficient accounted for 90% in crossover turn, respectively. The findings in this study were novel and provided relevant biomechanical contribution, focusing on the key kinematic–temporal determinant during turn-in, rotation, and push-off efficacy, and the kinetic and hydrodynamic during turn-out, which would lead to improved backstroke to breaststroke transition techniques in 11–13 years-old age-group swimmers.This study was supported by the Faculty of the Sport Science, Burapha University, Thailand (grant number 062/2554). RZ was founded by Research Center in Physical Activity, Health and Leisure—CIAFEL—Faculty of Sports, University of Porto—FADEUP (FCT UID/DTP/00617/2020 and Laboratory for Integrative and Translational Research in Population Health (ITR), Porto, Portugal (LA/P/0064/2020).info:eu-repo/semantics/publishedVersio

A biophysical analysis on the arm stroke efficiency in front crawl swimming : comparing methods and determining the main performance predictors

Purpose: to compare different methods to assess the arm stroke efficiency ( ηF ), when swimming front crawl using the arms only on the Measurement of Active Drag System (MAD System) and in a free-swimming condition, and to identify biophysical adaptations to swimming on the MAD System and the main biophysical predictors of maximal swimming speed in the 200 m front crawl using the arms only ( v200m ). Methods: fourteen swimmers performed twice a 5 × 200 m incremental trial swimming the front crawl stroke using the arms only, once swimming freely, and once swimming on the MAD System. The total metabolic power was assessed in both conditions. The biomechanical parameters were obtained from video analysis and force data recorded on the MAD System. The ηF was calculated using: (i) direct measures of mechanical and metabolic power (power-based method); (ii) forward speed/hand speed ratio (speed-based method), and (iii) the simplified paddle-wheel model. Results: both methods to assess ηF on the MAD System differed (p < 0.001) from the expected values for this condition ( ηF = 1), with the speed-based method providing the closest values ( ηF ~0.96). In the free-swimming condition, the power-based ( ηF ~0.75), speed-based ( ηF ~0.62), and paddle-wheel ( ηF ~0.39) efficiencies were significantly different (p < 0.001). Although all methods provided values within the limits of agreement, the speed-based method provided the closest values to the “actual efficiency”. The main biophysical predictors of v200m were included in two models: biomechanical (R2 = 0.98) and physiological (R2 = 0.98). Conclusions: our results suggest that the speed-based method provides the closest values to the “actual ηF ” and confirm that swimming performance depends on the balance of biomechanical and bioenergetic parameter

IS THERE ANY TRANSFER BETWEEN COUNTERMOVEMENT JUMP AND SWIMMING TRACK START PERFORMANCE?

The aim of this study was to determine if the countermovement jump could predict swimming starts performance. Ten elite swimmers performed one maximal countermovement jump on an extensometric force platform and three maximal track start on an instrumented starting block. Results showed an inverse relationship between 15 m starting time and jump variables (r = -0.86, -0.64 and -0.92 for jump height, peak vertical force and peak power, respectively; p \u3c 0.05) and no significant correlation between relative peak vertical force and start variables. Regression equation for 15 m time prediction was defined by jump height and peak vertical force (r = 0.890, adjusted r2 = 0.734). In addition, results suggest that swimmers with higher jumps and higher peak vertical force are faster on the 15m mark when using a track start

VO2FITTING : a free and open-source software for modelling oxygen uptake kinetics in swimming and other exercise modalities

The assessment of oxygen uptake (VO2) kinetics is a valuable non-invasive way to evaluate cardiorespiratory and metabolic response to exercise. The aim of the study was to develop, describe and evaluate an online VO2 fitting tool (VO2FITTING) for dynamically editing, processing, filtering and modelling VO2 responses to exercise. VO2FITTING was developed in Shiny, a web application framework for R language. Validation VO2 datasets with both noisy and non-noisy data were developed and applied to widely-used models (n = 7) for describing different intensity transitions to verify concurrent validity. Subsequently, we then conducted an experiment with age-group swimmers as an example, illustrating how VO2FITTING can be used to model VO2 kinetics. Perfect fits were observed, and parameter estimates perfectly matched the known inputted values for all available models (standard error = 0; p < 0.001). The VO2FITTING is a valid, free and open-source software for characterizing VO2 kinetics in exercise, which was developed to help the research and performance analysis communities

Eccentric flywheel post-activation potentiation influences swimming start performance kinetics

This study aimed to assess the effects of post-activation potentiation in the strength related variables of a kick start. Thirteen competitive swimmers performed three kick starts after a standardized warm up (denoted USUAL) and another after inducing post-activation through five isotonic repetitions on an eccentric flywheel (denoted PAP). A T-test was used to quantify differences between USUAL and PAP warm up. The best trial of each subject achieved by natural conditions (denoted PEAK) was compared with data obtained after PAP. An instrumented starting block with independent triaxial force plates, collected the strength variables related with the impulse at take off. Improvements in the vertical components of force were observed after PAP compared with USUAL, meanwhile no differences were detected on the horizontal components of it. The velocity at take off was higher after PAP compared with the USUAL (4.32 ± 0.88 vs 3.93 ± 0.60 m*s-1; p = 0.02). No differences in force or velocity were detected comparing PAP with PEAK (4.13 ± 0.62 m*s-1, p = 0.11). The PAP warm-up increased vertical force and it was transferred to a higher resultant velocity at take-off. This improvement would equal the best result possible obtained in natural conditions after some trials.CTS-527: Actividad física y deportiva en el medio acuátic