Performance In Young Swimmers Research Articles

Glycerophospholipids in Red Blood Cells Are Associated with Aerobic Performance in Young Swimmers.

This study aimed to characterize the composition of lipids in the red blood cells (RBCs) of adolescent swimmers and correlate this lipidome with the aerobic performance of the athletes. Five experimental assessments were performed by 37 adolescent swimmers. During the first session, the athletes went to the laboratory facility for venous blood sampling. The critical velocity protocol was conducted over the 4 subsequent days to measure aerobic performance (CV), comprising maximal efforts over distances of 100, 200, 400, and 800 m in a swimming pool. RBCs were obtained and extracted for analysis using the liquid chromatography-high resolution mass spectrometry untargeted approach. A total of 2146 ions were detected in the RBCs, of which 119 were identified. The enrichment pathway analysis indicated intermediary lipids in the glycerophospholipid, glycerolipid, sphingolipid, linoleic acid, and alpha-linolenic metabolisms, as well as pentose and glucuronate interconversions. A significant impact of the intermediary lipids was observed for the glycerophospholipid metabolism, including phosphatidylethanolamine (PE), phosphatidylcholine (PC), 1-acyl-sn-glycero-3-phosphocholine, sn-glycerol 3-phosphate, and phosphatidic acid. Inverse and significant associations were observed for PE 18:2/18:3 (r = -0.39; p = 0.015), PC 18:3/20:0 (r = -0.33; p = 0.041), and phosphatidic acid 18:0/0:0 (r = -0.47; p = 0.003) with aerobic performance. Swimmers who exhibited higher levels of aerobic performance also had the lowest abundance of PE, PC, and phosphatidic acid.

Effects of anthropometrics, thrust, and drag on stroke kinematics and 100 m performance of young swimmers using path-analysis modeling.

The aim of this study was to understand the interactions between anthropometric, kinetic, and kinematic variables and how they determine the 100 m freestyle performance in young swimmers. Twenty-five adolescent swimmers (15 male and 10 female, aged 15.75 ± 1.01 years) who regularly participated in regional and national competitions were recruited. The 100 m freestyle performance was chosen as the variable to be predicted. A series of anthropometric (hand surface area-HSA), kinetic (thrust and active drag coefficient (CDA )), and kinematic (stroke length (SL); stroke frequency (SF), and swimming speed) variables were measured. Structural equation modeling (via path analysis) was used to develop and test the model. The initial model predicted performance with 90.1% accuracy. All paths were significant (p < 0.05) except the thrust-SL. After deleting this non-significant path (thrust-SL) and recalculating, the model goodness-of-fit improved and all paths were significant (p < 0.05). The predicted performance was 90.2%. Anthropometrics had significant effects on kinetics, which had significant effects on kinematics, and consequently on the 100 m freestyle performance. The cascade of interactions based on this path-flow model allowed for a meaningful prediction of the 100 m freestyle performance. Based on these results, coaches and swimmers should be aware that the swimming predictors can first meaningfully interact with each other to ultimately predict the 100 m freestyle performance.

Oxygen uptake kinetics and biological age in relation to pulling force and 400-m front crawl performance in young swimmers.

Background: The study aimed to assess differences in the biological age (BA) of 13-year-old swimmers and show their ability, as biologically younger-late mature or older-early mature, to develop fast 60-s oxygen uptake () kinetics and tethered swimming strength. Furthermore, the interplay between swimming strength, , and 400-m front crawl race performance was examined. Methods: The study involved 36 competitive young male swimmers (metrical age: 12.9 ± 0.56years). Depending on BA examination, the group was divided into early-mature (BA: 15.8 ± 1.18years, n = 13) and late-mature (BA: 12.9 ± 0.60 years, n = 23) participants, especially for the purpose of comparing tethered swimming indices, i.e., average values of force (F ave) and (breath-by-breath analysis) kinetic indices, measured simultaneously in 1-min tethered front crawl swimming. From the 400-m racing stroke rate, stroke length kinematics was retrieved. Results: In the 1-min tethered front crawl test, early-mature swimmers obtained higher results of absolute values of and F ave. Conversely, when was present relatively to body mass and pulling force (in ml∙min-1∙kg-1∙N-1), late-mature swimmers showed higher relative usage. Late-mature swimmers generally exhibited a slower increase in during the first 30s of 60s. , F ave, BA, and basic swimming kinematic stroke length were significantly interrelated and influenced 400-m swimming performance. Conclusion: The 1-min tethered swimming test revealed significant differences in the homogeneous calendar age/heterogeneous BA group of swimmers. These were distinguished by the higher level of kinetics and pulling force in early-mature individuals and lower efficiency per unit of body mass per unit of force aerobic system in late-mature peers. The higher kinetics and tethered swimming force were further translated into 400-m front crawl speed and stroke length kinematics.

The Effect of Growth and Body Surface Area on Cardiopulmonary Exercise Testing: A Cohort Study in Preadolescent Female Swimmers.

The performance of young swimmers is the result of a multifactorial process that is influenced by anthropometric characteristics and biological maturation. The purpose of our study was to investigate the effect of stages of biological maturation and body surface area on cardiopulmonary fitness indicators in preadolescent female swimmers, for whom menstruation has not started. Thirty female preadolescent swimmers (age 13.4 ± 1.0 years) participated in this study. We recorded anthropometric and morphological characteristics, stages of biological maturation, and pulmonary function parameters, and the swimmers underwent cardiopulmonary exercise testing. The cut-off was set for body surface area (BSA) at 1.6 m2 and for biological maturation stages at score 3. The BSA results showed differences in variabilities in maximal effort oxygen pulse (p < 0.001), oxygen uptake (p < 0.001), ventilation (p = 0.041), tidal volume (p < 0.001), and oxygen breath (p < 0.001). Tanner stage score results showed differences in variabilities in maximal effort breath frequency (p < 0.001), tidal volume (p = 0.013), and oxygen breath (p = 0.045). Biological maturation stages and BSA were correlated during maximal effort with oxygen breath (p < 0.001; p < 0.001), oxygen uptake (p = 0.002; p < 0.001), and oxygen pulse (p < 0.001; p < 0.001). In conclusion, the findings of our study showed that the girls who had a smaller body surface area and biological maturation stage presented lower values in maximal oxygen uptake and greater respiratory work.

The effect of rhythm training on the motor coordination abilities of 8-12-year-old freestyle swimmers.

This study aims to evaluate the effect of rhythm training in the early coordination development and to find out its role in the transfer of specific performance in young swimmers. Eighty young swimmers aged eight to twelve were divided randomly into a control group (CON, n=40, M/F=17/23) or an experimental group (EXP, n=40, M/F=19/21). A total of 72 swimmers completed all the training programs and tests included in this study (CON, n=35, M/F=15/20; EXP, n=37, M/F=16/21). The training programme lasted 12 weeks. During the study period, all groups participated in the same swimming training program with the control group participating six times a week, and the experimental group participating four times a week with an additional two rhythm trainings each week. The height, weight, walking backwards ability, jumping sideways ability, and 25 m freestyle were measured for each participant and an index of coordination was analyzed from recordings of the participant's 25 m freestyle. The results indicated that participation in rhythm training resulted in improved general motor and swimming-specific coordination among the swimmers, but the results varied by number of years of sport-specific training experience. The swimmers with more training experience improved more in swimming-specific coordination but less in general motor coordination. This study strengthens the evidence for the effectiveness of early rhythm training in swimmers, indicating that it is feasible to design programs to address general and sport-specific coordination in young athletes.

Key Anthropometric Variables Associated With Front-Crawl Swimming Performance in Youth Swimmers: An Allometric Approach.

Sammoud, S, Negra, Y, Chaabene, H, Bouguezzi, R, Attia, A, Granacher, U, Younes, H, and Nevill, AM. Key anthropometric variables associated with front-crawl swimming performance in youth swimmers: an allometric approach. J Strength Cond Res 37(6): 1259-1263, 2023-This study aimed to establish key anthropometric characteristics (e.g., optimal body height, limb-segment length, and girth/breadth ratios) related to 100-m front-crawl performance in young swimmers. In total, 74 swimmers (boys [ n = 41; age: 18.1 ± 3.5 years]; girls [ n = 33; age: 15.9 ± 3.1 years]) participated in this study. We adopted a multiplicative allometric log-linear regression model to identify key anthropometric characteristics associated with 100-m front-crawl swimming performance. The main outcomes indicated that length ratio = ([height/leg length]), foot length and ankle girth, biacromial breadth, and % of body fat were associated with 100-m front-crawl mean swimming speed performance. These findings highlight the importance of assessing anthropometric characteristics in young front-crawl swimmers for talent identification and development.

Correction to: Effect of training at intensities around critical velocity on 400 meters front crawl performance in young swimmers.

This article was published in Volume 62, issue 6 of publishing year 2022, with a mistake in Table II. The correct Table II is the one included in this erratum.

Inter-Limb Jump Asymmetries and Their Association with Sport-Specific Performance in Young Male and Female Swimmers.

This study aimed to examine inter-limb jump asymmetries and their association with sport-specific performance in young swimmers. Thirty-eight (male, n = 19; female, n = 19) regional/national level young swimmers (age: 12.3 ± 1.2 years; height: 159.6 ± 8.2 cm; body mass: 52.5 ± 9.2 kg) participated in this study. Inter-limb asymmetries were assessed for single-leg countermovement jump (SLCMJ) and single-leg standing long jump (SLSLJ). Sport-specific performance was evaluated using front crawl (i.e., 50 m and 25 m) and front crawl kick (i.e., 50 m and 25 m). The kappa coefficient revealed a “slight” level of agreement (Κ = 0.156, 0.184, and 0.197 for female, male, and all, respectively) between the direction of asymmetry for SLCMJ and SLSLJ, indicating that asymmetries rarely favored the same limb during both tests. A paired sample t-test showed a significant difference (p = 0.025) between asymmetry scores obtained in SLCMJ and SLSLJ. No significant difference was found in asymmetry scores between males and females (p = 0.099 to 0.977). Additionally, no association between asymmetry scores and sport-specific performance was observed (p > 0.05). Our findings highlight the independent nature of inter-limb asymmetries derived from SLCMJ and SLSLJ among young male and female swimmers. Further, our results suggest no association between jumping asymmetries and sport-specific performance.

Fatigue and conformist traits in the performance of young swimmers

Objective: This study determines the relationship between the fatigue of adolescent swimmers in high-level competitions during two continuous periods of maximum performance and the degree that swimmers conform to norms during these periods.&#x0D; Methods: We evaluated the conformist trait and three areas of fatigue in two consecutive competitive periods, in 25 young elite swimmers. The measures were evaluated before (_B) and after (_A) of pre (t1; t3) and pos (t2; t4) competition in each period. Millon Adolescent Clinical Inventory was applied for identifies the more adherens (AD; n=12) or detached from the norm (DN; n=13) conformist traits. Wingate test, Heart rate variability (RMSSD; SDNN), WISC-V, and Stroop test were evaluated.&#x0D; Results: DN group present lower fatigue in t1 but an increase in t2, t3, and t4. AN present higher RMSSD_B and SDNN_B in t1. In t3, the mental fatigue of DN was correlated negatively with RMSSD_B; SDNN_B. Both groups had more SDNN_B than SDNN_A in t4.&#x0D; Conclusions: Physical fatigue was important conditioning in both groups, however, the DN group may be more sensitive to physiological and mental fatigue directly affecting the performance.

The influence of anthropometric variables, body composition, propulsive force and maturation on 50m freestyle swimming performance in junior swimmers: An allometric approach

ABSTRACT The purpose of the current article was to use allometric models to identify the best body size descriptors and other anthropometric variables, body composition, and offset maturity that might be associated with the youngsters’ 50m personal-best (PB) swim speeds (m·s-1). Eighty-five competitive swimmers (male, n=50; 13.5±1.8 y; female, n=35; 12.6±1.8 y) participated in this study. Height, body mass, sitting height, arm span, skinfolds, arm muscle area (AMA), and maturity offset were assessed. Swimming performance was taken as the PB time recorded in competition, and the propulsive force of their arm (PFA) was assessed by the tied swimming test. The multiplicative allometric model relating 50m PB swim speeds (m·s-1) to all the predictor variables found percentage body fat as a negative [(BF%) β= -.121±.036; P=0.001], and PFA (PFA β=.108±.033; P=0.001) and the girl's arm span (β=.850±.301; P=0.006), all log-transformed, as positive significant predictors of log-transformed swim speed. The adjusted coefficient of determination, Radj 2 was 54.8% with the log-transformed error ratio being 0.094 or 9.8%, having taken antilogs. The study revealed, using an allometric approach, that body fatness and PFA were significant contributors to 50m freestyle swim performance in young swimmers.

Effect of training at intensities around critical velocity on 400 meters front crawl performance in young swimmers.

Young swimmers are rarely involved in training control, leading to inadequate volume and prescription of training intensities. This study aimed to examine the effect of prescribing and monitoring training intensities around critical velocity (CV) on 400 m front-crawl performance during an 8-weeks period. Twenty young male swimmers (13.4±1.0 years) were randomly assigned into two groups. The experimental group (EG) used training monitoring based on intensities around CV (95, 100, 105 and 110% of CV), while for the control group (CG) different heart rate (HR) zones (EN1+, EN2, EN2+ and EN3) were used as an intensity criterion. The training volume was the same for both EG and CG. A maximal 400 m front-crawl test was performed before and after the 8-week period to determine CV intensities and to assess alternations in performance. The rate of perceived exertion (RPE) and HR values were also evaluated. Significant main effects of time were observed for T400, CV, HR and RPE. A significant group × time interaction was found for T400 (P=0.035, effect size = 1.07, moderate). Results revealed significant pre-to-postimprovements for both EG (from 328.46±26.25 to 305.88±20.09) and CG (from 329.07±25.24 to 314.75±19.87). A significant group × time interaction was also found for CV (P=0.005, effect size=1.51, large). Results revealed significant pre- to post improvements for both EG (from 1.126±0.08 to 1.207±0.07) and CG (from 1.124±0.08 to 1.173±0.07). Both training methods induced significant improvements in 400 m front-crawl performance with a greater degree for the training prescription and monitoring using CV intensities.

Tethered Swimming Ineffective As Post Activation Potentiation Procedure For 50-m Swimming Performance In Adolescent Swimmers

PURPOSE: The aim of the study was to investigate if tethered swimming (TS) performed 8 min before a 50-m freestyle swimming sprint could be an effective post-activation potentiation (PAP) method to improve performance. METHODS: Regional level male adolescent swimmers (age: 13.0±2.0 y; height: 161.1±12.4 cm; body mass: 52.5±9.5 kg) performed two trial conditions (1 experimental (TS), 1 control (CTR)) on different days. The control group performed a standardized 1200-m warm-up followed by 8 min of rest and a maximal 50 m freestyle swimming sprint. The experimental group performed the same protocol with an added TS component at the end of warm-up, which consisted of 3 x 10 s maximal effort of tethered swimming with 1 min rest in-between sprints. Performance (time-trial), selected biomechanical (stroke length), physiological (blood lactate concentrations, heart rate), psychophysiological (ratings of perceived exertion (RPE)) variables and Counter movement jump (CMJ) flight-time were collected. RESULTS: Pre-performance tethered swimming had no effect on swimming time, RPE, stroke rate or CMJ flight time. Before the 50 m race, blood lactate concentrations were significantly higher in TS than in control condition (p=0.03, η2 = 0.62). One minute after the 50 m sprint, heart rate was significantly higher in the control condition compared to the TS (P =0.046, η2 = 0.27). CONCLUSIONS: The present study showed that 3 x 10 s tethered swimming performed 8 min prior to the event did not impact the 50 m sprint performance in young swimmers and may not be considered an effective PAP stimulus.

Effect of Tethered Swimming as Postactivation Potentiation on Swimming Performance and Technical, Hemophysiological, and Psychophysiological Variables in Adolescent Swimmers

To investigate whether tethered swimming (TS) performed 8 minutes before a 50-m freestyle swimming sprint could be an effective postactivation potentiation method to improve performance in young swimmers. Fourteen regional-level male adolescent swimmers (age 13.0 [2.0]y; height 161.1 [12.4]cm; body mass 52.5 [9.5]kg) underwent 2 trial conditions in a randomized and counterbalanced order (1 experimental [TS], 1 control) on different days. During the experimental session, the participants performed a standard warm-up of 1200m followed by a TS exercise, which consisted of 3 × 10-second maximal efforts of TS with 1-minute rests between bouts. In the control condition, the warm-up phase was immediately followed by 200m at a moderate pace (same duration as the TS in the experimental session). Performance (time trial); biomechanical (stroke length), physiological (blood lactate concentrations), and psychophysiological (ratings of perceived exertion) variables; and countermovement-jump (CMJ) flight time were collected. TS warm-up had no significant effect on 50-m swimming performance (P = .27), postexercise ratings of perceived exertion, stroke length, or CMJ flight time (P ≥ .05). Blood lactate concentrations significantly increased at the end of the warm-up in the TS condition only (interaction effect: F1.91,29.91 = 4.91, P = .01, η2 = .27) and after the 50-m trial in both conditions (F1.57,20.41 = 62.39, P = .001, η2 = .82). The present study demonstrated that 3 × 10-second TS exercises performed 8 minutes prior to the event did not affect ratings of perceived exertion, stroke length, or CMJ flight time. In addition, tethered swimming did not affect 50-m freestyle sprint performance in young swimmers.

Fifty-meter swimming performance in young swimmers: the effect of anthropometric and motoric values on performance

Fifty-meter swimming performance in young swimmers: the effect of anthropometric and motoric values on performance

Relationship between anthropometry and stroking parameters of front crawl sprint performance in young swimmers

BACKGROUND The aim of this work was to study the relationship between anthropometry and stroking parameters of front crawl sprint performance in young swimmers. METHODS Forty swimmers (12.2 +/- 0.5 years) volunteered to participate. Anthropometric measures included height (H), body mass, Body Mass Index, arm span (AS), skinfold thickness and the ratio of AS to H. To avoid fatigue effects, each swimmer performed without diving a 25- meter swim using the front crawl stroke. Swim velocity, stroke rate (SR), stroke length (SL), and stroke index (SI) were calculated from video analysis. RESULTS Swim velocity was correlated to mass, H, AS, AS/H ratio, SR, SI, and SL. The SL was correlated to SI, mass, H, AS, and BMI. No correlation was found between the SR and the anthropometric measures. SI was correlated to all the anthropometric measures except the percent body fat (estimated). CONCLUSIONS This study demonstrates clearly the relationship between anthropometric and stroking parameters of young front crawl sprint swimmers and confirms the importance of considering specific stroke technical aspects and somatic traits when trying to predict success in young swimmers.

The Effect of Branched-Chain Amino Acids, Citrulline, and Arginine on High-Intensity Interval Performance in Young Swimmers.

High-intensity interval training has drawn significant interest for its ability to elicit similar training responses with less training volume compared to traditional moderate-intensity protocols. The purpose of this study was to examine the effect of co-ingestion of branched-chain amino acids (BCAA), arginine, and citrulline on 8 × 50 m high-intensity interval swim performance in trained young swimmers. This study used a randomized cross-over design. Eight male (age 15.6 ± 1.3 years) and eight female (age 15.6 ± 0.9 years) swimmers completed both amino acids (AA) and placebo (PL) trials. The participants ingested 0.085 g/kg body weight BCAA, 0.05 g/kg body weight arginine and 0.05 g/kg body weight citrulline before the swim test in the AA trial. The average 50 m time was significantly shorter in the AA trial than that in the PL trial. The AA trial was faster than the PL trial in the first, second, and the seventh laps. The AA trial showed significantly higher plasma BCAA concentrations and lower tryptophan/BCAA ratio. The other biochemical parameters and ratings of perceived exertion were similar between the two trials. The results showed that BCAA, arginine, and citrulline, allowed the participants to swim faster in a high-intensity interval protocol in young swimmers.

Key somatic variables in young backstroke swimmers

ABSTRACTThe purpose of this study was to estimate the optimal body size, limb-segment length, girth or breadth ratios for 100-m backstroke mean speed performance in young swimmers. Sixty-three young swimmers (boys [n = 30; age: 13.98 ± 0.58 years]; girls [n = 33; age: 13.02 ± 1.20 years]) participated in this study. To identify the optimal body size and body composition components associated with 100-m backstroke speed performance, we adopted a multiplicative allometric log-linear regression model, which was refined using backward elimination. The multiplicative allometric model exploring the association between 100-m backstroke mean speed performance and the different somatic measurements estimated that biological age, sitting height, leg length for the lower-limbs, and two girths (forearm and arm relaxed girth) are the key predictors. Stature and body mass did not contribute to the model, suggesting that the advantage of longer levers was limb-specific rather than a general whole-body advantage. In fact, it is only by adopting multiplicative allometric models that the abovementioned ratios could have been derived. These findings highlighted the importance of considering somatic characteristics of young backstroke swimmers and can help swimming coaches to classify their swimmers and enable them to suggest what might be the swimmers’ most appropriate stroke (talent identification).

Reliability and Validity of Tethered Swimming Lactate Minimum Test and Their Relationship With Performance in Young Swimmers

To test the reliability and validity of tethered swimming lactate minimum test in young swimmers. Lactate minimum test was performed twice to test the reliability (experiment 1; n = 13). In addition, the validity was investigated through lactate minimum test relationships with tethered swimming lactate threshold and peak force obtained during graded exercise test (experiment 2; n = 11). Finally, the correlations with mean speeds observed during 200-m (s200m) and 30-minute continuous efforts (s30min) were also analyzed (experiment 3; n = 15). In all experiments, the lactate minimum test began with 3-minute all-out effort to induce lactatemia, followed by an exhaustive graded exercise test. The lactate minimum intensity and mean force during the entire 3-minute all-out effort (MF) showed high reliability (coefficient of variation < 8.9% and intraclass correlation coefficient > .93). The lactate minimum intensity was not different compared with lactate threshold (P = .22), presenting high correlations (r = .92) and agreement (95% limits of agreement = ±7.9N). The mean force during the entire 3-minute all-out effort was similar to peak force obtained during graded exercise test (P = .41), presenting significant correlations (r = .88) and high indices of agreement (95% limits of agreement = ±11.3N). In addition, lactate minimum test parameters correlated both with mean speeds observed during 200-m (r > .74) and 30-minute continuous efforts (r > .70). Thus, tethered swimming lactate minimum test can be used for training recommendations and to monitor aerobic adaptations in young swimmers.

Serum IGF-I, IGFBP-3 and ALS concentrations and physical performance in young swimmers during a training season

IntroductionThe GH/IGF-I axis is a system of growth mediators, receptors, and binding proteins that regulate somatic and tissue growth; and it has been shown that exercise programs are related to the anabolic function of this axis. ObjectiveThe aim of this study was to analyse the changes of serum IGF-I concentration and that of its binding proteins IGFBP-3 and ALS in adolescent swimmers at different stages of a training season, and compare them with physical performance parameters and body composition of the athletes. Material and methodsNine male athletes, aged 16 to 19years and who trained regularly throughout the season, were included in this study. Serum IGF-I, IGFBP-3, and ALS concentrations were recorded before and after (pre×post) standardized training sessions during the different stages of a training season (extensive×intensive×tapering). Endurance in freestyle, anaerobic fitness in tied swimming (Peak Force and Average Force), body mass, fat percentage, and lean body mass were also analysed at the different stages of training in order to compare the changes of the IGF-I/IGFBP/ALS system with the physical performance and body composition of the athletes. Variations in the IGF-I/IGFBP-3-ALS system before and after a standardized training session, and at the different stages of training were analysed by the Wilcoxon and Friedman non-parametric tests, respectively. Significance was considered at 5%. ResultsThe results from this study demonstrate that IGF-I is sensitive to the acute and chronic effects of training, exhibiting biphasic behaviour throughout the season. The catabolic phase was characterized by a reduction in serum IGF-I concentrations during the intensive stage (∆IGF-I: - 43.33±47.32ng/ml; P<0.05) while the anabolic phase was marked by similar basal concentrations at the different stages of training and an increase in post-training serum IGF-I concentrations during the tapering stage (320±40; 298±36 and 359±94ng/ml; P<0.05). IGFBP-3 was only sensitive to the chronic effects of training, with a reduction in post-training serum concentrations during the intensive stage and an increase during the tapering stage (4.7±0.7, 4.6±0.4 and 5.0±0.7mg/l; P<0.05). No significant difference (P>0.05) was observed in pre- or post-training IGFBP-3 concentrations (∆IGFBP-3) at the different stages. ALS concentrations remained unchanged throughout the season, demonstrating that in adolescent athletes they are unaffected by the acute or chronic effects of swimming. Peak Force (25.0±6.3, 24.2±5.7 and 28.5±6.5N; P<0.05) and Average Force (10.3±3.6, 8.8±1.8 and 14.7±1.8N; P<0.05) followed IGF-I and IGFBP-3 variations, with a decrease during the intensive stage and a significant (P<0.05) increase during the tapering stage. The body composition and cardiorespiratory condition of the swimmers did not vary significantly throughout the season, exhibiting behaviour independent of IGF-I or IGFBP-3. ConclusionSerum IGF-I and IGFPB-3 concentrations have proven to be sensitive markers of training status and, thus, may be used as guides for coaches and athletes in the challenging task of modulating training intensity in young athletes.

Influence of short-term inertial training on swimming performance in young swimmers

The aim of this study was to evaluate the influence of dry-land inertial training (IT) on muscle force, muscle power, and swimming performance. Fourteen young, national-level, competitive swimmers were randomly divided into IT and control (C) groups. The experiment lasted four weeks, during which time both groups underwent their regular swimming training. In addition, the IT group underwent IT using the Inertial Training Measurement System (ITMS) three times per week. The muscle groups involved during the upsweep phase of the arm stroke in front crawl and butterfly stroke were trained. Before and after training, muscle force and power were measured under IT conditions. Simultaneously with the biomechanical measurements on the ITMS, the electrical activity of the triceps brachii was registered. After four weeks of training, a 12.8% increase in the muscle force and 14.2% increase in the muscle power (p < .05) were noted in the IT group. Moreover, electromyography amplitude of triceps brachii recorded during strength measurements increased by 22.7% in the IT group. Moreover, swimming velocity in the 100 m butterfly and 50 m freestyle improved significantly following the four weeks of dry-land IT (−1.86% and −0.76%, respectively). Changes in the C group were trivial. Moreover, values of force and power registered during the ITMS test correlated negatively with the 100 m butterfly and 50 m freestyle swimming times (r value ranged from −.80 to −.91). These results suggest that IT can be useful in swimming practice.