Jan M. Konarski

Purpose: The aim of this study was to assess the effect of completing a water rescue course on lower limb power parameters assessed using the countermovement jump test (CMJ) and on performance on task-based tests in the water. Methods: Nineteen female lifeguard candidates (aged 18.68 ± 5.89 years) participated in the study. A repeated measures design was used, with assessments conducted before (PRE) and after course completion (POST). The following CMJ variables were analyzed: jump height, push-off force, landing force, maximum concentric power, maximum speed, and take-off velocity. Functional performance in the water was assessed using tests in the 50m, freestyle, front crawl, breaststroke, and backstroke. Results: After completing the course, significant improvements were observed in selected CMJ parameters, including jump height (+8.47%; p = 0.008), rebound force (+23.42%; p = 0.006), maximum concentric power (+8.72%; p = 0.047), maximum velocity (+2.81%; p = 0.017), and rebound speed (+3.77%; p = 0.022). In the water rescue trials, significant reductions in completion times were observed for the front crawl (-4.23%; p = 0.013), 50m kick (-5.48%; p < 0.001), two-hand pull (-7.30%; p = 0.004), one-handed chin pull (-5.40%; p < 0.001), and chest pull (-3.89%; p = 0.006). Conclusions: Participation in a water rescue course significantly improves both lower limb strength and functional performance in the water. However, transfer of lower limb strength from land-based tasks to rescue tasks is moderate, and performance in the water depends more on specific functional adaptations and task-specific skills than on limb strength.

The aim of the study was to compare the body size, skeletal maturity status and functional characteristics of soccer players aged 9–16 years in competitive chronological age (CA) and bio-banded (BB) groups; the latter were defined by the percentage of predicted adult height (%PAH). Body height, mass and functional capacities (sprints, jumping, agility, strength) were measured for 110 players in four competitive CA groups (U10, U12, U14, U16). Assessments of skeletal age (SA) and predicted adult height (PAH) were based on methods developed in the Fels longitudinal study. Current body height was expressed as %PAH which was used to classify players into BB groups approximating take-off (TO) of the adolescent spurt [BB1, %PAH <85%], the interval between TO and peak height velocity (PHV) [BB2, ≥85<90%], PHV [BB3, ≥90<95%] and post-PHV [BB4, ≥95%]. Characteristics of players in adjacent CA and BB groups were compared. Differences in body size, SA and functional capacities between adjacent CA and BB groups were variable but were most marked between U12 and BB2 players. The latter were older in CA, advanced in SA, taller, heavier and stronger than U12 players, but other functional test results did not differ significantly. Though not as marked, a similar trend was apparent between U10 and BB1, as well as U14 and BB3 players, while differences between U16 and BB4 players were negligible. Allowing for variation within CA and BB groups, the results highlight the potential utility of bio-banding especially among early adolescent and adolescent players (U10, U12, U14). Considering that BB groups are not fixed, they can be modified as needed.

(1) Background: The aim of the present study was to assess changes in body composition following a water lifeguard training course and to examine the relationship between body composition parameters and the effectiveness of mannequin towing using different towing techniques. (2) Methods: Thirty-one male participants (22.69 ± 3.35 years) completed pre- and post-course assessments, including body composition analysis and 50-m mannequin towing tests performed using three techniques: Two-handed back tow, Chin tow, and Sailor’s tow. Body composition variables included body fat percentage (BF%), fat mass, fat-free mass (FFM), and total body water (TBW). Linear mixed-effects models were used to evaluate differences in towing performance and associations between body fat and towing time. (3) Results: No significant changes in body composition parameters were observed after the course (all pFDR ≥ 0.29). Towing performance improved significantly across all techniques (p < 0.001). A significant main effect of towing technique was detected by the mixed-effects model (p = 0.04), indicating overall differences among techniques. However, none of the post hoc pairwise comparisons remained significant after correction for multiple testing. Body fat percentage was not significantly associated with towing performance (p = 0.55), and no consistent relationships were found across techniques or timepoints. (4) Conclusions: Short-term lifeguard training improves mannequin towing performance primarily through functional and technical adaptations rather than changes in body composition. Technical proficiency and motor coordination may therefore play a greater role than somatic characteristics in young, trained lifeguards.

Background: Table tennis is a highly accessible sport practiced by individuals with various physical and intellectual impairments; however, limited research has examined how functional classification influences sport-specific technical performance. The aim of this study was to compare the precision of serves and strokes among male para table tennis players representing different integrated sport classes (1–5, 6–10, and 11). Methods: A total of 92 male athletes (age: 26.63 ± 14.31 years) participated in this cross-sectional study. Performance was evaluated using standardized tests assessing serve accuracy (Target Service Test, Extreme Side Service Test, Short Service Test), stroke precision (Alternate Push Test, Manual Quickness and Ability (Q&A) tests), and speed-related skills (Skill Speed and Displacement Speed tests). Due to non-normal data distribution, nonparametric statistical methods were applied. Between-group differences were analyzed using the Kruskal–Wallis test with post hoc Dunn–Bonferroni comparisons, while ordered trends across classes were examined using the Jonckheere–Terpstra test. Results: Significant differences were found between integrated sport classes for selected variables, with players in lower classes demonstrating higher serve precision, while those in higher classes showed superior performance in coordination and speed-related tests. The Jonckheere–Terpstra test revealed significant monotonic trends across all analyzed variables (p < 0.001), indicating systematic performance changes across classes. Conclusions: These findings emphasize the influence of functional classification on technical performance in para table tennis and support the need for classification-sensitive assessment tools.

Background: Effective lifeguard performance depends not only on physical preparedness but also on psychological functioning under stress. However, limited research has simultaneously examined anxiety levels and somatic-motor characteristics in lifeguard candidates at the initial stage of training. Methods: Fifty lifeguard candidates (19 women, 31 men) participated in the study. State and trait anxiety were assessed using the State–Trait Anxiety Inventory (STAI). Somatic parameters included body mass index (BMI) and body fat percentage (FAT%). Motor performance was evaluated using the countermovement jump (CMJ), with biomechanical variables recorded via an inertial measurement unit (IMU). Between-group comparisons and Spearman’s rank correlations were applied. Results: Mean anxiety levels were within normative ranges for non-clinical adult populations. No significant differences were observed between state and trait anxiety. Women demonstrated a tendency toward higher anxiety levels than men, though differences were not statistically significant. No significant associations were found between anxiety levels and somatic or motor parameters. A very strong positive correlation was identified between BMI and FAT% in both sexes (p < 0.001), with no sex differences in correlation strength. Conclusions: Anxiety levels in lifeguard candidates at the beginning of training appear independent of basic physical fitness and body composition parameters. Standard physical selection criteria may not identify individuals with elevated anxiety. Incorporating psychological screening and mental skills training into lifeguard education may enhance adaptation to training demands and improve operational effectiveness under stress.

The aim of study was to determine the influence of an experimental programme for grasping an effective swimming technique on the results of active swimming among youth swimmers at their initial stage of training. Methods: The subjects were 90 children of both sex aged 9–11 year and split into two groups: a) an experimental group (n = 45; girls: n = 18, boys: n = 27) that underwent the original programme and b) a controlled group (n = 45; girls: n = 18, boys: n = 27) that underwent a standard programme. The observation spanned 12 weeks, during which both groups had 24 training sessions. Swimming speed and effectiveness were assessed according to the following variants: A (full style), B (upper limbs), and C (lower limbs). Results: The intervention improved results for A (full style) among girls in the experimental group (F(2,68) = 6.37, p = 0.003; ηp2 = 0.16) and B (upper limbs) (F(2,68) = 7.78, p = 0. 001; ηp2 = 0.19). Among the boys in the experimental group, a trend towards significance (F(2,104) = 2.45, p = 0.091; ηp2 = 0.05) was observed regarding variant B. Regarding variant C (lower limbs), among girls, significant changes were noted in the relationship term*group (F(2,68) = 5.19, p = 0.008; ηp2 = 0.13) and in boys, among terms (F(2,104) = 8.71, p = 0.000; ηp2 = 0.14). No significant changes were noted in the control groups. Conclusions: The applied training improved performance in the experimental group, confirming the validity of introducing exercises to improve swimming technique at the initial stages of training.

Introduction. The Covid-19 pandemic influenced the world in many ways, including sport. Many competitions were held without spectators, creating a natural experiment for the evaluation of home advantage. The present study thus evaluates the impact of crowd presence on home advantage in high level football competitions, specifically outcomes of all games in four highest ranked European leagues (England – Premier League, Spain – La Liga, Italy – Serie A, Germany – Bundesliga) from the start of the 2018/2019 season until the FIFA World Cup in 2022. Material and Methods. The traditional method of Pollard was used to evaluate home advantage in divisions of leagues and on three time intervals relative to the Covid-19 pandemic – before, during and after. Test for one proportion was done to check if the result of home advantage was significant, while tests for two proportions were used to compare home advantage between the time intervals. Results. In three of the four leagues (English, Spanish, German), home teams had significantly lower coefficient of home advantage results in games without spectators compared to games with spectators, but in the four leagues combined, home advantage was significant in games without spectators. Conclusions. The results indicate that crowd support is a significant contributor to home advantage in the best European football leagues, although the presence of spectators per se is not the only factor which influences home advantage, suggesting a need to consider other factors that may be of relevance.

To evaluate variation in the growth status of rural school children 7–15 years by number of children in the family within and across four decennial surveys spanning 1986–2016. Heights and weights of children in the same 10 communities were measured; BMI was calculated. Samples included 1416 boys and 1326 girls in 1986; 971 boys and 947 girls in 1996; 871 boys and 843 girls in 2006, and 658 boys and 711 girls in 2016. Number of children in the family and level of parental education were reported. MANCOVAs (with age of the child and with age and parental level of education as covariates) were used to evaluate variation in growth status by number of children in the family within each survey, and by number of children in the family across the four surveys. Family size declined across surveys. Variation in body size by family size was not consistent within the four surveys. Estimated secular gains in height, weight, and BMI across the 30‐year interval were reasonably similar among boys and girls from families of 1, 2, 3, and 4+ children, while estimated gains between adjacent decadal surveys varied with the number of children in the family and between boys and girls.

Introduction: The aim of this study was to assess the impact of a 3-year swimming training programme on body fat measurements in adolescent girls, without prior selection. Method: Two groups of 10-year-old girls were analysed at the beginning of the study (4th grade in primary school). The experimental group consisted of 14 swimmers (body mass: 34.99 ± 2.77 kg; height: 146.00 ± 3.05 cm). The control group consisted of 14 girls (body mass: 37.93 ± 6.02 kg; height: 145.55 ± 3.88 cm) who only participated in mandatory physical education classes. The study was conducted over a period of 3 years, with measurements taken every 6 months. Body fat was measured through the thickness of skinfolds at four anatomical locations: above the biceps; above the triceps; below the lower angle of the scapula; and above the superior iliac crest. Based on these measurements, the percentage of body fat was calculated. Results: Statistical analysis revealed that despite the lack of initial selection, there was no significant difference in the percentage of body fat between the experimental and control groups at the start of the study—18.62% vs 24.85%. This difference persisted until the final measurement after 3 years, at which point it became statistically significant—17.31% vs 27.14% (F = 37.44, p < 0.05). Discussion: Our findings indicate that 3 years of swimming training in adolescent girls resulted in a reduction in fat tissue growth across all four measurement sites. Initially, body fat percentage had a strong negative impact on VO₂ max, particularly in the experimental group. However, this effect diminished in both groups over the course of the study. Conclusion: Swimming may be an effective means of preventing obesity. Coaches should consider a slim physique in swimming candidates.

The assessment of biological maturation is a central topic in pediatric exercise sciences. Skeletal age (SA) reflects changes in each bone of the hand and wrist from initial ossification to the adult state. This study examined intra-observer and inter-examiner agreement is Greulich-Pyle (GP) assessments of SA in 97 male tennis players 8.6–16.8 years of age. Two observers independently examined all films on two occasions using the GP method. The SA of each bone was evaluated. The mean and median of SAs assigned for each bone was the individual SA for each participant. The calculation was exclusively based on the bones that were not skeletally mature. Intra-observer mean differences were significant for several bones with better results by the experienced examiner (observer B). Comparisons between SA values of the two independent observers indicated significant differences for the ulna, metacarpals II and III, and distal phalanx V. Nevertheless, the magnitude of the bone-specific differences was small, perhaps trivial. Differences in individual SA values of the tennis players based on the non-mature bones of the hand-wrist were negligible based on the mean (0.04±0.39, t = 0.321, p = 0.749) or the median (0.05±0.58, t = 0.007, p = 0.994). Nevertheless, the current study confirmed examiners as a source of error in the estimation of SA using the Greulich-Pyle method and highlighted the importance of calculating SAs based on non-mature bones among adolescent players.