To apply a new method to identify, classify, and follow up young swimmers based on their performance and its determinant factors over a season and analyze the swimmers' stability over a competitive season with that method. Fifteen boys and 18 girls (11.8±0.7 y) part of a national talent-identification scheme were evaluated at 3 different moments of a competitive season. Performance (ie, official 100-m freestyle race time), arm span, chest perimeter, stroke length, swimming velocity, speed fluctuation, coefficient of active drag, propelling efficiency, and stroke index were selected as variables. Hierarchical and k-means cluster analysis were computed. Data suggested a 3-cluster solution, splitting the swimmers according to their performance in all 3 moments. Cluster 1 was related to better performances (talented swimmers), cluster 2 to poor performances (nonproficient swimmers), and cluster 3 to average performance (proficient swimmers) in all moments. Stepwise discriminant analysis revealed that 100%, 94%, and 85% of original groups were correctly classified for the 1st, 2nd, and 3rd evaluation moments, respectively (0.11≤Λ≤0.80; 5.64≤χ2≤63.40; 0.001<P≤.68). Membership of clusters was moderately stable over the season (stability range 46.1-75% for the 2 clusters with most subjects). Cluster stability is a feasible, comprehensive, and informative method to gain insight into changes in performance and its determinant factors in young swimmers. Talented swimmers were characterized by anthropometrics and kinematic features.

Obesity has grown to pandemic proportions. It affects an increasing number of children, adolescents and young adults exposed to the silent comorbidities of this disorder for a longer period. Infertility has arisen as one important comorbidity associated with the energy dysfunction promoted by obesity. Spermatogenesis is a highly regulated process that is determined by specific energetic requirements. The reproductive potential of males relies on hormonal-dependent and -independent stimuli that control sperm quality. There are conflicting data concerning the impact of male overweight and obesity on sperm quality, as well as on the possible paternal-induced epigenetic trait inheritance of obesity. In addition, it remains a matter of debate whether massive weight loss induced by lifestyle interventions, drugs or bariatric surgery may or may not benefit obese men seeking fatherhood. Herein, we propose to discuss how energy balance may modulate hormonal signalling and sperm quality in overweight and obese men. We also discuss some molecular mechanisms that mediate obesity-related dysfunction in male reproductive system and how paternal obesity may lead to trait inheritance. Finally, we will discuss how lifestyle modifications and sustained weight loss, particularly the loss achieved by bariatric surgery, may revert some of the deleterious effects of obesity in men and their offspring.

The benefits of warm-up in sports performance has received a special interest in the current literature. However, there is a large gap of knowledge about the tasks to be performed, specifically in the real competitive environment. The purpose of the study was to verify the acute effects of a warm-up including ballistic exercises in 100 m running performance. In addition, a second 100 m trial was assessed to better understand the warm-up effects in training and competition. Eleven men (25.4 ± 6.2 years of age, 1.76 ± 0.08 m of height, 78.2 ± 8.6 kg of body mass) were submitted to three different protocols, in a randomized order: no warm-up (NWU), typical warm-up (WU) and WU complemented with ballistic exercises (PAP). Biomechanical, physiological and psychophysiological variables were assessed. Differences were found between the three conditions assessed in the first 100 m sprint with 7.4% and 7.6% faster performances after the WU and PAP, compared to NWU. Stride length was higher in the second part of the 100 m after PAP compared with WU. These results highlight the positive effects of warm-up for sprinting performance. The inclusion of ballistic exercises, besides being used to improve sprint performance, can increase stride length in the final of the 100 m race.

Objectives: To assess the incidence, type and location of injuries sustained during the Portuguese rugby union sevens circuit. To investigate the influence of players’ training loads on injury risk. Methods: A prospective cohort study recording time-loss injuries was conducted with all teams competing in the Portuguese national rugby sevens circuit (eight from the top-tier and seven from the second-tier). Main outcome measures included: incidence rate, anatomical location, type, injury incident and severity. Data were also collected regarding players’ training loads. Fisher's exact test was used to estimate the relative risk of suffering an injury during the sevens season and training sevens during the fifteens season. Results: A total of 27 injuries were recorded corresponding to an incidence rate of 133.9 injuries per 1000 player match-hours. The average severity was 22.22 days. Contact events preceded 81.5% of injuries. Most injuries occurred in the lower limb (66.7%) and were joint/ligament or muscle/tendon injuries (85.1%). The association between injuries and lower volume of training during the sevens season was identified for the second-tier (p=0.021). For the same level, an inverse relation between training hours and injury severity was also found (p=0.008). Top-tier players training sevens and fifteens simultaneously during the year presented a significant increase of injury risk (relative risk=3.2; p=0.011). Conclusions: Injury incidence in our study is similar to that reported for international sevens, although severity is lower. An association between training loads and the occurrence of injuries was found for both tiers, although with differential results, thus reinforcing the need to customize players’ preparation. Further studies at non-elite competitions are needed to gather significant data to accurately formulate future injury prevention protocols or recommend modifications to game laws or competition formats, aiming at players’ welfare.

The purpose of this study was to analyze the effect of gender and energetics on biomechanics and performance of masters swimmers over 1 season. Twenty-five masters swimmers (14 male and 11 female) were assessed 3 times (TP1, TP2, and TP3) during a season (male personal record in 200-m freestyle event: 173.00 ± 31.41 seconds: female personal record in 200-m freestyle event: 200.73 ± 25.02 seconds). An incremental 5 × 200-m step test was selected to evaluate velocity at 4 mmol·l⁻¹ of blood lactate concentration (v4), maximal blood lactate concentration after exercise (La(peak)), maximal oxygen uptake (V̇O2max), stroke frequency, stroke length (SL), stroke index (SI), and propelling efficiency of the arm stroke (η(p)). The 200-m freestyle performance and average swimming velocity (v200) were also monitored. Significant differences were observed between males and females for the 200-m freestyle performance, SL, SI, and La(peak). Performance (205.18 ± 24.47 seconds; 197.45 ± 20.97 seconds; 193.45 ± 18.12 seconds), SL (1.69 ± 0.17 m; 1.79 ± 0.13 m; 1.78 ± 0.15 m), SI (1.68 ± 0.31 m²·c⁻¹·s⁻¹; 1.83 ± 0.27 m²·c⁻¹·s⁻¹; 1.85 ± 0.27 m²·c⁻¹·s⁻¹), η(p) (0.32 ± 0.04; 0.33 ± 0.03; 0.33 ± 0.04), and V̇O2max (38.71 ± 3.44 ml·kg⁻¹·min⁻¹; 43.43 ± 3.71 ml·kg⁻¹·min⁻¹; 43.95 ± 7.02 ml·kg⁻¹·min⁻¹) have changed significantly throughout the season (TP1, TP2, and TP3, respectively) in female swimmers. In male, significant changes were found in η(p) (0.33 ± 0.07; 0.36 ± 0.05; 0.36 ± 0.06) and V̇O2max (41.65 ± 7.30 ml·kg⁻¹·min⁻¹; 45.19 ± 6.55 ml·kg⁻¹·min⁻¹; 50.19 ± 9.65 ml·kg⁻¹·min⁻¹) over the season (TP1, TP2, and TP3, respectively). Gender presented a significant effect on SL (TP2: η(p)² = 0.29; TP3: η(p)² = 0.37), SI (TP2: η(p)² = 0.25), and La(peak) (TP3: η(p)² = 0.42). v4 (TP1: η(p)² = 0.23), SL (TP1: η(p)² = 0.46), SI (TP1: η(p)² = 0.78; TP2: η(p)² = 0.37; TP3: η(p)² = 0.32), and η(p) (TP1: η(p)² = 0.28) had a significant effect on performance. Male masters swimmers have better performance, SL, SI, and La(peak) than female counterparts. Female masters swimmers enhanced significantly the 200-m freestyle performance over the season due to the improvement in swimming technique (SL, SI, and η(p)) and energetic factors (v4 and V̇O2max). Nonsignificant improvements were observed for the males' performance. Gender has a significant effect on SL, SI, and La(peak). Therefore, performance is more dependent on technical factors than energetics.

The aim was to develop a path-flow analysis model for young swimmers' performance based on biomechanical and energetic parameters, using structural equation modeling. Thirty-eight male young swimmers served as subjects. Performance was assessed by the 200-m freestyle event. For biomechanical assessment the stroke length, the stroke frequency and the swimming velocity were analyzed. Energetics assessment included the critical velocity, the stroke index and the propulsive efficiency. The confirmatory model explained 79% of swimming performance after deleting the stroke index-performance path, which was nonsignificant (SRMR = 0.06). As a conclusion, the model is appropriate to explain performance in young swimmers.

The aim of this study was to compare the effects of 2 different warm-up intensities on 100-m swimming performance in a randomized controlled trial. Thirteen competitive swimmers performed two 100-m freestyle time-trials on separate days after either control or experimental warm-up in a randomized design. The control warm-up included a typical race-pace set (4 × 25 m), whereas the experimental warm-up included an aerobic set (8 × 50 m at 98-102% of critical velocity). Cortisol, testosterone, blood lactate ([La]), oxygen uptake (V[Combining Dot Above]O2), heart rate, core (Tcore and Tcorenet) and tympanic temperatures, and rating of perceived exertion (RPE) were monitored. Stroke length (SL), stroke frequency (SF), stroke index (SI), and propelling efficiency (ηp) were assessed for each 50-m lap. We found that V[Combining Dot Above]O2, heart rate, and Tcorenet were higher after experimental warm-up (d > 0.73), but only the positive effect for Tcorenet was maintained until the trial. Performance was not different between conditions (d = 0.07). Experimental warm-up was found to slow SF (mean change ±90% CL = 2.06 ± 1.48%) and increase SL (1.65 ± 1.40%) and ηp (1.87 ± 1.33%) in the first lap. After the time-trials, this warm-up had a positive effect on Tcorenet (d = 0.69) and a negative effect on [La] (d = 0.56). Although the warm-ups had similar outcomes in the 100-m freestyle, performance was achieved through different biomechanical strategies. Stroke length and efficiency were higher in the first lap after the experimental warm-up, whereas SF was higher after control warm-up. Physiological adaptations were observed mainly through an increased Tcore after experimental warm-up. In this condition, the lower [La] after the trial suggests lower dependency on anaerobic metabolism.

Countermovement jump (CMJ) has been extensively used in training; yet, limited and contradictory kinematic data are available for trained subjects. To our best knowledge, no other studies have evaluated the associations between force-time curve characteristics and CMJ in a large sample of trained athletes using a linear transducer. Thus, the aim of this study was to determine the association between force-time measures and CMJ performance collected with a linear transducer. Thirty-five trained athletes were asked to perform 3 maximal weighted CMJ using a linear transducer attached to a barbell (17 kg). The data indicated that the maximal rate of force development (RFD(max)) was strongly related to CMJ displacement (r = 0.809/0.807, p < 0.001) and also to the percentage of peak force (r = -0.823/-0.809, p < 0.001) at RFD(max). Velocity and displacement at RFD(max) were not correlated to CMJ height. It was therefore concluded that the percentage of PF applied at RFD(max) and RFD(max) were the best predictive variables for CMJ performance in this study.

To investigate the effect of warm-up on 100-m swimming performance. Twenty competitive swimmers (with a training frequency of 8.0 ± 1.0 sessions/wk) performed 2 maximal 100-m freestyle trials on separate days, with and without prior warm-up, in a counterbalanced and randomized design. The warm-up distance totaled 1000 m and replicated the swimmers' usual precompetition warm-up strategy. Performance (time), physiological (capillary blood lactate concentrations), psychophysiological (perceived exertion), and biomechanical variables (distance per stroke, stroke frequency, and stroke index) were assessed on both trials. Performance in the 100-m was fastest in the warm-up condition (67.15 ± 5.60 vs 68.10 ± 5.14 s; P = .01), although 3 swimmers swam faster without warm-up. Critical to this was the 1st 50-m lap (32.10 ± 2.59 vs 32.78 ± 2.33 s; P < .01), where the swimmers presented higher distance per stroke (2.06 ± 0.19 vs. 1.98 ± 0.16 m; P = .04) and swimming efficiency compared with the no-warm-up condition (stroke index 3.46 ± 0.53 vs 3.14 ± 0.44 m2 · c1 · s1; P < .01). Notwithstanding this better stroke-kinematic pattern, blood lactate concentrations and perceived exertion were similar between trials. These results suggest that swimmers' usual warm-up routines lead to faster 100-m freestyle swimming performance, a factor that appears to be related to better swimming efficiency in the 1st lap of the race. This study highlights the importance of performing swimming drills (for higher distance per stroke) before a maximal 100-m freestyle effort in similar groups of swimmers.

The aim of this study was to analyse the relative age effect (RAE) in competitive swimming. The best 50 Portuguese swimmers (12- to 18-year-olds) for the main individual swimming pool events of both genders were considered. Analysis was conducted on 7813 swimming event participants, taking account of respective swimmer birth dates and the Fédération Internationale de Natation points gained. Differences in the distribution of birth dates by quarter year were determined using the Chi-square. A one-way analysis of variance ANOVA was used to test for differences measured in points between individuals by quarterly birth year intervals. A two-way analysis of variance ANOVA was also conducted to test the interaction between gender and seasonal birth date with regard to performance. The results show an inequitable distribution (p<0.01) of birth dates by quarter for almost all age groups and both genders. However, the distribution of birth dates by quarter for each considered swim event shows that RAE seems to exist only for 12-year-old females and 12- to 15-year-old males. Analysing mean swimming performance, post-hoc results (p<0.01) show no consistency in RAE. Higher performance occurs among older swimmers only in 100 m butterfly (female 1998, 1st≠2nd quarter, p=0.003). The results also show no interaction between gender and seasonal birth date (p<0.01). Findings of this study show that a higher number of swimmers, particular males, are born in the first two quarters of the year, although there is mostly no effect of seasonal birth date on performance differences within the top 50 swimmers.