The aim of the study was to determine the effects of short-term (4 weeks, twice a week: 8 sessions) plyometric training on agility, jump, and repeated sprint performance in female soccer players. The study comprised 17 females performing this sports discipline. The players were randomly divided into two groups: with plyometric training (PLY) and the control (CON). All players followed the same training program, but the PLY group also performed plyometric exercises. Tests used to evaluate physical performance were carried out immediately before and after PLY. After implementing the short PLY training, significant improvement in jump performance (squat jump: p = 0.04, ES = 0.48, countermovement jump: p = 0.009, ES = 0.42) and agility (p = 0.003, ES = 0.7) was noted in the PLY group. In the CON group, no significant (p > 0.05) changes in physical performance were observed. In contrast, PLY did not improve repeated sprint performance (p > 0.05) among female soccer players. In our research, it was shown that PLY can also be effective when performed for only 4 weeks instead of the 6–12 weeks typically applied.

The Role of Training in the Development of Adaptive Mechanisms in Freedivers: Freediving is a sport in which athletes aim to achieve the longest or the deepest breath-hold dive. Divers are at risk of gradually increasing hypoxia and hypercapnia due to a long time spent underwater and additionally of increasing hyperoxia while depth diving. Exceeding the limits of hypoxia endurance leads to loss of consciousness or even to death whithout immediate first aid. Often enhanced world records indicate the ability to shape specific to the discipline adaptive mechanisms of cardio-pulmonary system which are individually conditioned. During stay underwater heartbeats decelerating called bradycardia, increase in blood pressure, peripheral blood vessels narrowing and blood centralization in freediver's organism. These mechanisms enhance blood oxygen management as well as transporting it first of all to essential for survival organs, i.e. brain and heart. These mechanisms are supported by spleen and adrenal glands hormonal reactions.

The Development and Prediction of Athletic Performance in Freestyle Swimming: This paper analyses the dynamics of changes between the performances of elite freestyle swimmers recorded at particular Olympic Games. It also uses a set of chronologically ordered results to predict probable times of swimmers at the 2012 Olympic Games in London. The analysis of past performances of freestyle swimmers and their prediction have revealed a number of interesting tendencies within separately examined results of men and women. Women's results improve more dynamically compared with men's. Moreover, the difference between women's and men's results is smaller, the longer the swimming distance. As both male and female athletes tend to compete more and more vigorously within their groups, the gap between the gold medallist and the last finisher in the final is constantly decreasing, which provides significant evidence that this sport discipline continues to develop.

Strzała, M, Stanula, A, Krężałek, P, Ostrowski, A, Kaca, M, and Głąb, G. Influence of morphology and strength on front crawl swimming speed in junior and youth age-group swimmers. J Strength Cond Res 33(10): 2836–2845, 2019—This study, conducted in 2 male age groups, was aimed at analyzing the influence of body properties, dry-land strength and swimming strength on 50-m crawl (V_Crawl). We examined 2 competitive groups, Youth (20.6 ± 1.05) and Junior (17.3 ± 0.59), based on (a) body mass (BM) and lean body mass (LBM), body height (BH) and total body length (TBL), and arm span (AS); (b) countermovement jump (CMJ) and maximum isometric strength of elbow and knee joints; and (c) tethered crawl strength. We hypothesized that a higher relationship of strength indices in younger swimmers in V_Crawl and tethered swimming would be a better sprint performance predictor. The Junior group revealed a significant relationship between somatic traits (BM r = 0.63; BH r = 0.55; TBL r = 0.58; AS r = 0.52 with p ≤ 0.05 LBM r = 0.78; with p < 0.01) and V_Crawl, whereas such interplay was not found in the Youth group. General dry-land strength indices CMJ (cm), CMJ (J) or isometric strength of knee joint muscle flexors and extensors (r = 0.57; r = 0.69; r = 0.56; r = 0.57, respectively) also significantly correlated with V_Crawl only in the Junior group. The Junior group's tethered swimming strength had a higher but not a significant relationship with V_Crawl. The Youth group instead achieved significantly higher V_Crawl and stroke rate (SR). The SR revealed (r = 0.41, p = 0.014) a relationship with V_Crawl only after the combination of both groups. This study demonstrates a better strength relationship with V_Crawl in the younger Junior group. In the future, the evaluation of sprint swimming aptitudes, besides on the basis of somatic traits and properties of dry-land or water strength measurement, should be complemented by measurements of real sprint swimming technique parameters.

The aim of this study was to investigate somatic properties and force production of leg extensor muscles measured in the countermovement jump test (CMJ), as well as to analyse kinematic variables of sprint surface butterfly swimming. Thirty-four male competitive swimmers were recruited with an average age of 19.3 ± 1.83 years. Their average body height (BH) was 183.7 ± 5.93 cm, body fat content 10.8 ± 2.64% and body mass (BM) 78.3 ± 5.0 kg. Length measurements of particular body segments were taken and a counter movement jump (CMJ) as well as an all-out 50 m butterfly speed test were completed. The underwater movements of the swimmers’ bodies were recorded with a digital camera providing side-shots. We registered a significant relationship between body mass (r = 0.46), lean body mass (r = 0.48) and sprint surface butterfly swimming (VSBF). The anaerobic power measured in the CMJ test, total body length (TBL) as well as upper and lower extremity length indices did not influence swimming speed significantly. The temporal entry-kick index (the time ratio between the first kick and arm entry) significantly influenced VSBF (r = -0.45). Similarly, medium power of the coefficient was indicated between a) stroke rate kinematics (SR), b) duration of the first leg kick (LP1), c) air phase duration of arm recovery (Fly-arm), and VSBF (r = 0.40; r = 0.40 and r = 0.41, respectively). The entry-kick temporal index showed that, in the butterfly cycle, an appropriately early executed initial kick when compared to arm entry was associated with a longer arm propulsion phase, which in turn was associated with minimizing resistive gliding phases and enabled relatively longer and less resistive air arm recovery (higher value of the fly-arm index). The higher value of SR kinematic was another important element of the best butterfly results in this study.