We aimed to assess the effects of an 8-week, online high-intensity interval training (HIIT) program on the parameters related to the anaerobic threshold (AT), body weight, and body composition in pregnant women. A total of 69 Caucasian women with an uncomplicated singleton pregnancy (age: 31 ± 4 years; gestational age: 22 ± 5 weeks; mean ± standard deviation) were randomly allocated to either an 8-week HIIT program (HIIT group) or to a comparative 8-week educational program (EDU group). Our most important finding was that even with the 8-week progression of pregnancy and physiological weight gain, the HIIT group maintained the same level of parameters related to AT: volume of oxygen at the AT (VO₂/AT), percentage of maximal oxygen uptake at the AT (%VO_2max/AT), and heart rate at the AT (HR/AT). In contrast, in the EDU group we observed a substantial deterioration of parameters related to the AT. The HIIT intervention substantially reduced the fat mass percentage (median: 30 to 28%; p < 0.01) and improved the total fat-free mass percentage (median: 70% to 72%; p < 0.01). In the EDU group, the body composition did not change significantly. An online, supervised HIIT program may be used to prevent the pregnancy-related risk of excessive weight gain and reduction in exercise capacity without yielding adverse obstetric or neonatal outcomes.

The use of herbal medicinal products and supplements in amateur and professional sports has increased in the last decades. This is because most of these products and supplements contain bioactive compounds with a variety of biological properties that exert a physiological effect on the human body. The aim of this study was to analyze the effect of dietary supplementation with lyophilized black chokeberry extract on the levels of pro-inflammatory cytokines, hepcidin, and selected markers of iron metabolism in a group of young football players. This double-blind study included 22 male football players (mean = 19.96 ± 0.56), divided into two groups: supplemented and placebo. Before and after a 90-day period of training combined with supplementation (6 g of lyophilized black chokeberry extract), participants performed maximal multistage 20-m shuttle run tests at the beginning and at the end of the supplementation period, with blood sampled for analysis at different times before and after exercise. The levels of IL-6, IL-10, ferritin, myoglobin, hepcidin, 8-OHdG, albumin, and TAC were analyzed. The analysis of variance revealed a significant effect of 90-day supplementation with the lyophilized extract on changes in the IL-6 and IL-10 levels, and TAC induced by maximal aerobic effort. In conclusion, supplementation with lyophilized black chokeberry extract improves the performance and antioxidant status of serum in humans and induces protective changes in inflammatory markers.

The main purpose of this study was to determine the effect of different interval training regimes on the physical capacity and soccer-specific skills of young soccer players. Twenty-two subjects were divided into two groups: small-sided games group (SSGG; age: 15.8 ± 0.63 y, body mass: 61.6 ± 8.97 kg, height: 175.0 ± 6.23 cm) or interval-running group (IRG; age: 15.8 ± 0.55 y, body mass: 62.7 ± 8.69 kg, height: 177.6 ± 6.48 cm). The groups completed two different 8-week training programs. The intervention consisted of two training sessions per week (IRG – 7 × 3 min running where each bout consisted of 15 s of high-intensity running and 15 s of jogging with an active recovery period of 3 min; SSGG – 3 vs. 3 games for 7 × 3 min, with an active recovery period of 3 min). Significant changes over time were found in V̇O₂max ( p = 0.009, η² = 0.29) and peak power ( p = 0.014, η² = 0.26). Post-hoc analysis revealed a significant increase in the maximal oxygen uptake only in the SSG group (p = 0.019). No significant improvement in running speed was found. The mean HR at AT increased significantly in both groups. A relevant correlation (group × time) was found for oxygen uptake at the AT intensity ( p = 0.015, η² = 0.26). A significant time effect was also present with respect to this variable ( p = 0.000, η² = 0.61). Post-hoc analysis of the V̇O₂/AT index revealed no relevant (p = 0.19) improvements in the IRG (from 44.1 ± 5.72 to 46.0 ± 5.03 ml·kg⁻¹·min⁻¹), but there was a significant ( p = 0.000) increase in the SSG (from 40.9 ± 3.51 to 46.0 ± 3.88 ml·kg⁻¹·min⁻¹). The improvement in soccer-specific skills was not significant (3.2 % in IRG and 5.3 % in SSGG). The results of this study show that small-sided games and running can both be efficient training strategies for developing aerobic capacity and soccer-specific skills.

The purpose of this study was to investigate whether the in-season pandemic lockdown influenced physical match performance in professional soccer players who participated in the competition of German Bundesliga and Polish Ekstraklasa. The data from 306 games for German Bundesliga and 296 games for Polish Ekstraklasa were divided into before- and after-lockdown periods. The physical performance of German Bundesliga teams after the 63-day COVID-19 lockdown did not differ significantly from that in the first part of the season. In contrast, Polish Ekstraklasa teams, after the 81-day lockdown, displayed significantly shorter total distances (p < 0.001), shorter high-intensity running distances (p = 0.03), and fewer high-intensity actions (p = 0.02). Moreover, when the effective playing time was considered, teams covered significantly less relative total distance (p < 0.001) and relative high-intensity running distance (p = 0.02). The results of the current study suggest that physical performance during the matches of the German Bundesliga was not influenced by the COVID-19 lockdown, contrary to those of the Polish Ekstraklasa. This difference could have been caused by different break lengths and different restrictions implemented in these countries during the pandemic lockdown.

The main purpose of this study is to assess the relations between training loads and selected blood parameters in professional soccer players during a preseason sports camp. Fifteen professional soccer players (age: 24.3 ± 5.25 year; height: 182.6 ± 6.75 cm; weight: 76.4 ± 6.72 kg) participated in the 12-day training camp. All the training sessions and friendly games were accurately analyzed with a GPS system. Blood samples were taken from the players and analyzed before the camp (PRE), in the middle (MID), and one day after the camp (POST). Mean total distance covered by the players during the camp was 85,205 ± 2685 m, high-intensity running 12,454 ± 1873 m, and sprinting 639 ± 219 m. The highest aspartate transaminase (AST), lactate dehydrogenase (LDH), creatine kinase (CK), and C-reactive protein (CRP) values were observed after six days of the camp. The application of intensive training during a 12-day sports camp can be associated with chronic muscle pain with high activity of some blood enzymes (CK, AST) and a high concentration of myoglobin (Mb). During training camps longer than 10 days, it would be necessary to apply, every second or third day, one day of rest, and the training load should not exceed two units every day.

The aim of the study was to assess the efficiencies of players in 1-on-1 situations in terms of their position on the pitch and the match time during the final matches of the World Cup and European Championships from 1990 to 2014. The research was conducted on a sample of 1012 football players whose teams competed in the semi-finals, finals and the third place matches during the Football World Cup and European Championships from 1990 to 2014. The study included the performances of 506 players in 1-on-1 situations during 46 matches that were terminated at the regulation 90 min. The study revealed that during an average match, the players performed 231 times in 1-on-1 situations with 51% accuracy. The level of accuracy in 1-on-1 situations was significantly higher (p ≤ 0.05) in winning teams than in losing teams particularly at the beginning of the game and in the middle zone of the pitch. Moreover, the results of our study showed that the highest effectiveness of the duels was noted in the defence zone and was decreasing along with moving the actions closer to the opponent’s goal. The players competed with similar frequencies on both defence (114 duels on average with 51% accuracy) and attack (113 duels on average with 52% accuracy). The players of the elite football teams exhibited high performance efficiencies in the 1-on-1 duels, especially on their own half of the field and during the early stages of both halves of the match. The accuracy of duels of their performances decreased when the action moved closer to the opponent’s goal and with the time in the game.