The aim of this study was to determine the effect of low and moderate doses of caffeine ingestion via caffeinated coffee on repeated sprint test (RST) and plasma catecholamine concentration in trained female team-sport athletes. In a randomized, double-blind, crossover design, 13 female team-sport athletes (VO_2max: 48.7 ± 4 mL·kg·min⁻¹) completed three RST trials, separated by 4-day, 60 min post-ingestion of either 3 mg·kg⁻¹ (LCOF) or 6 mg·kg⁻¹ (MCOF) or placebo (PLA). The RST consisted of 12 × 4 s sprints on a cycle ergometer interspersed with 20 s of active recovery. Blood lactate (BLa) and glucose (GLU) and epinephrine and norepinephrine concentrations were collected before and 60 min after coffee ingestion, and after RST. Heart rate (HR) and ratings of perceived exertion (RPE) were measured at the beginning of RST, and after the 6th and 12th sprints. Average peak power score during RST was significantly improved after LCOF (p = 0.016) and MCOF (p = 0.041) compared to PLA, but peak and mean power output of the individual sprints, and fatigue index were not different between trials (all p > 0.05). Epinephrine and norepinephrine concentrations were significantly higher before and after RST in LCOF and MCOF compared to PLA (all p < 0.05). BLa was also higher after RST in both LCOF and MCOF compared to PLA (p = 0.005). HR, RPE, and GLU were not different between conditions (p > 0.05). In conclusion, low and moderate dose of caffeine ingestion can enhance the average peak power score during repeated sprints. These findings partly support low and moderate doses of caffeine supplementation via coffee as a nutritional ergogenic aid for trained female team-sport players during repeated sprint exercise.

The effects of L-citrulline or L-arginine supplementation on exercise performance are equivocal, and the effects on swimming performance are unclear. We aimed to assess whether 8-day supplementation with L-arginine or L-citrulline supplementation would improve 200 m and 100 m freestyle swimming time-trial performances. After the baseline trial (first visit), in a double-blind, randomised design, 15 trained/developmental (5 females) swimmers and triathletes were assigned to three groups and underwent an 8-day supplementation period, with a daily dose of either 8 gr L-arginine (Arg, n = 5) or L-citrulline (Cit, n = 5) or placebo (Pla, n = 5). On day 9, participants completed experimental trial (second visit). In each trial, after blood sampling, participants performed both 200 m and 100 m freestyle swimming time-trials, with 30 min recovery between trials. Plasma nitric oxide (NOx) and blood lactate concentrations (BLa) were collected immediately before and after 200 m and 100 m TTs, respectively. No significant difference was observed in NOx between groups (p = 0.201). There was no significant difference in 200 m (p = 0.226) and 100 m swimming time-trials (p = 0.993) between groups. There was a main effect of time on BLa concentration (p < 0.001), but no trial × group (p = 0.243) and trial × lactate × group interaction effect (p = 0.276) was present. Furthermore, 8-day either L-citrulline or L-arginine supplementation did not enhance middle (200 m) and short-distance (100 m) swimming performance in trained/developmental swimmers and triathletes. These findings do not support the use of L-citrulline or L-arginine supplementation as ergogenic aids for swimming performance.

Although preliminary studies suggested sex-related differences in physiological responses to hypoxia, the effects of sex on sprint interval training (SIT) performance in different degrees of hypoxia are largely lacking. The aim of this study was to examine the acute effect of different doses of normobaric hypoxia on SIT performance as well as heart rate variability (HRV) and cognitive performance (CP) in amateur-trained team sport players by comparing potential sex differences. In a randomized, double-blind, crossover design, 26 (13 females) amateur team-sport (football, basketball, handball, rugby) players completed acute SIT (6 × 15 s all-out sprints, separated with 2 min active recovery, against a load equivalent to 9% of body weight) on a cycle ergometer, in one of four conditions: (I) normoxia without a mask (F_iO₂: 20.9%) (CON); (II) normoxia with a mask (F_iO₂: 20.9%) (NOR); (III) moderate hypoxia (F_iO₂: 15.4%) with mask (MHYP); and (IV) high hypoxia (F_iO₂: 13.4%) with mask (HHYP). Peak (PPO) and mean power output (MPO), HRV, heart rate (HR), CP, capillary lactate (BLa), and ratings of perceived exertion (RPE) pre- and post-SIT were compared between CON, NOR, MHYP and HHYP. There were no significant differences found between trials for PPO (p = 0.55), MPO (p = 0.44), RPE (p = 0.39), HR (p = 0.49), HRV (p > 0.05) and CP (response accuracy: p = 0.92; reaction time: p = 0.24). The changes in MP, PP, RPE, HR, CP and HRV were similar between men and women (all p > 0.05). While BLa was similar (p = 0.10) between MHYP and HHYP trials, it was greater compared to CON (p = 0.01) and NOR (p = 0.01), without a sex-effect. In conclusion, compared to normoxia, hypoxia, and wearing a mask, have no effect on SIT acute responses (other than lactate), including PP, MP, RPE, CP, HR, and cardiac autonomic modulation either in men or women.

This study evaluates the anatomical profiles, jump, sprint, power outputs, endurance, and peak blood lactate levels ([LA]_peak) of handball players of two age groups—U17 (n = 77) and U19 (n = 46)—and analyses the role of training in their physical abilities. Vertical jump performance was determined by counter movement jump (CMJ) and counter movement jump with free arms (CMJFA) tests. A running-based anaerobic sprint test (RAST) determined the relative power output (watts/kg body weight) and absolute power output (watts) of the players. Sprint performance over 5 m, 10 m, and 30 m distances was evaluated. An incremental shuttle run test (40 m) was designed to determine aerobic threshold (AeT), anaerobic threshold (AnT), and [LA]_peak. All parameters were measured for pivots, wingers, backs, and goalkeepers of each group. The U19 players were significantly heavier than the U17 group, but both the groups were nearly equal in height. The U19 group jumped higher than the U17 members, although the only significant difference (p = 0.032) was observed between the wingers of the groups in CMJ. Sprint performance varied marginally between the groups and only U19 pivots were found to be significantly (for distances of 5, 10, and 30 m: p = 0.047, p = 0.018, and p = 0.021, respectively) faster than U17 pivots. No difference in relative power output between the groups was noted, although the U19 players recorded higher absolute power outputs. Maximal velocity and velocities at the AeT and AnT were almost similar in the groups. Distance covered by the groups at the intensities of AeT and AnT varied only little. Higher [LA]_peak was observed in the U19 players. U19 players failed to convert their superior power into speed and jump. The training pattern of the handball players needs to be revised so that U19 players may develop faster and be more enduring than the U17 group.

Floorball is a young and rapidly developing team game. At the world floorball championships, the considerable disparity in performance can be seen between the individual countries. The aim of this study was to compare the level of floorball skills and motor abilities of children in the U-11 - U-14 age category at floorball clubs in the Czech Republic and Australia. The players from FBŠ Slavia Pilsen clubs (Czech Republic) (n=18; 12.1y±1.0; 155.4cm±10.6; 44.7kg±12.1) and Peninsula Floorball club (Australia) (n=18; 12.7y±1.0; 160.7cm±12.0; 53.2kg±11.6) participated in this study. To compare the tested groups, 6 items (3 motor abilities, 3 floorball skills) were used from the test battery prepared by the Czech Floorball Association for the given age category. In motor abilities, a statistically and substantially significant difference was found only for one item (Illinois agility test without stick). In floorball skills, a statistically and substantially significant difference was found for all of the tested items. Only for one criterion of the Shooting test, namely the time required for performing the task, the difference was not statistically significant, and substantial significance reached only a medium effect. The presented results clearly indicate the different level of floorball skills between the Czech and Australian floorball players in the age category tested by us.

Background: This study analyzed long-term trends and gender differences in adolescent physical activity (PA) in Southern and Western Bohemia, the Czech Republic, between 2014 and 2022. Material and methods: The study was conducted annually in 4 to 6 high schools. In total, 279 boys and 444 girls participated. Weekly PA was assessed using pedometers and Garmin Vivofit devices. In the analysis of weekly PA, a comparison was made between the number of steps taken on individual days of the week. Results: Girls showed significantly lower PA levels than boys on school days (F(1,709)=13.34, p<0.001, ηp²=0.018). Boys (12,431 steps) and girls (11,737 steps) had the highest average amount of steps/day on Friday. Significant year-to-year differences in PA were also observed (F(6,709)=6.83, p<0.001, ηp²=0.055). Only 54.1% of boys and 40.3% of girls met the recommended 11,000 steps per day (χ²=13.16, p<0.001, r=0.135). Conclusions: The findings raise concerns about the negative impact of the COVID-19 pandemic on adolescent PA, particularly among girls. The observed weekly PA structure highlights the need to promote PA among both sexes, especially on Mondays and weekends.