The COVID-19 pandemic has caused huge changes in people’s lifestyle, health, and social relationships. This situation has had an impact on children and adolescents, affecting their health, intellectual, physical, and emotional development. The survey aimed to compare eating behaviors, level of physical activity (PA), hours of sleep, and screen time among Polish children and adolescents aged 6–15 years before and during the COVID-19 pandemic. We obtained self-reported data from 1016 participants at two measurement points before and during the COVID-19 lockdown in Poland to examine the influence of the lockdown and the distance learning on PA, dietary habits, sleep, and media usage of children and adolescents aged 6–15 years. The study identified dietary differences and changes in daily activity patterns (reduced sleep duration with higher sleep quality and reduced physical activity). Additionally, the increase in general media usage was observed during the pandemic alongside a reduction in smartphone usage. Together, the findings indicate increased sleep, physical activity, and reduced media usage and screen time among Polish children and adolescents during the COVID-19 pandemic.

Background: The purpose of this research was to investigate the acute effects of a pre-workout supplement on anaerobic performance in resistance-trained men. Methods: Twenty-three men underwent three randomized, double-blind testing sessions separated by a seven-day break. The participants performed three tests: isokinetic strength, three repetition maximum (3-RM) strength and Wingate. Statistical analysis was conducted in R environment. Linear mixed models were estimated via R package lme4. Results: Mean T@0.2 s was significantly greater in supplemented condition for right and left knee flexors (PL: 103.2 ± 37.6 Nm; supplemented condition: 131.8 ± 29.3 Nm (p = 0.001)), and PL: 103.7 ± 39.3; supplemented condition: 129.4 ± 28.4 (p = 0.001)). T@0.2 s for right and left knee extensors (PL: 202.6 ± 58.6 Nm; supplemented condition: 237.2 ± 54.7 Nm (p = 0.001); PL: 203.3 ± 63.2 Nm, supplemented condition: 229.8 ± 50.8 Nm (p = 0.002)). Significant difference was in mean anaerobic power between supplemented and PL condition for right and left knee flexors (p = 0.002, p = 0.005) and for right and left knee extensors (p = 0.001 and p = 0.002). TTP was significantly shorter in supplemented condition for both sides knee flexors (p = 0.002). There was a significant difference for mean power in the Wingate test (placebo: 8.5 ± 0.6 W/kg; supplemented condition: 8.7 ± 0.5 W/kg (p = 0.038)). Mean 3-RM was significantly greater in supplemented condition (p = 0.001). Conclusions: The supplement significantly improves upper and lower body strength and power output in resistance-trained men.

Background: The purpose of this study was to investigate the acute effects of commercially available pre-workout supplement on anaerobic performance in resistance trained men.Methods: Twenty-three men underwent three testing sessions administrated in a randomized and double-blind fashion separated by a seven-day break. The participants performed three exercise tests: isokinetic strength test, maximal strength test and Wingate test. Statistical analysis was conducted in R environment. Linear mixed models were estimated via R package lme4.Results: The mean knee peak torque was significantly greater in supplemented group for right and left knee flexors (placebo: 103.17 ± 37.61 Nm, and supplemented group: 131.84 ± 29.31 Nm where p=0.001, and placebo: 103.72 ± 39.35, and supplemented group: 129.38 ± 28.44, where p=0.001; respectively) as well as for right and left knee extensors (placebo: 202.65 ± 58.64 Nm, and supplemented group: 237.22 ± 54.75 Nm where p=0.001, and placebo: 203.27 ± 63.2 Nm versus supplemented group: 229.84 ± 50.8 Nm where p=0.002; respectively).The significant difference was observed in mean anaerobic power between supplemented and placebo group for right and left knee flexors (p=0.002 and p=0.005, respectively) as well as for right and left knee extensors (p=0.001 and p=0.002; respectively).There was also observed that the time to peak torque was significantly greater in supplemented group for right and left knee flexors (p=0.002 for both legs). The significant difference was also observed in mean power between supplemented and placebo group during Wingate test (placebo: 8.49 ± 0.57 W/kg, and supplemented group: 8.66 ± 0.55 W/kg where p=0.038). Moreover the mean 3-RM strength test was significantly greater in supplemented group with p=0.001.Conclusions: The results of the study indicate that the supplement significantly improves upper and lower body strength and power output in resistance trained men.

Background: The purpose of this study was to investigate the acute effects of commercially available pre-workout supplement Knockout 2.0 ® on anaerobic performance in resistance trained men.Methods: Twenty-three men underwent three testing sessions administrated in a randomized and double-blind fashion separated by a seven-day break. The participants performed three exercise tests: isokinetic strength test, maximal strength test and Wingate test. Statistical analysis was conducted in R environment. Linear mixed models were estimated via R package lme4.Results: The mean knee peak torque was significantly greater in supplemented group for right and left knee flexors (placebo: 103.17 ± 37.61 Nm, and supplemented group: 131.84 ± 29.31 Nm where p=0.001, and placebo: 103.72 ± 39.35, and supplemented group: 129.38 ± 28.44, where p=0.001; respectively) as well as for right and left knee extensors (placebo: 202.65 ± 58.64 Nm, and supplemented group: 237.22 ± 54.75 Nm where p=0.001, and placebo: 203.27 ± 63.2 Nm versus supplemented group: 229.84 ± 50.8 Nm where p=0.002; respectively).The significant difference was observed in mean anaerobic power between supplemented and placebo group for right and left knee flexors (p=0.002 and p=0.005, respectively) as well as for right and left knee extensors (p=0.001 and p=0.002; respectively).There was also observed that the time to peak torque was significantly greater in supplemented group for right and left knee flexors (p=0.002 for both legs). The significant difference was also observed in mean power between supplemented and placebo group during Wingate test (placebo: 8.49 ± 0.57 W/kg, and supplemented group: 8.66 ± 0.55 W/kg where p=0.038). Moreover the mean 3-RM strength test was significantly greater in supplemented group with p=0.001.Conclusions: The results of the study indicate that Knockout 2.0® significantly improves upper and lower body strength and power output in resistance trained men.

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