The aim of this study was to investigate the effects of high-intensity interval running and small-sided game training programs on the physical capacity and the level of soccer-specific technical skills in young soccer players. Twenty male soccer players (U-16) were divided into two groups (running group – RG, small-sided game group – SSGG) and completed two different 8-week training programs. The intervention consisted of two training sessions a week (RG – 5×4 min running, with an active recovery period of 3 min; SSGG–3vs.3 games or 3vs.3 with a neutral player for 5×4 min, with an active recovery period of 3 min). A significant group × time interaction was found in the VO2max (p = 0.025). Moreover, the significant pre to post changes of VO2max were observed in the SSGG (p = 0.032). The differences between the results of shuttle runs and sprint tests were not significant with the exception of 5 m sprint in RG (p = 0.04). An improvement in the peak power and total work capacity was observed in the RG and SSGG. A significant improvement (p = 0.014) in soccer-specific technical skills level was noted only in the SSGG. The results of this study suggest that the small-sided games, compared with interval running, are more highly recommended training drills for the coincident development of physical capacity and technical skills in young soccer players.

Background This is the first study analysing levels of physical activity in a sample of quarantined adults with chronic conditions. The aim of this study was to compare moderate-intensity and vigorous-intensity physical activity levels in Spanish adults with chronic conditions before and during COVID-19 quarantine. Methods A cross-sectional online survey was administered during the COVID-19 quarantine in Spain. A total of 163 participants with chronic conditions (113 females and 47 males; age range 18-64 years) completed the survey. A total of 26 chronic conditions were included. Participants self-reported average minutes/day of moderate and vigorous physical activity before and during quarantine. Differences in moderate-intensity physical activity and vigorous-intensity physical activity levels before and during COVID-19 quarantine (overall, by gender, by age, by number of chronic conditions and by each chronic condition) were assessed by Wilcoxon signed-rank test. Results During COVID-19 quarantine, there was a significant decrease of moderate-intensity physical activity in Spanish people with chronic conditions (in both males and females, in those aged 18-24, 25-34, 35-44 and 55-64 years, in those with multimorbidity, in those with one/two chronic condition/s, and in those diagnosed with asthma/hypercholesterolemia/chronic skin disease/hemorrhoids). Also, there was a significant decrease of vigorous-intensity physical activity in Spanish males with chronic conditions and in those with multimorbidity. Conclusions These results should be considered to develop effective strategies of physical activity promotion targeting these specific groups when new quarantine or restriction measures are implemented, in order to avoid new significant decreases of physical activity in these vulnerable populations.

Jastrzębska, M, Kaczmarczyk, M, and Jastrzębski, Z. Effect of vitamin D supplementation on training adaptation in well-trained soccer players. J Strength Cond Res 30(9): 2648-2655, 2016-There is growing body of evidence implying that vitamin D may be associated with athletic performance, however, studies examining the effects of vitamin D on athletic performance are inconsistent. Moreover, very little literature exists about the vitamin D and training efficiency or adaptation, especially in high-level, well-trained athletes. The purpose of the current study was to investigate the effect of vitamin D supplementation on training adaptation in well-trained football players. The subjects were divided into 2 groups: the placebo group (PG) and the experimental group (SG, supplemented with vitamin D, 5,000 IU per day). Both groups were subjected to High Intensity Interval Training Program. The selection to the groups was based on peak power results attained before the experiment and position on the field. Blood samples for vitamin D level were taken from the players. In addition, total work, 5, 10, 20, and 30 m running speed, squat jump, and countermovement jump height were determined. There were no significant differences between SG and PG groups for any power-related characteristics at baseline. All power-related variables, except the 30 m sprint running time, improved significantly in response to interval training. However, the mean change scores (the differences between posttraining and pretraining values) did not differ significantly between SG and PG groups. In conclusion, an 8-week vitamin D supplementation in highly trained football players was not beneficial in terms of response to High Intensity Interval Training. Given the current level of evidence, the recommendation to use vitamin D supplements in all athletes to improve performance or training gains would be premature. To avoid a seasonal decrease in 25(OH)D level or to obtain optimal vitamin D levels, the combination of higher dietary intake and vitamin D supplementation may be necessary.

27Objectives: The A1470T polymorphism (rs1049434) in the monocarboxylate (lactate/pyruvate) transporter 1 28 gene (MCT1) has been suggested to influence athletic performance in the general population. We compared 29 genotype distributions and allele frequencies of the MCT1 gene A1470T polymorphism between endurance 30 athletes, sprint/power athletes and matched controls. We also examined the association between the MCT1 31A1470T and the athletes' competition level ('elite' and 'national' level

There is no clear evidence that vitamin D effectively improves physical capacity in high-level athletes. The aim of this study was to confirm that vitamin D supplementation of soccer players during eight-week high-intensity training would have a significant effect on their aerobic capacity. The subjects were divided into two groups: the experimental one that was supplemented with vitamin D (SG, n = 20), and the placebo group (PG, n = 16), not supplemented with vitamin D. All the players were subjected to the same soccer training described as High-Intensity Interval Training (HIIT). The data of the vitamin D level, PWC170, lactate threshold (LT) were collected just before and after the intervention. A significant increase in vitamin D concentration (119%) was observed in the supplemented group, while the non-supplemented group showed a decrease of 8.4%. The studied subjects improved VO2max results by 20% in the SG, and by 13% in the PG. The improvement in velocity at the LT was similar in both groups. Results of this study show that vitamin D can have a positive, though moderate, effect on aerobic performance in players subjected to high-intensity training in the form of small-sided games for 8 weeks.