No abstract

In this study we investigate the effects of unilateral voluntary contraction (VC) and electromyostimulation superimposed on VC (EV) training on maximal voluntary (MVC) force and cross-sectional area (CSA), as assessed by magnetic resonance imaging of knee extensors. Thirty young men were randomly assigned to either a control group (CG), VC group (VG), or EV group (EVG). The VG and EVG trained the right leg isometrically three sessions per week for 6 weeks. After training, MVC increased in the right leg in the VG and in both legs in the EVG, and EVG was significantly different from CG (all P < 0.01). Increased CSA was found only in the right leg in the VG and EVG (P < 0.01), and correlated with improvements of MVC (r = 0.49, P = 0.01). It appeared that the EV training was equally effective as VC at increasing MVC and CSA, while having a greater cross-education effect. Increased strength without muscle hypertrophy in the unexercised leg of the EVG indicated that neural adaptation was responsible for the cross-education effect.

The aim of the present study was (a) to describe the anthropometric profile of a large group of soccer players based on different age groups and their playing positions on the field, and (b) to examine the variations of body composition among adult soccer players using diverse equations based on skinfold thickness. A total of 618 Greek soccer players who were grouped by age (i.e., 12–14, 14–16, 16–18, and 18–37 years) and playing position (i.e., goalkeeper, defender, midfielder, and forward) were evaluated for weight, height, and skinfolds. The Pařízková formula was used to estimate the percentage of body fat. Furthermore, for players who were 18 years or older the Reilly and Evans formulas was used to estimate the percentage of body fat. Independent of the age, in this large sample, goalkeepers presented higher values for weight, height and the percentage of body fat estimation as compared with other field positions. An anthropometric pattern was observed in each tactical position, namely, across a specific age of increasing maturation process (14–16 years). With the Pařízková formula, we found a mean (SD) range of variation in the percentage of body fat estimation between 4.87 ± 1.46 and 5.51 ± 1.46 as compared with the Evans formula. The same pattern of differences was found when the Reilly equation was considered. In conclusion, we observed a position specificity of anthropometric characteristics across different age categories. Additionally, the same data supported different validated equations which resulted in large differences in the final outcome estimations.

This study had two main objectives: (1) to determine if differences in Functional Movement Screen (FMS) scores exist between two levels of competition; and (2) to analyze the association between FMS individual and overall scores and physical performance variables of lower-limb power (jumps), repeated sprint ability and shot speed. Twenty-two Under 16 (U16) and twenty-six Under 19 (U19) national competitive soccer players participated in this study. All participants were evaluated according to anthropometrics, FMS, jump performance, instep kick speed and anaerobic performance. There were no significant differences in the individual FMS scores between competitive levels. There were significant negative correlations between hurdle step (right) and Running-based Anaerobic Sprint Test (RAST) power average (ρ = −0.293; p = 0.043) and RAST fatigue index (RAST FatIndex) (ρ = −0.340; p = 0.018). The hurdle step (left) had a significant negative correlation to squat jump (SJ) (ρ = −0.369; p = 0.012). Rotary stability had a significant negative correlation to RAST fatigue index (Right: ρ = −0.311; p = 0.032. Left: ρ = −0.400; p = 0.005). The results suggest that individual FMS scores may be better discriminants of performance than FMS total score and established minimal association between FMS scores and physical variables. Based on that, FMS may be suitable for the purposes of determining physical function but not for discriminating physical performance.

The aim of this study was to examine ultra-short-term and short-term heart rate variability (HRV) in under-20 (U-20) national futsal players during pre-tournament training camps and an official tournament. Fourteen male U-20 national futsal players (age = 18.07 ± 0.73 yrs; height = 169.57 ± 8.40 cm; body weight = 64.51 ± 12.19 kg; body fat = 12.42% ± 3.18%) were recruited to participate in this study. Early morning 10 min resting HRV, Borg CR-10 scale session rating of perceived exertion (sRPE), and general wellness questionnaire were used to evaluate autonomic function, training load, and recovery status, respectively. Log-transformed root mean square of successive normal-to-normal interval differences (LnRMSSD) was used to compare the first 30 s, first 1 min, first 2 min, first 3 min, and first 4 min with standard 5 min LnRMSSD. Mean (LnRMSSDmean) and coefficient of variation (LnRMSSDcv) of LnRMSSD were used to compare the different time segments of HRV analysis. The result of LnRMSSDmean showed nearly perfect reliability and relatively small bias in all comparisons. In contrast, LnRMSSDcv showed nearly perfect reliability and relatively small bias from 2-4 min time segments in all study periods. In conclusion, for accuracy of HRV measures, 30 s or 1 min ultra-short-term record of LnRMSSDmean and short-term record of LnRMSSDcv of at least 2 min during the training camps are recommended in U-20 national futsal players.