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Castagna, C, Impellizzeri, F, Cecchini, E, Rampinini, E, and Barbero Alvarez, JC. Effects of intermittent-endurance fitness on match performance in young male soccer players. J Strength Cond Res 23(7) : 1954-1959, 2009-The purpose of this study was to examine the effect of specific endurance (Yo-Yo Intermittent recovery test level 1, Yo-Yo IR1) on match performance in male youth soccer. Twenty-one young, male soccer players (age 14.1 6 0.2 years) were involved in the study. Players were observed during international championship games of corresponding age categories and completed the Yo-Yo IR1 on a separate occasion. Physical (distance coverage) and physiological match demands were assessed using Global Positioning System technology and heart rate (HR) short-range telemetry, respectively. During the match (two 30-minutes halves), players covered 6,204 6 731 m, of which 985 6 362 m (16%) were performed at high intensities (speed .13 kmÁh 21 , HIA). A significant decrement (3.8%, p = 0.003) in match coverage was evident during the second half. No significant (p = 0.07) difference between halves was observed for HIA (p = 0.56) and sprint (speed .18 kmÁh 21 , SPR) distances. During the first and second halves, players attained the 86 6 5.5 and 85 6 6.0% of HRmax (p = 0.17), respectively. Peak HR during the first and second halves were 100 6 4 and 99.4 6 4.7% of HRmax, respectively. Yo-Yo IR1 performance (842 6 352 m) was significantly related to match HIA (r = 0.77, p , 0.001) and total distance (r = 0.65, p = 0.002). This study's results showed that specific endurance, as determined by Yo-Yo IR1 performance, positively affects physical match performance in male young soccer players. Consequently, the Yo-Yo IR1 test may be regarded as a valid test to assess game readiness and guide training prescription in male youth soccer players.

The purpose of this study was to examine the relationship between popular endurance field tests and physical match performance in elite male youth soccer players. Eighteen male young soccer players (age 14.4±0.1 years, height 1.67±4.8 cm, body mass 53.6±1.8 kg) were randomly chosen among a population of elite-level soccer players. Players were observed during international championship games of the corresponding age categories and randomly However the Hoff test was only significantly related with sprint distance (r=0.70, p=0.04).The Yo-Yo IR1 showed very large association with MSFT performance (r=0.89, p<0.0001). This study's results showed that Yo-Yo IR1 and MSFT test may be regarded as valuable tests to assess match fitness and subsequently guide training prescription in youth soccer players.The very large relationship between Yo-Yo IR1 and MSFT suggests their use according to 3 the period of the season and the aerobic-fitness level of the players. Due to the association of the Yo-Yo IR1 and MSFT with match physical performances these tests should be considered in talent selection and development.

Recently the use of small-sided games (mainly 5 vs. 5) proved to be a valid training method to improve aerobic fitness in soccer. Thus, it could be hypothesized that professional futsal (soccer 5-a-side indoor version) players may possess a well-developed aerobic fitness as a consequence of training and game participation. The aim of this study was to examine maximal oxygen uptake (VO2max), ventilatory threshold (VT), and running economy (RE, VO2 at 8 kmxh) of futsal players of different competitive levels to determine whether aerobic fitness is a discriminative variable for futsal success. Subjects were 24 male futsal players from a professional top-ranked second division team (PT, n = 11) and a semi-professional top-ranked third division team (ST, n = 13). Aerobic fitness was assessed with a running protocol performed on a motor-driven treadmill. Professional team and ST players' VO2max were 62.9 +/- 5.3 and 55.2 +/- 5.7 mLxkgxmin, respectively (p < 0.05). RE was 34.1 +/- 2.7 and 32.4 +/- 2.7 mLxkgxmin for PT and ST, respectively (p >0.05). PT and ST attained VT at 70.5 +/- 2.7 and 71.3 +/- 5.2% of VO2max, respectively (p > 0.05). Results showed that VO2max may be considered a competitive-level dependent physical variable in futsal. VO2max values of or above 60 mLxkgxmin are advisable to play futsal at the professional level.

The aim of this study was to provide evidence for specific physiological demands of a futsal time-motion analysis devised progressive and intermittent shuttle-running test (futsal intermittent endurance test [FIET]). Eighteen full-time professional futsal players (age 20.6 +/- 3.1 years, body mass 71.6 +/- 8.5 kg, height 175 +/- 7.9 cm) volunteered to participate in this study. In a random order and on separate days, they performed the FIET and a treadmill test (TM) to assess aerobic fitness. Physiological demands were examined by monitoring exercise heart rates (HRs), O2, and blood-lactate concentration (BLac) during FIET and TM conditions. During the FIET, players covered 1,464 +/- 136 m attaining a mean speed at exhaustion of 16.5 +/- 0.6 km h. The mean FIET duration was of 13.24 +/- 1.13 minutes. Peak O2, HR, and BLac were 95 +/- 6.4, 99 +/- 2, and 108 +/- 25% of treadmill O2max, HRmax, and BLac, respectively. Large correlations were found between speed at ventilatory threshold and maximal speed at O2max with FIET performance (r = 0.60 and 0.61, p < 0.01, respectively). Peak O2 during the FIET was significantly lower than O2max. Although there was no mean difference between peak exercise HR in the TM and FIET conditions, significant intraindividual bias was evident. This study showed that FIET heavily stresses both the aerobic and anaerobic energy systems to a level that is similar to what was reported in futsal game play. Coaches may use the FIET to examine futsal players' ability to cope with intermittent high-intensity exercise. It is suggested that the highest HR found during the FIET should be regarded as peak HR and not as individual HRmax.

The physical and physiological demands of high-level male soccer have been studied extensively, while few studies have investigated the demands placed on females during match-play, however, there is no information available about the heart rate and activity profile of young female soccer players during match play. Therefore, the aim of this study was to examine cardiovascular (heart-rates HR) and physical demands of young female soccer players during a match. Players were observed during a friendly competitive match (7-a-side) over 2 x 25-min halves. Match activities were assessed with Global Position System technology (1Hz). Result showed that young female soccer players attain 88±4.4% and 86.3±4.8% of HRmax during the first and second half respectively (P=0.3), the average heart rate was 87%. During the first and second half, they covered 2072±197 m and 1905±144 m (P<0.001) respectively. At speed faster than 13 km/hr, they covered 132.6 m and 116 m during the first and second halves respectively (P=0.4). The results show that, during competitive matches, YFPs experience a cardiovascular load similar to that reported for adolescent male soccer players and professional female soccer players. However match work-rate (total distance covered and distance at a speed of >13 km/h) resulted lower than that previously reported for age-matched male soccer players and elite female soccer players. This seems to indicate that gender and competitive level differences in match physical performance seem to occur mainly in the absolute match work-rate domain.Key words: female soccer, match analysis, physiological stress, GPS.Reference Data: Barbero-Álvarez, J.C., Gómez, M., Barbero, V., Granda J. y Castagna C. Heart rate and activity profile for young female soccer players.

This study was designed to examine effects of three practice models, blocked, variable, and combined, on the acquisition, retention, and transfer of new motor skills. 67 subjects (M age = 9.5 yr., SD = .3) from the fourth year of primary school (31 boys and 26 girls) were assigned at random to three different practice groups (Blocked = 22, Variable = 23, Combined = 22) to study acquisition of two skills, dribbling a soccer ball and kicking a soccer ball at a stationary target using the dominant foot. All participants received a pretest and posttest, a transfer test, and a retention test 2 wk. later. Analysis showed significant improvement after practice of kicking skills by the three groups but not in the dribbling skills, for which only the combined practice group showed any notable improvement. At the end of acquisition, the combined practice group had significantly better performance on the dribbling task than the other two groups. However, the only differences noted in performance of kicking the ball with the dominant foot were by combined practice and blocked groups.

Este artículo repasa la historia del magnetismo siguiendo un orden cronológico que comienza con la evolución del conocimiento científico en las primeras civilizaciones, después en Egipto y China, seguido de la antigua Grecia y Roma. Por último, se describen también la Edad Media y la Edad Moderna. Posteriormente, se comentan los hallazgos de los investigadores más importantes en el campo del electromagnetismo como son Oersted, Biot y Savart, Ampère, Sturgeon, Faraday, Lenz, Maxwell y Coulomb. Se resumen los principios básicos del electromagnetismo, con especial énfasis en la relación entre carga eléctrica y magnetismo. Asimismo, es parte esencial la relación entre campos magnéticos y sistemas biológicos, sobre todo semillas y plantas. Con la ayuda de una minuciosa recopilación de bibliografía, se tratan en detalle los efectos sobre diversas especies de plantas que tiene el campo magnético natural de la Tierra, como magnetismo natural, y de los causados por la aplicación de campos magnéticos estacionarios.