It has been suggested that assessment of high-intensity activities during a match is a valid measure of physical performance in elite soccer. Recently, sprinting activities have been analysed in more depth. The aim of this study was to develop a detailed analysis of the sprinting activities of different playing positions during European Champions League and UEFA Cup competitions. Altogether, 717 elite outfield soccer players were evaluated throughout 2002-2006 using ProZone® (Leeds, UK). Sprinting (explosive and leading) was analysed for each playing position. To compare positional differences, a Kruskal-Wallis analysis was performed. Differences were found among positions for total number of sprints and total sprint distance covered: wide midfielders > (attackers = wide defenders) > central midfielders > central defenders (P < 0.001), as well as for explosive sprints: (wide midfielders = attackers = wide defenders) > central defenders, wide midfielders > central midfielders > central defenders and attackers = wide defenders = central midfielders (P < 0.001), and leading sprints: wide midfielders > (attackers = wide defenders) > central midfielders > central defenders (P < 0.001). For each group, there were no differences in ratio of explosive to leading sprints. Wide midfielders performed a higher number of sprints in all five distance categories than all other positions. This study showed that sprinting characteristics are influenced by position. Wide midfielders have to complete additional high-intensity activities during training sessions compared with the other positions to achieve the performance level required during the match.

The purpose of this study was to compare motions of soccer players in the English Premier (1st) and Championship (2nd) League. A total of 26 449 observations were obtained from players during 4 seasons (2006-2010) in the 2 leagues. Time-motions of all players (attackers, central defenders, central midfielders, wide defenders, wide midfielders) were recorded during each match using the Prozone® System, (Leeds, UK), and categorized by speed intensity. Number of actions, total distance and the mean distance covered at each speed intensity were measured. Players in the Championship league covered a total match distance of 11.1±0.9 km compared with 10.8±1.0 km for players from the Premiership (p<0.001). Championship players also covered greater distances during jogging, running, high-speed running, and sprinting. Premiership players covered more distance walking. Players in the Soccer League Championship had more instances of each condition. Although these differences were statistically significant, they were negligible in practical terms, suggesting match-related activities do not explain the general superiority of Premiership players over Championship players in England.

Objective: To describe the fat-oxidation rate in triathlon and different modalities of endurance cycling. Methods: 34 endurance athletes (15 male triathletes, 4 female triathletes, 11 road cyclists and 4 male mountain bikers) underwent a progressive cycloergometer test until exhaustion. Relative work intensity (VO 2max ), minimal lactate concentration (La 2 min ), lactic threshold, individual lactic threshold (ILT), maximal fat-oxidation rate (Fat max , Fat max zone) and minimal fat-oxidation rate (Fat min ) were determined in each of the groups and were compared by means of one-way analysis of variance. Results: No significant differences were found for Fat max , Fat min or for the Fat max zone expressed as fat oxidation rate (g/min). Intensities 220%, 210% and 25% Fat max were significantly lower for mountain bikers with respect to road cyclists and female triathletes, expressed as % VO 2max . Intensities 20%, 10% and 5% Fat max were significantly lower for mountain bikers with respect to male triathletes and female triathletes, and for male triathletes in comparison with female triathletes, expressed as % VO 2max . Lactic threshold and La 2 min did not show significant differences with respect to Fat max . Lactic threshold was found at the same VO 2max with respect to the higher part of the Fat max zone, and La Moreover, it should be taken into account that, during exercise, women oxidise more intramuscular triglycerides than men, 2 and use less muscle glycogen. 3In endurance specialities, having a large capacity to metabolise CHO is a determining factor for performance, but so is the ability to economise this substrate as an effect of a greater capacity to use fat. 4 It has been observed that athletes have a lower fat-oxidation rate at low and high intensities compared with moderate intensities. 1 5 Also, there is a relative individual intensity at which the maximal fat-oxidation rate is produced.Until recently, the methods followed by some authors only measured the athletes fat-oxidation rate in a reduced number of work intensities: two, 5-7 three 1 8 9 or four. 10 Now there is a method to measure the fat-oxidation rate for each of the relative work intensities, by means of indirect calorimetry and using stoichiometric equations.11 However, this method has only been applied in a few studies carried out with cyclists. 11-13Some authors have observed that cycling endurance performance at a concrete work intensity improves with a training focused on this intensity. 14 After this principle (training specificity), other authors have observed that the fat-oxidation rate increases specifically for the concrete intensity that has been trained. 7 Thus, differences in the training of triathlon and cycling endurance modalities may produce different adaptations of the fat-oxidation rate at each of the aerobic work intensities.The aim of this study was to use a cross-sectional design to describe the fat-oxidation rate in different modalities of endurance cycling and triathlon (mountain biking and road cycling in men, a...

To assess the effect of diet enrichment with L-arginine or supplementation at high doses on physiological adaptation during exercise, 9 athletes followed 3 different diets, each over 3 consecutive days, with a wash-out period of 4 d between training sessions: control diet (CD), 5.5 +/- 0.3 g/d of L-arginine; Diet 1 (rich in L-arginine food), 9.0 +/- 1.1 g/d of L-arginine; and Diet 2 (the same as CD but including an oral supplement of 15 g/d), 20.5 +/- 0.3 g/d of L-arginine. Plasma nitrate levels of each participant were determined on the day after each treatment. Participants performed a submaximal treadmill test (initial speed 10-11 km/hr, work increments 1 km/hr every 4 min until 85-90% VO2max, and passive recovery periods of 2 min). Oxygen uptake and heart rate were monitored throughout the test. Blood lactate concentration ([La-]b) was determined at the end of each stage. Repeated-measures ANOVA and paired Student's t tests were used to compare the various physiological parameters between diets. The level of significance was set at p < .05. [La-]b showed a significant effect at the 5-min time point between CD and Diet 2 (CD 3.0 +/- 0.5 mM, Diet 2 2.5 +/- 0.5 mM, p = .03), but this tendency was not found at higher exercise intensities. No significant differences were observed in any of the cardiorespiratory or plasma nitrate levels. In conclusion, dietary L-arginine intake on the days preceding the test does not improve physiological parameters during exercise.

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