Performance In Professional Soccer Players Research Articles

Relationship Between Postactivation Potentiation of Knee Extensor Muscles, Sprinting and Vertical Jumping Performance in Professional Soccer Players

Little is known about the relationship between postactivation potentiation (PAP) in human muscles, assessed by enhancement of twitch torque after a conditioning maximal voluntary contraction (MVC), and performance in activities requiring power and speed. Moreover, no studies have assessed PAP in soccer players who train power and endurance simultaneously. The purpose of the present study was to examine the relationship between twitch PAP in knee extensor (KE) muscles, and sprinting and vertical jumping performance in soccer players. Fourteen professional male soccer players with mean (SD) age 20.0 (3.6) years, height 177.9 (6.9) cm and body mass 70.5 (5.7) kg) were tested for 15-m sprint time, vertical jump height in countermovement (CMJ) and squat (SJ) jumps. PAP in KE muscles was induced by a 10-s isometric MVC. Electrically evoked twitches of KE muscles were evoked before and after the conditioning MVC. Immediately after the conditioning MVC, twitch peak torque (PT) and maximal rates of torque development and relaxation were significantly potentiated. A significant negative correlation was found between 15-m sprint time and jump height in CMJ (r = -0.63) and SJ (r = -0.57). PAP of twitch PT correlated significantly positively with jump height in CMJ (r = 0.61) and SJ (r = 0.64), and negatively with 15-m sprint time (r = -0.59). In conclusion, twitch PAP in KE muscles was significantly correlated with performance in vertical jumping and sprinting in male professional soccer players, whereas the magnitude of PAP in soccer players was similar to that observed previously in power-trained athletes.

Comparison of physical and technical performance in European soccer match-play: FA Premier League and La Liga

The aim of this study was to compare match performance in professional soccer players across two major European championships: Spanish La Liga and English FA Premier League (FAPL). Data were collected using a computerized match analysis system. A total of 5938 analyses were recorded during the 2006–2007 season. The players were classified into six positional roles: central defenders, full backs, central defensive midfielders, wide midfielders, central attacking midfielders, and forwards. The match performance variables analysed included: (i) physical activity – total distance covered, distances covered at high-intensities both with and without possession of the ball; (ii) technical actions – heading and ground duels, passing, time in possession, and ball touches. Comparison of the total distance covered by FAPL and La Liga players showed no difference across individual playing positions but FAPL players generally covered greater distances in sprinting. In contrast, more of the total distance in sprinting was covered by La Liga players when their team was in possession (values from P < 0.05 to P < 0.001), while an equal total sprint distance, irrespective of possession, was observed in FAPL players. La Liga players won more heading duels (49.32% vs. 48.68%) and performed the same proportion of successful passes (76.17%). FAPL wide midfielders had ~20% more ball touches per possession than their La Liga counterparts (2.24±0.54 vs. 2.03±0.55, P < 0.001). In conclusion, our results show that FAPL and La Liga teams present differences in various physical and technical aspects of match-play, suggesting that cultural differences may exist across professional soccer leagues and playing positions.

Short-Term Effects of Strength and Plyometric Training on Sprint and Jump Performance in Professional Soccer Players

The purpose of this study was to compare the effects of combined strength and plyometric training with strength training alone on power-related measurements in professional soccer players. Subjects in the intervention team were randomly divided into 2 groups. Group ST (n = 6) performed heavy strength training twice a week for 7 weeks in addition to 6 to 8 soccer sessions a week. Group ST+P (n = 8) performed a plyometric training program in addition to the same training as the ST group. The control group (n = 7) performed 6 to 8 soccer sessions a week. Pretests and posttests were 1 repetition maximum (1RM) half squat, countermovement jump (CMJ), squat jump (SJ), 4-bounce test (4BT), peak power in half squat with 20 kg, 35 kg, and 50 kg (PP20, PP35, and PP50, respectively), sprint acceleration, peak sprint velocity, and total time on 40-m sprint. There were no significant differences between the ST+P group and ST group. Thus, the groups were pooled into 1 intervention group. The intervention group significantly improved in all measurements except CMJ, while the control group showed significant improvements only in PP20. There was a significant difference in relative improvement between the intervention group and control group in 1RM half squat, 4BT, and SJ. However, a significant difference between groups was not observed in PP20, PP35, sprint acceleration, peak sprinting velocity, and total time on 40-m sprint. The results suggest that there are no significant performance-enhancing effects of combining strength and plyometric training in professional soccer players concurrently performing 6 to 8 soccer sessions a week compared to strength training alone. However, heavy strength training leads to significant gains in strength and power-related measurements in professional soccer players.

Yohimbine: The Effects on Body Composition and Exercise Performance in Soccer Players

The main aim of this study was to determine the effects of yohimbine supplementation on body composition and exercise performance in professional soccer players. The athletes (20 top-level male soccer players) were allocated to two randomly assigned trials. Subjects in the yohimbine group orally ingested tablets that contains yohimbine at a dose of 20 milligrams per day in two equal doses for 21 days. Subjects in the placebo group ingested an equal number of identical-looking pills that contained cellulose. There were no statistically significant changes in body mass and muscle mass within or between trials (p > 0.05) after the supplementation protocol. Percentage of body fat significantly decreased in the yohimbine group after the supplementation protocol (9.3 ± 1.1 vs. 7.1 ± 2.2%; p < 0.05). Furthermore, fat mass was significantly lower in the yohimbine versus placebo trial at postsupplementation assessment (7.1 ± 2.2 vs. 9.2 ± 1.9%; p < 0.05). There were no changes in exercise performance indicators (bench and leg press, vertical jump, dribble and power test results, shuttle run) within or between trials (p > 0.05). No subject reported any side effects from yohimbine. The results of the current study indicate that supplementation with yohimbine combined with resistance training does not significantly alter the body mass, muscle mass, or performance indicators in professional soccer players. Nonetheless, yohimbine supplementation appears to be suitable as a fat loss strategy in elite athletes.

Vertical jump and knee extensors isokinetic performance in professional soccer players related to the phase of the training period

The aim of the present study was to determine the relationship between vertical jump performance and the isokinetic strength of the knee extensors in professional soccer players at the end of the of the competition period, after the detraining period (before the initiation of the preparatory period) and after the completion of the preparatory period. Eighteen professional soccer players participated in the present study. The peak jumping height (of the squat and counter movement jumps on an Ergojump device) was used as indicator of vertical jump performance. The subjects also performed three submaximal and three maximal isokinetic efforts of the knee extensors at angular velocities of 60 and 180 ◦ /s. Pearson product moment correlation analyses were conducted to determine the relationship between isokinetic strength and jumping parameters. The significance level was set at p< 0.05. The analysis indicated that jumping height was moderately correlated with the knee torques at the test velocities after the competition and preparatory period.

CREATINE SUPPLEMENTATION DOES NOT IMPROVE REPEAT SPRINT PERFORMANCE IN SOCCER PLAYERS.

794 This study investigated the effects of creatine supplementation (C) on 30 maximal sprints of 20m, each effort was repeated after 30secs rest. Eleven Bruneian national squad soccer players completed two testing sessions, one week apart, during a break in the Malaysian Premier League. Subjects were matched for age, playing position, sprint performance and then assigned to either (C) (n=5), or Placebo (P) (n=6) groups. A double blind research study was employed with group (C) consuming 24g of Creatine and 30g of glucose and group(P) consuming 30g glucose daily for 6 days. Plasma concentrations of lactate (LA), uric acid (UA) and hypoxanthine (Hx) were taken at baseline and at peak post exercise levels. At baseline the (C) group were 3.3kg lighter than the (P) group, however following supplementation the (C) group increased by an average of 1.9kg, whereas (P) group maintained their weight. Testing was performed at identical stages of the weekly training microcycle. Ambient temperature, relative humidity and wind speed did not differ appreciably between testing sessions. There were no significant changes in sprint performance between the two testing sessions for either group, additionally plasma concentrations of (LA), (UA) and (Hx) at baseline and post exercise did not reveal any significant changes between groups. In conclusion, any increases in muscular power due to (C) uptake did not translate into improved sprint performance times perhaps these benefits were offset by increased body weight in group (C), suggesting that creatine supplementation does not significantly improve repeat sprint performance in professional soccer players.

Effects of 100% Oxygen on Performance of Professional Soccer Players

Effects of 100% Oxygen on Performance of Professional Soccer Players

The Effects of 100% Oxygen on Soccer Players

To the Editor.— In the article entitled Effects of 100% Oxygen on Performance of Professional Soccer Players,1 the authors acknowledged the placebo effect of ergogenic aids on athletic performance. However, they did not control for a placebo effect in their study, that is, they compared the exercise performance of subjects after the subjects had breathed an unknown gas (either oxygen or air), but they did not measure exercise performance after the subjects breathed a gas known by them to be air. Hence, the subjects' exercise performance may have been influenced by their believing that the gas they had breathed during prior recovery was oxygen. This possibility is not negated by the information reported on subject preference, whereby four athletes retrospectively selected air as the preferred gas, four chose oxygen, and two thought both unknown gases were oxygen. Only two subjects had no preference. Because the placebo effect on performance was

Effects of 100% Oxygen on Performance of Professional Soccer Players

Supplemental oxygen is currently widely utilized in conjunction with athletic competition. To assess the utility of this practice, 12 professional soccer players performed two bouts of exhaustive exercise separated by 5 minutes of rest ("recovery period"). During the recovery period, the subjects breathed either room air or 100% oxygen, assigned by randomized, double-blind design. The entire procedure was repeated on each subject using the opposite gas. The administration of enriched oxygen during the recovery period had no effect on plasma lactate levels or on performance during the second period of exercise. The subjects were unable to identify which gas they received. In conclusion, data from this study indicate that using 100% oxygen applied for short periods offers no advantage on recovery from exhaustive exercise or on subsequent exercise performance.

Effects of 100% oxygen on performance of professional soccer players

Effects of 100% oxygen on performance of professional soccer players