In this study, we examined gender and age differences in physical performance in football. Thirty-four elite female and 34 elite male players (age 17 +/- 1.6 to 24 +/- 3.4 years) from a professional football club were divided into four groups (n=17 each) according to gender and competitive level (senior males, senior females, junior males, and junior females). Players were tested for specific endurance (Yo-YoIR1), sprint over 15 m (Sprint-15 m), vertical jump without (CMJ) or with (ACMJ) arm swing, agility (Agility-15 m), and ball dribbling over 15 m (Ball-15 m). The Yo-YoIR1 and Agility-15m performances showed both a gender and competitive level difference (P < 0.001). Senior and junior males covered 97 and 153% more distance during the Yo-YoIR1 than senior and junior females, respectively (P < 0.001). Gender but not age differences were found for Sprint-15 m performance (P < 0.001). No difference in vertical jump and Ball-15 m performances were found between senior and junior males (P > 0.05). More marked gender differences were evident in endurance than in anaerobic performance in female players. These results show major fitness differences by gender for a given competitive level in football players. It is suggested that training and talent identification should focus on football-specific endurance and agility as fitness traits in post-adolescent players of both sexes.

Using a video-based time-motion analysis system, a semi-automatic multiple-camera system, and two commercially available GPS systems (GPS-1; 5 Hz and GPS-2; 1 Hz), we compared activity pattern and fatigue development in the same football match. Twenty football players competing in the Spanish second and third divisions participated in the study. Total distance covered during the match for the four systems was as follows: 10.83 + or - 0.77 km (semi-automatic multiple-camera system, n = 20), 9.51 + or - 0.74 km (video-based time-motion analysis system, n = 17), 10.72 + or - 0.70 km (GPS-1, n = 18), and 9.52 + or - 0.89 km (GPS-2, n = 13). Distance covered by high-intensity running for the four systems was as follows: 2.65 + or - 0.53 km (semi-automatic multiple-camera system), 1.61 + or - 0.37 km (video-based time-motion analysing system), 2.03 + or - 0.60 km (GPS-1), and 1.66 + or - 0.44 km (GPS-2). Distance covered by sprinting for the four systems was as follows: 0.38 + or - 0.18 km (semi-automatic multiple-camera system), 0.42 + or - 0.17 km (video-based time-motion analysing system), 0.37 + or - 0.19 km (GPS-1), and 0.23 + or - 0.16 km (GPS-2). All four systems demonstrated greater (P < 0.05) total distance covered and high-intensity running in the first 15-min period and less (P < 0.05) total distance covered and high-intensity running during the last 15-min period than all other 15-min intervals, with a reduction (P < 0.05) in high-intensity running from the first to the last 15-min period of 46 + or - 19%, 37 + or - 26%, 50 + or - 26%, and 45 + or - 27% for the semi-automatic multiple-camera system, video-based time-motion analysis system, GPS-1, and GPS-2, respectively. Our results show that the four systems were able to detect similar performance decrements during a football game and can be used to study game-induced fatigue. Rather large between-system differences were present in the determination of the absolute distances covered, meaning that any comparisons of results between different match analysis systems should be done with caution.

The relative age effect is an uneven distribution of birth date favouring subjects born in the initial months of a selection year. This study compared the birth-date distributions between several subgroups of Basque football players to identify whether the relative age effect is influenced by age and/or skill level. The study comprised 13,519 players including 114 senior professionals from the Spanish league's AC Bilbao over 21 seasons; over the season 2005-2006, it comprised elite youth (n=189) from the same club's academy; regional youth (n=4382) U11-U14 locally federated players; school youth (n=8834) U10-U11 locally registered school district players. Differences between the observed and expected birth-date distributions were tested based on data from the general Basque male population. Significant chi-square values were followed up by calculating odds ratios and 95% confidence intervals (CI) for the quartile and half-year distributions to examine subgroup differences in the relative age effect. Birth-date distributions of all groups of players showed a significant bias towards early birth in the selection year compared with the reference population (senior, chi-2(3) = 24.4, P < 0.001; elite youth, chi-2(3) = 59.1, P < 0.001; regional youth, chi-2(3) = 41.4, P < 0.001; school youth, chi-2(3) = 40.9, P < 0.001). Between-group comparison revealed that the relative age effect incidence progressively increased with a higher level of involvement in youth football. This bias represents a significant loss of potential youth football talent.

%HRmax, time distribution around HROBLA and HRLT, TRIMP, and load zones reflected the physiological demands of different mass-start cycling stage categories. The knowledge of these demands could be useful for planning precompetition training strategies.

The study examines fatigue in elite soccer played in hot conditions. High-profile soccer players (n 5 20) were studied during match play at $ 31 1C. Repeated sprint and jump performances were assessed in rested state and after a game and activity profile was examined. Additionally, heart rate (HR), blood lactate, muscle temperature and body mass changes were determined. Repeated sprint and jump performances were reduced (Po0.05) by 2.6% and 8.2%, respectively, after the game. The fatigue index in the repeated sprint test was 6.0 AE 0.7% after the game compared with 1.7 AE 1.0% at rest (Po0.05). High-intensity running was 57 AE 4% lower (Po0.05) during the last 15-min interval of the game compared with the first 15-min period. No differences were observed in mean HR or blood lactates between halves. Muscle temperature was 40.5 AE 0.4 1C after the first half, which was 0.8 AE 0.2 1C higher (Po0.05) than after the second half. Net fluid loss during the game was 42% of the body mass. Correlations were observed between net-fluid loss and repeated sprint test fatigue index after the game (r 5 0.73, Po0.05) and YoYo intermittent recovery, level 1 test performance and highintensity running during the final 15 min of the game (r 5 0.51, Po0.05). The study provides direct evidence of compromised repeated sprint and jump performances induced by soccer match play and pronounced reduction in high-intensity running toward the end of an elite game played in a hot environment. This fatigue could be associated training status and hyperthermia/dehydration.Fatigue development in soccer has drawn extensive attention during the last decades and has become one of the primary research areas in the broader field of soccer physiology (

In this study, we investigated the age-related differences in repeated-sprint ability and blood lactate responses in 134 youth football players. Players from the development programme of a professional club were grouped according to their respective under-age team (U-11 to U-18). Following familiarization, the participants performed a repeated-sprint ability test [6 x 30-m sprints 30 s apart, with active recovery (2.0-2.2 m . s(-1)) between sprints]. The test variables were total time, percent sprint decrement, and post-test peak lactate concentration. Total time improved from the U-11 to U-15 age groups (range 33.15 +/- 1.84 vs. 27.25 +/- 0.82 s), whereas no further significant improvements were evident from U-15 to U-18. No significant differences in percent sprint decrement were reported among groups (range 4.0 +/- 1.0% to 5.5 +/- 2.1%). Post-test peak lactate increased from one age group to the next (range 7.3 +/- 1.8 to 12.6 +/- 1.6 mmol . l(-1)), but remained constant when adjusted for age-related difference in body mass. Peak lactate concentration was moderately correlated with sprint time (r = 0.70, P > 0.001). Our results suggest that performance in repeated-sprint ability improves during maturation of highly trained youth football players, although a plateau occurs from 15 years of age. In contrast to expectations based on previous suggestions, percent sprint decrement during repeated sprints did not deteriorate with age.

Despite the extremely poor prognosis of the case, complete articular cartilage healing was considerably accelerated, and the functional outcome was excellent, allowing a rapid resumption of symptom-free athletic activity. This technique opens new perspectives for human tissue regeneration.

The purpose of this investigation was to examine the influence of training frequency on performance and some physiological responses during a 6-day taper. After 18 weeks of training, 9 male middle-distance runners were assigned to a high frequency taper (HFT, n = 5) or a moderate frequency taper (MFT, n = 4), consisting of training daily or resting every third day of the taper. Taper consisted of an 80% nonlinear progressive reduction in high intensity interval training. Blood samples were obtained, and 800 m performance and peak blood lactate ([La] peak ) measured before and after taper. Performance improved significantly after HFT (121.8 +/- 4.7 vs 124.2 +/- 4.9 s, p < 0.05), but not after MFT (126.6 +/- 2.8 vs 127.1 +/- 2.1 s). Neutrophils (2.89 +/- 0.68 vs 2.56 +/- 0.61 10 (3) x mm(-3)), granulocytes (3.08 +/- 0.70 vs 2.77 +/- 0.66 10 (3) x mm(-3)), haptoglobin (79.7 +/- 47.9 vs 60.7 +/- 33.6 mg x dl(-1)), total testosterone (7.39 +/- 1.67 vs 5.52 +/- 0.88 microg x l(-1)) and [La] peak (15.5 +/- 1.5 vs 14.4 +/- 2.0 mmol x l(-1)) significantly increased with taper. [La] peak correlated with performance time before taper (r = -0.76, p < 0.05), and change in [La] peak with change in serum cortisol (r = -0.75, p < 0.05) and total testosterone:cortisol ratio (r = 0.82, p < 0.01). In conclusion, training daily during a 6-day taper brought about significant performance gains, whereas resting every third day did not. High [La] peak and a hormonal milieu propitious to anabolic processes seemed to be necessary for optimum performance.