Assessing maximal sprinting speed in highly trained young soccer players.

The aim of the present study was to locate the fastest 10-m split time (Splitbest) over a 40-m sprint in relation to age and maximal sprint speed in highly trained young soccer players. Analyses were performed on 967 independent player sprints collected in 223 highly trained young football players (Under 12 to Under 18). The maximal sprint speed was defined as the average running speed during Splitbest. The distribution of the distance associated with Splitbest was affected by age (X23 = 158.7, P < .001), with the older the players, the greater the proportion of 30-to-40-m Splitbest. There was, however, no between-group difference when data were adjusted for maximal sprint speed. Maximal sprint speed is the main determinant of the distance associated with Splitbest. Given the important disparity in Splitbest location within each age group, three (U12-U13) to two (U14-U18) 10-m intervals are still required to guarantee an accurate evaluation of maximal sprint speed in young players when using timing gates.

Does on-field sprinting performance in young soccer players depend on how fast they can run or how fast they do run?

The aim of this study was to examine the impact of maximal sprinting speed (MSS) on the peak speed attained during soccer matches. Time-motion analysis of running activity was collected from 14 highly trained young male outfield footballers (8 wide midfielders [WM] and 6 central defenders [CD], 173.2 ± 0.06 m, 60.8 ± 8.1 kg, 16.7 ± 0.7 years) during 14 different friendly international club level matches. The 2 fastest players (a WM and a CD) were compared with the slower players who played in the same position. Each player's MSS was determined using the fastest 10-m split time during an electronically timed 40-m sprint. Game speed was recorded via portable global positioning systems. Faster players reached higher absolute peak running speeds in games than did their slower counterparts regardless of the playing position, with large to very large effect sizes and qualitative indications of "almost certain" and "very likely" positive effects associated with being fast. None of the players reached their MSS during the matches; however, the fastest CD attained a lower percentage of his MSS compared to both, his slower CD counterparts and the fastest WM. Given the higher peak speeds reached in games by the fastest players, and the fact that all players (irrespective of their MSS) used a high percentage of their MSS, these preliminary results provide direct support to the hypothesis that MSS can impact on what a player can do in actual playing conditions. Our results also indicate that playing position has an important role in influencing the expression of MSS.

Age-related differences in acceleration, maximum running speed, and repeated-sprint performance in young soccer players.

We investigated age-related differences in the relationships among acceleration, maximum running speed, and repeated-sprint performance in 61 highly trained young male soccer players (Under 14, n = 14; Under 16, n = 22; Under 18, n = 25). We also examined the possible influence of anthropometry (stature, body mass, fat-free mass) and biological maturation (age at peak height velocity) on performance in those three sprint-running qualities. Players were tested for 10-m sprint (acceleration), flying 20-m sprint (maximum running speed), and 10 × 30-m sprint (repeated-sprint performance) times. Correlations between acceleration, maximum running speed, and repeated-sprint performance were positive and large to almost perfect (r = 0.55-0.96), irrespective of age group. There were age-based differences both in absolute performance in the three sprint-running qualities (Under 18 > Under 16 > Under 14; P < 0.001) and when body mass and fat-free mass were statistically controlled (P < 0.05). In contrast, all between-group differences disappeared after adjustment for age at peak height velocity (P > 0.05). The large correlations among acceleration, maximum running speed, and repeated-sprint performance in all age groups, as well as the disappearance of between-group differences when adjusted for estimated biological maturity, suggest that these physical qualities in young highly trained soccer players might be considered as a general quality, which is likely to be related to qualitative adaptations that accompany maturation.

Application of four different football match analysis systems: a comparative study.

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.

Is the relationship between sprinting and maximal aerobic speeds in young soccer players affected by maturation?

The purpose of this study was to investigate the relationship between maximal sprinting (MSS) and aerobic (MAS) speeds in a cohort of highly-trained young male soccer players with the influence of body mass controlled for using allometric scaling. MSS and MAS were obtained in 14 pre-age at peak height velocity (APHV) players (12.3 ± 0.7 years), 21 circum-APHV players (14.3 ± 0.9 year) and 26 post-APHV players (16.9 ± 0.7 years). The three groups showed similar positive correlations between MSS and MAS (r = 0.73 to 0.52; p < .01). In conclusion, our results suggest that the relationship between MSS and MAS is not affected by maturation.

Short-term plyometric training improves running economy in highly trained middle and long distance runners.

Fifteen highly trained distance runners VO(2)max 71.1 +/- 6.0 ml.min(-1).kg(-1), mean +/- SD) were randomly assigned to a plyometric training (PLY; n = 7) or control (CON; n = 8) group. In addition to their normal training, the PLY group undertook 3 x 30 minutes PLY sessions per week for 9 weeks. Running economy (RE) was assessed during 3 x 4 minute treadmill runs (14, 16, and 18 km.h(-1)), followed by an incremental test to measure VO(2)max. Muscle power characteristics were assessed on a portable, unidirectional ground reaction force plate. Compared with CON, PLY improved RE at 18 km.h(-1) (4.1%, p = 0.02), but not at 14 or 16 km.h(-1). This was accompanied by trends for increased average power during a 5-jump plyometric test (15%, p = 0.11), a shorter time to reach maximal dynamic strength during a strength quality assessment test (14%, p = 0.09), and a lower VO(2)-speed slope (14%, p = 0.12) after 9 weeks of PLY. There were no significant differences in cardiorespiratory measures or VO(2)max as a result of PLY. In a group of highly-trained distance runners, 9 weeks of PLY improved RE, with likely mechanisms residing in the muscle, or alternatively by improving running mechanics.