The purpose of this investigation was to caracterize the relationship between the level of physical fitness, performance and metabolic needs in soccer players during a real match-play. Six professional soccer players aged 20.8 ± 2.6 years old (17-25), weight 70.4 ± 7.5 kg (63-81.3) and height 173.3 ± 9.7 cm (166-188) were submitted to a fitness test which was performed in the soccer field. The players were assessed by a video-camera, in the field, during the match-play with lactate evaluation. The alactic metabolic pathway was evaluated by means of five 30 m sprints, in maximum velocity and one minute of passive pause between each sprint. The lactic acid concentrations were assessed at one, three and five minutes after the five sprints had been finished. To detect anaerobic threshold (AT), three 1,200 m races were performed at an intensity of 80, 85 and 90% from de maximum speed to that distance, with 5 minutes intervals between each running. The soccer players underwent individual film recording by a video-camera, during the match-play and the lactic acid concentrations were assessed before, during the interval and at the end of the match, to analyze the metabolic and energetics expenditure. The following results were verified: 1) the AT at running, relationed to 4 mmol.L_1 lactic acid concentration, was found at 268 ± 28 m.min_1 or 16.1 ± 1.6 km.h_1; 2) the average speed and the maximum lactate concentration at 30m sprint were 6.9 ± 0.2 to 4.5 ± 1.0 mmol.L_1, respectively; 3) the total performed distance was 10,392 ± 849 m, 5,446 ± 550 m was found in the first half of the match and 4,945 ± 366 m was found in the second half of the match; 4) the average values found in assessing blood lactate concentrations were 1.58 ± 0.37; 4.5 ± 0.42 and 3.46 ± 1.54 mmol.L_1; before, during the first to the second interval and at the end of the match, respectively; 5) the total average distance approached at the end of the matches by midfield players (10,910 ± 121 m) was slightly greater than the one reached by the forward players (10,377 ± 224 m) and defenders (9,889 ± 102 m), nevertheless, it was not significant. There was a negative correlation (r =- 0.84; p < 0.05) among the AT (268 ± 28 m.min_1 or 16.1 ± 1.6 km.h_1) and blood lactate concentration (4.5 ± 0.42 mmol.L_1) in the first half of the match-play. Thus, the results suggest that the aerobic capacity is an important determinant, which leads the soccer players to cover the long distance runnings in the matches, and be able to recover earlier from the high intensity effort with a lower development of blood lactic acid concentrations in the whole match-play.
Professional soccer players; Lactate; Anaerobic threshold; Covered distance; Sports medicine
