Muscle and Blood Metabolites during a Soccer Game

Abstract
Sies were taken before and after the game as well as immediately after an intense period in each half. The players performed five 30-m sprints interspersed by 25-s recovery periods before the game and immediately after each half (N = 11) or after an intense exercise period in each half (N = 20). Results: Muscle lactate was 15.9 ± 1.9 and 16.9 ± 2.3 mmol·kg−1 d.w. during the first and second halves, respectively, with blood lactate being 6.0 ± 0.4 and 5.0 ± 0.4 mM, respectively. Muscle lactate was not correlated with blood lactate (r2 = 0.06-0.25, P >0.05). Muscle glycogen decreased (P < 0.05) from 449 ± 23 to 255 ± 22 mmol·kg−1 d.w. during the game, with 47 ± 7% of the muscle fibers being completely or almost empty of glycogen after the game. Blood glucose remained elevated during the game, whereas plasma FFA increased (P < 0.05) from 0.45 ± 0.05 to 1.37 ± 0.23 mM. Mean sprint time was unaltered after the first half, but longer (P < 0.05) after the game (2.8 ± 0.7%) as well as after intense periods in the first (1.6 ± 0.6%) and second halves (3.6 ± 0.5%). The decline in sprint performance during the game was not correlated with muscle lactate, muscle pH, or total glycogen content. Conclusion: Sprint performance is reduced both temporarily during a game and at the end of a soccer game. The latter finding may be explained by low glycogen levels in individual muscle fibers. Blood lactate is a poor indicator of muscle lactate during soccer match play....