Resynthesis of muscle glycogen after soccer specific performance examined by C-13-magnetic resonance spectroscopy in elite players

The purpose of this study was to examine using C-13-magnetic resonance spec troscopy whether muscle glycogen (Gly) utilized during a simulation of a fa tiguing soccer match followed by repeated sprints would be resynthesized du ring the next 24 h while players consumed their habitual diet. A group of 1 2 elite young players [mean age 17.5 (SD 0.8) years, mean body mass 68.9 (S D 6.6) kg, mean height 177.0 (SD 5.4) cm] participated in the study. Averag e muscle Gly content before the simulation was 134 (SD 16) mmol(.)(kg wet m ass)(-1) and decreased during the test (P < 0.001) to 80 (SD 29) mmol(.)(kg wet mass)(-1). The value had increased (P < 0.01) to 122 (SD 33) mmol(.)(k g wet mass)(-1) 24 h later but it was not significantly different from the value obtained before the soccer test. Dietary analysis of the food intake during the 24 h after the running test revealed that players consumed an av erage of 2,681 (SD 970) kcal(.)day(-1). Mean daily protein, fat, and carboh ydrate (CHO) intakes were 85 (SD 29), 99 (SD 44), and 327 (SD 116) g, respe ctively. The mean amounts of CHO intake normalised to body mass were 4.8 (S D 1.8) g(.)(kg body mass)(-1). In conclusion, the results of this study sho wed that despite a CHO intake of less than 5 g(.)(kg body mass)(-1) the hab itual diet of soccer players might be sufficient to replenish in 24 h the m uscle Gly utilized during soccer specific performance. However, cumulative deficits of about 10% in Gly replenishment as found in the present study mi ght provoke decrements in performance. Thus, players should pay attention t o their habitual diets and add more carbohydrates to replenish their daily deficits and perhaps increase their basal levels of intake.