A comparison of plasma glutamine concentration in athletes from different sports

Purposes: The purposes of the current investigation were to compare resting plasma glutamine concentration in athletes from different sports and to de termine the relationship between resting plasma glutamine concentration and dietary protein intake. Methods: Resting plasma glutamine concentration wa s measured in five groups of eight distance runners, competitive swimmers, cyclists, powerlifters, and nonathletes. Dietary protein intake of each sub ject was measured (g.d(-1) and g.kg(-1).d(-1)). Results: Plasma glutamine c oncentration was significantly different between sports (P = 0.000, ANOVA) with mean plasma glutamine concentration of cyclists significantly higher t han in all other groups, and mean plasma glutamine concentration of powerli fters and swimmers significantly lower than in cyclists and nonathletes (P < 0.05, post hoc analysis). There was no significant relationship between p lasma glutamine concentration and total dietary protein intake when express ed as g.d(-1) (r = 0.11, P < 0.05); however, plasma glutamine concentration and dietary protein relative to body mass (g.kg(-1).d(-1)) were significan tly inversely correlated (r = -0.37, P = 0.007). Conclusions: These data su ggest that resting plasma glutamine concentration may vary between sports, possibly due to metabolic demands of the different sports; dietary factors may also affect plasma glutamine concentration.