Attenuation of exertional muscle damage with a nutritional supplement.

摘要

The purpose of this study was to determine the effects of glutamine added to a beverage containing carbohydrate (CHO) and essential amino acid (EAA) mixture during and after strenuous exercise on markers of exertional muscle damage (EMD) and performance in subjects after a strenuous physical training event. We used an in-vivo and in-vitro experimental approach.; Thirty-three subjects completed the blinded-crossover portion of this research. Subjects were randomized to ingest either a placebo or treatment beverage during and after two identical events (modified physical fitness test), with the alternate beverage provided at the second event. Beverages were matched for CHO and EAA content, the only difference being addition of glutamine to the treatment beverage.; There were no significant differences (p > 0.05) between beverages with respect to changes in biomarkers of muscle damage or inflammation, as measured at baseline and after exercise with respect to changes in creatine kinase, lactate dehydrogenase, CRP, white blood cell counts, and select pro- and anti-inflammatory cytokines. There was a trend in improved performance as measured by number of stairs-stepped after exercise, treatment compared to placebo (p = 0.13), but no difference between beverages for pain scores.; In the in-vitro experiment, macrophages were stimulated by exposure to hypoxia to mimic exercise stress. Cells were divided into control and 2 levels of glutamine supplementation, low = 1.0 mM, high = 2.0 mM. Glutamine increased production of TNF-alpha by macrophages exposed to hypoxia in a dose-dependent manner. Glutamine had little effect on production of the anti-inflammatory cytokine IL-10.; Our findings suggest that the addition of glutamine to a CHO/EAA beverage provided during exercise doesn't provide significant additional benefit over a CHO/EAA beverage alone in attenuating EMD or improving physical performance. As supported by our in-vitro study, these preliminary findings imply glutamine may enhance the inflammatory response, which may allow cells to better combat tissue damage. The trend in improved physical performance suggests that glutamine may also affect some aspect of protein synthesis during exercise or recovery, thus allowing subjects to better perform physical tasks.