No effect of glutamine ingestion on indices of oxidative metabolism in stable COPD

COPD patients have reduced muscle glutamate which may contribute to an impaired response of oxidative metabolism to exercise. We hypothesised that prior glutamine supplementation would enhance V˙O2 peak, V˙O2 at lactate threshold and speed pulmonary oxygen uptake kinetics in COPD. 13 patients (9 males, age 66 ± 5 years, mean ± SD) with severe COPD (mean FEV1 0.88 ± 0.23 l, 33 ± 7% predicted) performed on separate days ramp cycle-ergometry (5-10 W min−1) to volitional exhaustion and subsequently square-wave transitions to 80% estimated lactate threshold (LT) following consumption of either placebo (CON) or 0.125 g kg bm−1 of glutamine (GLN) in 5 ml kg bm−1 placebo. Oral glutamine had no effect on peak or V˙O2 at LT, {V˙O2 peak: CON = 0.70 ± 0.1 l min−1 vs. GLN = 0.73 ± 0.2 l min−1; LT: CON = 0.57 ± 0.1 l min−1 vs. GLN = 0.54 ± 0.1 l min−1} or V˙O2 kinetics {tau: CON = 68 ± 22 s vs. GLN = 68 ± 16 s}. Ingestion of glutamine before exercise did not improve indices of oxidative metabolism in this patient group.