No effect of glutamine supplementation and hyperoxia on oxidative metabolism and performance during high-intensity exercise

Abstract

Glutamine enhances the exercise-induced expansion of the tricarboxylic acid intermediate pool. The aim of the present study was to determine whether oral glutamine, alone or in combination with hyperoxia, influenced oxidative metabolism and cycle time-trial performance. 8 participants consumed either placebo or 0.125g.kg body mass -1 of glutamine in 5 ml.kg body mass -1 placebo 1 h prior to exercise in normoxic (control & glutamine respectively) or hyperoxic (FiO 2 =50%;hyperoxia & hyperoxia and glutamine respectively) conditions. Participants then cycled for 6 min at 70% 2 o V  max immediately before completing a brief high intensity time-trial (~ 4min) where a pre-determined volume of work was completed as fast as possible. The increment in pulmonary oxygen uptake during the performance test ( 2 o V  , p=0.02) and exercise performance {243  7 (control) vs 242  3 (glutamine) vs 231  3 (hyperoxia) vs 228  5 (hyperoxia and glutamine) s, p<0.01} were significantly improved in hyperoxic conditions. There was some evidence that glutamine ingestion increased  2 o V  in normoxia, but not hyperoxia (interaction drink/FiO 2 , p=0.04) however there was no main effect or impact on performance. Overall the present data show no effect of glutamine ingestion either alone or in combination with hyperoxia, and thus no limiting effect of the tricarboxylic acid intermediate pool size, on oxidative metabolism and performance during maximal exercise.

Effect of Hyperoxia on Critical Power and V˙O2 Kinetics during Upright Cycling

“…exercise and provides further evidence to the growing body of literature demonstrating that CP is an important parameter of aerobic function(6,10,16,20,25). In the present study, end-tidal PO 2 (and, therefore, alveolar PO 2 ) was enhanced in hyperoxia at baseline and end-exercise when O2 during either moderate or severe upright cycle exercise is consonant with previous reports(13,14,28), and bolsters the notion that O 2 availability is generally not the crucial ratelimiting step for oxidative metabolism in physically active, young individuals undertaking upright exercise(29). Hence the present data suggests that the differences in CP observed between conditions are instead likely attributable to the increased microvascular oxygenation observed in the hyperoxic condition.…”

“…As such, improved high-intensity exercise performance (12,13) has been reported during hyperoxia. However, hyperoxia does not appear to speed the pulmonary O 2 kinetics during upright cycling (13)(14)(15), which is seemingly inconsistent with the putative linkage between ! O2 and CP previously described (6)(7)(8)(9).…”

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

“…In the present study, glutamine ingestion was therefore used as a means by which to mitigate a chronically low muscle glutamate concentration, and thus enhance the exercise-induced increase in the TCAi pool, in an attempt to reduce some of the significant metabolic inertia which exists in COPD. However as previously demonstrated in healthy subjects (Bruce et al, 2001;Marwood and Bowtell, 2007;Marwood and Bowtell, 2008), in the present study glutamine ingestion had no effect on the measured indices of oxidative metabolism suggesting either that glutamine ingestion did not impact upon TCA cycle anaplerosis or that the normal rate and magnitude of the increase of the TCAi during exercise is not limiting to oxidative metabolism in COPD.…”

Guidelines to Classify Subject Groups in Sport-Science Research

“…Relative and absolute VO 2max were cited in 60.8% and 32.3% of the collected articles, respectively. Significant differences were clearly shown between performance * References 19,24,25,34,52,53,83,84,86,103,108,113. †References 10,18,20,27,32,33,41,62,76,79,81,115 Figure 2). The PPO, sometimes called maximum work rate, is obtained by measuring the highest, fully completed stage during an incremental maximal test.…”