The effects of oral glutamine supplementation on athletes after prolonged, exhaustive exercise.
Level 3 - non-randomized controlled study
Controlled trial comparing glutamine to placebo without explicit mention of randomization in the abstract.
PubMed 9263279 · doi:10.1016/s0899-9007(97)83036-5
What was done
The researchers examined the effects of oral glutamine supplementation compared with placebo in sedentary controls at rest and in athletes (middle-distance, marathon, and ultra-marathon runners, and elite rowers) during training and competition. Outcomes measured included plasma glutamine levels, white blood cell and lymphocyte counts, and T-helper/T-suppressor cell ratios before and after exhaustive exercise. Incidence of infection was monitored via questionnaires for 7 days post-exercise.
What was found
Plasma glutamine concentrations dropped by approximately 20% 1 hour after marathon running. Exhaustive exercise caused an immediate rise in total white blood cells followed by a decline in lymphocyte counts. Infection rates were highest among marathoners, ultra-marathoners, and elite rowers after intensive training. Post-exercise oral glutamine appeared to reduce subsequent infection incidence and increase the T-helper/T-suppressor cell ratio relative to placebo; exact numerical values, effect sizes, and p-values for these clinical differences were not reported in the abstract.
Why it matters
This study provides foundational evidence suggesting that post-exercise glutamine depletion may play a role in exercise-induced immunosuppression and that glutamine supplementation might mitigate transient infection risk.
Limits
The abstract omits the sample size, glutamine dosing regimen, participant demographics, and statistical significance values. Randomization and blinding procedures are not described, and infection outcomes were self-reported via questionnaires rather than verified by clinical or laboratory testing.
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- supports Glutamine supplementation reduces the incidence of respiratory illness in endurance athletes.