Endurance exercise increases skeletal muscle kynurenine aminotransferases and plasma kynurenic acid in humans.
Level 3 - non-randomized controlled study
Non-randomized comparative trial evaluating trained vs. untrained individuals alongside acute exercise challenges
PubMed 27030575 · doi:10.1152/ajpcell.00053.2016
What was done
Investigated the effect of exercise and training status on kynurenine pathway metabolism in humans. Skeletal muscle kynurenine aminotransferase (KAT) gene and protein expression were compared between endurance-trained and untrained individuals. In addition, plasma kynurenic acid (KYNA) responses were measured following a bout of endurance exercise and compared to responses following a bout of high-intensity eccentric exercise.
What was found
No quantitative values, effect sizes, or statistics were reported in the abstract. Directionally, muscle KAT gene and protein expression were increased in endurance-trained subjects compared with untrained subjects. Acute endurance exercise led to an increase in plasma KYNA within the first hour post-exercise, whereas acute high-intensity eccentric exercise did not increase plasma KYNA concentration.
Why it matters
This confirms in humans animal model findings that endurance exercise upregulates the KAT pathway and elevates kynurenic acid, offering a plausible biochemical mechanism for the antidepressant effects of aerobic exercise.
Limits
The abstract does not disclose sample sizes, participant demographics (such as age or sex), or precise exercise protocols. No numerical data or confidence intervals are provided. Comparisons between trained and untrained individuals are observational/cross-sectional, and the study evaluated biochemical markers rather than clinical depression outcomes.
Cited by
- supports Skeletal muscle acts as a sink to absorb and clear circulating compounds harmful to the brain, thereby protecting mental health and reducing the risk of neurodegenerative diseases.
- supports Exercise increases the muscle enzyme kynurenine aminotransferase, which converts kynurenine into kynurenic acid and prevents its accumulation as neurotoxic quinolinic acid.