Post-Exercise Kinetics of Breath Hydrogen: observational before-and-after pilot study

Molecular hydrogen (H₂) exerts pleiotropic bioactive effects via redox modulation, cell signaling, and anti-inflammatory pathways, enhancing cellular adaptability through hormetic mechanisms. Although increasingly studied, its dynamic behavior in response to acute physiological stressors remains insufficiently characterized. This pilot study investigated post-exercise breath H₂ kinetics as a potential non-invasive proxy for metabolic and redox shifts during recovery. Thirty healthy adults (mean age: 23.5 ± 3.8 years) completed an incremental treadmill test to voluntary exhaustion. Breath H₂ concentrations, assessed via electrochemical fuel cell analysis, declined sharply at 5 minutes post-exercise (36.37 ± 32.12 to 16.20 ± 16.22 ppm; Z = -4.352, p < 0.001), followed by partial recovery at 15 minutes (28.47 ± 33.76 ppm; p = 0.003) and near-baseline levels at 30 minutes (30.10 ± 37.20 ppm; p = 0.027). A secondary decrease emerged at 60 minutes (29.23 ± 36.55 ppm; p = 0.01). These temporal dynamics implicate breath H₂ as a sensitive marker of exercise-induced redox perturbations and microbial-host metabolic interplay.