Application of Molecular Hydrogen as an Antioxidant in Responses to Ventilatory and Ergogenic Adjustments during Incremental Exercise in Humans

We investigated effects of molecular hydrogen (H(2)) supplementation on acid-base status, pulmonary gas exchange responses, and local muscle oxygenation during incremental exercise. Eighteen healthy, trained subjects in a randomized, double-blind, crossover design received H(2)-rich calcium powder (HCP) (1500 mg/day, containing 2.544 µg/day of H(2)) or H(2)-depleted placebo (1500 mg/day) for three consecutive days. They performed cycling incremental exercise starting at 20-watt work rate, increasing by 20 watts/2 min until exhaustion. Breath-by-breath pulmonary ventilation ([Formula: see text] (E)) and CO(2) output ([Formula: see text] CO(2)) were measured and muscle deoxygenation (deoxy[Hb + Mb]) was determined via time-resolved near-infrared spectroscopy in the vastus lateralis (VL) and rectus femoris (RF). Blood gases’ pH, lactate, and bicarbonate (HCO(3)(−)) concentrations were measured at rest and 120-, 200-, and 240-watt work rates. At rest, the HCP group had significantly lower [Formula: see text] (E), [Formula: see text] CO(2), and higher HCO(3)(−), partial pressures of CO(2) (PCO(2)) versus placebo. During exercise, a significant pH decrease and greater HCO(3)(−) continued until 240-watt workload in HCP. The [Formula: see text] (E) was significantly lower in HCP versus placebo, but HCP did not affect the gas exchange status of [Formula: see text] CO(2) or oxygen uptake ([Formula: see text] O(2)). HCP increased absolute values of deoxy[Hb + Mb] at the RF but not VL. Thus, HCP-induced hypoventilation would lead to lower pH and secondarily impaired balance between O(2) delivery and utilization in the local RF during exercise, suggesting that HCP supplementation, which increases the at-rest antioxidant potential, affects the lower ventilation and pH status during incremental exercise. HPC induced a significantly lower O(2) delivery/utilization ratio in the RF but not the VL, which may be because these regions possess inherently different vascular/metabolic control properties, perhaps related to fiber-type composition.