Effect of hypoxic conditioning on exercise tolerance in post-stroke rehabilitation

Background. Stroke (15 million new cases annually, 5 million deaths) leaves most survivors with a persistent decline in exercise tolerance (ET) — the principal determinant of disability and poor quality of life. Standard rehabilitation in the chronic phase (≥6 months) only partially restores ET. Intermittent hypoxic — hyperoxic exposure (IHHE) cyclically activates HIF-1α/Nrf2 signalling pathways, stimulating angiogenesis, erythropoiesis, antioxidant defence, and neuroplasticity; however, its impact on physical endurance in post-stroke patients remains virtually unexplored. The aim of the study To evaluate the effect of a course of hypoxic conditioning on exercise tolerance in patients in the chronic period after stroke (≥6 months). Materials and Methods. A randomised controlled trial involving 23 patients (63.2±12.1 years). The main group (n=11) received IHHE (ReOxy®: FiO₂ 0.11–0.12 / 0.35–0.40, 4–6 cycles, 35–45 min, 3–4 times/week) in addition to standard rehabilitation; the control group (n=12) received standard rehabilitation alone. ET was assessed using the 6‑minute walk test (6MWT), external work performed (W), and the Borg scale. Statistics: Bonferroni correction (α=0.0167). Results. The increase in 6MWT distance in the main group was 78.8±28.5 m versus 21.6±19.4 m in the control group (p=0.008; threefold superiority); external work increased by +7.7±4.2 kJ versus +1.9±3.1 kJ, respectively (p=0.01). A clinically meaningful improvement (≥40 m) was achieved by 63.6 % of patients in the main group and only 25 % in the control group. The difference on the Borg scale was not significant (p=0.04). Conclusion. Adding IHHE to standard rehabilitation results in a pronounced and statistically significant increase in objective measures of ET in patients with chronic stroke sequelae, with good tolerability. The findings support the rationale for large-scale placebo-controlled RCTs to personalise protocols and evaluate long-term improvement in quality of life.