Ischemic Preconditioning Attenuates the Decline in Repeated Anaerobic Performance Under Simulated Altitude: A Randomized Crossover Study.

Background: This study examined the effects of repeated ischemic preconditioning (IPC) combined with normobaric hypoxia on anaerobic performance and physiological stress markers.

Methods: Fourteen physically active males (22.3 ± 3.1 years) completed three randomized, single-blind crossover sessions under the following conditions: (1) normoxia (NOR), (2) normobaric hypoxia (HYP; FiO₂ = 14.7%), and (3) hypoxia with IPC (IPC-HYP). Each session included three 30 s cycling Wingate tests separated by four minutes of passive recovery. Blood samples were collected pre-exercise, immediately post-exercise, and 15 min post-exercise to assess lactate, pH, bicarbonate (HCO₃^-), and creatine kinase (CK) activity.

Results: Peak power output was highest under NOR during Wingate II and III. IPC-HYP attenuated the decline in peak power compared to that under HYP (e.g., Wingate II: 15.56 vs. 12.52 W/kg). IPC-HYP induced greater lactate accumulation (peak: 15.45 mmol/L, p < 0.01), more pronounced acidosis (pH: 7.18 post-exercise), and lower bicarbonate (9.9 mmol/L, p < 0.01). CK activity, measured immediately and then 1 h and 24 h post-exercise, was highest under IPC-HYP at 24 h (568.5 U/L).

Conclusions: IPC-HYP mitigates the decline in peak anaerobic power observed under hypoxia, despite eliciting greater metabolic and muscular stress. These findings suggest that IPC may enhance physiological adaptation to hypoxic training, potentially improving anaerobic performance.