Ischemic preconditioning does not improve peak exercise capacity at sea level or simulated high altitude in trained male cyclists

Ischemic preconditioning (IPC) may improve blood flow and oxygen delivery to tissues, including skeletal muscle, and has the potential to improve intense aerobic exercise performance, especially that which results in arterial hypoxemia. The aim of the study was to determine the effects of IPC of the legs on peak exercise capacity (W-peak), submaximal and peak cardiovascular hemodynamics, and peripheral capillary oxygen saturation (SpO(2)) in trained males at sea level (SL) and simulated high altitude (HA; 13.3% FIO2, similar to 3650 m). Fifteen highly trained male cyclists and triathletes completed 2 W-peak tests (SL and HA) and 4 experimental exercise trials (10 min at 55% altitude-specific W-peak then increasing by 30 W every 2 min until exhaustion) with and without IPC. HA resulted in significant arterial hypoxemia during exercise compared with SL (73% +/- 6% vs. 93% +/- 4% SpO(2), p < 0.001) that was associated with 21% lower W-peak values. IPC did not significantly improve W-peak at SL or HA. Additionally, IPC failed to improve cardiovascular hemodynamics or SpO(2) during submaximal exercise or at W-peak. In conclusion, IPC performed 45 min prior to exercise does not improve W-peak or systemic oxygen delivery during submaximal or peak exercise at SL or HA. Future studies must examine the influence of IPC on local factors, such as working limb blood flow, oxygen delivery, and arteriovenous oxygen difference as well as whether the effectiveness of IPC is altered by the volume of muscle made ischemic, the timing prior to exercise, and high altitude acclimatization.