Active Relative to Passive Ischemic Preconditioning Enhances Intense Endurance Performance in Well-Trained Men

Purpose : This study tested the hypothesis of whether ischemic exercise preconditioning (IPC-Ex) elicits a better intense endurance exercise performance than traditional ischemic preconditioning at rest (IPC-rest) and a SHAM procedure. Methods : Twelve men (average ∼61 mL·kg −1 ·min −1 ) performed 3 trials on separate days, each consisting of either IPC-Ex (3 × 2-min cycling at ∼40 W with a bilateral-leg cuff pressure of ∼180 mm Hg), IPC-rest (4 × 5-min supine rest at 220 mm Hg), or SHAM (4 × 5-min supine rest at <10 mm Hg) followed by a standardized warm-up and a 4-minute maximal cycling performance test. Power output, blood lactate, potassium, pH, rating of perceived exertion, oxygen uptake, and gross efficiency were assessed. Results : Mean power during the performance test was higher in IPC-Ex versus IPC-rest (+4%; P = .002; 95% CI, +5 to 18 W). No difference was found between IPC-rest and SHAM (−2%; P = .10; 95% CI, −12 to 1 W) or between IPC-Ex and SHAM (+2%; P = .09; 95% CI, −1 to 13 W). The rating of perceived exertion increased following the IPC-procedure in IPC-Ex versus IPC-rest and SHAM ( P < .001). During warm-up, IPC-Ex elevated blood pH versus IPC-rest and SHAM ( P ≤ .027), with no trial differences for blood potassium ( P > .09) or cycling efficiency ( P ≥ .24). Eight subjects anticipated IPC-Ex to be best for their performance. Four subjects favored SHAM. Conclusions : Performance in a 4-minute maximal test was better following IPC-Ex than IPC-rest and tended to be better than SHAM. The IPC procedures did not affect blood potassium, while pH was transiently elevated only by IPC-Ex. The performance-enhancing effect of IPC-Ex versus IPC-rest may be attributed to a placebo effect, improved pH regulation, and/or a change in the perception of effort.