Acute Effect of Ischemic Preconditioning on VO 2 max and VO 2 Kinetics at Supramaximal Intensity in High‐Level Runners: A Randomized Placebo‐ and Nocebo‐Controlled Study

Background Ischemic preconditioning (IPC; brief cycles of ischemia) has been reported to acutely improve aerobic capacity and performance in recreational athletes. However, placebo and nocebo effects have not been adequately controlled, strict criteria to confirm the maximal oxygen uptake (V̇O 2 max) have not been used and high‐level aerobic athletes have not been assessed. Therefore, we controlled placebo and nocebo effects to investigate if IPC improves aerobic capacity and performance in high‐level runners. Methods Fifteen men (age = 22 ± 3 years; V̇O 2 max = 67.7 ± 4.9 mL/kg/min; mean ± SD) and four women (age = 24 ± 4 years; V̇O 2 max = 55.8 ± 4.1 mL/kg/min) were assessed. All have been training in running teams (5 ± 2 years) and participating in official competitive events. Three interventions were used, in random order [IPC; placebo ultrasound (PL); and resting control (CT)]. A standardized explanation was provided, before interventions were applied, to inform that both IPC and PL would improve performance compared to CT and that IPC and PL would not cause any harm. After each intervention, a maximal incremental test (MIT) was conducted to measure the V̇O 2 max. Ten minutes later, a supramaximal (peak velocity + 0.5 km/h) constant test was done until voluntary exhaustion. This test was used to verify the V̇O 2 max, measure the time sustained at V̇O 2 max and assess aerobic performance [time to exhaustion (TLim)]. Verbal incentive was given by a blinded investigator. Interventions were compared by repeated measures ANOVA, followed by Bonferroni's post hoc, when necessary. Results V̇O 2 max (65.5 ± 6.6, 65.4 ± 7.2, and 64.8 ± 5.8 mL/kg/min for IPC, PL, and CT, respectively; P = 0.52), time at V̇O 2 max(49 ± 35, 54 ± 45, and 37 ± 24 s; P = 0.36), and V̇O 2 kinetics (tau: 29 ± 4, 30 ± 4, and 28 ± 4 s; P = 0.84) were similar among interventions. TLim was longer in IPC (166 ± 13 s) and PL (165 ± 13 s) than CT (143 ± 13 s, P < 0.05). However, TLim was similar between IPC and PL ( P > 0.05). Conclusions IPC improved aerobic performance compared to CT in high‐level runners, but the improvement was not superior to PL. Moreover, V̇O 2 max, evaluated by strict criteria, time at V̇O 2 max, and V̇O 2 kinetics at supramaximal intensity were unchanged by IPC. Support or Funding Information J.L.C.S. and T.O. have been supported by scholarships from FAPESP (2014/15877‐8 and 2015/03572‐0, respectively). The project was funded by FAPESP (2014/25683‐6) and CNPq (461516/2014‐4).