Effects of ischemic preconditioning on economy, VO2 kinetics and cycling performance in endurance athletes.

Abstract

The aim of this study was to determine the effect of ischemic preconditioning (IPC) on several measures of aerobic function and 4-km cycling time-trial performance. An acute cross-over design was adopted involving eight well-trained cyclists (age 27.0 ± 7.0years) who completed incremental and square-wave exercise tests for determination of peak O2 uptake (VO2peak), ventilatory threshold (VT) and moderate- and heavy-intensity domain VO2 kinetics, as well as 4-km time trials. All were preceded by IPC, or sham-IPC, involving repeated bouts of thigh blood flow occlusion, interspersed with reperfusion. There was no significant difference between IPC and sham-IPC with respect to VO2peak (4.4 ± 0.6Lmin-1 vs 4.4 ± 0.5Lmin-1, effect size - 0.01 ± 0.09), VT (3.4 ± 0.6Lmin-1 vs 3.5 ± 0.5Lmin-1, effect size 0.07 ± 0.28), cycling economy (4.9 ± 4.9%, ES 0.24 ± - 0.24, P > 0.05) or any moderate-domain VO2 kinetic parameter. During heavy-intensity exercise, a reduced end-exercise VO2, slow component amplitude and overall gain was observed following IPC compared to sham-IPC. Though not statistically significant, there was a possibly beneficial effect of IPC on 4-km time-trial mean power output (2.2 ± 2.0%; effect size: 0.18 ± 0.15, P > 0.05). The observed reduction in VO2 slow component and tendency for improved economy and 4-km time-trial performance, albeit small, suggests that acute IPC shows some potential as a performance-enhancing priming strategy for well-trained cyclists prior to high-intensity exercise.